Correlations among South African indigenous ram-lambs’ physiological age and various mating behaviours at puberty

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One of these traits is the animal’s physiological age, which is correlated with, but not causal to its chronological age, and affects the animal’s age at attainment of puberty - an important management parameter and indicator of environmental adaptation. This study aimed to characterise the mating behaviours of pubertal ram-lambs of three of South Africa’s oldest indigenous sheep breeds, Bapedi (BP), Namaqua-Afrikaner (NM) and Zulu (ZL), which are landraces to areas of South Africa with different microclimates. Sampling included visual assessment of various mating behaviours (e.g., nosing, mounting) and measurement of bodyweight, scrotal circumference, and blood serum testosterone concentrations. The study found that NM ram-lambs were physiologically younger than BP and ZL ram-lambs at a similar chronological age, as bodyweights and blood serum testosterone concentrations between-breeds were similar (P > 0.05) but significant between-breed differences of scrotal circumferences were found (P < 0.05) at most ages, wherein NM ram-lambs had lower mean scrotal circumferences, had the lowest cumulative observations of all appraised mating behaviours; and began displaying their first mating behaviour (nosing) one month later than BP and ZL ram-lambs did. Thus, NM ram-lambs displayed younger physiological age, likely as an adaptation to the hotter and drier microenvironment to which they are indigenous. It is recommended that such breeds be profiled and used in mixed-breeding programs, as their adaptation to harsher environments will be invaluable as climate change’s impacts become more apparent in sub-Saharan Africa. Puberty indigenous sheep ram lamb mating behaviour Introduction In various emerging economies, it is particularly important to have livestock production that is commercially efficient but also sustainable, as it aids in alleviating poverty and increasing household food security (Webb et al., 2018 ). This sustainable model can be achieved through livestock reproductive management that ensures the proliferation and propagation of certain species and breeds, like the multi-purpose sheep: The sheep is one of the earliest species to be domesticated by humans (Ryder & Bridbury, 1984 ) and continues to be prized for its multi-purposefulness as it produces wool, meat, and milk. Contextually, animals that are ‘indigenous’ to an area, are more likely to be robust in that area, compared to foreign breeds, due to their adaptation to the specific pressures of the region. Three of South Africa’s oldest indigenous sheep breeds are the Bapedi (BP), Namaqua-Afrikaner (NM) and Zulu (ZL) sheep, which are lauded as hardy, disease resistant and robust (Maqhashu et al., 2019 ). ‘Robustness’ is the persistence of a phenotype during long-term stressors (Colditz & Hine, 2016 ). Thus, considering its environment’s stress, an animal must maintain traits that are beneficial to its survival, and subsequent propagation, so that those genotypes that express the optimal phenotype most reliably will be selectively favoured, particularly when faced with stressors. Considering the increasing impact of climate change, such as a minimum rise in temperature by 4°C that will have disastrous effects on many farmers’ livelihoods in Africa (Pickson & Boateng, 2022 ), it is important that governmental policy and academic research intensify their efforts towards sustainable and efficient livestock production. Breeds that are indigenous to South Africa having reduced economically-relevant growth parameters, such as average daily gain and milk yield, compared to exotic breeds, are too much of a disadvantage for the majority of animal product producers (Moulla et al., 2018 ). For example, the Bonsmara is a composite South African breed, composed of the Afrikaner, Shorthorn and Hereford breeds - two out of three which are exotic breeds. The Bonsmara capitalises on hybrid vigour and competes with the production ranges of exotic breeds, while being less prone to heat-stress and parasite-load that are characteristic of South Africa, in the way that its exotic composite lines are (SA Stud Breeder, 2015 ; Webb et al., 2017 ). Additionally, another parameter that is crucial for the efficiency of livestock production is an animal’s physiological age as this determines the animal’s ratio of fat to muscle to bone, which changes as the animal ages and thus influences puberty attainment and its associated mating behaviours, age at slaughter and meat composition (Kennedy & Mitra, 1963 ). Considering the above, this study sought to visually assess the mating behaviours of pubertal ram-lambs of three indigenous South African sheep breeds, the BP, NM and ZL, and use bodyweights, scrotal circumference (SC) and blood serum testosterone concentration (BST) measurements to correlate these mating behaviours with physiological or chronological age. The study’s null hypotheses were: A: H 0 = As they age, ram lambs will display no mating behaviour. B: H 0 = As they age, ram lambs will have static SC, bodyweight measurements and BST. C: H 0 = There will not exist a correlation between BST, bodyweight and SC. Sheep in sub-Saharan Africa In the Southern African Development Community (SADC), indigenous sheep play an integral role in the income and sustenance of smallholder farmers and livestock keepers (Molotsi et al., 2019 ). This is partially due to the arid/semi-arid environment of sub-Saharan Africa, to which sheep are adapted. Indigenous breeds like the BP, NM and ZL, are particularly suited to South African environmental conditions due to their indigenousness and continued adaptation. Despite their adaptation, however, indigenous breeds are continuously being replaced by foreign breeds like the Merino due to foreign breeds’ superior production (Snyman & Hersleman, 2005 ). This problem is exacerbated by there being no or slow genetic progress for the indigenous genetic resources used by livestock keepers and small holder farmers (Molotsi et al., 2019 ). Smallholder farmers are those farmers that depend solely on familial labour; those that own small plots of land where they grow subsistence crops; and those that farm one or two ‘cash crops’ - crops that are used less by the farmer and more for their commercial value (Department of Agriculture, Forestry and Fisheries, 2019 ). Small stock plays a foundational role in the economic security and food security of millions in sub-Saharan Africa, with small scale and communal farmers owning 12% of sheep (Meissner & Engelbrecht, 2014 ). Indigenous breeds are important and their genetic erosion is problematic because of the loss of their adaptability (Molotsi et al., 2019 ): When indiscriminately cross-bred with exotic/foreign breeds and not maintained as pure breeds, the loss of genetic diversity occurs. This is important particularly with regards to indigenous South African breeds because they are adapted to the environment. With climate change an ever-growing concern in sub-Saharan Africa, it is thus important to maintain breeds that are adapted. For example, higher temperatures may have led to a decrease in tsetse flies that cause trypanosomiasis in Zimbabwe’s Zambezi valley, these flies have now migrated to cooler regions (Lord et al., 2018 ). In addition, another effect that the loss of indigenous animals has is on the remaining animals: They are not adapted to heat and heat stress, which negatively affects their homeostatic mechanisms and subsequently affects growth, performance and reproduction (Marai et al., 2007 ). South Africa houses 46 of the 109 different sheep breeds in sub-Saharan Africa (African Union - Interafrican Bureau for Animal Resource, 2009 ); it also houses 19.9 million of the 39 million sheep in the SADC region (Department of Agriculture, Forestry and Fisheries, 2019 ). Three of South Africa’s oldest sheep breeds are the BP, NM and ZL sheep: The BP sheep are a fat tailed breed that is small-framed, hornless and has long legs and a shallow body. They are indigenous to South Africa (Maqhashu et al., 2019 ) are well adapted for the semi-arid bushveld. However, this breed is at risk of disappearing through gradual replacement by imported European sheep breeds due to non-selective cross-breeding and irregular mating (Maqhashu et al., 2019 ). Their tail is usually long and straight and they are hardy and disease tolerant and their colour differs from uniform brown to white to black and white patterns. Similarly, standing tall with a narrow body and with long and lean legs, the NM is also a South African indigenous sheep breed with fat tails where 38% of their body fat can be stored (Snyman et al., 1993 ). Namaqua-Afrikaners are not favoured for slaughter lamb production because, firstly, their body build is unique and their conformation different to other mutton breeds; and secondly, a noteworthy amount of their subcutaneous fat is stored in their tails which means that over the rest of the body there is only a thin layer of fat (Snyman et al., 1993 ). NM sheep are primarily found in the north-west Cape of South Africa, as well as Southern Namibia (Snyman, 2014 ). Lastly, the Nguni sheep of Zululand, the ZL sheep, are said to be adapted to the heat and humidity of Kwa-Zulu Natal in South Africa and are multi-coloured with a brown and white combination being most dominant (Kunene & Fossey, 2006 ). b. Puberty defined In males, the ram included, puberty may be defined as the initiation of the hypothalamic-pituitary axis (similar to gonadarche), making reference to the fertilizing ability or spermarche of the ram (Bearden et al., 2004 ; Foster & Hileman, 2015 ). Similarly, puberty in males as the age at which a ram develops a sexual interest in ewes and produces spermatozoa in numbers sufficient to cause pregnancy (Bearden et al., 2004 ; Edmondson et al., 2012 ). Overall, in all definitions of puberty, sensitivity to negative feedback on the testes caused by testosterone decreases over time and allows circulating gonadotropins (Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH)) to rise to the point wherein they can stimulate testicular development and differentiation of germ cells (Ramirez & McCann, 1963 ) and there are average chronological ages at the attainment of puberty for various livestock species and breeds. Chronological age is considered to be amount of time, according to years, months or days, that have passed since the birth of the animal whereas physiological age is represents the stage of biological development and functional maturation of an animal's body systems (Martin et al., 1992 ). Chronological age and physiological age are very often correlated positively, however, not necessarily causal. For example, a breed may decrease its muscle to fat ratio at a slower rate and thus achieve threshold leptin concentration necessary for puberty attainment at an older age, compared to another breed that rapidly decreases its muscle to fat ratio and is thus younger when it reaches threshold adipose levels for puberty attainment breeds (Williams et al., 2002 ). An example of the former, ‘late maturing’ breed is the South African Mutton Merino and the latter, ‘early maturing’ breed, the Dormer (Cloete et al., 2012 ). Further, leptin concentrations and adipose reserves are a prerequisite to begin reproduction in almost all living organisms (Foster & Hileman, 2015 ) as one of the cues for the attainment of puberty is changes in energy availability when excess energy is available for reproductive function as opposed to skeletal and muscle growth, when the rate of fat deposition increases (Kennedy & Mitra, 1963 ). For example, late maturing livestock will have less body fat at the same body weight compared to early maturing livestock, which is an environmental adaptation to an environment with less available feed to sustain fat deposition, and thus delays puberty. c. Mating behaviour Mating behaviour begins at puberty and its primary objective is copulation which requires a male that is fertile and has the desire and ability to mate (Kent, 2000 ; Bearden et al., 2004 ). Androgens are necessary for the peripheral elements related to tactile and penile stimulation and erection, however, the aromatisation of testosterone to estradiol may be necessary in the regulation of normal mating behaviour (Bearden et al., 2004 ). Additionally, pheromones serve as sexual attractants to the opposite sex. In sheep particularly, there exists specialised pheromone responses such as the ‘ram effect’: the stimulation of estrus and ovulation in ewes following exposure to a ram; and the ‘cycling ewe effect’: the triggering of puberty in rams periodically exposed to cycling ewes, who will then reach puberty earlier (Edmondson et al., 2012 ). These responses are triggered by pheromones located dorsally and medially from the horns and represent the olfactory effects on mating behaviour. The way that senses affect mating behaviour may indirectly affect puberty and its attainment: Many of the signs of mating behaviour are similar to those that indicate the approach or attainment of puberty thus this study focuses on mating behaviours in male small stock that will be directly linked to possible puberty attainment, and indirectly linked physiological age. Materials and Methods a. Animals and their management Eighteen immature ram lambs at 4 months of age (6 BP, 6 NM and 6 ZL) were sampled from February to May in South Africa. The chosen ram lambs were randomly selected from respective pure-bred flocks of animals with carefully recorded genealogies. All animals were kept in the same camp of approximately 5000 m² and grazed together on natural pasture and supplemented with pellets, while water was provided ad libitum in a metal drinking trough. b. Mating behaviour To assess mating behaviour, visual observation was used. The ram-lambs were exposed for 20 minutes to mature teaser ewes every second week from 4 months of age at a ratio of 6 rams: 1 ewe. The parameters observed as described below and marked as present if displayed by a ram-lamb (Ramukhithi et al., 2017 ): Table 1 Observed mating behaviours Mating behaviour Description Nudging When the ram-lamb pushed gently against the teaser ewe Pawing When the ram-lamb hit the ground several times with his hoof Bleating When the ram-lamb would release a loud cry Licking When the rem-lamb would pass his tongue upwards over his nostrils Flehmen’s response When the ram-lamb inhaled with his mouth open and upper lip curled to facilitate exposure of the pheromone into the vomeronasal organ for detection by the accessory olfactory system, particularly after being in close proximity with the teaser ewe Pelvis thrust When the ram-lamb thrusted his pelvic region towards the teaser ewe Penile erection When the ram-lamb’s penis would become engorged, firmer or enlarged and protrude from his penile sheath Nosing When the ram-lamb would audibly draw up air through his nostrils c. Bodyweights To determine body weights, animals were placed in a crush and individually led into the electronic livestock scale and their weight recorded in kilograms (kg) (Ramukhithi et al., 2017 ; Maqhashu et al., 2019 ). These weighings were done on a bi-weekly basis from 4 months of age. d. Scrotal circumference To determine the SC each of the ram’s testes were pulled down ventrally into the scrotum and measured at its largest circumference and recorded, using a tape measure marked in centimetres (cm). These measurements were done on a bi-weekly basis from 4 months of age. e. Blood serum testosterone concentrations To determine BST, a 10 mL blood sample was collected from the jugular vein using a 21-gauge needle into an anti-coagulant-vacutainer. Following collection, blood serum was harvested by pipetting and stored in 2 mL tubes at -20°C until analysed and BST levels obtained using a competitive microtiterplate enzyme immunoassay (EIA). These collections were done on a bi-weekly basis from 4 months of age. f. Statistical analysis Data was analysed using Statistical Analysis Software (SAS University Edition, 2020) at a 95% confidence limit. Correlation Analysis and N-way ANOVA were used to generate Pearson correlations ( r ) and means of variables. Results a. Mating behaviour The mating behaviour activities of South African indigenous ram lambs are shown in Graph 1: BP and ZL ram lambs began showing nosing at 4.0 months of age; this contrasts with NM ram lambs that only began showing sexual behaviour activities (Flehmen’s response and nosing) at 4.5 months of age. BP sheep’s mating behaviour steadily increased from 3.5 months of age to 6.5 months of age with their highest percentage of observed behaviours being for nosing (79%) and the lowest for bleating and nudging (2%) with there being no observations of pelvic thrusts (0%). For Namaqua-Afrikaner sheep, the mating behaviour with the highest percentage of observed behaviours was nosing (55%), as with BP sheep, and the lowest being licking and mounting (2%) with nudging, pawing, bleating, pelvic thrust and penile erection having no observations (0%). Lastly, for Zulu sheep, mating behaviour also steadily increased from 3.5 months to 6.5 months with their highest percentage of observed behaviour being nosing (80%) and the lowest being bleating, licking, and mounting (2%) with nudging, pelvic thrust and penile erection having no observations (0%). Graph 1: The effect of age (months) on displayed mating behaviour of indigenous ram-lambs (%) b. Bodyweight, scrotal circumference and blood serum testosterone Graph 2 reports the effect of age (months) on the bodyweight, SC and BST of BP, NM and ZL rams lambs: Graph 2: The effect of age (months) on the bodyweight, blood serum testosterone (BST) and scrotal circumference (SC) of indigenous ram-lambs (%) At 4.5 months of age, BP ram-lambs had a significantly higher bodyweight than ZL ram-lambs (P 0.05). Additionally, at 4 months of age, BP ram-lambs had higher SC than NM and ZL ram-lambs (23.5 ± 1.8, 12.5 ± 3.6 and 15.7 ± 1.0 cm, respectively) (P < 0.05); at 4.5 months of age, BP ram-lambs also had higher SC than ZL ram-lambs (P < 0.05); at 5 months, BP ram-lambs had higher SC than NM ram-lambs, and ZL ram-lambs had higher SC than NM ram-lambs (P < 0.05); and at 6 to 8 months, both BP and ZL ram-lambs had higher SC than NM ram-lambs. Lastly, there was a significant difference between the BST of BP and NM ram lambs at 6 months of age (6.0 ± 1.1 and 3.2 ± 0.6 ng/ml, respectively) (P < 0.05). c. Means and correlation coefficients Table 1 reports the mean bodyweight, BST and SC of BP, NM and ZL ram-lambs as well as the Pearson correlations ( r ) between these variables and the observed mating behaviours: Table 1 Mean bodyweight (kg), BST (ng/ml) and SC (cm) and Pearson correlation ( r ) between bodyweight (kg), BST (ng/ml), SC (cm) and observed mating behaviours. Bodyweight (kg) BST (ng/ml) SC (cm) Mean 20.30 4.42 17.04 BP Mean a 23.18 a 5.10 a 21.53 NM Mean b 19.05 b 3.50 b 11.55 ZL Mean b 18.67 a 4.65 c 18.05 Bodyweight ( r ) 1.00 0.47 0.65 BST ( r ) 0.47 1.00 0.58 SC ( r ) 0.65 0.58 1.00 Nudging ( r ) 0.42 -0.05 0.24 Pawing ( r ) 0.06 0.33 0.31 Bleating ( r ) 0.10 0.42 0.17 Licking ( r ) 0.45 0.19 0.23 Flehmen's response ( r ) 0.54 0.30 0.32 Pelvic thrust ( r ) - - - Mounting ( r ) 0.56 0.23 0.29 Penile erection ( r ) 0.55 0.13 0.31 Nosing ( r ) 0.16 0.13 0.11 a, b, c Means with different superscripts within the same column differ significantly (P < 0.05) BP ram-lambs displayed significantly higher mean bodyweights than both NM and ZL ram-lambs (P < 0.05) (23.18 kg, 19.05 kg and 18.67 kg, respectively). Additionally, NM ram-lambs displayed significantly lower mean SC than both BP and ZL ram-lambs (P < 0.05) (11.55 cm, 21.53 cm and 18.05 cm, respectively) with significant between-breed differences for all the studied breeds (P < 0.05). Lastly, NM ram-lambs displayed significantly lower BST than both BP and ZL ram-lambs (P < 0.05) (3.50 ng/ml, 5.10 ng/ml and 4.65 ng/ml. respectively). The strongest correlation ( r ) seen was bodyweight with SC (0.65) and that of BST with SC (0.58). However, the weakest correlation ( r ) seen was BST with nudging (-0.05). Discussion Importantly, the NM breed are indigenous to the Northern Cape province in South Africa (Snyman, 2014 ); this province has notably extreme weather, both hot and cold. If NM mature later and reach puberty later, the ewes are better able to protect their young from predators as they will give birth later in life and will be presumably larger in body size; additionally, growing lambs are able to allocate scarce nutrients towards survival and maintenance as opposed to reproduction. Late-maturing breeds are physiologically younger at the same chronological age (a chronological age which would be strongly correlated to body weight (Moulla et al., 2018 )) thus they would weigh the same as BP and ZL sheep but be at a different physiological age, particularly with regards to reproduction, as was the case in this study. Additionally, BP and ZL ram-lambs and began displaying nosing at 4.0 months of age whereas NM ram-lambs only began displaying this mating behaviour a month later, and NM ram-lambs also had the lowest cumulative observation percentage of all mating behaviours compared to BP and ZL ram-lambs. This suggests that on a spectrum, BP and ZL sheep are early maturing compared to Namaqua-Afrikaner sheep - This conclusion is supported by Graph 2 as BP displayed significantly higher bodyweights than both NM and ZL ram-lambs and bodyweight had a strong positive correlation to SC. Thus, results also show that BP ram-lambs also had significantly higher SC than NM ram-lambs. Additionally, nosing was the first and most frequently seen sexual behaviour across all three breeds; this supports the hypothesis that the olfactory senses are important in the attainment of puberty, and perhaps the ram lambs’ sensitivity to pheromones is the first indicator of approaching puberty (Edmondson et al., 2012 ). This is corroborated by Flehmen’s response being the second most seen observation across all three breeds as Flehmen’s response also makes use of the olfactory system. Additionally, nosing is the first sexual behaviour displayed in a sexual interaction, and that it functions to provide the ram with olfactory information - Interestingly, because nosing involves the ram pushing its face into the perineum of the ewe, nosing may also function in providing the ram with information about the ewe’s vulva’s surface temperature (Banks, 1964 ). Contrastingly, the sexual behaviour activity that was not observed across any breed was pelvic thrust – This may be because pelvic thrusts happen post-mounting, and ram lambs that have not attained puberty or have attained puberty but not sexual maturity, may not have experience with mounting an ewe. The ram lambs used in this study had no interaction with mature rams and were only exposed to teaser ewes for limited periods of time. It is also important to also consider whether or not the mating behaviour that was observed was due to the attainment of puberty, or simply a response to the teaser ewes – The cycling ewe effect (the triggering of puberty in rams periodically exposed to cycling ewes, who will then reach puberty earlier (Edmondson et al., 2012 )) may have played a role in the sexual development of the studied BP, NM and ZL ram lambs as they were exposed to teaser ewes that may have been in estrus. Lastly, the seasons during which mating behaviour activities were monitored are also important to note as sheep are seasonal short-day breeders. This means that they come into season naturally when the daylight length starts to decrease, therefore in autumn. Sheep can also be induced to breed in spring, either with daylight manipulation or hormone supplementation (Penna et al., 2013 ) This study’s sexual behaviour activities were monitored from February until May in South Africa i.e., from Summer until Autumn. This may suggest that the increase in mating behaviour activities may be due to the initiation and progression of the mating season. This finding is particularly interesting because it suggests that increased mating behaviour, which may be a prerequisite for puberty, may naturally coincide with the natural mating season of sheep. Where the first null hypothesis is that as ram lambs age, they will not display mating behaviour, results indicate that the null hypothesis is not accepted. Where the null hypothesis is that the ram lambs will display static bodyweights, SC and BST: The bodyweight for BP ram-lambs ranged from 21.5 ± 2.4 kg to 27.3 ± 2.4 kg; that of NM ram-lambs from 17.9 ± 1.7 kg to 24.2 ± 1.7 kg; and that of ZL ram lambs from 17.3 ± 1.3 kg to 23.1 ± 1.3 kg, thus this null hypothesis is also not accepted. With regards to BST, testosterone is responsible for sexual maturity and interest, and is produced by the Leydig cells of the testes. Leydig cell parameters (such as the number of Leydig cells per gram of testis, total number of Leydig cells per testis and percent cell volume of Leydig cell nuclei) are correlated significantly with testosterone levels and testosterone is responsible for secondary sex characteristics like mating behaviour (Bearden et al., 2004 ). Thus, because all three studied breeds have dissimilar SC at most ages, they presumably have correspondingly dissimilar Leydig cells (despite mean significant difference across all ages (P < 0.05)). SC is a useful selection indicator as males with larger testes are likelier to sire daughters that reach puberty at an earlier age and ovulate more ova during oestrus (Ramirez & McCann, 1963 ). This would be especially useful for smallholder farmers and livestock keepers as they would be able to get more lambs from one ewe, both because the age at first lambing is lower and the likelihood of multiple births is higher. Testosterone is also needed to initiate spermatogenesis at puberty and to maintain this process in the adult, thus the presence of fluctuating BST in all three breeds may indicate the attainment of puberty. Moreover, because the testis of sheep release testosterone that elevates with increasing testicular weight until puberty and maturity (Khalifa et al., 2013 ), it is understandable why the three studied breeds had similar BST (P > 0.05) for most ages (despite mean significant difference across all ages (P < 0.05)): BP, NM and ZL ram-lambs had similar body weights when compared with each other and since there existed a positive correlation (as per the Pearson correlation coefficients for this study) between bodyweight, SC and BST this relationship is expected. Thus, the last null hypothesis, that there would not exist a correlation between bodyweight, BST and SC, is also not accepted. The current study recommends that there be intensified research on indigenous sheep breeds for improved reproductive performance and conservation strategies – This study made use of in situ conservation over ex situ conservation and that allowed breeds to continue to develop and adapt to changing environmental pressures, enabling research to determine their performance more ingeniously. An indigenous breed’s capacity to display a adaptive phenotype that is relevant to a production parameter, in a manner that is reliable, is invaluable to the profitability and sustainability of both smallholder and commercial production systems. Abbreviations NM Namaqua-Afrikaner sheep BP Bapedi sheep ZL Zulu sheep BST Blood serum testosterone concentration SC Scrotal circumference Declarations Acknowledgements The authors thank the Agricultural Research Council Animal Production, the Mandela Rhodes Foundation, Agriseta, National Research Foundation (NRF) Thuthuka, the University of Pretoria and the Department of Agriculture, Land Reform and Rural Development (DALRRD). Funding This study received funding for post-graduate support from the Mandela Rhodes Foundation and the National Research Foundation (NRF) Thuthuka program. Data availability The datasets analyse in this study are available in the University of Pretoria’s Institutional Repository http://hdl.handle.net/2263/82755. Author contribution All authors contributed to the study’s design and data collection. The first draft of the manuscript was written by R. Shingange and all authors read, edited and approved the final manuscript. Statement of Animal Rights This study received ethical approval from the Agricultural Research Council Animal Production, Irene: APAEC 2020/07, as well as from the University of Pretoria: NAS207/2020. In addition, the study received Department of Agriculture, Land Reform and Rural Development (DALRRD) Section 20 approval. Conflict of Interest Statement The authors have no competing interests to declare that are relevant to the content of this article. References African Union - Interafrican Bureau for Animal Resource. 2009. Strategic Plan 2010 - 2014. Nairobi, Kenya. Banks, E. 1964. Some aspects of sexual behaviour in domestic sheep, Ovis aries. Behaviour 23, 249–279. Bearden, H., Fuquay, J., & Willard, S. 2004. Neuroendocrinology of livestock reproduction.in Applied Animal Reproduction. Pearson Prentice Hall, Upper Saddle River, United States of America. Cloete, J. J. E., Hoffman, L. C., & Cloete, S. W. P. 2012. 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Characterization of the onset of puberty in Tazegzawt lambs, an endangered Algerian sheep: Body weight, thoracic perimeter, testicular growth and seminal parameters. Veterinary World 11, 889–894. Penna, B., Libonati, H., Director, A., Sarzedas, A. C., Martins, G., Brandão, F. Z., Fonseca, J., & Lilenbaum, W. 2013. Progestin-impregnated intravaginal sponges for estrus induction and synchronization influences on goats vaginal flora and antimicrobial susceptibility. Animal Reproduction Science 142, 71–74 https://doi.org/10.1016/j.anireprosci.2013.09.006. Pickson, R. B., & Boateng, E. 2022. Climate change: a friend or foe to food security in Africa? Environ Dev Sustain 24, 4387–4412 https://doi.org/10.1007/s10668-021-01621-8. Ramirez, D. V., & McCann, S. M. 1963. Comparison of the regulation of luteinizing hormone (LII) secretion in immature and adult rats. Endocrinology 72, 452–464. Ramukhithi, F. V., Nephawe, K. A., Chokoe, T. C., Matabane, M. B., Mphaphathi, M. L., Lehloenya, K. C., & Nedambale, T. L. 2017. Attainment of puberty in South African unimproved indigenous bucks. Small Ruminant Research 153, 57–61 https://doi.org/10.1016/j.smallrumres.2017.05.009. Ryder, M. L., & Bridbury, A. R. 1984. Sheep and man. Economic History Review 37, 468. SA Stud Breeder. 2015. Why Bonsmara? : advertorial. 41, 35. Snyman, H. A. 2014. South African sheep breeds: Namaqua Afrikaner. Info-pack ref. 2014/023. Grootfontein Agricultural Development Institute, Middelburg, South Africa. Snyman, H. A., & Hersleman, M. J. 2005. Comparison of productive and reproductive efficiency of Afrino, Dorper and Merino sheep in the False Upper Karoo. South African Journal of Animal Science 35, 98–108. Snyman, H. A., Olivier, J. J., & Cloete, J. A. N. 1993. Productive and reproductive performance of Namaqua Afrikaner sheep. Karoo Agriculture 5, 21–24. Webb, E. C., Visage, P. C., & van der Westhuizen, J. 2018. Effect of Bioregion of the Size and Efficiency of Bonsmara Cattle in Semi-Arid Parts of Southern Africa. IntechOpen Ruminants-The Husbandry, Economic and Health Aspects. Webb, E. C., Visage, P. C., van der Westhuizen, J., & Snyman, H. A. 2017. Influence of bioregion and environmental factors on the growth, size, and reproduction of Bonsmara cows. 47. Williams, G. L., Amstalden, M., Garcia, M. R., Stanko, R. L., Nizielski, S. E., Morrison, C. D., & Keisler, D. H. 2002. Leptin and its role in the central regulation of reproduction in cattle. Domestic Animal Endocrinology 23, 339–349 https://doi.org/10.1016/S0739-7240(02)00169-8. Graph 1 and 2 Graph 1 and 2 are available in the Supplementary Files section. Supplementary Files Graph1.png Graph 1: The effect of age (months) on displayed mating behaviour of indigenous ram-lambs (%) Graph2.png Graph 2: The effect of age (months) on the bodyweight, blood serum testosterone (BST) and scrotal circumference (SC) of indigenous ram-lambs (%) Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Major revision with re-assessment 21 Aug, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers invited by journal 22 Jul, 2024 Editor assigned by journal 13 Jun, 2024 First submitted to journal 06 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4511150","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":330156773,"identity":"e74de758-5c3b-465c-9e8d-926c7e289442","order_by":0,"name":"Rimbilana Shingange","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYDACZgY2hgSGAzxQrg0QMzYeIEVLGkhLA34tDEAtDAxwNYfBJF4t5u3caQ8e/LkjY86/+NnDLxXn7da2HwbaUmMTjUuLzGHe7QaJbc94LGc8MzeWOXM7eduZRKCWY2m5DTi0SDDzbpNIbDjMY3DjgJm0ZNvtZLMDQC2MDYfxa0n4A9Jy/Ju05L9zyWbnHxKjhQ2o5XyPmeTHhgN2ZjcI2wLyC8gWnjJphmPJCWY3gLYk4PML/9ltD3/8OWxvcP74NskfNXb2ZufTHz74UGODUwuS5gQGZmCEJoJVJhBUDgL8BxgYfzAw2BOleBSMglEwCkYUAABVN2bp5T/j/QAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-7801-1653","institution":"University of Pretoria Faculty of Natural and Agricultural Sciences","correspondingAuthor":true,"prefix":"","firstName":"Rimbilana","middleName":"","lastName":"Shingange","suffix":""},{"id":330156774,"identity":"a5d358c6-7aa1-4da5-a248-7df878ac39bb","order_by":1,"name":"Fhulufhelo Ramikhuthi","email":"","orcid":"","institution":"ARC: Agricultural Research Council","correspondingAuthor":false,"prefix":"","firstName":"Fhulufhelo","middleName":"","lastName":"Ramikhuthi","suffix":""},{"id":330156775,"identity":"323148eb-ab33-4947-8b4c-13543e0c6abf","order_by":2,"name":"Ayanda Maqhashu","email":"","orcid":"","institution":"University of the Free State - Bloemfontein Campus: University of the Free State","correspondingAuthor":false,"prefix":"","firstName":"Ayanda","middleName":"","lastName":"Maqhashu","suffix":""}],"badges":[],"createdAt":"2024-05-31 22:00:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4511150/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4511150/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":62607489,"identity":"d3cd66a0-37f6-4429-b5c4-41613d55d49c","added_by":"auto","created_at":"2024-08-16 11:10:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":361312,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4511150/v1/37259d76-1bf5-45f5-85d0-7c6aa9506cae.pdf"},{"id":62606577,"identity":"d527b5cb-b100-4b7f-87b1-2c09a1aa8118","added_by":"auto","created_at":"2024-08-16 11:02:25","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":110029,"visible":true,"origin":"","legend":"\u003cp\u003eGraph 1: The effect of age (months) on displayed mating behaviour of indigenous ram-lambs (%)\u003c/p\u003e","description":"","filename":"Graph1.png","url":"https://assets-eu.researchsquare.com/files/rs-4511150/v1/6b7608d996174fedf625987c.png"},{"id":62606576,"identity":"707bac07-0d7d-412b-a4ab-e798efa5d46f","added_by":"auto","created_at":"2024-08-16 11:02:24","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":42182,"visible":true,"origin":"","legend":"\u003cp\u003eGraph 2: The effect of age (months) on the bodyweight, blood serum testosterone (BST) and scrotal circumference (SC) of indigenous ram-lambs (%)\u003c/p\u003e","description":"","filename":"Graph2.png","url":"https://assets-eu.researchsquare.com/files/rs-4511150/v1/4b2385e80da019c8ff326736.png"}],"financialInterests":"","formattedTitle":"Correlations among South African indigenous ram-lambs’ physiological age and various mating behaviours at puberty","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn various emerging economies, it is particularly important to have livestock production that is commercially efficient but also sustainable, as it aids in alleviating poverty and increasing household food security (Webb et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). This sustainable model can be achieved through livestock reproductive management that ensures the proliferation and propagation of certain species and breeds, like the multi-purpose sheep: The sheep is one of the earliest species to be domesticated by humans (Ryder \u0026amp; Bridbury, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1984\u003c/span\u003e) and continues to be prized for its multi-purposefulness as it produces wool, meat, and milk. Contextually, animals that are \u0026lsquo;indigenous\u0026rsquo; to an area, are more likely to be robust in that area, compared to foreign breeds, due to their adaptation to the specific pressures of the region. Three of South Africa\u0026rsquo;s oldest indigenous sheep breeds are the Bapedi (BP), Namaqua-Afrikaner (NM) and Zulu (ZL) sheep, which are lauded as hardy, disease resistant and robust (Maqhashu et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). \u0026lsquo;Robustness\u0026rsquo; is the persistence of a phenotype during long-term stressors (Colditz \u0026amp; Hine, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Thus, considering its environment\u0026rsquo;s stress, an animal must maintain traits that are beneficial to its survival, and subsequent propagation, so that those genotypes that express the optimal phenotype most reliably will be selectively favoured, particularly when faced with stressors.\u003c/p\u003e \u003cp\u003eConsidering the increasing impact of climate change, such as a minimum rise in temperature by 4\u0026deg;C that will have disastrous effects on many farmers\u0026rsquo; livelihoods in Africa (Pickson \u0026amp; Boateng, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), it is important that governmental policy and academic research intensify their efforts towards sustainable and efficient livestock production. Breeds that are indigenous to South Africa having reduced economically-relevant growth parameters, such as average daily gain and milk yield, compared to exotic breeds, are too much of a disadvantage for the majority of animal product producers (Moulla et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). For example, the Bonsmara is a composite South African breed, composed of the Afrikaner, Shorthorn and Hereford breeds - two out of three which are exotic breeds. The Bonsmara capitalises on hybrid vigour and competes with the production ranges of exotic breeds, while being less prone to heat-stress and parasite-load that are characteristic of South Africa, in the way that its exotic composite lines are (SA Stud Breeder, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Webb et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAdditionally, another parameter that is crucial for the efficiency of livestock production is an animal\u0026rsquo;s physiological age as this determines the animal\u0026rsquo;s ratio of fat to muscle to bone, which changes as the animal ages and thus influences puberty attainment and its associated mating behaviours, age at slaughter and meat composition (Kennedy \u0026amp; Mitra, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1963\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eConsidering the above, this study sought to visually assess the mating behaviours of pubertal ram-lambs of three indigenous South African sheep breeds, the BP, NM and ZL, and use bodyweights, scrotal circumference (SC) and blood serum testosterone concentration (BST) measurements to correlate these mating behaviours with physiological or chronological age. The study\u0026rsquo;s null hypotheses were:\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eA: H\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;As they age, ram lambs will display no mating behaviour.\u003c/p\u003e\u003cp\u003eB: H\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;As they age, ram lambs will have static SC, bodyweight measurements and BST.\u003c/p\u003e\u003cp\u003eC: H\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;There will not exist a correlation between BST, bodyweight and SC.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eSheep in sub-Saharan Africa\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eIn the Southern African Development Community (SADC), indigenous sheep play an integral role in the income and sustenance of smallholder farmers and livestock keepers (Molotsi et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This is partially due to the arid/semi-arid environment of sub-Saharan Africa, to which sheep are adapted. Indigenous breeds like the BP, NM and ZL, are particularly suited to South African environmental conditions due to their indigenousness and continued adaptation. Despite their adaptation, however, indigenous breeds are continuously being replaced by foreign breeds like the Merino due to foreign breeds\u0026rsquo; superior production (Snyman \u0026amp; Hersleman, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). This problem is exacerbated by there being no or slow genetic progress for the indigenous genetic resources used by livestock keepers and small holder farmers (Molotsi et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSmallholder farmers are those farmers that depend solely on familial labour; those that own small plots of land where they grow subsistence crops; and those that farm one or two \u0026lsquo;cash crops\u0026rsquo; - crops that are used less by the farmer and more for their commercial value (Department of Agriculture, Forestry and Fisheries, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Small stock plays a foundational role in the economic security and food security of millions in sub-Saharan Africa, with small scale and communal farmers owning 12% of sheep (Meissner \u0026amp; Engelbrecht, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIndigenous breeds are important and their genetic erosion is problematic because of the loss of their adaptability (Molotsi et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2019\u003c/span\u003e): When indiscriminately cross-bred with exotic/foreign breeds and not maintained as pure breeds, the loss of genetic diversity occurs. This is important particularly with regards to indigenous South African breeds because they are adapted to the environment. With climate change an ever-growing concern in sub-Saharan Africa, it is thus important to maintain breeds that are adapted. For example, higher temperatures may have led to a decrease in tsetse flies that cause trypanosomiasis in Zimbabwe\u0026rsquo;s Zambezi valley, these flies have now migrated to cooler regions (Lord et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In addition, another effect that the loss of indigenous animals has is on the remaining animals: They are not adapted to heat and heat stress, which negatively affects their homeostatic mechanisms and subsequently affects growth, performance and reproduction (Marai et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSouth Africa houses 46 of the 109 different sheep breeds in sub-Saharan Africa (African Union - Interafrican Bureau for Animal Resource, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e); it also houses 19.9\u0026nbsp;million of the 39\u0026nbsp;million sheep in the SADC region (Department of Agriculture, Forestry and Fisheries, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Three of South Africa\u0026rsquo;s oldest sheep breeds are the BP, NM and ZL sheep: The BP sheep are a fat tailed breed that is small-framed, hornless and has long legs and a shallow body. They are indigenous to South Africa (Maqhashu et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) are well adapted for the semi-arid bushveld. However, this breed is at risk of disappearing through gradual replacement by imported European sheep breeds due to non-selective cross-breeding and irregular mating (Maqhashu et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Their tail is usually long and straight and they are hardy and disease tolerant and their colour differs from uniform brown to white to black and white patterns. Similarly, standing tall with a narrow body and with long and lean legs, the NM is also a South African indigenous sheep breed with fat tails where 38% of their body fat can be stored (Snyman et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1993\u003c/span\u003e). Namaqua-Afrikaners are not favoured for slaughter lamb production because, firstly, their body build is unique and their conformation different to other mutton breeds; and secondly, a noteworthy amount of their subcutaneous fat is stored in their tails which means that over the rest of the body there is only a thin layer of fat (Snyman et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1993\u003c/span\u003e). NM sheep are primarily found in the north-west Cape of South Africa, as well as Southern Namibia (Snyman, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Lastly, the Nguni sheep of Zululand, the ZL sheep, are said to be adapted to the heat and humidity of Kwa-Zulu Natal in South Africa and are multi-coloured with a brown and white combination being most dominant (Kunene \u0026amp; Fossey, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eb. Puberty defined\u003c/p\u003e \u003cp\u003eIn males, the ram included, puberty may be defined as the initiation of the hypothalamic-pituitary axis (similar to gonadarche), making reference to the fertilizing ability or spermarche of the ram (Bearden et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Foster \u0026amp; Hileman, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Similarly, puberty in males as the age at which a ram develops a sexual interest in ewes and produces spermatozoa in numbers sufficient to cause pregnancy (Bearden et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Edmondson et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOverall, in all definitions of puberty, sensitivity to negative feedback on the testes caused by testosterone decreases over time and allows circulating gonadotropins (Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH)) to rise to the point wherein they can stimulate testicular development and differentiation of germ cells (Ramirez \u0026amp; McCann, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1963\u003c/span\u003e) and there are average chronological ages at the attainment of puberty for various livestock species and breeds.\u003c/p\u003e \u003cp\u003eChronological age is considered to be amount of time, according to years, months or days, that have passed since the birth of the animal whereas physiological age is represents the stage of biological development and functional maturation of an animal's body systems (Martin et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). Chronological age and physiological age are very often correlated positively, however, not necessarily causal. For example, a breed may decrease its muscle to fat ratio at a slower rate and thus achieve threshold leptin concentration necessary for puberty attainment at an older age, compared to another breed that rapidly decreases its muscle to fat ratio and is thus younger when it reaches threshold adipose levels for puberty attainment breeds (Williams et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). An example of the former, \u0026lsquo;late maturing\u0026rsquo; breed is the South African Mutton Merino and the latter, \u0026lsquo;early maturing\u0026rsquo; breed, the Dormer (Cloete et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurther, leptin concentrations and adipose reserves are a prerequisite to begin reproduction in almost all living organisms (Foster \u0026amp; Hileman, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) as one of the cues for the attainment of puberty is changes in energy availability when excess energy is available for reproductive function as opposed to skeletal and muscle growth, when the rate of fat deposition increases (Kennedy \u0026amp; Mitra, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1963\u003c/span\u003e). For example, late maturing livestock will have less body fat at the same body weight compared to early maturing livestock, which is an environmental adaptation to an environment with less available feed to sustain fat deposition, and thus delays puberty.\u003c/p\u003e \u003cp\u003ec. Mating behaviour\u003c/p\u003e \u003cp\u003eMating behaviour begins at puberty and its primary objective is copulation which requires a male that is fertile and has the desire and ability to mate (Kent, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Bearden et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Androgens are necessary for the peripheral elements related to tactile and penile stimulation and erection, however, the aromatisation of testosterone to estradiol may be necessary in the regulation of normal mating behaviour (Bearden et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2004\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAdditionally, pheromones serve as sexual attractants to the opposite sex. In sheep particularly, there exists specialised pheromone responses such as the \u0026lsquo;ram effect\u0026rsquo;: the stimulation of estrus and ovulation in ewes following exposure to a ram; and the \u0026lsquo;cycling ewe effect\u0026rsquo;: the triggering of puberty in rams periodically exposed to cycling ewes, who will then reach puberty earlier (Edmondson et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). These responses are triggered by pheromones located dorsally and medially from the horns and represent the olfactory effects on mating behaviour.\u003c/p\u003e \u003cp\u003eThe way that senses affect mating behaviour may indirectly affect puberty and its attainment: Many of the signs of mating behaviour are similar to those that indicate the approach or attainment of puberty thus this study focuses on mating behaviours in male small stock that will be directly linked to possible puberty attainment, and indirectly linked physiological age.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003ea. Animals and their management\u003c/p\u003e\n\u003cp\u003eEighteen immature ram lambs at 4 months of age (6 BP, 6 NM and 6 ZL) were sampled from February to May in South Africa. The chosen ram lambs were randomly selected from respective pure-bred flocks of animals with carefully recorded genealogies. All animals were kept in the same camp of approximately 5000 m\u0026sup2; and grazed together on natural pasture and supplemented with pellets, while water was provided ad libitum in a metal drinking trough.\u003c/p\u003e\n\u003cp\u003eb. Mating behaviour\u003c/p\u003e\n\u003cp\u003eTo assess mating behaviour, visual observation was used. The ram-lambs were exposed for 20 minutes to mature teaser ewes every second week from 4 months of age at a ratio of 6 rams: 1 ewe. The parameters observed as described below and marked as present if displayed by a ram-lamb (Ramukhithi et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e):\u0026nbsp;\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eObserved mating behaviours\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMating behaviour\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDescription\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNudging\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb pushed gently against the teaser ewe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePawing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb hit the ground several times with his hoof\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBleating\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb would release a loud cry\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLicking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the rem-lamb would pass his tongue upwards over his nostrils\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlehmen\u0026rsquo;s response\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb inhaled with his mouth open and upper lip curled to facilitate exposure of the pheromone into the vomeronasal organ for detection by the accessory olfactory system, particularly after being in close proximity with the teaser ewe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePelvis thrust\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb thrusted his pelvic region towards the teaser ewe\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePenile erection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb\u0026rsquo;s penis would become engorged, firmer or enlarged and protrude from his penile sheath\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNosing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhen the ram-lamb would audibly draw up air through his nostrils\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ch2\u003ec. Bodyweights\u003c/h2\u003e\n\u003cp\u003eTo determine body weights, animals were placed in a crush and individually led into the electronic livestock scale and their weight recorded in kilograms (kg) (Ramukhithi et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Maqhashu et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). These weighings were done on a bi-weekly basis from 4 months of age.\u003c/p\u003e\n\u003cp\u003ed. Scrotal circumference\u003c/p\u003e\n\u003cp\u003eTo determine the SC each of the ram\u0026rsquo;s testes were pulled down ventrally into the scrotum and measured at its largest circumference and recorded, using a tape measure marked in centimetres (cm). These measurements were done on a bi-weekly basis from 4 months of age.\u003c/p\u003e\n\u003cp\u003ee. Blood serum testosterone concentrations\u003c/p\u003e\n\u003cp\u003eTo determine BST, a 10 mL blood sample was collected from the jugular vein using a 21-gauge needle into an anti-coagulant-vacutainer. Following collection, blood serum was harvested by pipetting and stored in 2 mL tubes at -20\u0026deg;C until analysed and BST levels obtained using a competitive microtiterplate enzyme immunoassay (EIA). These collections were done on a bi-weekly basis from 4 months of age.\u003c/p\u003e\n\u003cp\u003ef. Statistical analysis\u003c/p\u003e\n\u003cp\u003eData was analysed using Statistical Analysis Software (SAS University Edition, 2020) at a 95% confidence limit. Correlation Analysis and N-way ANOVA were used to generate Pearson correlations (\u003cem\u003er\u003c/em\u003e) and means of variables.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003ea. Mating behaviour\u003c/p\u003e \u003cp\u003eThe mating behaviour activities of South African indigenous ram lambs are shown in Graph 1: BP and ZL ram lambs began showing nosing at 4.0 months of age; this contrasts with NM ram lambs that only began showing sexual behaviour activities (Flehmen\u0026rsquo;s response and nosing) at 4.5 months of age. BP sheep\u0026rsquo;s mating behaviour steadily increased from 3.5 months of age to 6.5 months of age with their highest percentage of observed behaviours being for nosing (79%) and the lowest for bleating and nudging (2%) with there being no observations of pelvic thrusts (0%). For Namaqua-Afrikaner sheep, the mating behaviour with the highest percentage of observed behaviours was nosing (55%), as with BP sheep, and the lowest being licking and mounting (2%) with nudging, pawing, bleating, pelvic thrust and penile erection having no observations (0%). Lastly, for Zulu sheep, mating behaviour also steadily increased from 3.5 months to 6.5 months with their highest percentage of observed behaviour being nosing (80%) and the lowest being bleating, licking, and mounting (2%) with nudging, pelvic thrust and penile erection having no observations (0%).\u003c/p\u003e \u003cp\u003eGraph 1: The effect of age (months) on displayed mating behaviour of indigenous ram-lambs (%)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eb. Bodyweight, scrotal circumference and blood serum testosterone\u003c/p\u003e \u003cp\u003eGraph 2 reports the effect of age (months) on the bodyweight, SC and BST of BP, NM and ZL rams lambs:\u003c/p\u003e \u003cp\u003eGraph 2: The effect of age (months) on the bodyweight, blood serum testosterone (BST) and scrotal circumference (SC) of indigenous ram-lambs (%)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAt 4.5 months of age, BP ram-lambs had a significantly higher bodyweight than ZL ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); this is also the case for BP and NM ram-lambs at 6 months of age and for BP and ZL ram-lambs at 6 months of age. Thus, at the rest of the ages all breeds had similar bodyweights (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eAdditionally, at 4 months of age, BP ram-lambs had higher SC than NM and ZL ram-lambs (23.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8, 12.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6 and 15.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 cm, respectively) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); at 4.5 months of age, BP ram-lambs also had higher SC than ZL ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); at 5 months, BP ram-lambs had higher SC than NM ram-lambs, and ZL ram-lambs had higher SC than NM ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); and at 6 to 8 months, both BP and ZL ram-lambs had higher SC than NM ram-lambs.\u003c/p\u003e \u003cp\u003eLastly, there was a significant difference between the BST of BP and NM ram lambs at 6 months of age (6.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1 and 3.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 ng/ml, respectively) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003ec. Means and correlation coefficients\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e1\u003c/span\u003e reports the mean bodyweight, BST and SC of BP, NM and ZL ram-lambs as well as the Pearson correlations (\u003cem\u003er\u003c/em\u003e) between these variables and the observed mating behaviours:\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMean bodyweight (kg), BST (ng/ml) and SC (cm) and Pearson correlation (\u003cem\u003er\u003c/em\u003e) between bodyweight (kg), BST (ng/ml), SC (cm) and observed mating behaviours.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBodyweight (kg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBST (ng/ml)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSC (cm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBP Mean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e23.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e5.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e21.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNM Mean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003csup\u003eb\u003c/sup\u003e19.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003csup\u003eb\u003c/sup\u003e3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003eb\u003c/sup\u003e11.55\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZL Mean\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003csup\u003eb\u003c/sup\u003e18.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003e4.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003csup\u003ec\u003c/sup\u003e18.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBodyweight (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBST (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSC (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNudging (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePawing (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBleating (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLicking (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFlehmen's response (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.32\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic thrust (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMounting (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePenile erection (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNosing (\u003cem\u003er\u003c/em\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003csup\u003ea,\u003c/sup\u003e b, c Means with different superscripts within the same column differ significantly (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBP ram-lambs displayed significantly higher mean bodyweights than both NM and ZL ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (23.18 kg, 19.05 kg and 18.67 kg, respectively). Additionally, NM ram-lambs displayed significantly lower mean SC than both BP and ZL ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (11.55 cm, 21.53 cm and 18.05 cm, respectively) with significant between-breed differences for all the studied breeds (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Lastly, NM ram-lambs displayed significantly lower BST than both BP and ZL ram-lambs (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (3.50 ng/ml, 5.10 ng/ml and 4.65 ng/ml. respectively).\u003c/p\u003e \u003cp\u003eThe strongest correlation (\u003cem\u003er\u003c/em\u003e) seen was bodyweight with SC (0.65) and that of BST with SC (0.58). However, the weakest correlation (\u003cem\u003er\u003c/em\u003e) seen was BST with nudging (-0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eImportantly, the NM breed are indigenous to the Northern Cape province in South Africa (Snyman, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2014\u003c/span\u003e); this province has notably extreme weather, both hot and cold. If NM mature later and reach puberty later, the ewes are better able to protect their young from predators as they will give birth later in life and will be presumably larger in body size; additionally, growing lambs are able to allocate scarce nutrients towards survival and maintenance as opposed to reproduction. Late-maturing breeds are physiologically younger at the same chronological age (a chronological age which would be strongly correlated to body weight (Moulla et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)) thus they would weigh the same as BP and ZL sheep but be at a different physiological age, particularly with regards to reproduction, as was the case in this study. Additionally, BP and ZL ram-lambs and began displaying nosing at 4.0 months of age whereas NM ram-lambs only began displaying this mating behaviour a month later, and NM ram-lambs also had the lowest cumulative observation percentage of all mating behaviours compared to BP and ZL ram-lambs. This suggests that on a spectrum, BP and ZL sheep are early maturing compared to Namaqua-Afrikaner sheep - This conclusion is supported by Graph 2 as BP displayed significantly higher bodyweights than both NM and ZL ram-lambs and bodyweight had a strong positive correlation to SC. Thus, results also show that BP ram-lambs also had significantly higher SC than NM ram-lambs.\u003c/p\u003e \u003cp\u003eAdditionally, nosing was the first and most frequently seen sexual behaviour across all three breeds; this supports the hypothesis that the olfactory senses are important in the attainment of puberty, and perhaps the ram lambs\u0026rsquo; sensitivity to pheromones is the first indicator of approaching puberty (Edmondson et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This is corroborated by Flehmen\u0026rsquo;s response being the second most seen observation across all three breeds as Flehmen\u0026rsquo;s response also makes use of the olfactory system. Additionally, nosing is the first sexual behaviour displayed in a sexual interaction, and that it functions to provide the ram with olfactory information - Interestingly, because nosing involves the ram pushing its face into the perineum of the ewe, nosing may also function in providing the ram with information about the ewe\u0026rsquo;s vulva\u0026rsquo;s surface temperature (Banks, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1964\u003c/span\u003e). Contrastingly, the sexual behaviour activity that was not observed across any breed was pelvic thrust \u0026ndash; This may be because pelvic thrusts happen post-mounting, and ram lambs that have not attained puberty or have attained puberty but not sexual maturity, may not have experience with mounting an ewe. The ram lambs used in this study had no interaction with mature rams and were only exposed to teaser ewes for limited periods of time.\u003c/p\u003e \u003cp\u003eIt is also important to also consider whether or not the mating behaviour that was observed was due to the attainment of puberty, or simply a response to the teaser ewes \u0026ndash; The cycling ewe effect (the triggering of puberty in rams periodically exposed to cycling ewes, who will then reach puberty earlier (Edmondson et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2012\u003c/span\u003e)) may have played a role in the sexual development of the studied BP, NM and ZL ram lambs as they were exposed to teaser ewes that may have been in estrus.\u003c/p\u003e \u003cp\u003eLastly, the seasons during which mating behaviour activities were monitored are also important to note as sheep are seasonal short-day breeders. This means that they come into season naturally when the daylight length starts to decrease, therefore in autumn. Sheep can also be induced to breed in spring, either with daylight manipulation or hormone supplementation (Penna et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) This study\u0026rsquo;s sexual behaviour activities were monitored from February until May in South Africa i.e., from Summer until Autumn. This may suggest that the increase in mating behaviour activities may be due to the initiation and progression of the mating season. This finding is particularly interesting because it suggests that increased mating behaviour, which may be a prerequisite for puberty, may naturally coincide with the natural mating season of sheep.\u003c/p\u003e \u003cp\u003eWhere the first null hypothesis is that as ram lambs age, they will not display mating behaviour, results indicate that the null hypothesis is not accepted. Where the null hypothesis is that the ram lambs will display static bodyweights, SC and BST: The bodyweight for BP ram-lambs ranged from 21.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4 kg to 27.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4 kg; that of NM ram-lambs from 17.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 kg to 24.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 kg; and that of ZL ram lambs from 17.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3 kg to 23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3 kg, thus this null hypothesis is also not accepted.\u003c/p\u003e \u003cp\u003eWith regards to BST, testosterone is responsible for sexual maturity and interest, and is produced by the Leydig cells of the testes. Leydig cell parameters (such as the number of Leydig cells per gram of testis, total number of Leydig cells per testis and percent cell volume of Leydig cell nuclei) are correlated significantly with testosterone levels and testosterone is responsible for secondary sex characteristics like mating behaviour (Bearden et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Thus, because all three studied breeds have dissimilar SC at most ages, they presumably have correspondingly dissimilar Leydig cells (despite mean significant difference across all ages (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05)). SC is a useful selection indicator as males with larger testes are likelier to sire daughters that reach puberty at an earlier age and ovulate more ova during oestrus (Ramirez \u0026amp; McCann, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1963\u003c/span\u003e). This would be especially useful for smallholder farmers and livestock keepers as they would be able to get more lambs from one ewe, both because the age at first lambing is lower and the likelihood of multiple births is higher.\u003c/p\u003e \u003cp\u003eTestosterone is also needed to initiate spermatogenesis at puberty and to maintain this process in the adult, thus the presence of fluctuating BST in all three breeds may indicate the attainment of puberty. Moreover, because the testis of sheep release testosterone that elevates with increasing testicular weight until puberty and maturity (Khalifa et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), it is understandable why the three studied breeds had similar BST (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) for most ages (despite mean significant difference across all ages (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05)): BP, NM and ZL ram-lambs had similar body weights when compared with each other and since there existed a positive correlation (as per the Pearson correlation coefficients for this study) between bodyweight, SC and BST this relationship is expected. Thus, the last null hypothesis, that there would not exist a correlation between bodyweight, BST and SC, is also not accepted.\u003c/p\u003e \u003cp\u003eThe current study recommends that there be intensified research on indigenous sheep breeds for improved reproductive performance and conservation strategies \u0026ndash; This study made use of in situ conservation over ex situ conservation and that allowed breeds to continue to develop and adapt to changing environmental pressures, enabling research to determine their performance more ingeniously. An indigenous breed\u0026rsquo;s capacity to display a adaptive phenotype that is relevant to a production parameter, in a manner that is reliable, is invaluable to the profitability and sustainability of both smallholder and commercial production systems.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eNM\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Namaqua-Afrikaner sheep\u003c/p\u003e\n\u003cp\u003eBP\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Bapedi sheep\u003c/p\u003e\n\u003cp\u003eZL\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Zulu sheep\u003c/p\u003e\n\u003cp\u003eBST\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Blood serum testosterone concentration\u003c/p\u003e\n\u003cp\u003eSC \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Scrotal circumference\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThe authors thank the Agricultural Research Council Animal Production, the Mandela Rhodes Foundation, Agriseta, National Research Foundation (NRF) Thuthuka, the University of Pretoria and the Department of Agriculture, Land Reform and Rural Development (DALRRD).\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThis study received funding for post-graduate support from the Mandela Rhodes Foundation and the National Research Foundation (NRF) Thuthuka program.\u003c/p\u003e\n\u003cp\u003eData availability\u003c/p\u003e\n\u003cp\u003eThe datasets analyse in this study are available in the University of Pretoria\u0026rsquo;s Institutional Repository http://hdl.handle.net/2263/82755. \u003c/p\u003e\n\u003cp\u003eAuthor contribution\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study\u0026rsquo;s design and data collection. The first draft of the manuscript was written by R. Shingange and all authors read, edited and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eStatement of Animal Rights\u003c/p\u003e\n\u003cp\u003eThis study received ethical approval from the Agricultural Research Council Animal Production, Irene: APAEC 2020/07, as well as from the University of Pretoria: NAS207/2020. In addition, the study received Department of Agriculture, Land Reform and Rural Development (DALRRD) Section 20 approval.\u003c/p\u003e\n\u003cp\u003eConflict of Interest Statement\u003c/p\u003e\n\u003cp\u003eThe authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAfrican Union - Interafrican Bureau for Animal Resource. 2009. Strategic Plan 2010 - 2014. Nairobi, Kenya.\u003c/li\u003e\n\u003cli\u003eBanks, E. 1964. Some aspects of sexual behaviour in domestic sheep, Ovis aries. Behaviour 23, 249\u0026ndash;279.\u003c/li\u003e\n\u003cli\u003eBearden, H., Fuquay, J., \u0026amp; Willard, S. 2004. Neuroendocrinology of livestock reproduction.in Applied Animal Reproduction. Pearson Prentice Hall, Upper Saddle River, United States of America.\u003c/li\u003e\n\u003cli\u003eCloete, J. J. E., Hoffman, L. C., \u0026amp; Cloete, S. W. P. 2012. A comparison between slaughter traits and meat quality of various sheep breeds: Wool, dual-purpose and mutton. Meat Science 91, 318\u0026ndash;324 https://doi.org/10.1016/j.meatsci.2012.02.010.\u003c/li\u003e\n\u003cli\u003eColditz, I. G., \u0026amp; Hine, B. C. 2016. Resilience in farm animals: biology, management, breeding and implications for animal welfare. Anim. Prod. Sci. 56, 1961 https://doi.org/10.1071/AN15297.\u003c/li\u003e\n\u003cli\u003eDepartment of Agriculture, Forestry and Fisheries. 2019. Abstract of agricultural statistics. Pretoria, South Africa.\u003c/li\u003e\n\u003cli\u003eEdmondson, M. A., Roberts, J. F., Baird, A. N., Bychawski, S., \u0026amp; Pugh, D. G. 2012. Theriogenology of Sheep and Goats.Pages 150\u0026ndash;230 in Sheep and Goat Medicine. Elsevier, Missouri, United States of America.\u003c/li\u003e\n\u003cli\u003eFoster, D. L., \u0026amp; Hileman, S. M. 2015. Puberty in the Sheep.Pages 1441\u0026ndash;1485 in Knobil and Neill\u0026rsquo;s Physiology of Reproduction. Academic Press, Cambridge, United Kingdom.\u003c/li\u003e\n\u003cli\u003eKennedy, G. C., \u0026amp; Mitra, J. 1963. Body weight and food intake as initiating factors for puberty in the rat. Journal of Physiology 166, 408\u0026ndash;418.\u003c/li\u003e\n\u003cli\u003eKent, M. 2000. Advanced biology.Pages 250\u0026ndash;253 in Oxford University Press, United Kingdom.\u003c/li\u003e\n\u003cli\u003eKhalifa, E. L., Ahmed, M. E., Hafez, Y. H., El-Zolaky, O. A., Bahera, K. M., \u0026amp; Abido, A. A. 2013. Age at puberty and fertility of Rahmani sheep fed on biological inoculated corn silage. Annals of Agricultural Science 58, 163\u0026ndash;172.\u003c/li\u003e\n\u003cli\u003eKunene, W. N., \u0026amp; Fossey, A. 2006. A survey on livestock production in some traditional areas of Northern Kwa-Zulu Natal in South Africa. Livestock Research for Rural Development 18, 30\u0026ndash;33.\u003c/li\u003e\n\u003cli\u003eLord, J. S., Hargrove, J. W., Torr, S. J., \u0026amp; Vale, G. A. 2018. Climate change and African trypanosomiasis vector populations in Zimbabwe\u0026rsquo;s Zambezi valley: A mathematical modelling stud. PLoS Medicine 15, 26\u0026ndash;45.\u003c/li\u003e\n\u003cli\u003eMaqhashu, A., O\u0026rsquo;Neil, H. A., Sebei, P. J., Ramukhithi, F. V., Mapholi, N. O., Nephawe, K. A., \u0026amp; Nedambale, T. L. 2019. The relationship between morphometric characteristics and semen parameters in Bapedi rams. Reproduction, Fertility and Development 32, 196\u0026ndash;201.\u003c/li\u003e\n\u003cli\u003eMarai, I. F. M., El-Darawany, A. A., Fadiel, A., \u0026amp; Abdel-Hafez, M. A. M. 2007. Physiological traits as affected by heat stress in sheep\u0026mdash;A review. Small Ruminant Research 71, 1\u0026ndash;12.\u003c/li\u003e\n\u003cli\u003eMartin, L. C., Brinks, J. S., Bourdon, R. M., \u0026amp; Cundiff, L. V. 1992. Genetic effects on beef heifer puberty and subsequent reproduction. Journal of Animal Science 70, 4006\u0026ndash;4017.\u003c/li\u003e\n\u003cli\u003eMeissner, H., \u0026amp; Engelbrecht, F. 2014. Sustainability of the South African livestock sector towards 2050 Part 2: Challenges, changes and required implementations. South African Journal of Animal Science 43, 289\u0026ndash;301.\u003c/li\u003e\n\u003cli\u003eMolotsi, A. H., Dube, B., \u0026amp; Cloete, S. W. P. 2019. The current status of indigenous ovine genetic resources in southern Africa and future sustainable utilisation to improve livelihoods. Diversity 12, 14\u0026ndash;20.\u003c/li\u003e\n\u003cli\u003eMoulla, F., El-Bouyahiaoui, R., Nazih, R., Abdelaziz, N., Zerrouki, N., \u0026amp; Iguer-Ouada, M. 2018. Characterization of the onset of puberty in Tazegzawt lambs, an endangered Algerian sheep: Body weight, thoracic perimeter, testicular growth and seminal parameters. Veterinary World 11, 889\u0026ndash;894.\u003c/li\u003e\n\u003cli\u003ePenna, B., Libonati, H., Director, A., Sarzedas, A. C., Martins, G., Brand\u0026atilde;o, F. Z., Fonseca, J., \u0026amp; Lilenbaum, W. 2013. Progestin-impregnated intravaginal sponges for estrus induction and synchronization influences on goats vaginal flora and antimicrobial susceptibility. Animal Reproduction Science 142, 71\u0026ndash;74 https://doi.org/10.1016/j.anireprosci.2013.09.006.\u003c/li\u003e\n\u003cli\u003ePickson, R. B., \u0026amp; Boateng, E. 2022. Climate change: a friend or foe to food security in Africa? Environ Dev Sustain 24, 4387\u0026ndash;4412 https://doi.org/10.1007/s10668-021-01621-8.\u003c/li\u003e\n\u003cli\u003eRamirez, D. V., \u0026amp; McCann, S. M. 1963. Comparison of the regulation of luteinizing hormone (LII) secretion in immature and adult rats. Endocrinology 72, 452\u0026ndash;464.\u003c/li\u003e\n\u003cli\u003eRamukhithi, F. V., Nephawe, K. A., Chokoe, T. C., Matabane, M. B., Mphaphathi, M. L., Lehloenya, K. C., \u0026amp; Nedambale, T. L. 2017. Attainment of puberty in South African unimproved indigenous bucks. Small Ruminant Research 153, 57\u0026ndash;61 https://doi.org/10.1016/j.smallrumres.2017.05.009.\u003c/li\u003e\n\u003cli\u003eRyder, M. L., \u0026amp; Bridbury, A. R. 1984. Sheep and man. Economic History Review 37, 468.\u003c/li\u003e\n\u003cli\u003eSA Stud Breeder. 2015. Why Bonsmara? : advertorial. 41, 35.\u003c/li\u003e\n\u003cli\u003eSnyman, H. A. 2014. South African sheep breeds: Namaqua Afrikaner. Info-pack ref. 2014/023. Grootfontein Agricultural Development Institute, Middelburg, South Africa.\u003c/li\u003e\n\u003cli\u003eSnyman, H. A., \u0026amp; Hersleman, M. J. 2005. Comparison of productive and reproductive efficiency of Afrino, Dorper and Merino sheep in the False Upper Karoo. South African Journal of Animal Science 35, 98\u0026ndash;108.\u003c/li\u003e\n\u003cli\u003eSnyman, H. A., Olivier, J. J., \u0026amp; Cloete, J. A. N. 1993. Productive and reproductive performance of Namaqua Afrikaner sheep. Karoo Agriculture 5, 21\u0026ndash;24.\u003c/li\u003e\n\u003cli\u003eWebb, E. C., Visage, P. C., \u0026amp; van der Westhuizen, J. 2018. Effect of Bioregion of the Size and Efficiency of Bonsmara Cattle in Semi-Arid Parts of Southern Africa. IntechOpen Ruminants-The Husbandry, Economic and Health Aspects.\u003c/li\u003e\n\u003cli\u003eWebb, E. C., Visage, P. C., van der Westhuizen, J., \u0026amp; Snyman, H. A. 2017. Influence of bioregion and environmental factors on the growth, size, and reproduction of Bonsmara cows. 47.\u003c/li\u003e\n\u003cli\u003eWilliams, G. L., Amstalden, M., Garcia, M. R., Stanko, R. L., Nizielski, S. E., Morrison, C. D., \u0026amp; Keisler, D. H. 2002. Leptin and its role in the central regulation of reproduction in cattle. Domestic Animal Endocrinology 23, 339\u0026ndash;349 https://doi.org/10.1016/S0739-7240(02)00169-8.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Graph 1 and 2","content":"\u003cp\u003eGraph 1 and 2 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Puberty, indigenous, sheep, ram lamb, mating behaviour","lastPublishedDoi":"10.21203/rs.3.rs-4511150/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4511150/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLivestock must maintain traits that are beneficial to their survival and propagation, so that those genotypes that express the optimal phenotype most reliably, will be selectively favoured. One of these traits is the animal\u0026rsquo;s physiological age, which is correlated with, but not causal to its chronological age, and affects the animal\u0026rsquo;s age at attainment of puberty - an important management parameter and indicator of environmental adaptation. This study aimed to characterise the mating behaviours of pubertal ram-lambs of three of South Africa\u0026rsquo;s oldest indigenous sheep breeds, Bapedi (BP), Namaqua-Afrikaner (NM) and Zulu (ZL), which are landraces to areas of South Africa with different microclimates. Sampling included visual assessment of various mating behaviours (e.g., nosing, mounting) and measurement of bodyweight, scrotal circumference, and blood serum testosterone concentrations. The study found that NM ram-lambs were physiologically younger than BP and ZL ram-lambs at a similar chronological age, as bodyweights and blood serum testosterone concentrations between-breeds were similar (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) but significant between-breed differences of scrotal circumferences were found (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) at most ages, wherein NM ram-lambs had lower mean scrotal circumferences, had the lowest cumulative observations of all appraised mating behaviours; and began displaying their first mating behaviour (nosing) one month later than BP and ZL ram-lambs did. Thus, NM ram-lambs displayed younger physiological age, likely as an adaptation to the hotter and drier microenvironment to which they are indigenous. It is recommended that such breeds be profiled and used in mixed-breeding programs, as their adaptation to harsher environments will be invaluable as climate change\u0026rsquo;s impacts become more apparent in sub-Saharan Africa.\u003c/p\u003e","manuscriptTitle":"Correlations among South African indigenous ram-lambs’ physiological age and various mating behaviours at puberty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-16 11:02:20","doi":"10.21203/rs.3.rs-4511150/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision with re-assessment","date":"2024-08-21T14:29:40+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-07-22T13:35:56+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-22T11:19:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-14T00:35:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"Tropical Animal Health and Production","date":"2024-06-06T05:28:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"tropical-animal-health-and-production","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trop","sideBox":"Learn more about [Tropical Animal Health and Production](https://www.springer.com/journal/11250)","snPcode":"11250","submissionUrl":"https://submission.nature.com/new-submission/11250/3","title":"Tropical Animal Health and Production","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"aa1558d1-0c3a-4611-a3b1-d01b3bc075d1","owner":[],"postedDate":"August 16th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2025-04-11T15:16:31+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-16 11:02:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4511150","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4511150","identity":"rs-4511150","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}