Successful induction of artificial lactation in non-pregnant gilts

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This study tested a protocol for induction of artificial lactation (AL) in non-pregnant gilts as a mean to supply milk to newborn piglets. In Experiment I, five gilts received 10 mg estradiol cypionate (EC) on the last day of estrus expression (D0), 10 mg EC and 300 mg long-acting progesterone (P4) on D26, and two doses of a prostaglandin F2α analogue (PGF) I.M. on D36 (0.53 mg each, 12 h apart). Blood was collected on D12, D19, D26 and D33. Milk secretion occurred in all treated gilts 24 h after the PGF administration, lasting at least 8 d. Milk samples were collected from D37 to D45. The circulatory P4 concentration was lower on D12 than subsequently (P 0.05). The milk produced during the AL was generally richer in protein and poorer in fat than the milk produced during the lactation of a control sow, but both concentrations were only altered near to the 3rd d of the AL. In Experiment II, the same protocol for induction of AL was administered to two gilts. After milk secretion started, each gilt received four 5-d old piglets fostered from other litters. The piglets were nursed for 22 d and weaned weighing approximately 5 kg. Considering both experiments, AL was induced in all treated gilts and the milk produced was capable to nurture fostered piglets. artificial lactation estradiol cypionate long-acting progesterone fostered piglets gilts Figures Figure 1 Figure 2 Introduction The increase in ovulation rate over the last decades resulted in a remarkable increase in the prolifacy of swine females (reviewed by Kemp et al. 2018 ). As the uterine space did not increase proportionally (Matheson et al. 2018 ), piglets born with low weight and reduced viability became more frequent (Alvarenga et al. 2013 ). Such piglets have difficulties to ingest colostrum and are more likely to become runts (Quesnel et al. 2012 ), to die during lactation (Kilbride et al. 2012 ; Kirkden et al. 2013 ), or to have low weaning weight (Devillers et al. 2011 ; Declerck et al. 2016 ). As the number of functional teats in sows also did not increase proportionally to the increase in litter size (Declerck et al. 2016 ; Kobek-Kjeldager et al. 2020 ), such problems were not mitigated by conventional farrowing room management practices, such as cross fostering (Alexopoulos et al. 2018 ), intermittent suckling (Chen et al. 2017 ) and split weaning (Terry et al. 2014 ). Nurse sows are frequently used to nurture piglets fostered out of other litters after weaning their original litters, to minimize piglet losses during lactation (Schmitt et al. 2019 ). Compared to regular females, nurse sows may subsequently farrow litters of similar size (Bruun et al. 2016 ). Nevertheless, the extended lactation of nurse sows may result in prolonged weaning-to-estrus interval, which contributes to increase the number of nonproductive days at herd level (Dial et al. 1992 ) and may incur in negative welfare implications (Sørensen et al. 2016 ; Schmitt et al. 2019 ). The induction of artificial lactations (AL) through hormonal protocols has been employed for decades in the dairy industry to produce milk from non-cycling cows (reviewed by Tucker 2000 ). Besides the obvious economic benefit, induction of AL is related to the subsequent restoration of the cyclicity of the treated cows and to reduced culling of high merit females (Magliaro et al. 2004 , Macrina et al. 2011 ). Initially, induction of AL required parenteral administration of high doses of progestogens and estrogens for several weeks (Fleming et al., 1986 ), but the currently used protocols are shorter (reviewed by Tucker 2000 ). Such treatment simulates the endocrine environment observed during late gestation. Thereafter, prostaglandin F2α (PGF), dexametasone and/or oxytocin may be administered, to promote an increase in the circulatory concentration of prolactin and glucocorticoids, as occurs physiologically prior to parturition, stimulating the growth of the mammary tissue (Loisel et al. 2015 ). Thus, induction of AL in female swine may be an alternative to increase milk availability in farrowing rooms. Physiologically, mammary gland development starts at puberty as the estradiol circulatory concentration increases, remains slow during the two initial parts of the first gestation and accelerates in the final third of the gestation (reviewed by Hurley 2019 ). Experimentally, AL was induced in transgenic gilts that received subcutaneous implants for slow release of estrogens and progestogens for 21 d (Shamay et al. 1992 ). Nonetheless, slow release of progestogen through intravaginal devices, as often used in cattle (reviewed by Bó et al. 2016 ), produces irregular response in sows (Ulguim et al. 2019 ; Quirino et al. 2020 ). Progestogen administration in swine is more common through diet supplementation to induce estrus (Martinat-Botté et al. 1995 ; Werlang et al. 2011 ), but the response may be inconsistent. Although supplementation of a phytoestrogen to gilts in the diet was associated with hyperplasia of the mammary parenchyma after puberty, no effect was observed on circulatory concentrations of steroids and prolactin (Farmer et al. 2010 ). Parenteral treatment with steroids would be more efficient to induce lactation in non-pregnant swine females, as reported elsewhere (Noguchi et al. 2020 ), but, in such study, the steroids were from sources not used in livestock. Hormones frequently used in ruminants to control the estrus cycle, such as estradiol esters (reviewed by Bó et al. 2016 ) and the long-acting progesterone (P4) (Alvarado-Espino et al. 2019 ; de Lima et al. 2020 ) may be capable to induce lactation in non-pregnant females, which was not yet tested. The objective of this study was to test a protocol for AIL in non-pregnant gilts through parenteral administration of steroid hormones, to determine the serum levels of reproductive steroids and the composition of the milk during the artificial lactation and to evaluate whether that milk could nourish fostered piglets. Material And Methods In both experiments, the females were under the same conditions, were fed the same diet, and had ad libitum access to water. Experiment I This experiment was conducted at an experimental station in the Universidade de Passo Fundo (Passo Fundo, RS, Brazil; 28°15'40'' S, 52°24'30''W), including five cycling gilts of the native breed Moura, with 240 d of age and 100 kg liveweight, in average. The gilts were housed in a collective barn and were fed a commercial gestation diet: 14.4% crude protein; 3,100 Kcal/kg ME; and 3.2% fat. Initially, the gilts were submitted to an estrus synchronization protocol through the daily oral administration of 20 mg Altrenogest (Regumate®, MSD Saúde Animal), for 18 d (Martinat-Botté et al. 1995). Thereafter, estrus detection was conducted by a trained technician twice daily, in the presence of a sexually mature boar. Estrus signs were observed 2-3 d after ceasing the Altrenogest treatment. The protocol for induction of AL (Fig. 1) considered the last day of estrus expression as D0. On D12, all gilts received 10 mg estradiol cypionate (SincroCP®, Ourofino saúde animal, Cravinhos, SP, Brazil), via I.M. On D26, gilts once again received 10 mg estradiol cypionate plus 300 mg long-acting P4 (Sincrogest® injetável, Ourofino saúde animal), I.M. Ten days later, two doses of 0.53 mg of a PGF analogue (Cloprostenol, Ciosin®, MSD Saúde Animal) were administered, within a 12-h interval. On D12, D19, D26 and D33, blood samples were collected from the gilts by puncturing the jugular vein. Those samples were centrifuged at 2,000 rpm for 5 min to separate the serum, fractioned in 500 μl aliquots and frozen at a -20ºC. Subsequently, blood samples were sent to a commercial laboratory to determine the serum concentrations of estradiol and P4, through chemiluminescence: Elecsys estradiol III, Roche, Ref. 06656021119, sensitivity of 5 pg/mL; and ADVIA Centaur systems progesterone kit, Siemens, Ref. 01586287, sensitivity of 0.21 ng/mL. For both assays, the intra and inter-assay coefficients of variation were inferior to 12%. After verifying the presence of milk secretion in the mammary glands of the gilts, samples were milked by hand daily, 5 min after administering 2 mL oxytocin I.M., until milk secretion ceased. The milk composition was analyzed using the Delta LactoScope milk and dairy products analyzer (PerkinElmer do Brasil Ltda., São Paulo, SP, Brazil). The analysis of the centesimal milk composition included the concentrations of protein, fat, lactose and total solids and the count of somatic cells. For reference, blood and milk samples were also collected from a multiparous sow of the same genetic composition (from now on referred as a control sow), which was gestating simultaneously to the experiment. Blood samples were collected at two (D -14) and one weeks (D -7) prior to the expected day of farrowing. Milk samples were collected at the day of farrowing (D0), at 24 and 48 h post-partum, and at 7 days after farrowing (D7). Experiment II This experiment was conducted at an experimental station in Embrapa suínos e aves (Concórdia, SC, Brazil; 27°14'3'' S, 52°1'43''W), including two 120 d-old gilts from Embrapa’s commercial genetics. The gilts were housed in individual crates and received the same protocol for induction of AL described for Experiment I. After the observation of milk secretion, the gilts were transferred to farrowing crates. At D37, four 5-d old runt piglets from litters farrowed by other sows housed in the same facility were fostered to each gilt, to be nursed until weaning. Statistical analyses After applying the Shapiro-Wilk test to all responses of interest, the serum levels of estradiol and P4 were transformed to arcsine and the count of somatic cells in milk samples was transformed to the logarithmic scale, due to lack of normality. Comparisons across periods of sample collection were done by analyses of variance, adjusted for individual female effects. Comparisons of means were done with the Tukey test. The analyses of the milk composition considered an 8-d period, even though one gilt produced milk for 10 d. All analyses were conducted with Statistix® (2013). Results Experiment I Serum P4 levels on the three subsequent weeks of the AL (Fig. 2A) were greater than on D12 (P 0.05) across periods (Fig. 2B). For the control sow, serum P4 levels were 35.6 ± 28.8 ng/mL on D -14 and 16.3 ± 0.9 ng/mL on D -7, whereas estradiol levels were 642.6 ± 146.6 pg/mL on D -14 and 1,037.2 ± 847.8 pg/mL, on D -7. The composition of the milk produced during the natural lactation of the control sow is shown in Table 1. All treated gilts responded to the AL protocol. Milk secretion started 24 h after the first administration of PGF and it was maintained for 8 d for most gilts, except for one gilt that produced milk for 10 d. The fat concentration in the milk of the AL was 6.3 ± 2.5 g/100 g. Fat concentration during the first 3 d of the AL was lower (P < 0.05) than on subsequent periods (Table 2), achieving the greatest concentration at the 7 th and the 8 th d (P < 0.05). During the AL, the protein milk concentration was 13.2 ± 2.0 g/100 g and the total solids concentration was 23.4 ± 3.3 g/100 g. Both such concentrations were unaltered during most of the AL (P > 0.05) but were both lowest at the 3 rd d (P < 0.05, Table 2). The lactose milk concentration during the AL was 2.6 ± 0.8 g/100 g. Greater lactose concentration was observed until the 2 nd d (Table 2), with reduced concentration occurring from the 4 th d on (P < 0.05). The average somatic cells count was 3,241.0 ± 2,437.2 x 100/mL of milk secreted during the AL. Compared to D0, greater counts were observed on the 1 st , the 7 th , and the 8 th d of the AL (P < 0.05, Table 2). Experiment II Both treated gilts responded to the protocol for induction of AL with milk secretion. After adaptation to the presence of the fostered piglets during the first day of lactation, the piglets were nursed for 22 d and weaned with an average liveweight of 5 kg, although one of the fostered piglets died during the lactation. Discussion In the present study, for the first time, AL was induced in non-gestating gilts parenterally treated with estradiol cypionate and long-acting P4. Considering both experiments, milk secretion occurred in all treated gilts. Previously, AL was reported in non-gestating sows treated with exogenous estradiol, but only for 53.8% of the treated females (Noguchi et al. 2020 ). That may reflect the fact that the estradiol source used in the referred study is originally prescribed to treat gynecological disorders in women (Sosic-Jurjevic et al. 2005 ; Abdel-Dayem and Elge 2009 ) and is not commercially available for use in swine. In contrast, estradiol cypionate is commonly used in programs to control the estrous cycle of cows (reviewed by Bó et al. 2016 ), although it is not frequently used in female swine. Physiologically, estradiol and P4 act in synergy to boost mammogenesis during pregnancy, since estradiol increases the number of P4 receptors in the mammary tissue (reviewed by Tucker 2000 ). Therefore, the positive response observed in the present study for all treated gilts likely also reflects the action of the long-acting P4. As P4 supplementation stimulates endometrium vascular activity in gestating sows, improving embryo survival (Muro et al. 2020 ; Szymanska and Blitek 2020 ), the P4 treatment may have indirectly modulated a response at mammary gland level. Those findings suggest alternative applications for both those steroids in female swine. The serum estradiol concentration was not altered during the AL, whereas the serum P4 concentration was increased during the three subsequent weeks after D12. Hence, the tested protocol was effective to simulate a pseudo gestation. That endocrine environment may explain the lack of estrus expression in the treated gilts, which is considered a disadvantage in cows with prolonged AL, due to the long exposure to estrogens (Magliaro et al. 2004 , Macrina et al. 2011 ). On the other hand, estrus expression during lactation may occur naturally in nurse sows and in lactating sows exposed to reduced suckling frequency, such as those submitted to intermittent suckling (Gerritsen et al. 2008) and split weaning (Terry et al. 2014 ). Furthermore, the use of AL in dairy cows is still subjected to controversies because of the concern that residues of steroid hormones in the milk might lead to collateral effects on consumers of dairy products (Qin et al. 2004 ; Gamma and Sato 2005 ). In swine, that is unlikely to be an issue, since the milk of sows is not destined to human consumption. In Experiment I, milk secretion lasted 8 d for most gilts. A previous study reported milk secretion in an AL for at least 144 h (Noguchi et al. 2020 ). The longer duration of the AL observed in the present study may be another effect of the supplementation with both estradiol cypionate and long-acting P4. Nevertheless, a novel finding of the present study is the fact that, in Experiment II, some piglets were successfully nursed during the AL until weaning. The milk produced during the AL by the gilts of Experiment I apparently presented greater protein concentration and lower concentration of fat and lactose compared not only to the milk produced during the natural lactation of the control sow, but also to reference values (reviewed by Hurley 2019 ). A previous study reported that the milk produced during AL contains immunoglobulin levels as high as those found in colostrum (Noguchi et al. 2020 ). Additionally, likely due to the continuous stimulation of the mammary gland by the piglets, the AL was extended for 22 d in Experiment II, approaching the duration of the natural lactations applied in commercial swine farms. Nonetheless, each treated gilt nursed only 4 runt piglets. As those runt piglets may have had retarded prenatal intrauterine growth (Bérard et al. 2010 , Alvarenga et al. 2012), were 5-d old when fostered in and probably did not have adequate colostrum ingestion (Quesnel et al. 2012 ), their average weaning weight was nearly 1.5 kg lower compared to weaned piglets of contemporary litters, which may be expected from piglets with low birth weight (Quiniou at al. 2002). Thus, future studies should evaluate if the induction of AL can be efficient for females nursing larger litters compared to natural lactations of females nursing litters of similar size. The present study is the first one to suggest that induction of AL in pseudo pregnant females may be an alternative to provide nutritional support to the excess piglets in farrowing rooms. However, further research is necessary to determine if the induction of AL could be applied in commercial farms. As the tested protocol may be considered labor intensive, alternatives to reduce its duration should be investigated. In the present study, we observed that some treated gilts required an adaptation period to become accustomed to the presence of the fostered piglets, which suggest that the tested protocol may be more efficient on older sows, with better maternal ability. As gilts not selected for reproduction would have greater market value at slaughterhouses, sows destined to culling, either due to old age or to previous reproductive failure, would likely be better candidates for induction of AL. If sows to be culled after weaning are chosen, the duration of the protocol to induce AL may be reduced, since the natural estrous synchronization post-weaning may eliminate the need of a previous pharmacological estrous synchronization, as conducted in the present study. Moreover, the treatment applied to induce AL may reestablish the cyclicity of anestrous sows, as reported for cows (Magliaro et al. 2004 , Macrina et al. 2011 ), which may contribute to reduce culling rates. Furthermore, compared to the common practice of using nurse sows with prolonged lactations, the induction of AL in sows to be culled (no longer part of the regular breeding inventory), would not disrupt the production flow, which would be important in farms using batch farrowing management systems (Lurette et al. 2008 ). Conclusions Lactation was successfully induced in non-gestating gilts parenterally treated with estradiol cypionate and long-acting progesterone. Compared to a natural lactation, the milk produced during the artificial lactation presented increased protein and reduced fat and lactose contents. Runt piglets were nursed during the artificial lactation until weaning. Declarations Author’s contributions AD Cordeiro: investigation, experimental procedures, and writing; AJB Conterato: investigation, and experimental procedures; DLA Dartora: investigation, and experimental procedures; I Bianchi: experimental design and article review; R Zanella: experimental design and article review; MG Marques: experimental design and article review; BG Gasperin: conceptualization, experimental design and article review; T Lucia Jr.: conceptualization, experimental design, funding acquisition, supervision, article review and editing. Data availability The datasets in this study are available from the corresponding author on reasonable request. All data and materials are available for publication. Consent to participate All authors read and approved the manuscript. Consent to publish All authors read and approved the manuscript. 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Reprod Dom Anim 46:818–823. https://doi.org/10.1111/j.1439-0531.2010.01747.x Tables Table 1 Composition (means ± DP) of the milk produced during the first week of natural lactation of a multiparous control sow (n = 2 collections/day) Day of lactation Protein (g/100 g) Fat (g/100 g) Lactose (g/100 g) Total solids (g/100 g) Somatic cells (x 100/mL) 0 14.6 ± 0.1 4.7 ± 0.2 2.8 ± 0,1 24.3± 0,2 1,115.0 ± 69.3 1 9.3 ± 0.1 8.3 ± 0.7 3.1 ± 0.6 22.5 ± 0.1 5,047.1 ± 177.5 2 7.3 ± 0.6 14. ± 0.1 3.1± 0.2 26.3± 0.5 4,500.5 ± 430.6 7 5.0 ± 0.2 7.2 ± 0.1 4.9 ± 0.1 18.5 ± 0.2 3,387.0 ± 326.7 Overall 9.0 ± 3.8 8.7 ± 3.8 3.5 ± 0.9 22.9 ± 3.1 3,512.6 ± 1,626.6 Table 2 Composition of the milk produced by non-pregnant gilts during an artificial lactation (n = 5 gilts)* Day of lactation Protein (g/100 g) Fat (g/100 g) Lactose (g/100 g) Total solids (g/100 g) Somatic cells (x 100/mL) 0 15.4 A 3.3 C 3.6 A 23.5 ABC 2,039.6 B 1 13.4 ABC 4.2 C 3.4 A 22.2 ABC 4,705.0 A 2 11.7 BC 4.3 C 3.6 A 20.6 BC 3,517.4 AB 3 11.1 C 4.2 C 2.9 AB 19.4 C 1,798.6 AB 4 12.9 ABC 6.8 B 2.5 BC 23.5 ABC 1,853.2 AB 5 13.0 ABC 6.7 B 2.2 CD 23.2 ABC 2,603.2 AB 6 12.9 ABC 8.4 AB 2.1 CD 24.7 AB 3,014.2 AB 7 13.9 ABC 9.5 A 1.8 D 26.6 A 4,148.4 A 8 14.5 ABC 9.2 A 1.6 D. 26.7 A 5,492.6 A EPM 0.7 0.5 0.1 1.0 1,086.9 A,B Means ± SEM having distinct superscripts differ by at least P < 0.05 Additional Declarations No competing interests reported. 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0.05\u003c/p\u003e\u003cp\u003e*10 mg estradiol cypionate, 12 d after the last day of estrus; 10 mg estradiol cypionate plus 300 mg long-acting P4, 26 d after the last day of estrus; and two doses of 0.530 mg of a PGF analogue within a 12-h interval, 26 d after the last day of estrus.\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-1817065/v1/ffbeab0a6fec67263127a6ae.png"},{"id":24898701,"identity":"96b3a9f7-46c3-4176-9acf-10a78c9dd376","added_by":"auto","created_at":"2022-08-08 05:29:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":376255,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1817065/v1/e3e802ad-8294-485b-aecb-e49fab351f3b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Successful induction of artificial lactation in non-pregnant gilts","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe increase in ovulation rate over the last decades resulted in a remarkable increase in the prolifacy of swine females (reviewed by Kemp et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). As the uterine space did not increase proportionally (Matheson et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), piglets born with low weight and reduced viability became more frequent (Alvarenga et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Such piglets have difficulties to ingest colostrum and are more likely to become runts (Quesnel et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), to die during lactation (Kilbride et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Kirkden et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), or to have low weaning weight (Devillers et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Declerck et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). As the number of functional teats in sows also did not increase proportionally to the increase in litter size (Declerck et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Kobek-Kjeldager et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), such problems were not mitigated by conventional farrowing room management practices, such as cross fostering (Alexopoulos et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), intermittent suckling (Chen et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) and split weaning (Terry et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Nurse sows are frequently used to nurture piglets fostered out of other litters after weaning their original litters, to minimize piglet losses during lactation (Schmitt et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Compared to regular females, nurse sows may subsequently farrow litters of similar size (Bruun et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Nevertheless, the extended lactation of nurse sows may result in prolonged weaning-to-estrus interval, which contributes to increase the number of nonproductive days at herd level (Dial et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1992\u003c/span\u003e) and may incur in negative welfare implications (S\u0026oslash;rensen et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Schmitt et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe induction of artificial lactations (AL) through hormonal protocols has been employed for decades in the dairy industry to produce milk from non-cycling cows (reviewed by Tucker \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Besides the obvious economic benefit, induction of AL is related to the subsequent restoration of the cyclicity of the treated cows and to reduced culling of high merit females (Magliaro et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Macrina et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Initially, induction of AL required parenteral administration of high doses of progestogens and estrogens for several weeks (Fleming et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1986\u003c/span\u003e), but the currently used protocols are shorter (reviewed by Tucker \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Such treatment simulates the endocrine environment observed during late gestation. Thereafter, prostaglandin F2α (PGF), dexametasone and/or oxytocin may be administered, to promote an increase in the circulatory concentration of prolactin and glucocorticoids, as occurs physiologically prior to parturition, stimulating the growth of the mammary tissue (Loisel et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Thus, induction of AL in female swine may be an alternative to increase milk availability in farrowing rooms.\u003c/p\u003e \u003cp\u003ePhysiologically, mammary gland development starts at puberty as the estradiol circulatory concentration increases, remains slow during the two initial parts of the first gestation and accelerates in the final third of the gestation (reviewed by Hurley \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Experimentally, AL was induced in transgenic gilts that received subcutaneous implants for slow release of estrogens and progestogens for 21 d (Shamay et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). Nonetheless, slow release of progestogen through intravaginal devices, as often used in cattle (reviewed by B\u0026oacute; et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), produces irregular response in sows (Ulguim et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Quirino et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Progestogen administration in swine is more common through diet supplementation to induce estrus (Martinat-Bott\u0026eacute; et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; Werlang et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), but the response may be inconsistent. Although supplementation of a phytoestrogen to gilts in the diet was associated with hyperplasia of the mammary parenchyma after puberty, no effect was observed on circulatory concentrations of steroids and prolactin (Farmer et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Parenteral treatment with steroids would be more efficient to induce lactation in non-pregnant swine females, as reported elsewhere (Noguchi et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), but, in such study, the steroids were from sources not used in livestock. Hormones frequently used in ruminants to control the estrus cycle, such as estradiol esters (reviewed by B\u0026oacute; et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) and the long-acting progesterone (P4) (Alvarado-Espino et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; de Lima et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) may be capable to induce lactation in non-pregnant females, which was not yet tested. The objective of this study was to test a protocol for AIL in non-pregnant gilts through parenteral administration of steroid hormones, to determine the serum levels of reproductive steroids and the composition of the milk during the artificial lactation and to evaluate whether that milk could nourish fostered piglets.\u003c/p\u003e"},{"header":"Material And Methods","content":"\u003cp\u003eIn both experiments, the females were under the same conditions, were fed the same diet, and had \u003cem\u003ead libitum\u003c/em\u003e access to water.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExperiment I\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis experiment was conducted at an experimental station in the Universidade de Passo Fundo (Passo Fundo, RS, Brazil;\u0026nbsp;28°15'40'' S, 52°24'30''W), including five cycling gilts of the native breed Moura, with 240 d of age and 100 kg liveweight, in average. The gilts were housed in a collective barn and were fed a commercial gestation diet:\u0026nbsp;14.4% crude protein; 3,100 Kcal/kg ME; and 3.2% fat.\u003c/p\u003e\n\u003cp\u003eInitially, the gilts were submitted to an estrus synchronization protocol through the daily oral administration of 20 mg Altrenogest (Regumate®, MSD Saúde Animal), for 18 d (Martinat-Botté et al.\u0026nbsp;1995). Thereafter, estrus detection was conducted by a trained technician twice daily, in the presence of a sexually mature boar. Estrus signs were observed 2-3 d after ceasing the\u0026nbsp;Altrenogest treatment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe protocol for\u0026nbsp;induction of AL\u0026nbsp;(Fig. 1) considered the last day of estrus expression as D0. On D12, all gilts received 10 mg estradiol cypionate (SincroCP®, Ourofino saúde animal, Cravinhos, SP, Brazil), via I.M. On D26, gilts once again received 10 mg estradiol cypionate plus\u0026nbsp;300 mg long-acting\u0026nbsp;P4\u0026nbsp;(Sincrogest® injetável, Ourofino saúde animal), I.M. Ten days later, two doses of 0.53 mg of a\u0026nbsp;PGF\u0026nbsp;analogue\u0026nbsp;(Cloprostenol, Ciosin®, MSD Saúde Animal) were administered, within a 12-h interval.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOn D12, D19, D26 and D33, blood samples were collected from the gilts by puncturing the jugular vein. Those samples were centrifuged at 2,000 rpm for 5 min to separate the serum, fractioned in 500\u0026nbsp;μl aliquots and frozen at a\u0026nbsp;-20ºC. Subsequently, blood samples were sent to a commercial laboratory to determine the serum concentrations of estradiol and\u0026nbsp;P4, through\u0026nbsp;chemiluminescence: Elecsys estradiol III, Roche, Ref. 06656021119, sensitivity of 5 pg/mL; and ADVIA Centaur systems progesterone kit, Siemens, Ref. 01586287, sensitivity of 0.21 ng/mL. For both assays, the intra and inter-assay coefficients of variation were inferior to 12%.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAfter verifying the presence of milk secretion in the mammary glands of the gilts, samples were milked by hand daily, 5 min after administering 2 mL oxytocin I.M., until milk secretion ceased. The milk composition was analyzed using the Delta\u0026nbsp;LactoScope milk and dairy products analyzer (PerkinElmer do Brasil Ltda., São Paulo, SP, Brazil). The analysis of the centesimal milk composition included the concentrations of protein, fat, lactose and total solids and the count of somatic cells.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor reference, blood and milk samples were also collected from a multiparous sow of the same genetic composition (from now on referred as a control sow), which was gestating simultaneously to the experiment. Blood samples were collected at two (D -14) and one weeks (D -7) prior to the expected day of farrowing. Milk samples were collected at the day of farrowing (D0), at 24 and 48 h post-partum, and at 7 days after farrowing (D7). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExperiment II\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis experiment was conducted at an experimental station in Embrapa suínos e aves (Concórdia, SC, Brazil;\u0026nbsp;27°14'3'' S,\u0026nbsp;52°1'43''W), including two 120 d-old gilts from Embrapa’s commercial genetics. The gilts were housed in individual crates and received the same protocol for\u0026nbsp;induction of AL\u0026nbsp;described for Experiment I.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAfter the observation of milk secretion, the gilts were transferred to farrowing crates. At D37, four 5-d old runt piglets from litters farrowed by other sows housed in the same facility were fostered to each gilt, to be nursed until weaning.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analyses\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter applying the Shapiro-Wilk test to all responses of interest, the serum levels of estradiol and P4 were transformed to arcsine and the count of somatic cells in milk samples was transformed to the logarithmic scale, due to lack of normality. Comparisons across periods of sample collection were done by analyses of variance, adjusted for individual female effects. Comparisons of means were done with the Tukey test. The analyses of the milk composition considered an 8-d period, even though one gilt produced milk for 10 d. All analyses were conducted with Statistix® (2013). \u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eExperiment I\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSerum\u0026nbsp;P4\u0026nbsp;levels on the three subsequent weeks of the AL (Fig. 2A) were greater than on D12 (P \u0026lt; 0.05), but serum estradiol levels did not differ (P \u0026gt; 0.05) across periods (Fig. 2B). For the control sow, serum\u0026nbsp;P4\u0026nbsp;levels were 35.6 ± 28.8 ng/mL on D -14 and 16.3 ± 0.9 ng/mL on D -7, whereas estradiol levels were 642.6 ± 146.6 pg/mL on D -14 and 1,037.2 ± 847.8 pg/mL, on D -7. The composition of the milk produced during the natural lactation of the control sow is shown in Table 1.\u003c/p\u003e\n\u003cp\u003eAll treated gilts responded to the AL protocol. Milk secretion started 24 h after the first administration of PGF and it was maintained for 8 d for most gilts, except for one gilt that produced milk for 10 d.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe fat concentration in the milk of the AL was\u0026nbsp;6.3 ± 2.5 g/100 g. Fat concentration\u0026nbsp;during the first 3 d of the\u0026nbsp;AL\u0026nbsp;was lower (P \u0026lt; 0.05) than on subsequent periods (Table 2), achieving the greatest concentration at the 7\u003csup\u003eth\u003c/sup\u003e and the 8\u003csup\u003eth\u003c/sup\u003e d (P \u0026lt; 0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDuring the\u0026nbsp;AL, the protein milk concentration was\u0026nbsp;13.2 ± 2.0 g/100 g and the total solids concentration was 23.4 ± 3.3 g/100 g. Both such\u0026nbsp;concentrations were unaltered during most of the AL (P \u0026gt; 0.05) but were both lowest at the 3\u003csup\u003erd\u003c/sup\u003e d (P \u0026lt; 0.05, Table 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe lactose milk concentration during the AL was\u0026nbsp;2.6 ± 0.8 g/100 g.\u0026nbsp;Greater lactose concentration was observed until the 2\u003csup\u003end\u003c/sup\u003e d (Table 2), with reduced concentration occurring from the 4\u003csup\u003eth\u003c/sup\u003e d on (P \u0026lt; 0.05).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe average somatic cells count was\u0026nbsp;3,241.0 ± 2,437.2 x 100/mL of milk secreted during the AL.\u0026nbsp;Compared to D0, greater counts were observed on the 1\u003csup\u003est\u003c/sup\u003e, the 7\u003csup\u003eth\u003c/sup\u003e, and the 8\u003csup\u003eth\u003c/sup\u003e d of the AL (P \u0026lt; 0.05, Table 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExperiment II\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth treated gilts responded to the protocol for induction of AL with milk secretion. After adaptation to the presence of the fostered piglets during the first day of lactation, the piglets were nursed for 22 d and weaned with an average liveweight of 5 kg, although one of the fostered piglets died during the lactation. \u0026nbsp; \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn the present study, for the first time, AL was induced in non-gestating gilts parenterally treated with estradiol cypionate and long-acting P4. Considering both experiments, milk secretion occurred in all treated gilts. Previously, AL was reported in non-gestating sows treated with exogenous estradiol, but only for 53.8% of the treated females (Noguchi et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). That may reflect the fact that the estradiol source used in the referred study is originally prescribed to treat gynecological disorders in women (Sosic-Jurjevic et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Abdel-Dayem and Elge \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) and is not commercially available for use in swine. In contrast, estradiol cypionate is commonly used in programs to control the estrous cycle of cows (reviewed by B\u0026oacute; et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), although it is not frequently used in female swine. Physiologically, estradiol and P4 act in synergy to boost mammogenesis during pregnancy, since estradiol increases the number of P4 receptors in the mammary tissue (reviewed by Tucker \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Therefore, the positive response observed in the present study for all treated gilts likely also reflects the action of the long-acting P4. As P4 supplementation stimulates endometrium vascular activity in gestating sows, improving embryo survival (Muro et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Szymanska and Blitek \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), the P4 treatment may have indirectly modulated a response at mammary gland level. Those findings suggest alternative applications for both those steroids in female swine.\u003c/p\u003e \u003cp\u003eThe serum estradiol concentration was not altered during the AL, whereas the serum P4 concentration was increased during the three subsequent weeks after D12. Hence, the tested protocol was effective to simulate a pseudo gestation. That endocrine environment may explain the lack of estrus expression in the treated gilts, which is considered a disadvantage in cows with prolonged AL, due to the long exposure to estrogens (Magliaro et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Macrina et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). On the other hand, estrus expression during lactation may occur naturally in nurse sows and in lactating sows exposed to reduced suckling frequency, such as those submitted to intermittent suckling (Gerritsen et al. 2008) and split weaning (Terry et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Furthermore, the use of AL in dairy cows is still subjected to controversies because of the concern that residues of steroid hormones in the milk might lead to collateral effects on consumers of dairy products (Qin et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Gamma and Sato \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). In swine, that is unlikely to be an issue, since the milk of sows is not destined to human consumption.\u003c/p\u003e \u003cp\u003eIn Experiment I, milk secretion lasted 8 d for most gilts. A previous study reported milk secretion in an AL for at least 144 h (Noguchi et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The longer duration of the AL observed in the present study may be another effect of the supplementation with both estradiol cypionate and long-acting P4. Nevertheless, a novel finding of the present study is the fact that, in Experiment II, some piglets were successfully nursed during the AL until weaning. The milk produced during the AL by the gilts of Experiment I apparently presented greater protein concentration and lower concentration of fat and lactose compared not only to the milk produced during the natural lactation of the control sow, but also to reference values (reviewed by Hurley \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). A previous study reported that the milk produced during AL contains immunoglobulin levels as high as those found in colostrum (Noguchi et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Additionally, likely due to the continuous stimulation of the mammary gland by the piglets, the AL was extended for 22 d in Experiment II, approaching the duration of the natural lactations applied in commercial swine farms. Nonetheless, each treated gilt nursed only 4 runt piglets. As those runt piglets may have had retarded prenatal intrauterine growth (B\u0026eacute;rard et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2010\u003c/span\u003e, Alvarenga et al. 2012), were 5-d old when fostered in and probably did not have adequate colostrum ingestion (Quesnel et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), their average weaning weight was nearly 1.5 kg lower compared to weaned piglets of contemporary litters, which may be expected from piglets with low birth weight (Quiniou at al. 2002). Thus, future studies should evaluate if the induction of AL can be efficient for females nursing larger litters compared to natural lactations of females nursing litters of similar size.\u003c/p\u003e \u003cp\u003eThe present study is the first one to suggest that induction of AL in pseudo pregnant females may be an alternative to provide nutritional support to the excess piglets in farrowing rooms. However, further research is necessary to determine if the induction of AL could be applied in commercial farms. As the tested protocol may be considered labor intensive, alternatives to reduce its duration should be investigated. In the present study, we observed that some treated gilts required an adaptation period to become accustomed to the presence of the fostered piglets, which suggest that the tested protocol may be more efficient on older sows, with better maternal ability. As gilts not selected for reproduction would have greater market value at slaughterhouses, sows destined to culling, either due to old age or to previous reproductive failure, would likely be better candidates for induction of AL. If sows to be culled after weaning are chosen, the duration of the protocol to induce AL may be reduced, since the natural estrous synchronization post-weaning may eliminate the need of a previous pharmacological estrous synchronization, as conducted in the present study. Moreover, the treatment applied to induce AL may reestablish the cyclicity of anestrous sows, as reported for cows (Magliaro et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Macrina et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), which may contribute to reduce culling rates. Furthermore, compared to the common practice of using nurse sows with prolonged lactations, the induction of AL in sows to be culled (no longer part of the regular breeding inventory), would not disrupt the production flow, which would be important in farms using batch farrowing management systems (Lurette et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eLactation was successfully induced in non-gestating gilts parenterally treated with estradiol cypionate and long-acting progesterone. Compared to a natural lactation, the milk produced during the artificial lactation presented increased protein and reduced fat and lactose contents. Runt piglets were nursed during the artificial lactation until weaning.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor\u0026rsquo;s contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAD Cordeiro: investigation, experimental procedures, and writing; AJB Conterato: investigation, and experimental procedures; DLA Dartora: investigation, and experimental procedures; I Bianchi: experimental design and article review; R Zanella: experimental design and article review; MG Marques: experimental design and article review; BG Gasperin: conceptualization, experimental design and article review; T Lucia Jr.: conceptualization, experimental design,\u0026nbsp;funding acquisition,\u0026nbsp;supervision, article review and editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets in this study are available from the corresponding author on reasonable request. All data and materials are available for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics in animal experimentation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures involving animals (hormonal treatments, blood sampling and collection of mild samples) were approved by the Committee in Animal Experimentation of the Universidade Federal de Pelotas (# 68/2021).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests \u0026nbsp;\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no conflict of interest to declare. \u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbdel-Dayem MM, Elge MS (2009) Effects of chronic estradiol treatment on the thyroid gland structure and function of ovariectomized rats. 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Reprod Dom Anim 46:818\u0026ndash;823. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1439-0531.2010.01747.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1439-0531.2010.01747.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e Composition (means \u0026plusmn; DP) of the milk produced during the first week of natural lactation of a multiparous control sow (n = 2 collections/day)\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003eDay of lactation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003eProtein (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003eFat (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003eLactose (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003eTotal solids (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003eSomatic cells (x 100/mL)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e14.6 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e4.7 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003e2.8 \u0026plusmn; 0,1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003e24.3\u0026plusmn; 0,2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003e1,115.0 \u0026plusmn; \u0026nbsp; \u0026nbsp; 69.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e9.3 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e8.3 \u0026plusmn; 0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003e3.1 \u0026plusmn; 0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003e22.5\u0026nbsp;\u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003e5,047.1\u0026nbsp;\u0026plusmn; 177.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e7.3 \u0026plusmn; 0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e14. \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003e3.1\u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003e26.3\u0026plusmn; 0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003e4,500.5\u0026nbsp;\u0026plusmn; 430.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e5.0 \u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e7.2 \u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003e4.9\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u0026plusmn; 0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003e18.5\u0026nbsp;\u0026plusmn; 0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003e3,387.0\u0026nbsp;\u0026plusmn; 326.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.666666666666668%\"\u003e\n \u003cp\u003eOverall\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e9.0 \u0026plusmn; 3.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e8.7 \u0026plusmn; 3.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.536723163841808%\"\u003e\n \u003cp\u003e3.5 \u0026plusmn; 0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.63276836158192%\"\u003e\n \u003cp\u003e22.9 \u0026plusmn; 3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.338983050847457%\"\u003e\n \u003cp\u003e3,512.6\u0026nbsp;\u0026plusmn; 1,626.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eComposition of the milk produced by non-pregnant gilts during an artificial lactation (n = 5 gilts)*\u003c/p\u003e\n \u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003eDay of lactation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003eProtein (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003eFat (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003eLactose (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003eTotal solids (g/100 g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003eSomatic cells (x 100/mL)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;15.4\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e3.3\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp;3.6\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;23.5\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e2,039.6\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e13.4\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e4.2\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp;3.4\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;22.2\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e4,705.0\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;11.7\u003csup\u003eBC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e4.3\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp;3.6\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; 20.6\u003csup\u003eBC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e3,517.4\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;11.1\u003csup\u003eC\u0026nbsp;\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e4.2\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; 2.9\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e19.4\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e1,798.6\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e12.9\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e6.8\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; 2.5\u003csup\u003eBC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;23.5\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e1,853.2\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e13.0\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e6.7\u003csup\u003eB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; 2.2\u003csup\u003eCD\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;23.2\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e2,603.2\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e12.9\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e\u0026nbsp; 8.4\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp; 2.1\u003csup\u003eCD\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e\u0026nbsp; 24.7\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e3,014.2\u003csup\u003eAB\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e13.9\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e9.5\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e\u0026nbsp;1.8\u003csup\u003eD\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e26.6\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e4,148.4\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e14.5\u003csup\u003eABC\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e9.2\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e1.6\u003csup\u003eD.\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e26.7\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e5,492.6\u003csup\u003eA\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"16.52542372881356%\"\u003e\n \u003cp\u003eEPM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.429378531073446%\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.3954802259887%\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.774011299435028%\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"20.480225988700564%\"\u003e\n \u003cp\u003e1,086.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003csup\u003eA,B\u003c/sup\u003eMeans \u0026plusmn; SEM having distinct superscripts differ by at least P \u0026lt; 0.05\u003c/p\u003e\n\u003c/div\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"artificial lactation, estradiol cypionate, long-acting progesterone, fostered piglets, gilts","lastPublishedDoi":"10.21203/rs.3.rs-1817065/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1817065/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe increase in litter resulted in increased demand for milk in farrowing rooms to improve piglet survival. This study tested a protocol for induction of artificial lactation (AL) in non-pregnant gilts as a mean to supply milk to newborn piglets. In Experiment I, five gilts received 10 mg estradiol cypionate (EC) on the last day of estrus expression (D0), 10 mg EC and 300 mg long-acting progesterone (P4) on D26, and two doses of a prostaglandin F2α analogue (PGF) I.M. on D36 (0.53 mg each, 12 h apart). Blood was collected on D12, D19, D26 and D33. Milk secretion occurred in all treated gilts 24 h after the PGF administration, lasting at least 8 d. Milk samples were collected from D37 to D45. The circulatory P4 concentration was lower on D12 than subsequently (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), but the estradiol concentration did not differ (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The milk produced during the AL was generally richer in protein and poorer in fat than the milk produced during the lactation of a control sow, but both concentrations were only altered near to the 3rd d of the AL. In Experiment II, the same protocol for induction of AL was administered to two gilts. After milk secretion started, each gilt received four 5-d old piglets fostered from other litters. The piglets were nursed for 22 d and weaned weighing approximately 5 kg. Considering both experiments, AL was induced in all treated gilts and the milk produced was capable to nurture fostered piglets.\u003c/p\u003e","manuscriptTitle":"Successful induction of artificial lactation in non-pregnant gilts","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-07-13 16:40:30","doi":"10.21203/rs.3.rs-1817065/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"98265094-2e28-411f-957a-fc67036ac546","owner":[],"postedDate":"July 13th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-08-08T05:29:23+00:00","versionOfRecord":[],"versionCreatedAt":"2022-07-13 16:40:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1817065","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1817065","identity":"rs-1817065","version":["v1"]},"buildId":"DfRiq_wiF3Ryq-tyrab2w","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}