Negative effects of overmilking on mastitis in dairy cows

Negative effects of overmilking on mastitis in dairy cows | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Negative effects of overmilking on mastitis in dairy cows Sebastian Smulski, Tomasz Pelec, Zofia Ferens, Martyna Pietrzak, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7717983/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Overmilking (OVM)—the continuation of the milking process after milk flow has ceased—is a common issue in dairy management. Prolonged overmilking adversely affects udder health, but the threshold duration for significant impact remains undefined. This study, therefore, aims to assess the impact of varying overmilking durations on somatic cell count (SCC), milk yield, incidence of clinical mastitis (CM), lactation stage, days in milk (DIM), and the relationship between teat-end vacuum duration (i.e., overmilking or idle milking time) and the occurrence of bacterial intramammary infections, to provide practical insights to improve milking practices on dairy farms. This study used Vadia Biocontrol devices with milk point controllers (MPC) to monitor Holstein-Friesian cows on three farms, recording and categorizing overmilking durations, particularly those exceeding 240 seconds. Milk samples were analyzed for SCC and cases of clinical mastitis were documented. Additional data on milk yield, lactation stage, and DIM were also collected and analyzed in order to evaluate the broader impact of overmilking. The study found that overmilking for longer than 240 seconds had a statistically significant (p < 0.05) negative effect on udder health. However, the study found that extended overmilking did not contribute to a higher incidence of bacterial intramammary infections. Biological sciences/Immunology Biological sciences/Microbiology Biological sciences/Zoology overmilking mastitis milking equipment dairy cow Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Overmilking occurs when the milking process continues past the natural point at which a cow’s udder has been emptied, often as the result of the prolonged attachment of milking equipment or of incorrect calibration of milking machines. This practice can damage the cow’s teat ends and mammary tissues, compromising their integrity and weakening natural defenses against pathogens. The resulting damage can increase the risk of infections, such as mastitis, and can lead to chronic inflammation. In addition to the health risks, overmilking disrupts the cow’s natural lactation cycle. Prolonged suction on the udder without milk flow can prematurely exhaust milk-producing cells, reducing overall productivity and potentially shortening the cow’s lifespan. Proper timing of the milking process and regular calibration of equipment are essential to minimizing these risks and maintaining the cow’s health and sustainable milk production [ 1 , 2 ]. Causes of overmilking Incorrect equipment settings : Incorrect vacuum levels or pulsation cycles can unnecessarily extend the milking process [ 3 ]. Inadequate monitoring : Failure to observe the milking process can result in equipment remaining attached longer than is necessary [ 4 ]. Lack of staff training : Inexperienced personnel may fail to recognize when to detach milking units, increasing the risk of overmilking [ 5 , 6 ]. Addressing these factors involves proper training, equipment maintenance, and real-time monitoring to minimize risks. Effects of overmilking on dairy cows Overmilking subjects the mammary gland, especially the teat ends, to excessive suction, which weakens their natural protective barriers. This prolonged pressure can cause microinjuries, leading to soreness, inflammation, and chronic tissue damage. Compromised teat ends allow bacteria to infiltrate the udder, increasing the risk of mastitis. Chronic inflammation may necessitate veterinary intervention and increase maintenance costs. To mitigate these risks, farmers must consider reducing milking frequency and adjusting equipment settings, which may complicate herd management routines [ 7 ]. Extended milking, referring to prolonging milking time beyond the cessation of milk flow, delays the natural closure of teat sphincters, a critical defense mechanism of the mammary gland. This delay leaves the gland vulnerable to bacterial invasion, allowing pathogens such as Staphylococcus aureus , Escherichia coli , and other mastitis-causing bacteria to establish infections. Mastitis, an inflammatory condition, reduces milk yield and compromises milk quality, often rendering it unfit for sale or processing. Treating mastitis frequently involves antibiotics which, while effective in managing infections, significantly increase production costs and raise concerns about antimicrobial resistance (AMR) within farm environments. Resistant bacterial strains can spread within herds and even to humans, complicating treatment and regulatory compliance [ 8 ]. Repeated episodes of mastitis further exacerbate these challenges, causing chronic inflammation and tissue damage that impair milk production efficiency and shorten cows’ productive lifespans. Farmers consequently face economic strain from early culling and the associated costs of herd replacement [ 9 ]. Effective mastitis management is essential to mitigate these risks. Key strategies include regular teat sanitization before and after milking to minimize bacterial load, adherence to well-structured milking schedules to prevent overmilking, and frequent monitoring of teat condition and somatic cell count (SCC) in order to detect issues early. Additionally, the adoption of technologies such as automated milking systems and teat condition sensors can enhance precision and reduce variability in manual milking practices [ 10 ]. Preventative measures addressing overmilking, such as staff training and proper maintenance of milking equipment, play a pivotal role in protecting teat health. Training milkers to recognize the cessation of milk flow and to promptly detach milking equipment significantly reduces the risk of overmilking. Ensuring proper machine calibration, including vacuum settings and pulsation rates, further minimizes teat tissue damage. Overmilking poses significant risks to udder health, milk quality, and farm profitability. Its effects include increased susceptibility to mastitis, disrupted lactation cycles, and long-term economic consequences. By prioritizing equipment maintenance, staff training, and stringent milking schedules, farmers can mitigate these risks and promote sustainable dairy farming. This study evaluated the impact of overmilking duration on SCC, average milk yield, and the incidence of mastitis. Its findings indicate that overmilking of more than 240 seconds significantly increases SCC, impairs efficiency of milk flow, and elevates the risk of mastitis. These results emphasize the importance of improving milking practices to safeguard cow health, optimize milk production, and minimize economic losses [ 11 ]. Materials and methods Animals and sample collection The study was conducted on three commercial Holstein-Friesian dairy farms in Poland’s western and southern regions. All farms used a similar management system, operating under a free-stall barn. The research was conducted during the autumn–spring period of 2023/2024, when the negative impact of environmental pathogens and elevated ambient temperature on the incidence of mastitis was reduced. The farms housed 450 (farm A), 800 (farm B), and 850 (farm C) lactating cows. Over a 305-day lactation period, the average milk yield was 9976 kg on farm A, 11,245 kg on farm B, and 10,367 kg on Farm C. On all the farms, the cows were milked twice a day. All experimental farms were free from udder infectious pathogens, as confirmed by PCR testing of bulk tank milk, and their bulk somatic cell count was lower than 250,000/mL. The herds' clinical mastitis cases (CM- visible clinical signs, such as udder swelling and/or macroscopic changes) did not exceed 30% of lactating cows yearly. The number of CM cases was recorded over one month following the experiment. The milking system was based on milking parlors: farm 1: FarmTec herringbone system (2 x 12 milking units); farm 2: Delaval side-by-side system (2 x 20 milking units); farm 3: FarmTec side-by-side system (2 x 20 milking units). Before the experiment began, Wet Test and pulsator testing were carried out on all milking parlors using VaDia Wet test (BioControl, Norway). The functioning of the milking systems did not differ from the norm [ 12 ]. From these farms (40, 40, and 45), cows were randomly selected for the study. Four VaDias (Biocontrol, Norway) were used to collect data throughout an entire morning or afternoon milking session, with two for each milking cluster. These numbers were determined by the design of the milking parlour, where a research setup (Vadia) was installed on one row of milking units. The study was conducted during a single complete milking session. The VaDias were connected to a mouthpiece chamber (MPC) (4 channels), a short milk tube (2 channels diagonally), and a short air tube (2 channels diagonally) (Fig. 1 ) in Wet test [ 13 ]. The OVM times were arbitrarily divided into one-minute intervals, giving the following groups: below 60 s, 60–120 s, 121–240 s, and over 240 s. The following data were collected for all cows: DIM and number of lactations, number of clinical inflammations in the tested lactation, and performance per day of the experiment; approximately 10 ± 2 mL of milk was taken for each cow from all quarters. Quarters with CM, nonfunctional quarters, and quarters with SCC > 700,000/mL were excluded from the experiment [ 14 ]. After collection, milk samples were cooled to 5–8°C and transported to the laboratory within 30–50 minutes. Upon arrival, SCC was performed using a DeLaval cell counter (DeLaval, Tumba, Sweden), and the samples were also assessed for microbiological quality. Microbiological identification Quarter milk samples (QMS) were taken following the procedure described by NMC [ 15 ] and delivered refrigerated to the university laboratory, where bacteriological analysis was performed by streaking 0.01 mL of the milk sample on a blood agar plate with 5% bovine blood, following NMC 2017 [ 15 ]. After incubation (18–24 h at 37°C), bacterial isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), following the protocol outlined by Mikulec et al. [ 16 ]. The results of bacteriological analysis allowed each quarter to be assigned either a positive result or a negative result. The bacterial species was identified for each positive result. Statistical analysis Selective parameters were analyzed using one-way ANOVA (IBM SPSS, version 24.0). Overmilking times were compared with other variables using Student’s t-test (SCC, DIM, L, milk yield, no of mastitis). In the group with SCC data, comparisons were performed using the Kruskal–Wallis test. Correlation and regression analyses were also conducted, with overmilking time (OVM) as the independent variable. The dependent variables included SCC, days in milk (DIM), milk yield, number of lactations, and number of clinical mastitis cases, which were also considered the primary outcomes. Statistically significant differences between groups (p < 0.05) were marked with superscript letters. Results are presented as arithmetic means ± standard deviations, percentages of samples or animals, and levels of significant differences. Results A total of 125 cows (500 quarters) were included in the experiment. However, two cows were excluded due to a nonfunctioning (dry) quarter, and one cow was excluded due to CM one month before and during the experiment. The total number of experimental cows was therefore 122 (488 quarters). The results are shown in Table 1. Table 1. Variable means and standard deviations Overmilking group (s) SCC DIM L Milk yield Mastitis cases Mean SD Mean SD Mean SD Mean SD Mean SD < 60 (n = 78) 174.59 a 125.98 184.63 102.07 2.44 1.03 42.81 a 10.26 0.03 a 0.19 60–120 (n = 102) 194.33 a 185.56 187.48 96.30 2.31 1.04 43.06 a 10.24 0.009 b 0.09 120–240 (n = 149) 263.94 a 224.69 180.61 103.00 3.16 1.41 38.91 a 8.90 0.006 b 0.08 > 240 (n = 159) 388.75 b 454.27 178.57 104.92 3.05 1.43 37.28 b 8.18 0.28 b 0.74 Note: a, b : statistically significant differences at p < 0.05. The results in Table 1 allow us to conclude that overmilking of over 240 seconds is significantly associated with an increase in SCC in the quarter’s milk. Where overmilking lasted 120–240 seconds, the average SCC was higher than in those cases where it lasted less than 120 seconds, but these differences were not statistically significant. No relationship was found between the DIM, lactation number (L), or the duration of overmilking. Analyzing the relationship between milk yield and the duration of overmilking exceeding 240 seconds allowed us to observe a lower milk yield of about 4–5 kg of milk in daily production. Simultaneously, cows that experienced overmilking of more than 240 seconds showed significantly higher incidences of CM during one month after the experiment (p < 0.05). The number of CM cases for each overmilking group was as follows (tab. 2): Table 2. CM cases by overmilking duration Overmilking group (s) No clinical mastitis 240 46* Note: * statistically significant difference at p 5 ×10 6 per mL. A similar relationship can be observed in the regression analysis between the time of overmilking and the lactation number. It can be seen that shorter overmilking is more often seen in younger animals (first and second lactation) (fig. 2). An inverse relationship was observed between milk yield and overmilking time. Longer overmilking intervals were observed in cows with lower milk yields (fig. 3). In cows whose milking period exceeded 240 seconds, a significantly greater number of CM cases were observed in the month following the experiment (Fig. 4). There was no correlation between overmilking time and lactation day (Fig. 5). Finally, we performed a correlation analysis. The results are presented in Figure 6. Considering all parameters, we can note that the greatest correlation was seen between the time of overmilking and SCC (R = 0.24). A similar correlation (R = 0.23) also occurred between the time of overmilking and the number of CM. An inverse level of correlation also occurred between the time of overmilking and milk yield (R = -0.22). Bacteriology of milk samples Microbiological analysis of the quarter milk samples was performed to detect bacterial infections. The majority of samples (n = 469) showed no bacterial growth, indicating a low prevalence of infections. Of the positive cases, Streptococcus uberis was identified in thirteen samples, Escherichia coli in ten, and Enterococcus spp. in six cases. These bacteria are commonly associated with mastitis, but their infrequent occurrence did not justify further microbiological investigation. The high percentage of aseptic samples aligns with findings from previous studies, where inflammation of the udder is often attributed to mechanical factors rather than infections. Overmilking, as noted by Kamel et al. [17], is a primary cause of udder inflammation, leading to tissue damage rather than bacterial colonization. Based on these results, no correlation was found between overmilking time and the presence of bacterial pathogens in the quarter milk samples. While overmilking may contribute to udder stress, it does not appear to increase the likelihood of bacterial infections. Discussion This is the first study of its kind to examine the relationship between the duration of overmilking expressed in seconds and SCC, milk yield, number of lactations, DIM, number of mastitis cases, and bacteriology results. The literature presents conflicting results regarding the effects of overmilking on udder health. It is, however, widely accepted that overmilking negatively affects teat condition. Overmilking should ideally be minimized to the extent possible. When assessing the end of milk flow by checking one or two teats out of four in an udder, we must account for the possibility that one or more teats may still contain milk despite the examined teats appearing empty. In such cases, an indicated overmilking duration of up to thirty seconds is typically acceptable [ 18 ]. However, reviewing results from individual animals in greater detail can provide valuable additional insights. Relationship between overmilking and SCC Overmilking can significantly influence dairy cows’ SCC, primarily exacerbating udder health issues. Research indicates prolonged milking intervals can increase SCC, which is often associated with mastitis and reduced milk quality. Overmilking longer than 120 seconds doubles SCC, highlighting the adverse effect of overmilking on udder function (Lakic 2011) [ 19 ]. The studies of Miseikiene et al. [ 20 ] and of Edwards et al. [ 21 ] both found that overmilking exceeding 120 seconds increased milk SCC. Prolonged overmilking can increase SCC, indicating potential stress or infection in the udder and affecting milk quality and animal health. Our study observed a significant effect of overmilking exceeding 240 seconds. Shorter overmilking times also produced this effect, but not statistically significantly. A threshold value for overmilking of 60 or 120 seconds would thus seem too low. Relationship between overmilking and lactation number The relationship between overmilking and the number of lactations is complex and affects both udder health and milk yield. Overmilking, in the sense of excessive milking beyond optimal conditions, can adversely affect teat health, particularly in late lactation stages. The number of lactations a cow has experienced can make her more susceptible to these effects, with older cows exhibiting milk flow characteristics that differ from those of first-lactation heifers. Research indicates that older cows (fifth lactation and beyond) produce more milk than those in their first lactation, suggesting that experience may mitigate some adverse effects of overmilking. The relationship between lactation number and milk yield is significant, with higher yields observed in multiparous animals [ 22 ]. In contrast, while older animals may have higher overall milk production, they may also be more prone to the cumulative effects of overmilking, necessitating a balance between maximizing yield and maintaining udder health. Our analysis found no differences in the relationship between the time of overmilking and the number of lactations. Likewise, the correlation level was low (R = 0.18). This observation differs from the findings of other authors. Relationship between overmilking and milk yield Research indicates that overmilking may lead to teat-end hyperkeratosis, increased SCC, and a higher risk of mastitis, which can negatively affect milk yield. Overmilking in dairy cows significantly affects milk yield, primarily regarding bimodal milk flow and teat health. Research indicates that overmilking decreases milk flow efficiency and lowers overall milk production. The following sections elaborate on the critical aspects of this relationship. Cows that experience overmilking of more than thirty seconds showed a decrease in average milk flow that directly affects yield [ 2 ]. Hillerton et al. [ 23 ] examined the effects of overmilking on teat tissue condition. The researchers found that overmilking caused significant changes in teat tissue, including increased teat-end thickness and hyperkeratosis; these are associated with udder health issues and can potentially reduce milk production. Another study by Olney and Mitchell [ 24 ] investigated the effects of milking machine factors, including overmilking, on the somatic cell count of milk from cows free of intramammary infection. The study concluded that overmilking led to increased somatic cell count, indicating a deterioration in udder health, which can adversely affect milk yield. While these studies highlight the adverse effects of overmilking on udder health indicators such as teat condition and somatic cell count, the direct impact on overall milk yield is unclear. However, since udder health is closely linked to milk production, it is reasonable to infer that the detrimental effects of overmilking on udder health could lead to decreased milk yield over time. Our study found cows less susceptible to overmilking than other authors, with the adverse effects observed by us appearing only with overmilking exceeding 240 seconds. Relationship between overmilking and clinical cases of mastitis Overmilking can significantly impact the incidence of CM in dairy cows, leading to economic losses and animal welfare concerns. The relationship between overmilking and mastitis is complex, involving milking frequency, udder health, and milking techniques. The following sections outline the critical aspects of this relationship. Overmilking, particularly when combined with pulsation failure, significantly increases the new infection rate (NIR). One study pointed to a 3.5-fold increase in NIR due to prolonged overmilking under conditions of high bacterial challenge [ 25 ]. Milking duration also varies with mastitis status; cows with CM exhibit altered milk flow rates and milking durations compared to healthy cows [ 26 ]. There is a lack of information regarding the relationship between the duration of overmilking and the occurrence of CM. In this study, the negative effects of overmilking on the incidence of mastitis were observed when the overmilking duration exceeded 120 seconds. Relationship between overmilking and days in milk The literature on dairy cattle presents no clear evidence of a direct relationship between cows’ susceptibility to overmilking (prolonged milking after milk flow ceases) and the number of days in milk (DIM). However, some studies have suggested that cows in early lactation might be more vulnerable to the adverse effects of overmilking due to higher milk production and more significant udder stress. As lactation progresses and milk yield declines, the risks associated with overmilking may decrease. However, it is essential to note that there is a lack of conclusive studies that confirm this relationship, and the effects of overmilking on udder health may vary depending on individual cow characteristics and herd management practices. Our research also failed to confirm this relationship. Overmilking is known to harm teat health, but its direct effects on bacterial infections, mastitis risk, and milk production are more complex and depend on how long overmilking lasts and the individual cow. Our study found that most quarter milk samples were bacteria-free, suggesting no direct link between overmilking and infections. However, prolonged overmilking, especially when it exceeded 240 seconds, led to higher somatic cell counts (SCC), supporting previous research on the threshold for negative effects. Interestingly, we found no significant link between overmilking duration and the number of lactations, indicating that individual cow responses may vary and require further study. While overmilking is known to affect teat health and SCC, its impact on milk yield remains unclear. We observed negative effects on yield only with extreme overmilking times, suggesting that cows may tolerate moderate overmilking to some extent. Similarly, while overmilking can increase the risk of mastitis, our study found this effect significant only when overmilking lasted more than 120 seconds. The connection between overmilking and days in milk (DIM) is also uncertain, as neither our study nor previous research provides strong evidence of a clear relationship. This highlights the need for further research on the long-term effects of overmilking throughout lactation. Relationship between overmilking and bacteriology results Some studies describe increased susceptibility to infections following prolonged overmilking [ 27 , 28 ]. However, there is a lack of research detailing the bacteriology of these infections. In the present study, mastitis pathogens were noted in cows with extended overmilking. Nevertheless, the primary cause of elevated SCC was non-bacterial inflammation. In conclusion, while minimizing overmilking is essential for teat health and udder function, defining a universal limit for its harmful effects is challenging. Future studies should refine milking protocols, consider differences between individual cows, and find the best balance between efficient milk extraction and udder health. Declarations Conflict of interest statement: The authors declare that there are no conflicts of interest regarding the publication of this article. Animal rights statement According to the opinion of the local Ethical Committee in Poznań University of Life Sciences, Poland, the consent for the research obtained for the project was not required. All procedures of this study were carried out in accordance with the Polish Animal Protection Law. Ethics and consent to participate Informed consent for the use of animals in the experimental procedures was obtained from the owners. Consent for publication Not applicable. Availability of data and materials The data underlying this article will be shared at a reasonable request by the corresponding author. Author Contribution Conceptualization: S.S. T.P. ; methodology: S.S., M.P., Z.F., A.K., M.G. ; formal analysis: S.S., A.K., M.G. investigation: S.S., T.P., Z.F., M.P., A.K., M.G. ; writing—original draft preparation: S.S., Z.F., M.P. ; writing—review and editing: S.S., T.P., A.K., M.G. ; visualization: Z.F., M.P.: supervision: S.S., A.K., ; project administration: S.S., M.G. ; funding acquisition: S.S. All authors have read and agreed to the published version of the manuscript. Funding This study was financed by the statutory fund of the Department of Internal Diseases and Diagnosis, Faculty of Veterinary Medicine and Animal Science, Poznań University of Life Sciences (no. 506.513.05.00). References Neil, C., & Quesenberry, A. The effects of overmilking on the mammary gland and the incidence of mastitis. [Dissertation, Montana State University], 1–55 (1963). Fernandes, S., Pereira, G., & Bexiga, R. Bimodal milk flow and overmilking in dairy cattle: Risk factors and consequences. Animal 17 (3), 100716. (2023). 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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-7717983","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":536476499,"identity":"2f45d668-f43b-47f7-9301-e7f09c04e29c","order_by":0,"name":"Sebastian 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Sciences","correspondingAuthor":false,"prefix":"","firstName":"Tomasz","middleName":"","lastName":"Pelec","suffix":""},{"id":536476501,"identity":"286a1d77-2aed-4d32-b98c-d2d3a622c155","order_by":2,"name":"Zofia Ferens","email":"","orcid":"","institution":"Poznan University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Zofia","middleName":"","lastName":"Ferens","suffix":""},{"id":536476502,"identity":"b7f56fbc-f368-47a3-932a-80af05c157fe","order_by":3,"name":"Martyna Pietrzak","email":"","orcid":"","institution":"Poznań University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Martyna","middleName":"","lastName":"Pietrzak","suffix":""},{"id":536476503,"identity":"d6c672fb-b12c-4187-89f3-958d1b706d28","order_by":4,"name":"Aleksandra Kalińska","email":"","orcid":"","institution":"Warsaw University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Aleksandra","middleName":"","lastName":"Kalińska","suffix":""},{"id":536476504,"identity":"80d40869-c30a-4fc3-9481-1363e89cb854","order_by":5,"name":"Marcin Gołębiewski","email":"","orcid":"","institution":"Warsaw University of Life Sciences","correspondingAuthor":false,"prefix":"","firstName":"Marcin","middleName":"","lastName":"Gołębiewski","suffix":""}],"badges":[],"createdAt":"2025-09-26 05:38:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7717983/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7717983/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":94855178,"identity":"8f606293-f687-4a52-b3de-0be80519f002","added_by":"auto","created_at":"2025-10-31 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12:01:28","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":49749,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/b5818223c622293cae5ab0b2.png"},{"id":94985789,"identity":"5eaf97db-81a7-40bf-bbcf-4f542422abca","added_by":"auto","created_at":"2025-11-03 06:58:59","extension":"xml","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":76578,"visible":true,"origin":"","legend":"","description":"","filename":"2d6494cc31e34743b371d2a55c364f441structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/be755aa8ac0125f4babae512.xml"},{"id":94855193,"identity":"cac0d25c-7143-4c77-9950-3be684c6922b","added_by":"auto","created_at":"2025-10-31 12:01:28","extension":"html","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":84739,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/6ef7a3e6606d1107a21fbb2b.html"},{"id":94855171,"identity":"0c02c8a6-9167-4b03-836b-7906741b5e69","added_by":"auto","created_at":"2025-10-31 12:01:28","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":126215,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis between overmilking time and SCC.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/234731e2e5b0dc64cb765e88.png"},{"id":94985741,"identity":"4933f012-67ac-4b18-b57c-45817321d121","added_by":"auto","created_at":"2025-11-03 06:58:49","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":77997,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis between overmilking time and lactation number.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/85d6afdd4236f5446961d2e2.png"},{"id":94985891,"identity":"66fd11e7-b22d-48b6-9037-b5facffa83ec","added_by":"auto","created_at":"2025-11-03 06:59:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":103096,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis between overmilking time and average milk yield.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/94c8b804714bf39f28adfdba.png"},{"id":94855172,"identity":"a06c603c-ea59-4de5-bff3-bf7f38fc2c7c","added_by":"auto","created_at":"2025-10-31 12:01:28","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":60254,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis between overmilking time and number of CM.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/8b498841c176a0aa121f79b5.png"},{"id":94985969,"identity":"805fe2c6-3b05-4e7f-b8dd-e507d86085ca","added_by":"auto","created_at":"2025-11-03 06:59:26","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":108551,"visible":true,"origin":"","legend":"\u003cp\u003eRegression analysis between overmilking time and DIM.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/163679c8196ec6a3f6a66d89.png"},{"id":94855194,"identity":"6b5a9ff5-be5e-4b86-a08e-3774ebabb6c1","added_by":"auto","created_at":"2025-10-31 12:01:28","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":74899,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelations between the tested parameters.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/08a76bc8bdbe0322f8b74154.png"},{"id":95267840,"identity":"7bba8850-ae52-4d51-b586-210aa57d1f6e","added_by":"auto","created_at":"2025-11-06 06:23:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1191530,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7717983/v1/c41d67b8-862c-439d-8959-9e6e02cf615b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Negative effects of overmilking on mastitis in dairy cows","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOvermilking occurs when the milking process continues past the natural point at which a cow\u0026rsquo;s udder has been emptied, often as the result of the prolonged attachment of milking equipment or of incorrect calibration of milking machines. This practice can damage the cow\u0026rsquo;s teat ends and mammary tissues, compromising their integrity and weakening natural defenses against pathogens. The resulting damage can increase the risk of infections, such as mastitis, and can lead to chronic inflammation. In addition to the health risks, overmilking disrupts the cow\u0026rsquo;s natural lactation cycle. Prolonged suction on the udder without milk flow can prematurely exhaust milk-producing cells, reducing overall productivity and potentially shortening the cow\u0026rsquo;s lifespan. Proper timing of the milking process and regular calibration of equipment are essential to minimizing these risks and maintaining the cow\u0026rsquo;s health and sustainable milk production [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cb\u003eCauses of overmilking\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eIncorrect equipment settings\u003c/b\u003e: Incorrect vacuum levels or pulsation cycles can unnecessarily extend the milking process [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eInadequate monitoring\u003c/b\u003e: Failure to observe the milking process can result in equipment remaining attached longer than is necessary [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eLack of staff training\u003c/b\u003e: Inexperienced personnel may fail to recognize when to detach milking units, increasing the risk of overmilking [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eAddressing these factors involves proper training, equipment maintenance, and real-time monitoring to minimize risks.\u003c/p\u003e\n\u003ch3\u003eEffects of overmilking on dairy cows\u003c/h3\u003e\n\u003cp\u003eOvermilking subjects the mammary gland, especially the teat ends, to excessive suction, which weakens their natural protective barriers. This prolonged pressure can cause microinjuries, leading to soreness, inflammation, and chronic tissue damage. Compromised teat ends allow bacteria to infiltrate the udder, increasing the risk of mastitis. Chronic inflammation may necessitate veterinary intervention and increase maintenance costs. To mitigate these risks, farmers must consider reducing milking frequency and adjusting equipment settings, which may complicate herd management routines [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eExtended milking, referring to prolonging milking time beyond the cessation of milk flow, delays the natural closure of teat sphincters, a critical defense mechanism of the mammary gland. This delay leaves the gland vulnerable to bacterial invasion, allowing pathogens such as \u003cem\u003eStaphylococcus aureus\u003c/em\u003e, \u003cem\u003eEscherichia coli\u003c/em\u003e, and other mastitis-causing bacteria to establish infections. Mastitis, an inflammatory condition, reduces milk yield and compromises milk quality, often rendering it unfit for sale or processing.\u003c/p\u003e\u003cp\u003eTreating mastitis frequently involves antibiotics which, while effective in managing infections, significantly increase production costs and raise concerns about antimicrobial resistance (AMR) within farm environments. Resistant bacterial strains can spread within herds and even to humans, complicating treatment and regulatory compliance [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Repeated episodes of mastitis further exacerbate these challenges, causing chronic inflammation and tissue damage that impair milk production efficiency and shorten cows\u0026rsquo; productive lifespans. Farmers consequently face economic strain from early culling and the associated costs of herd replacement [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eEffective mastitis management is essential to mitigate these risks. Key strategies include regular teat sanitization before and after milking to minimize bacterial load, adherence to well-structured milking schedules to prevent overmilking, and frequent monitoring of teat condition and somatic cell count (SCC) in order to detect issues early. Additionally, the adoption of technologies such as automated milking systems and teat condition sensors can enhance precision and reduce variability in manual milking practices [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePreventative measures addressing overmilking, such as staff training and proper maintenance of milking equipment, play a pivotal role in protecting teat health. Training milkers to recognize the cessation of milk flow and to promptly detach milking equipment significantly reduces the risk of overmilking. Ensuring proper machine calibration, including vacuum settings and pulsation rates, further minimizes teat tissue damage.\u003c/p\u003e\u003cp\u003eOvermilking poses significant risks to udder health, milk quality, and farm profitability. Its effects include increased susceptibility to mastitis, disrupted lactation cycles, and long-term economic consequences. By prioritizing equipment maintenance, staff training, and stringent milking schedules, farmers can mitigate these risks and promote sustainable dairy farming.\u003c/p\u003e\u003cp\u003eThis study evaluated the impact of overmilking duration on SCC, average milk yield, and the incidence of mastitis. Its findings indicate that overmilking of more than 240 seconds significantly increases SCC, impairs efficiency of milk flow, and elevates the risk of mastitis. These results emphasize the importance of improving milking practices to safeguard cow health, optimize milk production, and minimize economic losses [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003eAnimals and sample collection\u003c/h2\u003e\u003cp\u003eThe study was conducted on three commercial Holstein-Friesian dairy farms in Poland\u0026rsquo;s western and southern regions. All farms used a similar management system, operating under a free-stall barn. The research was conducted during the autumn\u0026ndash;spring period of 2023/2024, when the negative impact of environmental pathogens and elevated ambient temperature on the incidence of mastitis was reduced. The farms housed 450 (farm A), 800 (farm B), and 850 (farm C) lactating cows. Over a 305-day lactation period, the average milk yield was 9976 kg on farm A, 11,245 kg on farm B, and 10,367 kg on Farm C. On all the farms, the cows were milked twice a day. All experimental farms were free from udder infectious pathogens, as confirmed by PCR testing of bulk tank milk, and their bulk somatic cell count was lower than 250,000/mL. The herds' clinical mastitis cases (CM- visible clinical signs, such as udder swelling and/or macroscopic changes) did not exceed 30% of lactating cows yearly. The number of CM cases was recorded over one month following the experiment. The milking system was based on milking parlors:\u003c/p\u003e\u003cp\u003efarm 1: FarmTec herringbone system (2 x 12 milking units);\u003c/p\u003e\u003cp\u003efarm 2: Delaval side-by-side system (2 x 20 milking units);\u003c/p\u003e\u003cp\u003efarm 3: FarmTec side-by-side system (2 x 20 milking units).\u003c/p\u003e\u003cp\u003eBefore the experiment began, Wet Test and pulsator testing were carried out on all milking parlors using VaDia Wet test (BioControl, Norway). The functioning of the milking systems did not differ from the norm [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. From these farms (40, 40, and 45), cows were randomly selected for the study. Four VaDias (Biocontrol, Norway) were used to collect data throughout an entire morning or afternoon milking session, with two for each milking cluster. These numbers were determined by the design of the milking parlour, where a research setup (Vadia) was installed on one row of milking units. The study was conducted during a single complete milking session. The VaDias were connected to a mouthpiece chamber (MPC) (4 channels), a short milk tube (2 channels diagonally), and a short air tube (2 channels diagonally) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) in Wet test [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe OVM times were arbitrarily divided into one-minute intervals, giving the following groups: below 60 s, 60\u0026ndash;120 s, 121\u0026ndash;240 s, and over 240 s. The following data were collected for all cows: DIM and number of lactations, number of clinical inflammations in the tested lactation, and performance per day of the experiment; approximately 10\u0026thinsp;\u0026plusmn;\u0026thinsp;2 mL of milk was taken for each cow from all quarters. Quarters with CM, nonfunctional quarters, and quarters with SCC\u0026thinsp;\u0026gt;\u0026thinsp;700,000/mL were excluded from the experiment [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. After collection, milk samples were cooled to 5\u0026ndash;8\u0026deg;C and transported to the laboratory within 30\u0026ndash;50 minutes. Upon arrival, SCC was performed using a DeLaval cell counter (DeLaval, Tumba, Sweden), and the samples were also assessed for microbiological quality.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eMicrobiological identification\u003c/h3\u003e\n\u003cp\u003eQuarter milk samples (QMS) were taken following the procedure described by NMC [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and delivered refrigerated to the university laboratory, where bacteriological analysis was performed by streaking 0.01 mL of the milk sample on a blood agar plate with 5% bovine blood, following NMC 2017 [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. After incubation (18\u0026ndash;24 h at 37\u0026deg;C), bacterial isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), following the protocol outlined by Mikulec et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The results of bacteriological analysis allowed each quarter to be assigned either a positive result or a negative result. The bacterial species was identified for each positive result.\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eSelective parameters were analyzed using one-way ANOVA (IBM SPSS, version 24.0). Overmilking times were compared with other variables using Student\u0026rsquo;s t-test (SCC, DIM, L, milk yield, no of mastitis). In the group with SCC data, comparisons were performed using the Kruskal\u0026ndash;Wallis test. Correlation and regression analyses were also conducted, with overmilking time (OVM) as the independent variable. The dependent variables included SCC, days in milk (DIM), milk yield, number of lactations, and number of clinical mastitis cases, which were also considered the primary outcomes. Statistically significant differences between groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) were marked with superscript letters. Results are presented as arithmetic means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviations, percentages of samples or animals, and levels of significant differences.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 125 cows (500 quarters) were included in the experiment. However, two cows were excluded due to a nonfunctioning (dry) quarter, and one cow was excluded due to CM one month before and during the experiment. The total number of experimental cows was therefore 122 (488 quarters). The results are shown in Table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003eVariable means and standard deviations\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"Left\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"604\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003eOvermilking group\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(s)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eSCC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003eDIM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003eMilk yield\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003eMastitis cases\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026lt; 60\u003c/p\u003e\n \u003cp\u003e(n = 78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e174.59\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e125.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e184.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e102.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e2.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e42.81\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003e10.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e0.03\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e60\u0026ndash;120\u003c/p\u003e\n \u003cp\u003e(n = 102)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e194.33\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e185.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e187.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e96.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e2.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e43.06\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003e10.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e0.009\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e120\u0026ndash;240\u003c/p\u003e\n \u003cp\u003e(n = 149)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e263.94\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e224.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e180.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e103.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e3.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e1.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e38.91\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003e8.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e0.006\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026gt; 240\u003c/p\u003e\n \u003cp\u003e(n = 159)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e388.75\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e454.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e178.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e104.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e3.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e37.28\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 48px;\"\u003e\n \u003cp\u003e8.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 53px;\"\u003e\n \u003cp\u003e0.28\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e0.74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eNote: \u003csup\u003ea, b\u003c/sup\u003e: statistically significant differences at p \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003eThe results in Table 1 allow us to conclude that overmilking of over 240 seconds is significantly associated with an increase in SCC in the quarter\u0026rsquo;s milk. Where overmilking lasted 120\u0026ndash;240 seconds, the average SCC was higher than in those cases where it lasted less than 120 seconds, but these differences were not statistically significant. No relationship was found between the DIM, lactation number (L), or the duration of overmilking. Analyzing the relationship between milk yield and the duration of overmilking exceeding 240 seconds allowed us to observe a lower milk yield of about 4\u0026ndash;5 kg of milk in daily production. Simultaneously, cows that experienced overmilking of more than 240 seconds showed significantly higher incidences of CM during one month after the experiment (p \u0026lt; 0.05). The number of CM cases for each overmilking group was as follows (tab. 2):\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e CM cases by overmilking duration\u003c/p\u003e\n\u003cdiv align=\"Left\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"397\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003eOvermilking group (s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eNo clinical mastitis\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e\u0026lt; 60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e60\u0026ndash;120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e120\u0026ndash;240\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 189px;\"\u003e\n \u003cp\u003e\u0026gt; 240\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e46*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eNote: \u003csup\u003e*\u003c/sup\u003e statistically significant difference at p \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003eThe regression analysis below shows a clear relationship between overmilking duration and SCC. The data in figure 1 show the results excluding one outlier value with SCC \u0026gt; 5 \u0026times;10\u003csup\u003e6\u003c/sup\u003e per mL.\u003c/p\u003e\n\u003cp\u003eA similar relationship can be observed in the regression analysis between the time of overmilking and the lactation number. It can be seen that shorter overmilking is more often seen in younger animals (first and second lactation) (fig. 2).\u003c/p\u003e\n\u003cp\u003eAn inverse relationship was observed between milk yield and overmilking time. Longer overmilking intervals were observed in cows with lower milk yields (fig. 3).\u003c/p\u003e\n\u003cp\u003eIn cows whose milking period exceeded 240 seconds, a significantly greater number of CM cases were observed in the month following the experiment (Fig. 4).\u003c/p\u003e\n\u003cp\u003eThere was no correlation between overmilking time and lactation day (Fig. 5).\u003c/p\u003e\n\u003cp\u003eFinally, we performed a correlation analysis. The results are presented in Figure 6.\u003c/p\u003e\n\u003cp\u003eConsidering all parameters, we can note that the greatest correlation was seen between the time of overmilking and SCC (R = 0.24). A similar correlation (R = 0.23) also occurred between the time of overmilking and the number of CM. An inverse level of correlation also occurred between the time of overmilking and milk yield (R = -0.22).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBacteriology of milk samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMicrobiological analysis of the quarter milk samples was performed to detect bacterial infections. The majority of samples (n = 469) showed no bacterial growth, indicating a low prevalence of infections. Of the positive cases, \u003cem\u003eStreptococcus uberis\u003c/em\u003e was identified in thirteen samples, \u003cem\u003eEscherichia coli\u003c/em\u003e in ten, and \u003cem\u003eEnterococcus\u003c/em\u003e spp. in six cases. These bacteria are commonly associated with mastitis, but their infrequent occurrence did not justify further microbiological investigation. The high percentage of aseptic samples aligns with findings from previous studies, where inflammation of the udder is often attributed to mechanical factors rather than infections. Overmilking, as noted by Kamel et al. [17], is a primary cause of udder inflammation, leading to tissue damage rather than bacterial colonization.\u003c/p\u003e\n\u003cp\u003eBased on these results, no correlation was found between overmilking time and the presence of bacterial pathogens in the quarter milk samples. While overmilking may contribute to udder stress, it does not appear to increase the likelihood of bacterial infections.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis is the first study of its kind to examine the relationship between the duration of overmilking expressed in seconds and SCC, milk yield, number of lactations, DIM, number of mastitis cases, and bacteriology results. The literature presents conflicting results regarding the effects of overmilking on udder health. It is, however, widely accepted that overmilking negatively affects teat condition. Overmilking should ideally be minimized to the extent possible. When assessing the end of milk flow by checking one or two teats out of four in an udder, we must account for the possibility that one or more teats may still contain milk despite the examined teats appearing empty. In such cases, an indicated overmilking duration of up to thirty seconds is typically acceptable [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, reviewing results from individual animals in greater detail can provide valuable additional insights.\u003c/p\u003e\n\u003ch3\u003eRelationship between overmilking and SCC\u003c/h3\u003e\n\u003cp\u003eOvermilking can significantly influence dairy cows\u0026rsquo; SCC, primarily exacerbating udder health issues. Research indicates prolonged milking intervals can increase SCC, which is often associated with mastitis and reduced milk quality. Overmilking longer than 120 seconds doubles SCC, highlighting the adverse effect of overmilking on udder function (Lakic 2011) [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The studies of Miseikiene et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and of Edwards et al. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] both found that overmilking exceeding 120 seconds increased milk SCC. Prolonged overmilking can increase SCC, indicating potential stress or infection in the udder and affecting milk quality and animal health. Our study observed a significant effect of overmilking exceeding 240 seconds. Shorter overmilking times also produced this effect, but not statistically significantly. A threshold value for overmilking of 60 or 120 seconds would thus seem too low.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eRelationship between overmilking and lactation number\u003c/h2\u003e\u003cp\u003eThe relationship between overmilking and the number of lactations is complex and affects both udder health and milk yield. Overmilking, in the sense of excessive milking beyond optimal conditions, can adversely affect teat health, particularly in late lactation stages. The number of lactations a cow has experienced can make her more susceptible to these effects, with older cows exhibiting milk flow characteristics that differ from those of first-lactation heifers. Research indicates that older cows (fifth lactation and beyond) produce more milk than those in their first lactation, suggesting that experience may mitigate some adverse effects of overmilking. The relationship between lactation number and milk yield is significant, with higher yields observed in multiparous animals [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn contrast, while older animals may have higher overall milk production, they may also be more prone to the cumulative effects of overmilking, necessitating a balance between maximizing yield and maintaining udder health.\u003c/p\u003e\u003cp\u003eOur analysis found no differences in the relationship between the time of overmilking and the number of lactations. Likewise, the correlation level was low (R\u0026thinsp;=\u0026thinsp;0.18). This observation differs from the findings of other authors.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eRelationship between overmilking and milk yield\u003c/h2\u003e\u003cp\u003eResearch indicates that overmilking may lead to teat-end hyperkeratosis, increased SCC, and a higher risk of mastitis, which can negatively affect milk yield. Overmilking in dairy cows significantly affects milk yield, primarily regarding bimodal milk flow and teat health. Research indicates that overmilking decreases milk flow efficiency and lowers overall milk production. The following sections elaborate on the critical aspects of this relationship. Cows that experience overmilking of more than thirty seconds showed a decrease in average milk flow that directly affects yield [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Hillerton et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] examined the effects of overmilking on teat tissue condition. The researchers found that overmilking caused significant changes in teat tissue, including increased teat-end thickness and hyperkeratosis; these are associated with udder health issues and can potentially reduce milk production. Another study by Olney and Mitchell [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] investigated the effects of milking machine factors, including overmilking, on the somatic cell count of milk from cows free of intramammary infection. The study concluded that overmilking led to increased somatic cell count, indicating a deterioration in udder health, which can adversely affect milk yield.\u003c/p\u003e\u003cp\u003eWhile these studies highlight the adverse effects of overmilking on udder health indicators such as teat condition and somatic cell count, the direct impact on overall milk yield is unclear. However, since udder health is closely linked to milk production, it is reasonable to infer that the detrimental effects of overmilking on udder health could lead to decreased milk yield over time. Our study found cows less susceptible to overmilking than other authors, with the adverse effects observed by us appearing only with overmilking exceeding 240 seconds.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eRelationship between overmilking and clinical cases of mastitis\u003c/h2\u003e\u003cp\u003eOvermilking can significantly impact the incidence of CM in dairy cows, leading to economic losses and animal welfare concerns. The relationship between overmilking and mastitis is complex, involving milking frequency, udder health, and milking techniques. The following sections outline the critical aspects of this relationship. Overmilking, particularly when combined with pulsation failure, significantly increases the new infection rate (NIR). One study pointed to a 3.5-fold increase in NIR due to prolonged overmilking under conditions of high bacterial challenge [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMilking duration also varies with mastitis status; cows with CM exhibit altered milk flow rates and milking durations compared to healthy cows [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThere is a lack of information regarding the relationship between the duration of overmilking and the occurrence of CM. In this study, the negative effects of overmilking on the incidence of mastitis were observed when the overmilking duration exceeded 120 seconds.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eRelationship between overmilking and days in milk\u003c/h2\u003e\u003cp\u003eThe literature on dairy cattle presents no clear evidence of a direct relationship between cows\u0026rsquo; susceptibility to overmilking (prolonged milking after milk flow ceases) and the number of days in milk (DIM). However, some studies have suggested that cows in early lactation might be more vulnerable to the adverse effects of overmilking due to higher milk production and more significant udder stress. As lactation progresses and milk yield declines, the risks associated with overmilking may decrease. However, it is essential to note that there is a lack of conclusive studies that confirm this relationship, and the effects of overmilking on udder health may vary depending on individual cow characteristics and herd management practices. Our research also failed to confirm this relationship.\u003c/p\u003e\u003cp\u003eOvermilking is known to harm teat health, but its direct effects on bacterial infections, mastitis risk, and milk production are more complex and depend on how long overmilking lasts and the individual cow. Our study found that most quarter milk samples were bacteria-free, suggesting no direct link between overmilking and infections. However, prolonged overmilking, especially when it exceeded 240 seconds, led to higher somatic cell counts (SCC), supporting previous research on the threshold for negative effects. Interestingly, we found no significant link between overmilking duration and the number of lactations, indicating that individual cow responses may vary and require further study.\u003c/p\u003e\u003cp\u003eWhile overmilking is known to affect teat health and SCC, its impact on milk yield remains unclear. We observed negative effects on yield only with extreme overmilking times, suggesting that cows may tolerate moderate overmilking to some extent. Similarly, while overmilking can increase the risk of mastitis, our study found this effect significant only when overmilking lasted more than 120 seconds.\u003c/p\u003e\u003cp\u003eThe connection between overmilking and days in milk (DIM) is also uncertain, as neither our study nor previous research provides strong evidence of a clear relationship. This highlights the need for further research on the long-term effects of overmilking throughout lactation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eRelationship between overmilking and bacteriology results\u003c/h2\u003e\u003cp\u003eSome studies describe increased susceptibility to infections following prolonged overmilking [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. However, there is a lack of research detailing the bacteriology of these infections. In the present study, mastitis pathogens were noted in cows with extended overmilking. Nevertheless, the primary cause of elevated SCC was non-bacterial inflammation.\u003c/p\u003e\u003cp\u003eIn conclusion, while minimizing overmilking is essential for teat health and udder function, defining a universal limit for its harmful effects is challenging. Future studies should refine milking protocols, consider differences between individual cows, and find the best balance between efficient milk extraction and udder health.\u003c/p\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest statement:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there are no conflicts of interest regarding the publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnimal rights statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccording to the opinion of the local Ethical Committee in Poznań University of Life Sciences, Poland, the consent for the research obtained for the project was not required. All procedures of this study were carried out in accordance with the Polish Animal Protection Law.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent for the use of animals in the experimental procedures was obtained from the owners.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The data underlying this article will be shared at a reasonable request by the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: S.S. T.P. ; methodology: S.S., M.P., Z.F., A.K., M.G. ; formal analysis: S.S., A.K., M.G. investigation: S.S., T.P., Z.F., M.P., A.K., M.G. ; writing—original draft preparation: S.S., Z.F., M.P. ; writing—review and editing: S.S., T.P., A.K., M.G. ; visualization: Z.F., M.P.: supervision: S.S., A.K., ; project administration: S.S., M.G. ; funding acquisition: S.S. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was financed by the statutory fund of the Department of Internal Diseases and Diagnosis, Faculty of Veterinary Medicine and Animal Science, Poznań University of Life Sciences (no. 506.513.05.00).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eNeil, C., \u0026amp; Quesenberry, A. The effects of overmilking on the mammary gland and the incidence of mastitis. 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Effects of a single prolonged milking interval in cows: Study of indicators and mediators of inflammation, milk composition and yield [Dissertation, Swedish University of Agricultural Sciences], 59\u0026ndash;61 (2011).\u003c/li\u003e\n \u003cli\u003eMi\u0026scaron;eikienė, R., Rudejevienė, J., \u0026amp; Pečiulaitienė, N. Influence of cows\u0026rsquo; udder preparation and overmilking on milk somatic cell count. \u003cem\u003eVeterinarija Ir Zootechnika\u003c/em\u003e, 2 (2010).\u003c/li\u003e\n \u003cli\u003eEdwards, J.P., O\u0026rsquo;Brien, B., Lopez-Villalobos, N., \u0026amp; Jago, J.G. Overmilking causes deterioration in teat-end condition of dairy cows in late lactation. \u003cem\u003eJ. Dairy Res.\u003c/em\u003e\u003cstrong\u003e80\u003c/strong\u003e(3), 344\u0026ndash;348. (2013).\u003c/li\u003e\n \u003cli\u003eRalević, R., et al Influence of lactation number and parity on milk yield of Saanen goat\u0026rsquo;s breed. \u003cem\u003eBMC Vet. Res.\u003c/em\u003e (2021).\u003c/li\u003e\n \u003cli\u003eHillerton, J. E., Ohnstad, I., Baines, J. R., \u0026amp; Leach, K. A. Changes in cow teat tissue created by two types of milking cluster.\u003cem\u003e\u0026nbsp;J. Dairy Res.\u003c/em\u003e\u003cstrong\u003e67\u003c/strong\u003e(3), 309\u0026ndash;317. (2000).\u003c/li\u003e\n \u003cli\u003eOlney, G. R., \u0026amp; Mitchell, R. K. Effect of milking machine factors on the somatic cell count of milk from cows free of intramammary infection: II. Vacuum level and overmilking. \u003cem\u003eJ. Dairy Res\u003c/em\u003e. \u003cstrong\u003e50\u003c/strong\u003e(2) 141\u0026ndash;148 (1983).\u003c/li\u003e\n \u003cli\u003eMein, G. A., Brown, \u0026nbsp;M. R., \u0026amp; Williams, \u0026nbsp;D. M. Effects on mastitis of overmilking in conjunction with pulsation failure. \u003cem\u003eJ. 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Association between milking machine overmilking and teat-end condition of dairy cows. \u003cem\u003eAnimal\u003c/em\u003e\u003cstrong\u003e17\u003c/strong\u003e(1), 100708. (2023).\u003c/li\u003e\n\u003c/ol\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":"overmilking, mastitis, milking equipment, dairy cow","lastPublishedDoi":"10.21203/rs.3.rs-7717983/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7717983/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOvermilking (OVM)\u0026mdash;the continuation of the milking process after milk flow has ceased\u0026mdash;is a common issue in dairy management. Prolonged overmilking adversely affects udder health, but the threshold duration for significant impact remains undefined. This study, therefore, aims to assess the impact of varying overmilking durations on somatic cell count (SCC), milk yield, incidence of clinical mastitis (CM), lactation stage, days in milk (DIM), and the relationship between teat-end vacuum duration (i.e., overmilking or idle milking time) and the occurrence of bacterial intramammary infections, to provide practical insights to improve milking practices on dairy farms. This study used Vadia Biocontrol devices with milk point controllers (MPC) to monitor Holstein-Friesian cows on three farms, recording and categorizing overmilking durations, particularly those exceeding 240 seconds. Milk samples were analyzed for SCC and cases of clinical mastitis were documented. Additional data on milk yield, lactation stage, and DIM were also collected and analyzed in order to evaluate the broader impact of overmilking. The study found that overmilking for longer than 240 seconds had a statistically significant (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) negative effect on udder health. However, the study found that extended overmilking did not contribute to a higher incidence of bacterial intramammary infections.\u003c/p\u003e","manuscriptTitle":"Negative effects of overmilking on mastitis in dairy cows","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-31 12:01:23","doi":"10.21203/rs.3.rs-7717983/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":"9a6af0ed-9824-4019-bd60-fa0d09a67151","owner":[],"postedDate":"October 31st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":57044257,"name":"Biological sciences/Immunology"},{"id":57044258,"name":"Biological sciences/Microbiology"},{"id":57044259,"name":"Biological sciences/Zoology"}],"tags":[],"updatedAt":"2025-11-06T06:23:25+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-31 12:01:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7717983","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7717983","identity":"rs-7717983","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}