Dairy Herds Research Articles

Основные факторы успеха молочного производства в Чувашской Республике

The article discusses the dairy industry in the Chuvash Republic, Russia. The Russian Federation is experiencing a shortage of milk. Currently, the per capita milk consumption in the country is by more than a quarter behind the rational intake recommended by the Ministry of Health, which is 325 kg. However, the Chuvash Republic boasts 373 kg of per capita milk production, which is by 71% higher than the average data for the rest of the country, and the high quality of Chuvash milk is unanimously confirmed by leading domestic experts. The authors analyzed the success factors of milk production in the Chuvash Republic to be extrapolated on the entire domestic industry.
 The research relied on such demographic data as the ratio of urban vs. rural population; dairy herd data, e.g., livestock population, farm types, dairy productivity, etc.; dairy production and processing business data. The methods included systematization, generalization, grouping, statistical data processing, and analysis of temporal dynamics indicators. 
 The Chuvash Republic has a large percentage of rural population and a lot of subsidiary dairy farms: 22 000 farms own more than 60% of dairy cows in the region and provide 55% of milk processing volumes. Subsidies allocated by the local government allow farm owners to ensure the high dairy productivity of cows. Most of the milk in the Chuvash Republic can be classified as near-organic. Leading regional milk producers have their own agricultural lands to provide environmentally friendly feed, as well as specialized premises for herd keeping and milking, retail outlets to sell their products, etc. A third of enterprises maintain the milk productivity at 7800–9200 kg, which is as high as in Denmark, the Netherlands, Great Britain, and Germany. Most Chuvash dairy farmers owe their high results to the state support funds allocated for the purchase of breeding cattle. The twelve largest milk producers in the region provide 100% of the output of drinking milk, so private farms mainly focus on meeting the needs of dairy processing enterprises. The latter also receive seasonal subsidies.
 The Chuvash milk miracle can be explained by the following factors: big rural population; private subsidiary farms; high-quality breeding dairy livestock; high-quality feed; good milk production and processing equipment. However, the comprehensive system of state support measures remains the most important success factor.

Plant Extracts: Potential Alternative Treatment for Bovine Mastitis Causing Pathogen Staphylococcus aureus

Bovine mastitis is a significant disease affecting dairy herds worldwide. Mastitis can be characterized by physical, chemical, and bacteriological changes in milk and various pathological changes in the glandular tissues. This disease can invariably affect the health status of cattle and eventually have a direct economic impact on the dairy industry. Mastitis can be caused by the interaction of pathogens and their environment, and one of the disease-causing pathogens, Staphylococcus aureus, remains the leading cause of mastitis. Treatment is directed towards the use of broad-spectrum antimicrobials. However, with the threat of antibiotic-resistant pathogens, alternative treatments are being explored. The use of plants with ethnoveterinary origins can be promising in the search for novel therapeutic regimens. This review focuses on various studies using plant extracts as a possible alternative treatment for this specific bovine-causing pathogen, Staphylococcus aureus. Several studies that were conducted will serve as preliminary data in the development of alternative treatments for bovine mastitis.

Epidemiology of Bovine Hemorrhagic Bowel Syndrome in Belgium and The Netherlands.

Hemorrhagic bowel syndrome (HBS) is a poorly understood, sporadic and often fatal disease in cattle. Although, HBS is considered an important disease in dairy cattle, epidemiological data is largely lacking. This study describes the epidemiology of HBS in Belgium and the Netherlands, based on necropsy records from 2009 to 2022, and reports characteristics from 27 cows and 35 dairy operations with HBS, gathered through a survey. The annual incidence of HBS has a significantly increasing trend both at cow and herd level, with incidence above 3.2% in necropsied mature dairy cattle in the most recent years. Estimated herd-level incidence in the Netherlands was double the estimated incidence in Belgium, which might be explained by higher herd size in the Netherlands. Occurrence of HBS was most prevalent in fall, being 40.1% higher than the average of the other seasons. In 35 Flemish (Belgian) surveyed dairy herds with HBS, manifestation of HBS was mostly as solitary cases, and if multiple cases occurred, the time interval was highly variable. In addition, the majority of cows with HBS (61.1%; 16/26) were in more than 100 days lactation. In conclusion, HBS is an important and possibly emerging disease in dairy cattle in Belgium and the Netherlands.

Early life events associated with first lactation reproductive performance in southwest Victorian pasture-based dairy herds.

This was a prospective cohort study to determine how events from birth until first calving affect reproductive performance in the first lactation in pasture-based dairy herds in Victoria, Australia. Events during the preweaning (0 to 84 days), weaning to first breeding (85 to 473 days) and first breeding to first calving periods (474 to 804 days) were recorded and their association with reproductive performance during the first lactation was quantified. Reproductive performance outcomes included the number of days from first mating start date to first service (MSD-S1) and the number of days from first mating start date to first conception (MSD-CON). Predictors for reproductive performance included: passive transfer status as a calf; season of birth; age and breed of the dam; breed; the presence or absence of dystocia at the time of the heifer's birth; active feeding of colostrum versus being left on the dam for colostrum intake; presence of twinning; the presence or absence of preweaning diarrhoea; preweaning, prepubertal and postpubertal average daily gain; the presence or absence of periparturient disease at first calving; age at first calving; body condition score at first calving; sex of the first-born calf; the presence or absence of a stillborn calf at the first calving and requirement of assistance at first calving. Two Cox proportional hazards regression models were developed: the first for early life event variables associated with MSD-S1 and the second for early life events associated with MSD-CON. Heifers born in autumn and winter had 2.89 (95% CI 1.50 to 5.59, P = 0.002) times and 1.97 (95% CI 1.12 to 3.44, P = 0.018) times the daily hazard of being inseminated compared with heifers born in spring, respectively. For the MSD-S1 analyses heifers that gave birth to a live calf had 1.64 (95% CI 1.14 to 2.36, P = 0.008) times the daily hazard of being inseminated compared with heifers that had a stillborn calf. Increases in weight gain during the first breeding to first calving period by 0.1 kg/day increments increased the daily hazard of first insemination by a factor of 1.10 (95% CI 1.00 to 1.22, P = 0.043). Heifers that experienced periparturient disease had a significantly lower hazard of conception per day compared with heifers that did not experience periparturient disease at the first calving (HR 0.67, 95% CI 0.50 to 0.91, P = 0.009). Increases in weight gain during the first breeding to first calving period by 0.1 kg/day increased the daily hazard of conception by a factor of 1.10 (95% CI 1.01 to 1.21, P = 0.038). We conclude that of all the growth periods assessed in this study, events that occurred during the first breeding to first calving period (474 to 804 days) had the greatest association with reproductive performance in the first lactation. There should be a focus on increasing growth rates during this period and reducing the risk of stillbirth and periparturient disease to improve reproductive performance in the subsequent mating period after calving.

Recent Advances in Dairy Animal Breeding and Reproduction: A Review

This review has highlighted the transformative impact of recent technologies on dairy animal breeding and reproduction. Recent advances in the breeding and reproduction of dairy cows involve the integration of molecular genetics, cytogenetics, and reproductive biology into animal breeding practices. This integration of precision technologies has played a critical role in increasing the efficiency and productivity of breeding programs. The development of modern genetic technologies, such as genome mapping, marker-assisted selection, and transgenesis, has revolutionized the identification of superior genetic traits, contributing to accelerated genetic progress in dairy herds. Furthermore, advancements in reproductive technologies, including artificial insemination, embryo transfer, sperm sexing, and synchronization of estrus and ovulation in dairy cows, have supported the optimization of breeding strategies and facilitated improvements in economically important traits in livestock. Efforts have also been directed toward advancing the early detection of estrus stress in dairy cows using sensitive physiological indicators and sensor technologies, aiming to enhance decision-making in estrus management on dairy farms. In conclusion, recent improvements in the breeding and reproduction of dairy animals have demonstrated significant potential for enhancing reproductive efficiency, profitability, and the quality of milk and milk products. However, these technologies face limited applicability in developing countries due to challenges such as poor infrastructure, low costs, or a lack of human resources. Therefore, it is imperative to develop cost-effective technologies tailored to local and regional contexts, subsequently facilitating their broad dissemination within these regions.

Calculating herbage utilization and intake by dairy cows under subtropical conditions using conventional field measurement techniques or the HerbValo method.

This study aimed to evaluate the HerbValo method in comparison to conventional field measurement techniques as a tool for estimating the herbage utilization and dry matter (DM) intake by grazing dairy cows under subtropical conditions. It was carried out during 18 months in a commercial farm of Southern Brazil. The herbage utilization was estimated monthly in two to four randomly selected paddocks (total n = 40) using the rising-plate meter or the double-sampling technique. In parallel, the herbage utilization was estimated by the HerbValo method, which is based on simple descriptions of the herd, supplements, pasture and grazing management. Values of herbage utilization estimated by field techniques were linearly (P < 0.01) related to those estimated by HerbValo, with no effect of pasture type (tropical vs. temperate) on the origin or on the slope of the regression (slope = 0.97; origin = -0.1; R2 = 0.81; rsd = 0.17 t DM/ha). At cow × day level, values of herbage intake estimated by field techniques were also linearly related to those estimated by HerbValo (P < 0.01; R2 = 0.82; rsd = 1.30 kg DM/cow/day). A negative linear relationship (P < 0.01) between herbage and supplement intake was obtained for both field (slope = -1.06; R2 = 0.72; rsd = 1.64) and HerbValo (slope = -0.92; R2 = 0.82; rsd = 1.08) approaches. Herbage utilization and intake by a dairy herd in a subtropical grazing-based system can be reliably estimated by the HerbValo method with the advantage of not requiring direct field pasture measurements.

Using registry data to identify individual dairy cows with abnormal patterns in routinely recorded somatic cell counts

Data from the Danish milk recording system routinely enter the Danish Cattle Database, including somatic cell counts (SCC) for individual animals. Elevated SCC can signal intramammary inflammation, suggesting subclinical mastitis. Detecting mastitis is pivotal to limit severity, prevent pathogen spread, and target treatment or culling. This study aimed to differentiate normal and abnormal SCC patterns using recorded registry data.We used registry data from 2010 to 2020 for dairy cows in herds with 11 annual milk recordings. To create consistency across herds, we used data from 13,996 unique animals and eight different herds, selected based on the amount of data available, only selecting Holstein animals and conventional herds. We fitted log10-transformed SCC to days in milk (DIM) using the Wilmink and Wood’s curve functions, originally developed for milk yield over the lactation. We used Nonlinear Least Square and Nonlinear Mixed Effect models to fit the log10-transformed SCC observations to DIM at animal level.Using mean squared residuals (MSR), we found a consistently better fit using a Wood’s style function. Detection of MSR outliers in the model fitting process was used to identify animals with log10(SCC) curves deviating from the expected “normal” curve for that same animal. With this study, we propose a method to identify single animals with SCC patterns that indicate abnormalities, such as mastitis, based on registry data. This method could potentially lead to a registry data-based detection of mastitis cases in larger dairy herds.

Quantifying and mapping digital dermatitis–associated bacteria in lesion and nonlesion body sites and dairy farm environment

The source of infection of digital dermatitis (DD), an infectious lameness condition, is still uncertain. In this cross-sectional study, we aimed to identify potential reservoirs of DD bacteria in dairy cattle body sites with different stages of the disease and farm environments. We collected skin swabs from 85 dairy cows from 5 herds, 3 with and 2 without DD, from foot, hock, and udder cleft skin (with lesions or not), saliva, urine, and feces. We also obtained environmental samples. Real-time quantitative PCR targeted Treponema phagedenis, Treponema medium, Treponema pedis, Porphyromonas levii, Bacteroides pyogenes, Fusobacterium necrophorum, and Fusobacterium mortiferum. Digital dermatitis-associated Treponema spp. were exclusively detected in DD-affected herds in DD-foot and other skin lesions, healthy skin, saliva, and environmental samples. In contrast, the non-Treponema spp. were found in samples from both DD-negative and affected herds. As expected, DD lesions had higher bacterial loads than healthy skin. Interestingly, similar counts were observed in udder cleft lesions, indicating a potential opportunistic behavior on compromised skin. None of the targeted species were detected in fecal samples, but P. levii, B. pyogenes, and F. necrophorum were detected in urine. All 7 species were detected in saliva, although in low quantities. No associations were observed between the presence of each bacterial species in DD lesions and urine; however, there was an association between the presence of DD-Treponema spp. in lesions and saliva, hock, and udder skin. Feces and urine do not seem to be a DD bacteria primary source, but saliva and other skin lesions may play a role. Longitudinal studies would improve our understanding of DD-associated bacteria's transient or persistent presence in these sites. Investigating the sources of DD-associated bacteria will guide future interventions to minimize bacterial shedding and transmission, ultimately more effectively reducing bacterial load, transmission, and sources of infection in dairy herds.

Seroprevalence and herd-level associated factors of pathogenic Leptospira spp. circulating locally in dairy cattle in Uruguay

Leptospirosis is a zoonotic disease of worldwide importance. In Uruguay, it is endemic in cattle and primarily affects people with occupational exposure to livestock. The aim of this study was to determine the national seroprevalence and associated factors of local pathogen Leptospires in dairy cattle. A cross-sectional study was carried out. Herds were stratified by size (1–50, 51–250, and > 250 cattle), and up to 60 dairy cows per herd were randomly selected. A total of 4269 serum samples from 101 dairy herds were analyzed by microscopic agglutination test (MAT). A two-stage sampling design was used to estimate population seroprevalence of Leptospira spp. In order to determine the factors associated with the disease, herds with at least 1 seropositive animal were considered as case herds. Seroprevalence of Leptospira was 27.80% with a 95% CI [21.06, 34.54] at the animal level and 86.92% with a 95% CI [80.00, 93.75] at the herd level. The serology confirms the predominance of serogroups Sejroe and Pomona in our herd with the presence of incidental leptospires infection, in smaller proportion, but with a wide distribution at farm level. The population size and purchasing replacement of cows on dairy farms were associated with infection at farm level. The serologic studies confirmed that exposure to Leptospira spp. is endemic in our herds, and the spreading over dairy herds. Although the movement of purchased females and the size of the herd were associated with the disease, more studies should be conducted, to better understand the epidemiology of the disease and to highlight the possible risks to public health, especially in rural workers, farmers and veterinarians.

Occurrence of mastitis before and after homeopathic treatment in dairy cattle, in the state of Rio de Janeiro, Brazil.

Bovine mastitis is an infectious disease that impacts milk production, leads to economic losses and public health problems. It can present in subclinical and clinical forms, with subclinical being the most common. Currently, there is concern about the health of dairy cattle and alternatives are being sought for the treatment of bacterial infections, as those available may have low efficacy, promote antimicrobial resistance and/or have toxic effects. From a One Health perspective, multiple sectors must work together to control the rise in antimicrobial resistance. Regarding animal production, this implies changes in some traditional agricultural practices (WHO, 2022; OIE, 2022). According to Rabello et al. (2020), resistance to antimicrobials for Staphylococcus aureus isolated from bovine mastitis has recently increased compared to studies published in previous periods, in Brazil. In this context, homeopathy can represent an important therapy. In our study, two dairy herds in the state of Rio de Janeiro were evaluated, regarding the presence of mastitis, in two subsequent periods: 1- Control Stage (CS): using antibiotic therapy, and 2- Experimental Stage (ES): homeopathic treatment (Nosode 30CH). The CS took place from February to April 2022 and the ES from May to July 2022. For the analysis of the treatments, the animals were evaluated with the California Mastitis Test (CMT) and the milk from the positive mammary quarters, that presented mastitis, were collected and analyzed in the laboratory for bacterial isolation and identification. During the CS, 7 CMT were performed, and the same number in the ES. The occurrence of subclinical mastitis in the CS in 1681 analyzed quarters was 36.4% (n= 608), while in the ES, in 1290 analyzed quarters, subclinical mastitis was 26.5% (n= 335). There was a reduction (p&lt;0.0001) in the occurrence of subclinical mastitis after homeopathic treatment. In both stages Staphylococcus spp. was the most prevalent microorganism.

The past and present of breeding in dairy cattle breeding in the Far North-East

Based on historical facts and past achievements, the work is designed to update the importance and prove the possibility of successful breeding work at the regional level in order to increase the production of high-quality, socially significant food products to ensure food security. At the beginning of the formation of agricultural science in the Magadan region, scientists were faced with the task of selecting the optimal breeds for the region. More than 4000 cows were examined during 1964–1967. It was found that in extreme natural and climatic conditions of the Magadan region the Kholmogory breed proved to be the best one. In 1967, in order to further improve the Kholmogory breed, the first attempt was made to study the genealogical structure of the herd, to identify and evaluate highly productive lines. In 1974, in order to increase the milk fat content of crossbred cows of the Kholmogory breed, introductory crossing with the bulls of the Ayrshire breed, tested for the quality of the offspring, was used. In order to improve dairy herds, the selection of cows for hereditary traits is combined with checking them for the first lactation. Since 1976, state farms began to study the breeding and productive qualities of the Ayrshire cattle, which were distinguished by high milk production and high fat content in milk. Since 1982, the Ayrshire breed has been approved as a planned breed for breeding in the farms of the Okhotsk zone. In the same year, absorptive crossbreeding of the animals of the Kholmogory breed with the sires of the Ayrshire breed began. In order to increase the efficiency of breeding for abundant milk production, work began on the farms to increase the hereditary variability of this trait through breeding along lines and families. At the same time, the work on improving the Kholmogory cattle by introductory crossbreeding with the purebred bulls of the Holstein-Friesian breed continued. By the 1990s, the main vector of development was the creation of highly productive herds of dairy cattle, but the difficult financial situation at farms in the 1990s led to a sharp decrease in the number of cattle and the productivity of the remaining animals.

Prevalence, Associated Risk Factors and Major Bacterial Pathogens causing Bovine Mastitis on Selected Dairy Farms in and around Harar, Ethiopia

Aim Mastitis, an inflammation of the mammary gland, is a complex and costly disease in dairy herds. The main aim of this study was to estimate the prevalence of mastitis and associated risk factors for bacterial pathogens in lactating dairy cows. Methods A cross-sectional study was carried out. The study was conducted in Harar town and its district from November 2016 to April 2017. A total of 384 (264 crossbreds and 120 Holstein Frisian) milking cows were tested using the California mastitis test (CMT), direct diagnosis of obverse clinical mastitis, and bacterial culture in Harar City and its district. Results The result of the study indicated the prevalence of mastitis at the cow level was 58.60% (225/384), out of which 10.7% (41/384) and 47.9% (184/384) were clinical and subclinical, respectively. The quarter-level prevalence was 34.1% (513/1536); from this, the clinical and subclinical forms were 8.7% (131/1536) and 25.4% (382/1536), respectively, while 2% (31/1536) had blind teats. From 341 culture-positive samples, the following bacteria were isolated: Out of the total, Coagulase-negative Staphylococcus (CNS) (28.5%) was the most prevalent isolate, followed by Streptococcus species (27.5%), Staphylococcus aureus (21.4%), Escherichia coli species (14.4%), Micrococcus species (5.3%) and Corynebacterium species (2.9%). Age, parity, breed, production, and hygiene were significant associated risk factors, whereas management risk factors such as house types, milking systems, farming systems, and treatment history do not have a significant association with the prevalence of mastitis in the study area at this level of significance. Conclusion Based on the findings of this study, a thorough screening of high-producing and aged cows should be needed; optimum space should be required for those cows kept in intensive and closed houses to reduce the risk of contagious mastitis; attention should be paid to the informal use of drugs; and further research should be needed to view other risk factors for mastitis

Medium-term storage of calf beddings affects bacterial community and effectiveness to inactivate zoonotic bacteria

Land-spreading of animal faecal wastes -such as animal beddings- can introduce zoonotic enteropathogens into the food system environment. The study evaluated the effectiveness of animal beddings naturally contaminated by calf manure to reduce E. coli O157:H7 or Salmonella enterica. The two pathogens were introduced separately as a four strains-cocktail and at high (&gt;6.5 Log10 g-1) concentration into bedding materials, and their inactivation over a 10 weeks-period was monitored by using a Most Probable Number (MPN) enumeration method. Inactivation of E. coli O157:H7 was more effective in the bedding inoculated immediately after collection from calf pens than in the beddings inoculated after a 2 months-pre-storage period: E. coli O157:H7 levels were reduced by 6.6 Log10 g-1 in unstored bedding (0.5 Log10 g-1 recovered; 95%CI: 0.0–1.2), and by 4.9 Log10 g-1 in pre-stored bedding (2.2 Log10 g-1 recovered; 95%CI: 1.5–2.8) with a significant (p&lt;0.05) difference between unstored and pre-stored. S. enterica was inactivated less effectively as counts were reduced by one order of magnitude, with no significant difference in inactivation between unstored and pre-stored beddings. Low levels of naturally occurring E. coli O157 and Salmonella spp. were detected in the non-inoculated beddings, as well as in the straw prior to use in the animal facility. To better understand the possible biological processes involved, the bacterial community present in the beddings was characterised by short-read 16S rRNA sequencing. Pre-storage of the bedding affected the composition but not the diversity of the bacterial community. Analyses of the key bacterial phyla suggested that the presence of a diverse and stable bacterial community might facilitate inactivation of the introduced pathogens, and a possible role of bacterial orders associated with lignocellulolytic resources. Overall, the study contributed to the understanding of the fate of zoonotic bacteria introduced in animal beddings during storage and identified bedding storage practices pre-and post-use in animal facilities that could be important to prevent the risk of zoonosis dissemination to the environment or to the dairy herds.

Etiology of severe mastitis in French dairy herds

Severe clinical mastitis is not so frequent in dairy cows, but it can have a significant economic impact due to its high mortality rate and adverse effects on milk production. Surveys about the cause of mastitis typically provide overall findings without connecting them to a specific medical condition. There are few studies on the specific etiology of severe mastitis. Only etiological results obtained during field studies are available in France, and the number of mastitic milk samples analyzed is always low. In recent years, veterinary clinics have improved their ability to identify bacteria causing bovine mastitis using a widely used method. This in-clinic milk culture made it possible to better understand the etiology of mastitis according to the symptoms observed. Regarding clinical mastitis, veterinarians treat severe cases differently than less severe ones. Based on data from nineteen veterinary clinics in France and over 2000 severe mastitis cases, the current study revealed that Enterobacteriaceae, particularly Escherichia coli, is the most common cause, isolated on average from 53.9% of milk samples. This information is highly reliable for practitioners to quickly and effectively treat the condition, because early and targeted treatment is crucial to avoid the complication of endotoxic shock.

Estimation of genetic parameters and single-step genome-wide association studies for eating time and rumination time in Holstein dairy cows

The aims of this study were to estimate genetic parameters and to identify genomic regions associated with eating time (ET) and rumination time (RUT) in Holstein dairy cows. Genetic correlations among ET, RUT, and milk yield traits were also estimated. The data were collected from 2019 to 2022 in 6 dairy herds located in the Walloon Region of Belgium. The dataset consisted of daily ET and RUT records on 284 Holstein cows, from which 41 cows had records only for the first parity (P1), 101 cows had records from both the first and second parities, and 142 cows had records only for the second parity (P2). The number of daily ET and RUT records in the P1 and P2 cows were 18,569 (on 142 cows) and 34,464 (on 243 cows), respectively. Data on 28,994 SNPs located on 29 Bos taurus autosomes (BTA) of 747 animals (435 males) were used. Random regression test-day models were used to estimate genetic parameters through the Bayesian Gibbs sampling method. The SNP solutions were estimated using a single-step genomic best linear unbiased prediction approach. The proportion of genetic variance explained by each 20-SNP sliding window (with an average size of 1.52 Mb) was calculated, and regions accounting for at least 1.0% of the total additive genetic variance were used to search for candidate genes. Mean (standard deviation; SD) averaged daily ET and RUT were 327.0 (85.66) and 559.4 (77.69) min/d for cows in P1 and 316.0 (82.24) and 574.2 (75.42) min/d for cows in P2, respectively. Mean (standard deviation; SD) heritability estimates for daily ET and RUT were 0.42 (0.09) and 0.45 (0.06) for cows in P1 and 0.45 (0.04) and 0.43 (0.02) for cows in P2, respectively. Mean (SD) daily genetic correlations between daily ET and RUT were 0.27 (0.07) for P1 and 0.34 (0.08) for P2. Genome-wide association analyses identified 6 genomic regions distributed over 5 chromosomes (BTA1, BTA4, BTA11, 2 regions of BTA14, and BTA17) associated with ET or RUT. The findings of this study increase our preliminary understanding of the genetic background of feeding behavior in dairy cows; however, larger datasets are needed to determine whether ET and RUT might have the potential to be used in selection programs.

Clinical and Subclinical Bovine Mastitis: Staphylococcus aureus Isolation and Identification from Dairy Farms Located in and Around Hawassa Town, Southern Ethiopia

BACKGROUND: Mastitis is an expensive disease of dairy cattle in most countries, including Ethiopia. The most commonly recovered bacterial pathogen from mastitis milk is _Staphylococcus aureus_ in dairy herds worldwide, with huge economic losses in the dairy industry. OBJECTIVE: To isolate and identify _Staphylococcus aureus_ from bovine mastitis milk. Additionally, risk factors associated with the occurrence of mastitis were determined. METHODS: A cross-sectional study was conducted from March 2021 to August 2021 on dairy farms in and around Hawassa town. A total of 250 lactating cows were examined for clinical and subclinical mastitis from randomly selected dairy farms. Clinical signs and the California Mastitis Test (CMT) were used to identify clinical and subclinical mastitis, respectively. RESULTS: During the study period, 50.8% of cows had mastitis, of which 4.8% and 46% showed clinical and subclinical mastitis, respectively. The quarter-level prevalence was 27.4%; of which the clinical form was 2.9%, while the subclinical mastitis was 24.5%. Logistic regression analysis showed a significant association among cows of different age groups, lactation stages, and farm hygienic status with the occurrence of mastitis (p &lt; 0.05). A bacteriological study targeting _S. aureus_ was conducted with all (n=127) milk samples collected from clinical and subclinical mastitis cows. Bacterial identification targeting _S. aureus_ was done, and this agent was identified in 60 (47.2%) milk samples. This pathogen was found to be higher (47.8%) in subclinical than in clinical (41.6%) mastitis. CONCLUSION: This study showed that mastitis was prevalent in dairy cattle of the study area, with a higher case of _S. aureus_ in subclinical mastitis. However, the recovery of _S. aureus_ in nearly half of the mastitis milk indicated the possible presence of other pathogens. Therefore, further study to recover other potential pathogens commonly causing mastitis can be a good approach.

Preparation and Antimicrobial Activity of a Film-Forming Polyhexamethylene Biguanide Teat Disinfectant.

Bovine mastitis caused by infectious pathogens can lead to a decline in production performance and an increase in elimination rate, resulting in huge losses to the dairy industry. This study aims to prepare a novel dairy cow teat disinfectant with polyhexamethylene biguanide (PHMB) as the main bactericidal component and to evaluate its bactericidal activity in vitro and its disinfection effect in dairy cow teats. PHMB disinfectant with a concentration of 3 g/L was prepared with PVA-1788, propylene glycol and glycerol as excipients. When the dilution ratio is 1:4800 and the action time is 5 min, the PHMB teat disinfectant can reduce the four types of bacteria (S. agalactiae ATCC 12386, S. dysgalactiae ATCC 35666, S. aureus ATCC 6538, and E. coli ATCC 8099) by 99.99%. PHMB teat disinfectant applied on the skin of rabbits with four bacteria types achieved an average log10 reduction greater than 4. After 30 s of PHMB teat disinfectant dipping, the bacteria of cow teats were counted prior to disinfection. The mean log10 reduction in bacteria on the skin surface of 12 cows ranged from 0.99 to 3.52 after applying the PHMB teat disinfectant for 10 min. After 12 h, the PHMB teat disinfectant achieved an average log10 reduction in bacteria from 0.27 to 0.68 (compared with that prior to disinfection). These results suggested that PHMB teat disinfection has the potential to prevent and treat mastitis-causing bacteria in dairy herds.

Innovative Elastomers with Antimicrobial Activity May Decrease Infection Risks during Milking.

Contagious pathogens are very costly to dairy herds, and they may have zoonotic and reverse-zoonotic potentials and may contribute to the spread of antimicrobial resistance. One of the most important risk factors for spreading these infections is milking, when liner contamination may transfer the pathogens from infected to healthy cows. There is no effective protocol to prevent the transmission of infection without the segregation of infected cows. Recently, the availability of elastomers with patented antimicrobial components in their formulations has allowed the exploration of alternative methods to reduce the risk of infection. Two different types of elastomers (rubber and silicone) and nine different formulations were challenged with three major mastitis pathogens (S. aureus, S. agalactiae, and E. coli). The results that were obtained in this study were interesting and unexpected. Indeed, to our knowledge, this is the first study to show that basic rubber materials have intrinsic antimicrobial activity. Silicone elastomers did not exhibit the same levels of bactericidal activity, although they did exhibit some antibacterial capacity. A significant decrease in bacterial survival curves was observed for all the formulations tested when antimicrobial components were added. The different results observed for the various products are likely due to the different formulations and diverse manufacturing processes. The availability of these new materials that significantly reduce the bacterial load on the liner surface may reduce the risk of spreading intramammary infections during milking. This would be an important step forward in achieving global sustainability of dairy herds, consistent with the objectives of One Health, by reducing the risks of zoonotic diseases and antimicrobial treatments.

136 Reducing the incidence of postpartum bovine metritis by administration of mycobacterium cell wall fraction immunostimulant in a high-producing Holstein dairy herd

136 Reducing the incidence of postpartum bovine metritis by administration of mycobacterium cell wall fraction immunostimulant in a high-producing Holstein dairy herd

The use of machine learning to predict somatic cell count status in dairy cows post-calving.

Udder health remains a priority for the global dairy industry to reduce pain, economic losses, and antibiotic usage. The dry period is a critical time for the prevention of new intra-mammary infections and it provides a point for curing existing intra-mammary infections. Given the wealth of udder health data commonly generated through routine milk recording and the importance of udder health to the productivity and longevity of individual cows, an opportunity exists to extract greater value from cow-level data to undertake risk-based decision-making. The aim of this research was to construct a machine learning model, using routinely collected farm data, to make probabilistic predictions at drying off for an individual cow's risk of a raised somatic cell count (hence intra-mammary infection) post-calving. Anonymized data were obtained as a large convenience sample from 108 UK dairy herds that undertook regular milk recording. The outcome measure evaluated was the presence of a raised somatic cell count in the 30 days post-calving in this observational study. Using a 56-farm training dataset, machine learning analysis was performed using the extreme gradient boosting decision tree algorithm, XGBoost. External validation was undertaken on a separate 28-farm test dataset. Statistical assessment to evaluate model performance using the external dataset returned calibration plots, a Scaled Brier Score of 0.095, and a Mean Absolute Calibration Error of 0.009. Test dataset model calibration performance indicated that the probability of a raised somatic cell count post-calving was well differentiated across probabilities to allow an end user to apply group-level risk decisions. Herd-level new intra-mammary infection rate during the dry period was a key driver of the probability that a cow had a raised SCC post-calving, highlighting the importance of optimizing environmental hygiene conditions. In conclusion, this research has determined that probabilistic classification of the risk of a raised SCC in the 30 days post-calving is achievable with a high degree of certainty, using routinely collected data. These predicted probabilities provide the opportunity for farmers to undertake risk decision-making by grouping cows based on their probabilities and optimizing management strategies for individual cows immediately after calving, according to their likelihood of intra-mammary infection.