The effect of a national control program on mastitis occurrence in the Netherlands

Cow-specific risk factors for clinical mastitis in Brazilian dairy cattle

Bovine leukocyte antigen DRB3 alleles from Holstein x Zebu crossbred dairy cows (n = 409) were analyzed using the PCR-RFLP technique. Exon II of DRB3 was amplified using locus-specific primers (HLO30/HLO32), followed by digestion with 3 restriction enzymes (RsaI, BstyI, and HaeIII). Forty alleles were found with frequency ranging from 0.005 to 0.139. The most frequently detected alleles of Holstein x Zebu were DRB3*16, *51, *23, *11, *8, and *1, accounting for 61.12% of the alleles in the population. Detection of candidate alleles for clinical mastitis occurrence was performed by logistic regression. It was found that percentage of Holstein fraction in crossbred cows had a nonsignificant effect (P > 0.05). However, parity had a significant effect on mastitis occurrence. In addition, DRB3*1 and *52 were the most associated with the occurrence of clinical mastitis, whereas *15, *51, and *22 were associated with resistance in crossbred populations. This is the first report of association of DRB3*15 and *51 with mastitis resistance. The association was validated by examining the candidate alleles in another commercial population. Highly susceptible (n = 43) and resistant (n = 42) groups of Holstein x Zebu cows were investigated. The result confirmed that DRB3*1 and *52 could be considered as susceptibility alleles, whereas *15, *51, and *22 could be considered as resistant alleles in Holstein x Zebu raised under tropical conditions. In addition, allele effects on 305-d milk production were estimated by BLUP. It was shown that most alleles associated with high clinical mastitis occurrence were related to increased milk yield. This study revealed that allele DRB3*10 had the greatest effect on increasing milk yield with moderate resistance to clinical mastitis, which could be used as a potential marker for selection in dairy genetic evaluation.

Monitoring udder health on routinely collected census data: Evaluating the short- to mid-term consequences of implementing selective dry cow treatment

Endemic diseases can be counted among the most serious sources of losses for livestock production. In dairy farms in particular, one of the most common diseases is Johne's disease, caused by Mycobacterium avium ssp. paratuberculosis (MAP). Infection with MAP causes direct costs because it affects milk production, but it has also been suspected to increase the risk of clinical mastitis (CM) among infected animals. This might contribute to further costs for farmers. We asked whether MAP infection represents a risk factor for CM and, in particular, whether CM occurrences were more common in MAP-infected animals. Our results, obtained by survival analysis, suggest that MAP-infected cows had an increased probability of experiencing CM during lactation. These results highlight the need to account for the interplay of infectious diseases and other health conditions in economic and epidemiological modeling. In this case, accounting for MAP-infected cows having an increased CM occurrence might have nonnegligible effects on the estimated benefit of MAP control.

The objective of this study was to estimate genetic parameters for milk yield, stayability, and the occurrence of clinical mastitis in Holstein cows, as well as studying the genetic relationship between them, in order to provide subsidies for the genetic evaluation of these traits. Records from 5,090 Holstein cows with calving varying from 1991 to 2010, were used in the analysis. Two standard multivariate analyses were carried out, one containing the trait of accumulated 305-day milk yields in the first lactation (MY1), stayability (STAY) until the third lactation, and clinical mastitis (CM), as well as the other traits, considering accumulated 305-day milk yields (Y305), STAY, and CM, including the first three lactations as repeated measures for Y305 and CM. The covariance components were obtained by a Bayesian approach. The heritability estimates obtained by multivariate analysis with MY1 were 0.19, 0.28, and 0.13 for MY1, STAY, and CM, respectively, whereas using the multivariate analysis with the Y305, the estimates were 0.19, 0.31, and 0.14, respectively. The genetic correlations between MY1 and STAY, MY1 and CM, and STAY and CM, respectively, were 0.38, 0.12, and -0.49. The genetic correlations between Y305 and STAY, Y305 and CM, and STAY and CM, respectively, were 0.66, -0.25, and -0.52.

Bovine mastitis is a common and costly disease in dairy herds. Strategies to control mastitis occurrence include understanding the risk factors and causes, as well as identifying measures to reduce udder exposure to pathogens. To address these topics, this thesis was organized into three studies. The first study characterized the frequency and profile of pathogens isolated from clinical (CM) and subclinical (SCM) mastitis in dairy cows housed in compost-bedded pack barn (CB), aiming to evaluate the association between mastitis occurrence and bedding characteristics in CB systems. Over six months, seven dairy herds were visited monthly for milk and bedding sample collections. Our results showed that Escherichia coli and environmental streptococci were the most frequently isolated pathogens from CM cases, while Staphylococcus chromogenes and contagious pathogens were the mostly isolated from SCM cases. We also demonstrated that bedding physical-chemical (specifically moisture, carbon to nitrogen ratio) and microbiological characteristics affect the mastitis occurrence in dairy cows housed in the CB system. The second study investigated the effect of a lime-based conditioner (LBC), at different concentrations (0, 10, 15, and 20%), on the physical-chemical and microbiological characteristics of anaerobically digested manure solids (ADMS) and separated raw manure solids (SRMS). Untreated ADMS and SRMS were assessed for dry matter (DM) content, pH, and microbiological counts immediately after LBC treatment (0 h) and at 24, 72, and 168 h of storage at 28ºC. It was observed a linear increase in both DM and pH with increasing LBC concentration. On the other hand, a linear decrease in bacterial counts was observed with increasing LBC concentration, highlighting the potential of LBC to control pathogen proliferation in manure-derived bedding. The third study evaluated retrospective data from six years to determine the speciation and distribution of non-aureus staphylococci and mammaliicocci (NASM) isolated CM cases. Twenty-nine NASM species were identified from bovine CM cases, with S. chromogenes, S. haemolyticus, S. simulans, S. epidermidis, Mammalicoccus sciuri, S. agnetis/S. hyicus, S. borealis, and S. xylosus being the eight most prevalent NASM species. A similar NASM distribution was observed across seasons, even though large variability in the isolation frequency between the eight most prevalent NASM was observed according to season and year. The results of this thesis may assist consultants and dairy farmers in developing strategies for bedding management and mastitis control.

The objective of this observational study was to estimate effects of clinical mastitis (CM) cases caused by different pathogens (Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and CM cases with no growth) occurring in the first 100 d in lactation 1, of a dairy cow on the future rate of occurrence of different types of CM during a cow's full lifetime. The outcomes were occurrence of Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and CM cases with no growth, after the first 100 d of lactation 1, until a cow's removal through death or sale in that or a subsequent lactation. Data, including information on CM cases, milk production, and event dates (including death or sale dates), were collected from 14,440 cows in 5 New York State Holstein herds from January 2004 until February 2014. Generalized linear mixed models with a Poisson distribution and log link function were fit for each pathogen. The individual cow was the unit of analysis. Escherichia coli was a predictor of future occurrence of E. coli, Klebsiella spp., and CM cases with no growth. Early-occurring Klebsiella spp. was a predictor of future cases of Klebsiella spp. Cases with no growth were predictors of future occurrence of Staphylococcus spp., E. coli, Klebsiella spp., and cases with no growth. Thus, E. coli and cases with no growth occurring early in lactation 1 appear to be consistent risk factors for future cases of CM, whether cases with the same pathogen or a different pathogen. In this study, farm effects on later pathogen occurrence differed somewhat, so treatment protocol and culling strategy may play a role in the findings. Nevertheless, the findings may help farmers in managing young cows with CM in early productive life, especially those with E. coli or cases with no growth, in that they may be more susceptible to future CM cases in their later productive life, thus meriting closer attention.

This study aimed to explore the occurrence and risk factors associated with clinical mastitis within the Hardhenu cattle herd over a span of 14 years (2008-2021). A comprehensive analysis of 1515 lactation records was conducted to ascertain the incidence of clinical mastitis. The investigation determined an overall incidence rate of 26.80% in the studied population. A significant relationship between the year and clinical mastitis incidence was established through Chi-square analysis (p < .05). Temporal variations in clinical mastitis odds were apparent, with the highest odds (ranging from 0.91 to 1.00) observed during the initial years of 2008-2009 and 2009-2010. Logistic regression revealed that odds values for clinical mastitis incidence were highest in 2008-2009 (1.00), succeeded by 2009-2010 (0.91), 2012-2013 (0.88), 2018-2019 (0.67) and reaching the lowest in 2021-2022 (0.35). Subsequent rankings included 2010-2011 (0.39), 2014-2015 (0.43) and 2019-2020 (0.45). Parity was found to be significantly associated with clinical mastitis occurrence. When compared to Parity 3, both Parity 1 (odds ratio: 1.516, 95% confidence interval: 0.881-2.612) and Parity 2 (odds ratio: 2.626, 95% confidence interval: 1.568-4.398) exhibited higher odds values for clinical mastitis incidence. While the period of calving did not exert a significant influence on clinical mastitis incidence, a heightened occurrence was observed during the rainy season within the targeted population. These findings offer valuable insights into the patterns of incidence, temporal fluctuations, and non-genetic determinants impacting clinical mastitis within the Hardhenu cattle. The implications of this study can facilitate the development of targeted strategies and management protocols aimed at enhancing udder health and overall productivity in dairy cattle.

SUMMARY In a study involving 56 quarters (14 cows), it was seen that standing estrus did not affect circulating neutrophil and milk somatic cell concentrations, neutrophil phagocytosis, milk production, or occurrence of clinical mastitis. The subcutaneous injection of 17 β-estradiol (E2) (0.05 mg/kg of body weight 2 times daily for 2 consecutive days) did not affect neutrophil phagocytosis or milk somatic cell values. However, a significant increase in circulating neutrophils and a significant decrease in milk production were observed. The injection of E2 was followed by clinical mastitis in 4 uninfected quarters, in 7 quarters infected with Corynebacterium bovis, and in 1 quarter infected with Streptococcus uberis and Escherichia coli.

Systematic clinical examinations for identification of latent udder health types in Danish dairy herds.

Mastitis is a widely distributed disease of dairy cattle in most countries, including Ethiopia. The most commonly recovered bacterial pathogen during mastitis is Staphylococcus aureus in dairy cows worldwide.With this, a cross-sectional study was conducted from March 2021 to August 2021 on dairy farms in and around Hawassa town to isolate and identify Staphylococcus aureusfrom bovine mastitis milk and to determinerisk factors associated with the occurrence of mastitis. A total of 250 lactating cows wererandomly selected for clinical and subclinical mastitis from 29 small holder dairy farms.Clinical signs and the California Mastitis Test (CMT) were used to identify clinical andsubclinical mastitis, respectively. Accordingly, a standard bacteriological study targetingS. aureus was conducted with all (n=127) milk samples collected from clinical andsubclinical mastitis cows. Data generated from these methods were analyzed usingSTATACorp. Version 12. Association between the risk factors and mastitis weredetermined with p&lt;0.05 to be a statistically significant one. During the study period,50.8% of cows had mastitis, of which 4.8% and 46% showed clinical and subclinicalmastitis, respectively. The quarter-level proportion was 27.4%; of which the clinical formwas 2.9%, while the subclinical mastitis was 24.5%. Logistic regression analysis showed asignificant association among cows of different age groups, lactation stages, andfrequency of farm cleaning status per day with the occurrence of mastitis (p &lt; 0.05).Bacterial identification targetingS. aureuswas done, and this agent was identified in 60(47.2%) milk samples. This pathogen was found to be higher (47.8%) in subclinical thanin clinical (41.6%) mastitis. In conclusion, this study showed that mastitis was prevalent indairy cattle of the study area, with a higher case of S. aureus in subclinical mastitis.However, the detection of S. aureus in nearly half of the milk sample collected frommastitic cows indicated the possible presence of other pathogens. Therefore, further studyto recoverother potential pathogens commonly causing mastitis can be a good approach.

This study aimed to (1) estimate the prevalence of cow-level high somatic cell count (SCC) in Chinese dairy herds and (2) identify potential factors associated with cow- and herd-level SCC variables. The monthly data on dairy herd improvement were collected from a total of 131 dairy herds in 11 provinces in China in 2019. Mixed models were constructed using the cow composite milk SCC and the variance of cow SCC as dependent variables separately and parity, seasons, days in milk (DIM), herd size, and farm types (family-owned vs. company-owned) as fixed effects, accounting for the nested random herd and cow effect. We used negative binomial regression using herd-level SCC-related variables, namely, monthly proportion of high SCC, monthly proportion of new high SCC, monthly proportion of chronic high SCC, and monthly proportion of new chronic high SCC as dependent variables separately against seasons, herd size, and farm types with the random herd effect. The overall average prevalence of high SCCs for each month per farm was 0.26 (2.5-97.5% quantile: 0-0.56). Company-owned farms performed better in herd SCC management. Seasons were significantly associated with all the aforementioned variables, and summer and autumn were the seasons associated with worse outcomes in herd SCCs. This study is the first to assess high SCC in a large number of Chinese dairy herds, which is useful for farms to tailor the on-farm mastitis control programs in China.

Bovine mastitis is the most commonly diagnosed disease of dairy cows worldwide and causes extensive economic losses to milk producers. Intramammary infection status before dry-off plays a decisive role with respect to udder health and milk yield in the subsequent lactation. The aim of this study was to compare the effect of antibiotic dry cow therapy (DCT) versus no treatment at dry-off on milk yield, somatic cell count (SCC), inflammation of the mammary gland (IMG), and the incidence of clinical mastitis in the subsequent lactation. Dairy herd data from 251 Austrian dairy farms were recorded over an observation period of 12 mo and subsequently analyzed. The data set included 5,018 dairy cows: 2,078 were treated with antibiotics (abDCT group) and 2,940 were not treated (noDCT group) at dry-off. The abDCT group was subdivided, based on the antimicrobial active substances used for drying off, into 4 different groups (penicillins, cloxacillin, cephalosporins, and rifaximin). Based on bacteriological culture results, infections were grouped into those caused by major, minor, and other pathogens. Additionally, the IMG was defined via SCC from milk recording data using a cutoff of 200,000 cells/mL before drying off and after calving. The incidence of clinical mastitis cases within 30 and 90 d in milk was calculated using veterinary diagnosis data. To investigate the effect of different dry cow therapies on the following parameters: milk yield, SCC, and diagnosed clinical mastitis cases, different linear mixed models were constructed. Overall, the abDCT group was determined to have a significantly higher milk yield over 305 d in milk in the subsequent lactation (increase of 6.18%), compared with the noDCT group (increase of 4.29%). Both groups (abDCT and noDCT) demonstrated a decrease in the first SCC after calving compared with the SCC before dry-off, although the treated cows had a significantly higher reduction. Regarding the different antibiotic groups, with exception of the rifaximin treated cows, all antibiotic groups showed a significant difference from not treated cows with respect to SCC. Additionally, we were able to demonstrate that cows with IMG before dry-off had a 2.073 times higher chance of an increased SCC (>200,000 cells/mL) after calving. With respect to the veterinary diagnosis data, neither the IMG before drying off nor the type of DCT had a significant influence on the probability of developing clinical mastitis within 30 or 90 d in milk. Only a small number of treatments was accompanied with a bacteriological examination before drying off. However, the existing data in this study indicates that the intramammary infection status before dry-off in combination with different dry cow treatments influences udder health and milk yield after calving. Nevertheless, further studies with larger data sets of bacteriological examinations are necessary to enable a more in-depth investigation into the effects of different antibiotic substances used for DCT.

Understanding trust between dairy farmers and other actors in the dairy chain, as well as the reciprocity norms among them are fundamental to encouraging collective action and decision-making to improve milk production and udder health. The objective of this study was to understand the relationships of trust between dairy farmers and other actors in the dairy chain related to udder health in the north of Antioquia. Mixed methods (cross-sectional and grounded theory) with a convergent triangulation design were used. A total of 216 dairy farmers participated in the quantitative component, and 17 dairy farmers and 9 veterinarians in the qualitative component, they were located in 9 milk-producing municipalities in the north of Antioquia. A characterization survey of the dairy farmers, a survey on reliability and udder health, an analysis of each farm’s annual average BTSCC and CFU, and semi-structured interviews on the same topic were conducted. Problems were found in the biological indicators of udder health on the farms: BTSCC was poor for 67% of the dairy farmers, and CFU was poor for 22% of the dairy farmers. Veterinarians are the actors whom dairy farmers trust the most. Trust in dairy chain actors is complex, variable, and depends on many aspects. Trust representation, Socio-cultural Factors, Economic and Commercial Factors, Labor, Clinical and Laboratory Conditions of Milk, and Norms of Reciprocity constitute the categories of analysis when theorizing about trust and udder health. Each of the theoretical and emerging categories in this study describes actors, attitudes, behaviors, relationships between actors, and norms, allowing us to understand that trust between dairy farmers and other actors in the dairy chain in order to face the problems of udder health and milk production depends on technical processes, individual and collective human attitudes and behaviors, supply of services, political, regulative and economic determinants, the latter being transcendental in decision-making to invest in mastitis control and udder health care.

The association between clinical mastitis and milk yield in dairy cows