Genetic research for the assessment of mastitis and milk production traits simultaneously has a long history. The main issue that arises in this context is the known existence of a positive correlation between the risk of mastitis and lactation performance due to selection. The transcriptome-wide association study (TWAS) approach endeavors to combine the expression quantitative trait loci and genome-wide association study summary statistics to decode complex traits or diseases. Accordingly, we used the farmgtex project results as a complete bovine database for mastitis and milk production. The results of colocalization and TWAS approaches were used for the detection of functional associated candidate genes with milk production and mastitis traits on multiple tissue-based transcriptome records. Also, we used the david database for gene ontology to identify significant terms and associated genes. For the identification of interaction networks, the genemania and string databases were used. Also, the available z-scores in TWAS results were used for the calculation of the correlation between tissues. Therefore, the present results confirm that LYNX1, DGAT1, C14H8orf33, and LY6E were identified as significant genes associated with milk production in eight, six, five, and five tissues, respectively. Also, FBXL6 was detected as a significant gene associated with mastitis trait. CLN3 and ZNF34 genes emerged via both the colocalization and TWAS approaches as significant genes for milk production trait. It is expected that TWAS and colocalization can improve our perception of the potential health status control mechanism in high-yielding dairy cows.

BACKGROUND: Staphylococcus aureus is a multi-host zoonotic pathogen causing human and livestock diseases. Dairy farms that make artisan cheese have distinctive concerns for S. aureus control. Antimicrobial-resistant (AMR) S. aureus is a public and animal health concern. There is a need to study the population structure of AMR S. aureus at the human-animal interface and understand the path of zoonotic transmission. This cross-sectional observational study aimed to assess the genetic diversity and AMR patterns of S. aureus isolated from cattle and humans on conventional and organic Vermont dairy farms that produce and sell farmstead cheese.
RESULTS: A convenience sample of 19 dairy farms in Vermont was enrolled, and 160 S. aureus isolates were collected from cow quarter milk (CQM), bulk tank milk (BTM), human-hand and -nasal swabs. After deduplication, 89 isolates were used for the analysis. Sequence types (STs) were determined by multilocus sequence typing and cataloged to the PubMLST database. Nine defined and five novel STs were identified. For BTM and CQM samples, six STs were identified within cow-adapted CC97 and CC151. Two human-adapted STs were isolated from BTM and CQM. Seven human-adapted clonal complexes with eight STs were identified from human samples. One cow-adapted ST was isolated from a human. Antimicrobial susceptibility of the isolates was tested using disc diffusion and broth microdilution methods. Approximately 27% of the isolates were beta-lactam resistant and blaZ gene-positive. S. aureus isolates from human swabs were more likely to carry blaZ compared to isolates from CQM or BTM. S. aureus isolated from cows and humans on the same farm belonged to different STs.
CONCLUSIONS: Humans were more likely to carry beta-lactam-resistant S. aureus compared to cows, and on organic farms only human-adapted blaZ positive STs were isolated from BTM. Moreover, we identified potential spillover events of S. aureus sequence types between host species. The presence of penicillin-resistant-human-adapted S. aureus on both organic and conventional dairy farms highlights a \"One Health\" concern at the junction of public and animal health requiring further surveillance.

Individual quarter dry-off (QDO) has been increasingly employed as a strategy for managing cows with chronically elevated SCC and recurrent clinical mastitis. However, little knowledge is available on the effects of QDO on milk production, SCC, the risk of clinical mastitis, and the risk of removal from the herd. Therefore, this retrospective cohort study aimed to investigate these associations. Data from 471 dairy cows subjected to QDO were analyzed. The cows were housed on a 4,000-cow dairy farm with a thrice-daily milking schedule. The cows were grouped based on the reason for QDO: (1) cows detected with a nonlactating quarter at a fresh cow check (QFRESH); (2) cows with recurrent clinical mastitis (QMAST); (3) cows diagnosed with Staphylococcus aureus IMI (QSA); and (4) cows with chronic subclinical mastitis (QSCC). Additionally, we randomly selected herd mates at a ratio of 1:1 to serve as a control group (CON). Cows in the CON group were matched in terms of parity and stage of lactation. Generalized linear mixed models with an identical link were used to estimate milk yield and SCC at 1 test day before QDO (T-1) as well as 1, 2, and 3 (T1, T2, and T3) test days after QDO. All cows subjected to QDO exhibited a decrease in milk yield following QDO compared with their respective control groups. All QDO cows approached the yield of their control group by T3. In particular, the difference in milk yield between QMAST cows and their controls at T3 was less than the difference at T1. Cows in the QMAST and QSCC groups exhibited a decrease in their SCC following QDO. In particular, the SCC was significantly higher among QMAST cows than among their controls at T1, but this difference was no longer significant by T3. Proportional hazards regression models revealed that QDO was associated with clinical mastitis occurrence and removal from the herd. Compared with CON cows, the hazard ratio (95% CI) for clinical mastitis occurrence was 3.70 (1.65-8.28), 1.80 (1.31-2.47), and 2.27 (0.93-5.54) among QFRESH, QMAST, and QSA cows, respectively. The hazard ratio among QSCC cows was modified by the effect of parity. The hazard ratio (95% CI) for removal from the herd was higher among cows subjected to QDO than among CON cows (hazard ratio [95% CI] values of 2.30 [0.99-5.33], 3.27 [2.20-4.86], and 4.87 [1.81-13.12] for QFRESH, QMAST, and QSCC cows, respectively). We conclude that QDO can be a viable strategy for managing cows with recurrent clinical mastitis. However, the results for the cows that underwent QDO for other reasons are less clear, partially due to low statistical power. Therefore, future research should examine how to decrease the risks of clinical mastitis and removal from the herd among cows subjected to QDO.

Acidogenic boluses can mitigate potential negative effects of high milk yield at dry-off on udder health. This randomized controlled trial aimed to investigate the effect of administering acidogenic boluses at dry-off on dry period intramammary infection (IMI) dynamics and on milk production parameters, somatic cell count linear score (LSCC), clinical mastitis (CM), and herd removal in the next lactation. A total of 901 cows from 3 dairy farms were randomly allocated to a control (CON, n = 458; no administration of acidogenic boluses at dry-off) or treatment group (TRT, n = 443; administration of 2 acidogenic boluses at dry-off). Quarter milk samples were collected at dry-off and after calving and submitted for bacteriological milk culture. The effects of treatment on the presence of quarter-level postpartum IMI, cure of existing IMI, and acquisition of new IMI, and on the prevalence of cow-level high LSCC (LSCC ≥4) in the first 30 days in milk (DIM) were analyzed using mixed effects logistic regression. Mixed linear regression was used to analyze cow-level milk production parameters (i.e., milk yield, fat corrected milk, fat and protein yield, and LSCC) in the first 90 DIM and until 300 DIM. For CM and herd removal, Cox proportional hazard regression models were used. In addition to treatment group, lactation group at dry-off, presence of high LSCC in the last test-day, average milk yield in the week before dry-off, presence of CM in the lactation of enrollment, and biologically relevant interactions were offered in all models. There was no evidence of a difference in IMI dynamics or in milk, fat corrected milk, protein or fat yields in the subsequent lactation between groups. The TRT group had a lower LSCC in the first 2 mo postpartum compared with the CON group (2.58 ± 0.3 vs. 2.92 ± 0.3 and 2.42 ± 0.3 vs. 2.81 ± 0.3, for first and second month postpartum). The prevalence of high LSCC in the first 30 DIM was 9.1% lower in the TRT compared with the CON group (16.3% vs. 25.5%; risk difference: -9.2; 95% confidence interval [CI]: -15.8, -2.5). Cows in the TRT group exhibited reduced hazards of CM in the subsequent lactation compared with cows in the CON group (hazard ratio: 0.75; 95% CI: 0.63, 0.89) as well as a reduced hazard of herd removal (hazard ratio: 0.82, 95% CI: 0.77, 0.88). The administration of acidogenic boluses as a component of dry-off management is a promising approach to maintain good udder health and reduce the hazard of CM and herd removal during the subsequent lactation.

Non-aureus staphylococci and mammaliicocci (NASM) are the most frequently isolated bacterial group from bovine milk samples. Most studies focus on subclinical mastitis caused by NASM; however, NASM can cause clinical mastitis (CM) as well. We evaluated retrospective data from 6 years (2017-2022) to determine the species and frequency of NASM isolated from quarter bovine CM. The data was comprised of microbiological results from quarter CM samples routinely submitted to Quality Milk Production Services at Cornell University for microbial identification by MALDI-TOF mass spectrometry. A total of 9,909 microbiological results from 410 dairy herds were evaluated. Our results showed that 29 distinct NASM species were identified, with the 8 most prevalent NASM species being Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus simulans, Staphylococcus epidermidis, Staphylococcus sciuri (now Mammaliicoccus sciuri), Staphylococcus agnetis/Staphylococcus hyicus, Staphylococcus borealis, and Staphylococcus xylosus. The NASM distribution remained similar among seasons, but the frequency of NASM CM cases was higher during the summer. Our results showed different patterns of variations in the isolation frequency over time, depending on the bacterial species: increasing or decreasing trends, cyclic fluctuations, and, except for Staphylococcus borealis, a significant seasonality effect for our study\'s most prevalent NASM. This study showed that Staphylococcus chromogenes remains the most frequent (43%) NASM species identified from bovine CM, followed by Staphylococcus haemolyticus (18%), and Staphylococcus simulans (12%).

Staphylococcus aureus is one of the agents of bovine mastitis of hardest control due to a complex pathogenesis comprising a variety of virulence factors, which ensures its persistence in the mammary gland, causing significant health and economic losses. Therefore, understanding the pathogenesis of this agent is imperative. Galleria mellonella has stood out as an invertebrate animal model for the study of infectious diseases that affect several hosts. This work aimed to evaluate G. mellonella larvae as an experimental model for the study of virulence phenotypes in an S. aureus population isolated from bovine mastitis. Thirty genetically divergent S. aureus strains were chosen based on PFGE analysis. After experimental infection, larvae survival rates, bacterial growth in hemolymph, melanization intensity of the dorsal vessel, and histological characteristics of the infected tissues were evaluated. The G. mellonella model showed a clear diversity in the S. aureus pathogenicity pattern, allowing the differentiation of strains with virulence phenotypes ranging from high to low degrees. Histological analysis confirmed that the strains tested were capable of inducing the formation of nodules and melanization spots in the dorsal vessels of the larvae in different magnitudes. The strains 16S-717, 19C-828, and 31S-1443 presented the highest virulence intensity among the bacteria tested and will be used further for the generation of S. aureus mutant populations to prospect genetic targets aimed to develop control strategies of bovine mastitis. Altogether, our results suggest that G. mellonella is an attractive and low-cost animal model for characterizing virulence phenotypes of large S. aureus populations.

An epidemiological analysis was conducted on production records in Hokkaido, Japan, to investigate the potential association between improved milk quality and longevity outcomes. The study found significant variations in herd somatic cell count levels and chronic subclinical mastitis morbidity based on geographical area and herd size. The analysis also revealed a positive correlation between herd somatic cell count and chronic subclinical mastitis morbidity. Although the hypothesis of a causal link between milk quality and longevity was examined, no such association was found. However, intensive assistance for identified high-risk areas and farms is expected to enhance overall milk quality.

The early detection of major mastitis pathogens is crucial for the udder health management of dairy herds. Testing of pooled milk samples, either individual test-day cow samples (TDCS) or aseptically collected pre-milk quarter samples (PMQS) may provide an easy to use and cost-effective group level screening tool. Therefore, the aim of this study was (1) to evaluate the sensitivity (Se) and specificity (Sp) of 2 commercial multiplex real-time PCR test kits applied to pooled milk samples using a Bayesian latent class analysis and (2) to estimate the probability of detection in relation to the pool size and the number of cows positively tested by bacteriological culture (BC) within a pool. Pools of 10, 20 and 50 cows were assembled from 1,912 test-day samples and 7,336 PMQS collected from a total of 2,045 cows from 2 commercial dairy farms. Two commercial quantitative real-time PCR kits were applied to detect Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae in the pooled samples, and a BC was applied to PMQS yielding a cumulative pool result. A pool was considered BC-positive if it contained at least one BC-positive PMQS. Pathogens were more frequently detected in the PMQS pools than in the TDCS pools. Pools of 10 cows showed the highest probability of detection irrespective of sample type or type of PCR kit compared with larger pool sizes. Estimation with a Bayesian latent class analysis resulted in a median Se in PMQS pools of 10 cows for Staph. aureus of 63.3% for PCR kit I, 78.1% for PCR kit II, and 95.5% for BC; the Sp values were 97.0%, 97.6%, and 89.1%, respectively. The estimated median Se for Strep. species for PCR kits ranged between 77.5 and 85.6% and for BC between 73.7% and 79.2%; the median Sp values ranged between 93.6 and 99.2% for PCR kits, and between 96.9% and 97.4% for BC. In addition, the probability of detection increased with an increasing number of BC-positive cows per pool. To achieve a probability of detection of 90%, the estimated number of positive cows in PMQS pools of 10 cows for kit I was 4.1 for Staph. aureus, 1.5 for Strep. agalactiae, and 1.3 for Strep. dysgalactiae; for the equivalent TDCS pools and pathogens, 6.9, 1.9, and 2.0 positive cows were required, respectively. For Kit II and PMQS pools, the number of positive cows required was 2.8 for Staph. aureus, 1.4 for Strep. agalactiae, and 1.2 for Strep. dysgalactiae; for the equivalent TDCS pools and pathogens, 5.3, 1.8, and 2.0 positive cows were required, respectively. In conclusion, the type of samples used for pooling, the pool size and the number of infected cows per pool determine the probability of detecting an infection with major mastitis pathogens within a pool by PCR testing.

The intramammary infusion at the end of lactation of a bismuth subnitrate internal teat sealant (ITS), with no antibiotic component has been shown to be an effective means of reducing new intramammary infections over the dry period. There has, however, been very few comparative studies between different brands of ITS under grazed pasture conditions. The objectives of this study were, therefore, to determine if a new bismuth subnitrate internal teal sealant (ShutOut, MSD Animal Health) was noninferior to Teatseal (Zoetis) regarding end-points such as (a) detection of the ITS product after calving, (b) clinical mastitis during the dry period and early lactation, and (c) subclinical mastitis at 30 to 60 d in milk. A total of 1,105 mixed-age cattle were enrolled across 2 farms comparing 2 ITS products for detection of the ITS at calving and prevention of clinical and subclinical mastitis. Both ITS contained 65% (2.6 g) bismuth salts emulsified in ≤ 1.4 g of mineral oil (ShutOut as investigational product, IVP; Teatseal as control product, CPT). At dry-off, treatment was allocated to every second cow. All cows met industry best practice criteria for using ITS treatment without antibiotics. Outcomes included detection of ITS at first stripping of the udder by the farmer, clinical mastitis (CM) from dry-off to 30 d following calving and subclinical mastitis at 30 to 60 d following calving. For ITS detection, a generalized mixed linear regression model was used to model the data, with clustering of quarters within cow accounted for by including cow as a random intercept. Clinical mastitis was analyzed at the cow-level using a Fisher\'s exact test, and SCC was modeled using a negative binomial distribution. The IVP was noninferior to the CPT for ITS detection following calving. There were 1344/1800 (71.5%) of quarters with ITS detection in the IVP in comparison to 1076/1604 (67.1%) of quarters in the CPT treated group. The quarter-level CM incidence risk was low (45 cases out 4,324 quarters; 1.04%). The overall cow-level CM risk was 4.1% (44/1081), with 20/540 (3.7%) cases in animals in the IVP group and 24/541 (4.4%) cases in animals in the CPT group. The IVP was noninferior to the CPT for cow-level mastitis incidence. The median SCC for all animals was 23,000 cells/mL, with a mean of 92,000 cells/mL. The back-transformed estimated marginal mean estimated SCC was 84,800 (95% CI 75,200-95,600) cells/mL for animals in the IVP group, and 98,800 (95% CI 87,600-111,300) cells/mL for animals in the CPT group. The IVP was, therefore, noninferior for all outcomes measured.

BACKGROUND:  Bovine mastitis is characterized by an inflammatory process in the mammary gland and represents one of the main diseases affecting a dairy herd. Management of mastitis is most commonly via antibiotics, but the rising incidence of multiple antibiotic resistance (MAR) means that additional options are needed. Homeopathic products can be administered in dairy farming for a range of clinical reasons and may be preferential due to the absence of residues.
OBJECTIVE:  The aim of this study was to assess the potential of a novel homeopathic complex medicine in managing bovine mastitis.
METHODS:  Twenty-four lactating Holstein cows with mastitis were divided into two groups: the homeopathic complex group received a homeopathic complex daily for 60 days at a dose of 20 g/d; the placebo group received the calcium carbonate vehicle without homeopathic medicines at the same dose and repetition. The main outcome measure was somatic cell count (SCC; cells/mL), with additional outcome measures including milk production (kg/d), milk constituents (percentage of protein, fat, lactose and total milk solids), and serum levels of cortisol, glucose, ammonia and lactic acid. All outcomes were measured at the beginning of the study and after 30 and 60 days. Milk samples were also collected from all animals at the beginning of the study, confirming a high (>0.2) MAR index for isolated bacterial cultures.
RESULTS:  Assessment of SCC showed a statistically significant difference favoring the homeopathic complex versus placebo group at day 60. A reduction in serum cortisol levels and an increase in fat, lactose and total milk solids in animals treated with the homeopathic complex at day 60 were also seen. Other outcome measures did not show statistically significant inter-group differences.
CONCLUSIONS:  The results of this non-randomized, open-label, placebo-controlled trial suggest the potential for a novel homeopathic complex medicine in management of multiple antibiotic-resistant bovine mastitis, thus offering dairy farmers an additional option to antibiotics and making dairy products safer for consumer health and milk production more sustainable.