Search Results (126)

The objective of this study was to evaluate the effects of feeding a combination of chicory–plantain silage and supplementing Se yeast on the response of early-lactating ewes to induce subclinical mastitis. Polypay ewes (n = 32) were fed either chicory–plantain silage or grass silage and supplemented with 3.6 mg Se yeast/ewe/day for approximately 2 months prior to the infusion of S. uberis into both mammary glands (i.e., intramammary infection or IMI). The ewes had a typical subclinical mastitis response with an 8-fold increase in milk somatic cell count within 24 h post-IMI, a decrease in milk yield, and changes in all milk components measured. The ewes experienced a mild systemic inflammation post-IMI as determined by an increase in rectal temperature and decrease in feed and water intake and, in blood, by an increase in the concentration of ceruloplasmin, haptoglobin, and myeloperoxidase and a decrease in paraoxonase, Zn, advanced oxidation protein products, and hematocrit with no effect on pro-inflammatory cytokines. No effect of silage type, likely due to a low concentration of secondary compounds, or Se supplementation was detected in response to IMI. In summary, the subclinical mastitis model used was effective in mounting an inflammatory response, although this was mild; however, feeding chicory–plantain silage with a low concentration of secondary compounds and supplementing Se yeast had no significant effect on the response of ewes to mammary infection. Full article

Staphylococcus aureus frequently causes intramammary infections in dairy cows (bovine mastitis), which impair animal welfare, milk yield, and food safety. This study determined the prevalence and genetic diversity of S. aureus in bulk tank milk (BTM) samples from community-based Alpine dairy pastures in Tyrol, a major milk-producing region in Austria. Throughout the 2023 Alpine season (May–September), 60.3% (94/156) of BTM samples tested positive for S. aureus at least once over the course of up to four samplings. A total of 140 isolates collected from the 94 S. aureus-positive community-based Alpine dairy pastures revealed 33 distinct spa types, with t2953 (n = 33), t529 (n = 12), t267 (n = 11), and t024 (n = 10) being the most common. Selected isolates representing the different spa types were characterised by DNA microarray-based genotyping, multi-locus sequence typing (MLST), and antimicrobial susceptibility testing. Isolates with spa types associated with bovine-adapted CC8 (CC8bov/GTB) were identified as the most common subtype, being detected in BTM samples from 35.3% (55/156) of the pastures. This emphasises the high prevalence of this subtype in dairy herds across European Alpine countries. Other common bovine-associated subtypes were also detected, including CC97, CC151, and CC479. While antimicrobial resistance was rare, enterotoxin-producing genes were detected in all CC8bov-associated spa types. Overall, these findings underscore the importance of rigorous hygiene practices in dairy farming, particularly in community-based Alpine dairy pastures, where the risk of transmission is particularly high. It also emphasises the need for continued surveillance and subtyping to improve animal health, ensure food safety, and promote sustainable milk production. Full article

Clinical mastitis in small ruminants is usually seen with an incidence of less than 5% and most cases, especially with hyperacute evolution, are not referred for hospital care. During the 5-year survey, 16 goats and 7 sheep, totaling 23 small ruminants, met the inclusion criteria with a definitive diagnosis of clinical mastitis. Clinical signs ranged greatly among cases, varying from septic state in hyperacute cases, and enlarged, pendulous udder associated with chronic pain and abnormal gait in chronic cases. Microbiological culture revealed a wide array of bacterial pathogens, including Staphylococcus aureus, Escherichia coli, Streptococcus spp., and Pasteurella spp. In vitro antimicrobial susceptibility profiles varied greatly among bacteria isolates, ranging from sensitive to all tested antimicrobials to a multi-resistant profile. Pathological features included hyperemia and dark red areas of necrosis in the skin, marked hyperemia of the affected gland at the cut surface, lactiferous ducts and gland cisterns filled by cloudy or suppurative fluid, abscesses, and hardness of the mammary gland parenchyma. This retrospective study highlights the multifactorial nature and clinical variability of mastitis in small ruminants, demonstrating its significant impact on animal health, welfare, and production. Full article

Dairy herds around the world are undergoing several changes. Herd sizes are increasing, as are both milk yield and quality. The implementation of new technologies in various domains of dairy production is leading to an increase in the quantity of data available. This, in turn, creates a need to extract useful information from these data to improve production efficiency. This paper presents the findings of a preliminary study that utilizes a machine learning (ML) approach to assess the accuracy of somatic cell count (SCC) and neutrophils + lymphocytes count/mL (PLCC) in identifying cows at risk of developing intramammary infection (IMI) due to major pathogens. These pathogens (MajPs) include S. aureus, S. agalactiae, S. uberis, and S. dysgalactiae. This study identified these pathogens either by real-time PCR (qPCR) methods or by conventional bacteriology, following the cows’ calving process. This study encompassed a total of 424 cows and 1696 quarter milk samples. A comparison of the two methods revealed significant disparities in the prevalence of MajPs, with the qPCR method demonstrating a higher prevalence than conventional bacteriology. However, the prevalence of negative results was comparable, with both methods yielding approximately 71.0% and 72.1%, respectively. The comprehensive results of this study substantiated that all the cellular markers exhibited the most accurate when MajP IMI was diagnosed using quarter milk samples, but this result is mainly due to the very high specificity. The cellular markers exhibited nearly equivalent performance, irrespective of the ML algorithm employed. The findings indicate that approaches based on SCC or PLCC may be useful for identifying healthy cows or quarters. However, it is essential to confirm all “non-negative” results through subsequent analysis within 7–15 days to ensure accuracy. However, further studies are necessary to enhance diagnostic accuracy. Full article

This study clarified the effectiveness of external teat sealant (ETS) in preventing intramammary infections during lactation, using a cross-over study of two experiments (3 cows × 2 periods each) on a dairy farm. In Experiment 1, the control (Group A) received pre-dip and post-dip treatments, while the experimental group (Group B) received ETS application instead of post-dip treatment. In Experiment 2, Group C was treated the same as Group B, and Group D received ETS treatment only. After the intervention, teat ends were tested using ATP swabs, and milk collections from the first and last foremilk (Samples 1 and 2, respectively) were conducted over 4 days (8 times in total). In Experiment 1, the ETS application group exhibited lower ATP (p < 0.01) and bacterial counts (BC1, p = 0.02) compared to the control. Conversely, no differences in variables were observed in Experiment 2. The isolation rate of Staphylococcus spp. (>500 colony forming units) from Sample 2 in Groups C and D was significantly higher than that in groups A and B (p < 0.01). Replacing post-milking teat disinfection with ETS does not decrease viable bacterial counts and actually increases the proportion of Staphylococcus spp. ETS application is thus not an effective substitute for teat orifice disinfection. Full article

Background/Objectives: In the Aosta Valley, the alpine grazing system integrates livestock production and land management. Valdostana breeding has adapted to this mountainous region, but the spread of Staphylococcus aureus within pastures may impact animal health. The aim of this study was to provide an overview of S. aureus genotypes associated with antimicrobial resistance (AMR) and virulence profiles in four dairy herds in the Aosta Valley from July 2022 to August 2023. Methods: A total of 468 composite milk samples were collected at three timepoints: T1 (pasture-livestock system), T2 (farm-livestock system), and T3 (pasture-livestock system). S. aureus isolates were characterized by antimicrobial susceptibility testing, ribosomal spacer (RS)-PCR, multilocus sequence typing (MLST), PCR analysis for 28 virulence genes and 6 AMR genes, and adlb-targeted real-time PCR. Results: RS-PCR analysis of 82 S. aureus strains revealed 12 genotypes (GT) in eight clusters (CL). The most prevalent variant was GTR^I (61%), followed by GTB (15%). Resistance to penicillin was high (69%), with CLR strains showing 88% resistance, and 51% resistance to amoxicillin plus clavulanate. All strains were susceptible to cephalosporins and oxacillin. Macrolide resistance was low (4%), and multi-drug resistance was 6%. AMR gene presence corresponded with susceptibility, with blaZ detected in 94% of CLR strains. CLR strains also possessed genes for biofilm formation and virulence factors. Conclusions: This study highlights the presence of AMR and virulence factors in S. aureus strains from alpine grazing systems, underscoring the need for ongoing monitoring to mitigate risks to animal health. Full article

In the present study, we isolated S. canis from milk samples in a dairy farm with suspicions of subclinical mastitis. Milk samples testing positive on California Mastitis Test (CMT) were collected from different cows for bacteriological and genomic analyses to identify the causative pathogen, and somatic cell counts (SCC) were determined. A multiplex qPCR assay was conducted to detect 15 potential pathogens, and all samples showed negative results. Conventional bacteriology procedures were performed; DNA of the bacterial strains was extracted, sequenced, and submitted to bioinformatic analysis. Three CMT positive milk samples showed SCC > 200 × 10³ cell/mL. However, these same three samples were positive for bacteria phenotypically identified as Streptococci, and the strains were confirmed as S. canis using MS MALDI-TOF methodology. In susceptibility testing, resistance against tetracycline was detected, revealing a potential chronic infection in one cow, while the presence of the same bacteria was observed in two other cows. Genomic DNA from four S. canis isolates, obtained in the first and second sampling, was sequenced. Genetic relationships revealed a unique sequence type (ST24). The gene (tetM) related with resistance to TE was highlighted. Although the association between S. canis and mastitis is not routinely detected, early diagnosis of bacterial infections and the study of the antimicrobial profile are crucial for effective therapy. Pets could act as a potential reservoir, so improving hygienic conditions is needed to prevent new infections. Full article

Introduction: Streptococcus uberis is a poorly controlled cause of bovine intramammary infections and a common motivation for the use antibiotics in dairy farms worldwide. Therefore, studying the genomic characteristics of this pathogen is fundamental to understand its complex epidemiology and behavior against antimicrobials. Methods: A comparative genomic analysis of 10 S. uberis strains was performed and their antimicrobial susceptibility was assessed. Results: Ten different novel sequence types were found, and genes (tetM, tetO, patB, lnuC, lnuA, lsaE, ermB, ANT(6)-la) and mobile genetic elements previously associated with antimicrobial resistance (repUS43, ISSag2, and ISEnfa4) and virulence (315.2 phage) were detected. Additionally, our strains had the highest relative rate of recombination to mutation (8.3) compared to other S. uberis strains isolated from different continents (America: 7.7, Asia: 2.9, Europe: 5.4, and Oceania: 6.6). Most of the strains (80%) tested showed phenotypic resistance to clindamycin and 70% exhibited intermediate susceptibility to penicillin. Conclusions: The high heterogeneity of strains observed and the presence of genetic factors linked to antimicrobial resistance represent a challenge for the implementation and surveillance of measures focused on the control and elimination of this pathogen. Full article

In Manchega sheep, correlations between temperatures across various body regions, including the udder, under differing environmental conditions, stages of lactation, and states of mammary gland health have not been extensively explored. To address this, a group of 108 Manchega sheep was evaluated monthly over a period of six months. Ambient, rectal, lacrimal, perianal, and udder surface temperatures, alongside mammary gland health status indicators such as somatic cell count (SCC) and microbiological milk culture, were recorded. This study investigated the correlations between these temperature measurements and SCC levels. Mammary glands were classified based on their SCC (greater or lesser than 400,000 cells/mL) and the results of the microbiological cultures (more or less than five colonies in 20 µL of milk). This study found no correlation between body surface temperatures and rectal temperatures. SCC showed a low negative correlation with udder surface temperatures. Notably, mammary glands with SCC levels exceeding 400,000 cells/mL exhibited lower udder surface temperatures. This research underscores the Manchega breed’s ability to adapt to varying ambient temperatures and the necessity for further studies to better elucidate the relationship between inflammation and temperature changes in the udder during intramammary infections. Full article

The somatic cell count (SCC) is widely used to assess milk quality and diagnose intramammary infections. Several whey proteins have been shown to correlate significantly with SCC and are considered potential indicators of udder health. However, the relationship between milk whey proteins and SCC has not been fully elucidated. In this study, milk samples were grouped into five categories based on SCC levels. Subsequently, whey proteins were identified using a label-free proteomics approach, and the differential abundance of proteins was validated through a selected reaction monitoring (SRM) method. The levels of various proteins, including azurocidin 1 and kininogen-2, exhibited an increase, whereas topoisomerase I, tropomyosin-1, and desmin showed a significant decrease depending on the SCCs. Principal component analysis unveiled that these proteins contributed to the developmental alterations in milk proteins. A majority of these differentially abundant proteins were associated with response to stimulus, localization, and defense response. Our results provide fundamental information on the SCC that can be utilized for evaluating milk quality and serve as potential indicators for detecting intramammary infections. Full article

Sixty Holstein cows were enrolled at −76 days from calving (DFC) and classified based on the daily SCC during the previous week from an automated milking system. The separation thresholds for low (L, n = 46) and high (H, n = 14) classifications were 100 K/mL for primiparous and 200 K/mL for multiparous cows. Cows were then assigned to two homogeneous groups to receive diets supplemented with 19 g/d of a Saccharomyces cerevisiae fermentation product (TRT; NutriTek, Diamond V, Cedar Rapids, IA, USA) or without supplementation (CTR) until 60 DFC. Cows were dried off at −56 DFC and monitored for disease incidence, milk yield and composition, plasma metabolic profile, and whole blood count from −76 to 60 DFC. Data were analyzed utilizing ANOVA and mixed models for repeated measures. During the dry period, TRT cows had greater plasma thiol and albumin compared to CTR. TRT-L cows had greater plasma protein and globulin than CTR-L. TRT-H cows had heightened hematocrit; reduced plasma globulin and haptoglobin; and higher albumin, albumin to globulin ratio, and thiol than CTR-H. TRT-H cows had greater concentrations of leukocytes and lymphocytes and lower plasma protein and ceruloplasmin at −54 DFC; lower reactive oxygen species to ferric ion-reducing antioxidant power ratios at −44 DFC; and greater concentrations of lymphocytes and plasma gamma glutamyl transferase at −7 DFC than CTR-H. After calving, TRT cows had a lower incidence of mastitis and higher butterfat, as well as greater plasma haptoglobin and aspartate amino transferase (AST) and reduced Mg compared to CTR. TRT cows had lower SCC between 1 and 7 DFC and a greater ECM between 41 and 60 DFC compared to CTR. TRT-H cows had lower SCC between 1 and 7 DFC and greater hemoglobin and plasma AST than CTR-H. Ameliorated immune system functions due to Saccharomyces cerevisiae fermentation product administration lowered the SCC in TRT-H cows and prevented the onset of new intramammary infections across both L and H SCC groups, supporting the improved productive performance of dairy cows. Full article

Background/Objectives: Pasteurella multocida commonly colonizes the bovine respiratory tract and can occasionally cause intramammary infections. Here, eight P. multocida isolates from clinical cases of bovine mastitis were investigated for their molecular characteristics as well as phenotypic and genotypic antimicrobial resistance (AMR) properties. Methods: The isolates originated from quarter milk samples obtained in Germany for diagnostic purposes. Antimicrobial susceptibility testing (AST) by broth microdilution was performed according to the Clinical and Laboratory Standards Institute. Closed whole-genome sequences were generated by hybrid assembly of Illumina MiSeq short-reads and Oxford Nanopore MinION long-reads, followed by consecutive sequence analysis. Results: The P. multocida isolates belonged either to capsular:lipopolysaccharide type A:3 (n = 7) or A:6 (n = 1), and multi-locus sequence types 1 (n = 7) or 7 (n = 1). Seven isolates carried AMR genes, such as mef(C), mph(G), strA, strB, aphA1, aadA31, tet(H), tet(Y), floR, catA3, and sul2, as part of an integrative and conjugative element (ICE). These mobile genetic elements, 58,382–78,401 bp in size, were highly similar to the ICEs Tn7406 or Tn7407 that have been previously described in bovine Mannheimia haemolytica and P. multocida, respectively. Moreover, the isolates showed elevated minimal inhibitory concentrations corresponding to the identified AMR determinants. Conclusions: Molecular typing and ICE organization suggest the bovine respiratory tract as reservoir of the investigated mastitis-associated P. multocida. Horizontal cross-genus transfer of multidrug-resistance-mediating ICEs seems to occur under in vivo conditions among different pathogens from cattle in Germany, which underlines the importance of pathogen identification followed by AST for successful bovine mastitis therapy. Full article

The aim of this study was to analyse the effect of intramammary infection (IMI) on N-acetyl-β-D-glucosaminidase (NAGase) enzyme values and to study its predictive capacity using different algorithms. To do this, 26 sheep free of intramammary infection were selected, and their somatic cell count (SCC), NAGase and bacteriological culture were monitored for 2 weeks. They were then subjected to a series of unhealthy situations (UHS) for the mammary gland, and these variables were monitored for a further 4 weeks. IMI was established in 12 of the 26 sheep. In the 4 days following infection, a very marked increase in enzyme values was observed in the infected glands. The algorithm that obtained the best result was the one that detected, in at least two of the first four days after infection, an increase in NAGase values greater than 30% compared to the average of the 3 days prior to infection, obtaining an area under the curve (AUC) of 0.90, an accuracy of 89.8%, a sensitivity of 95.2% and a specificity of 85.7%. Full article

Bovine mastitis, a prevalent disease in dairy farms, exerts a profound negative influence on both the health and productivity of dairy cattle, leading to substantial economic losses for the dairy industry. The disease is associated with different bacterial agents, primarily Gram-positive cocci (e.g., Staphylococcus spp., Streptococcus spp.) and Gram-negative bacilli (e.g., Escherichia coli, Klebsiella pneumoniae). These pathogens induce mastitis through diverse mechanisms, intricately linked to the virulence factors they carry. Despite previous research on the virulence factors of mastitis-causing bacteria in dairy cattle, there remains a significant gap in our comprehensive understanding of these factors. To bridge these gaps, this manuscript reviews and compiles research on the virulence factors of these pathogens, focusing on their roles in mammary tissue infection, immune evasion, adherence to mammary epithelial cells, and invasion and colonization of the mammary gland. These processes are analyzed in depth to provide a comprehensive framework to promote a deeper understanding of dairy pathogenic bacteria and their pathogenic mechanisms and to provide new insights into the control of mastitis in dairy cattle. Full article

Adopting a new milking system at a dairy farm causes various changes. This study examined the impact on udder health when changing from a conventional milking system to an automatic milking system. For this purpose, quarter milk samples were taken six times from 138 cows at one conventional dairy farm in Northern Germany over a five-week period around the time of the milking system changeover. To assess udder health, the absolute number of new intramammary infections and the causative pathogen genera and species were analysed for each individual study time point. Pathogen species were detected using matrix-assisted laser desorption ionisation time-of-flight, and the infection dynamics were analysed using two Poisson regression models. In addition, the prevalence and incidence of new intramammary infections and the infection dynamics of the four most frequently isolated pathogen species were calculated. Mixed models were used to determine the development of the new infection rate, the somatic cell count, the teat-end condition, and the udder hygiene between the individual study time points and to compare the new infection rate before and after the changeover of the milking system. After the automatic milking system had been installed, a significant increase in the quarter-level somatic cell count occurred (p < 0.001). Two days before the installation of the automatic milking system, the mean quarter-level somatic cell count was 11,940 cells/mL milk; one sampling date later, 8 days after the changeover, a mean quarter-level somatic cell count of 60,117 cells/mL milk was measured. The significant increase in somatic cell count was probably caused by the time between the last milking and the quarter milk sampling. Additionally, significantly more udders were scored as clean 8 days (95%) and 15 days (96%) after the changeover of the milking system compared to at the last sampling date (88%). Also, significantly more teat ends were classified as free of hyperkeratosis 15 days (80%) compared to 22 days (67%) after the changeover of the milking system. The highest number of absolute new intramammary infections was detected 8 days before the transition of the milking system (28.6%). The lowest number of absolute new intramammary infections occurred 8 days after the change to the automatic milking system (11.0%). Minor mastitis pathogens, such as non-aureus staphylococci and coryneform bacteria, were mainly responsible for the development of new intramammary infections. The most frequently isolated pathogen species were Staphylococcus sciuri, Staphylococcus chromogenes, Staphylococcus haemolyticus, and Corynebacterium amycolatum, with a prevalence of up to 23.9, 10.7, 8.4, and 5.3%, respectively. By comparing the new infection rate before and after the changeover of the milking system, it was possible to establish that the changeover to the automatic milking system had no significant influence on the new intramammary infection rate (p = 0.988). Therefore, this trial confirmed that the changeover from a conventional milking system to an automatic milking system had no negative influence on udder health. Full article