Bovine major histocompatibility complex (MHC) class II region contains many genes. The bovine leukocyte antigen (BoLA)-DRB3 was reportedly associated with susceptibility of various phenotypes of infections including bovine leukemia virus-induced lymphoma. However, the association of the remaining genes with various phenotypes has not been clarified due to the complicated genomic structure of the MHC class II region. Thus, in this study, we elucidated the MHC class II genomic structure, including the novel alleles and copy number variations (CNVs). We determined the copy numbers of BOLA-DQA2 (DQA2), BOLA-DQB (DQB2), BOLA-DQA5 (DQA5), BLA-DQB (DQB1), LOC100848815 (DQA1), and BOLA-DRB3 (DRB3) in 127 unrelated Holstein cows by TaqMan copy number assay. The genomes were sequenced using target next-generation sequencing (NGS) based on multiplex polymerase chain reaction. Combining the results of the copy numbers and alleles, we identified the BoLA alleles directly without haplotype estimation. Pairwise linkage disequilibrium (LD) analysis between alleles and genes were performed. The CNVs of DQA2, DQB2, and DQA5 in Holstein cows were detected. The frequency of the whole gene deletion in DQA2, DQB2, and DQA5 was 35.4%, 93.7%, and 93.7%, respectively. After target NGS, we identified 37 alleles in the six genes. Fifteen novel alleles (40.5%) were not registered in the IPD-MHC Database. LD analysis showed strong LD among the DQB2*deletion, DQA5*deletion, and DRB3*27:03 alleles. Our findings will provide important insights into the identification of the BoLA genes associated with various infection-related phenotypes.
We examined the uterine microbiota associated with low fertility in dairy cows derived from four commercial farms via a metataxonomic approach using endometrial tissues prior to the first artificial insemination. The present study provided two new insights into the relevance of uterine microbiota with respect to fertility.
Background: The deterioration in reproductive performance associated with low fertility leads to significant economic losses in dairy farms. Some causes of low fertility have not been identified and adequate countermeasures have not been undertaken. In recent years, the uterine microbiota has begun to attract attention as a possible cause of unexplained low fertility. This study analyzed the uterine microbiota associated with low fertility in dairy cows by 16S rRNA gene amplicon sequencing using endometrial biopsies sampled from cows that had passed the voluntary waiting period before the first artificial insemination (AI). Results: First, the uterine microbiota of 69 cows from four farms was analyzed regarding parity and AI frequency to conception, together with factors including housing style and feeding management, as each farm was managed differently. The analysis of microbial diversity revealed differences with respect to feeding management and housing style, but not parity and AI frequency. Next, to avoid the effect of housing style and feeding management, we performed the microbiota analysis in relation to parity and AI frequency in 31 cows from one farm. According to the microbiota diversity analysis, the weighted UniFrac beta diversity metric was correlated with AI frequency, but not with parity. A differential abundance analysis of AI frequency found that the abundance of the Arcobactergenus was increased, whereas the co-occurrence network analysis showed that Arcobacter cooperated with several other bacterial taxonomy units. A comparison of the network of the co-occurrence abundance patterns of normal and low-fertility cows (£3 and ³4 AIs, respectively) showed that bacterial associations related to low fertility, including the Arcobacter association, were observed in low-fertility cows. Finally, the examination of the ratio of the Arcobacter-hub model among the tested farms revealed that it was present to a certain extent, despite the skew toward certain farms. Thus, the Arcobacter genus may be key bacteria in the network module for low infertility in certain farms. Conclusion: This study provided new insights into the relevance of the uterine microbiota as a cause of low fertility, which significantly reduces cows’ reproductive performance.
The purpose of this study was to clarify the effects of antimicrobial treatment for mild mastitis caused by Gram-positive bacteria on the milk microbiota in dairy cattle. Sixteen quarters of sixteen cows with mild clinical mastitis from the same herd were included in the study. On the day of onset (day 0), the cows were randomly allocated to a no-treatment (NT; n = 10) group or an intramammary antimicrobial treatment (AMT) group that received AMT starting on day 0 (AMT-AMT group; n = 6). The next day (day 1), the cows in the NT group were randomly allocated into an NT group (NT-NT group; n = 3) that received no treatment or an AMT group that received AMT starting on day 1 (NT-AMT group; n = 7). Milk samples were collected on days 0, 1, 3 and 7, and the milk microbiota of each sample was comprehensively analyzed via 16S rRNA gene amplicon sequencing of the milk DNA. During the treatment period, the milk microbiota of the NT-NT group did not change, but those of the NT-AMT and AMT-AMT groups changed significantly on days three and seven. Thus, the use of antimicrobials for mild mastitis caused by Gram-positive bacteria changes the milk microbiota composition.
In bovine mastitis, antimicrobial treatment is often initiated before the causative organism is identified a problem in the prudent use of antimicrobials. In this study, we aimed to reduce the total amount of antimicrobials used in mastitis treatment by administering glycyrrhizin, an anti-inflammatory drug, instead of antimicrobials at the onset of clinical mastitis without systemic symptoms, followed by symptom-based antimicrobial selection therapy (ST), to examine the effect of this treatment strategy on treatment outcomes and antimicrobial use. Comparisons between cases that received antimicrobial treatment starting from the day of diagnosis (blanket antibiotic therapy [BT] group: 33 cases) and cases that received ST starting from the day after the diagnosis (ST group: 57 cases) revealed no difference in the cure rate, milk withholding period, or recurrence rate. However, the ST group had a significantly lower amount of antimicrobials than the BT group. Additionally, a single administration of glycyrrhizin before ST significantly relieved the udder symptoms and reduced the antimicrobial amount when compared with cases without glycyrrhizin administration. Thus, a single 3 administration of glycyrrhizin followed by ST can reduce the total antimicrobial use.
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