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Background: Host-associated microbes are major determinants of the host phenotypes. In the present study, we used dairy cows with different scores of susceptibility to mastitis with the aim to explore the relationships between microbiota composition and different factors in various body sites throughout lactation as well as the intra- and inter-animal microbial sharing. Results: Microbiotas from the mouth, nose, vagina and milk of 45 lactating dairy cows were characterized by metataxonomics at four time points during the first lactation, from 1-week pre-partum to 7 months post-partum. Each site harbored a specific community that changed with time, likely reflecting physiological changes in the transition period and changes in diet and housing. Importantly, we found a significant number of microbes shared among different anatomical sites within each animal. This was between nearby anatomic sites, with up to 32% of the total number of Amplicon Sequence Variants (ASVs) of the oral microbiota shared with the nasal microbiota but also between distant ones (e.g. milk with nasal and vaginal microbiotas). In contrast, the share of microbes between animals was limited (< 7% of ASVs shared by more than 50% of the herd for a given site and time point). The latter widely shared ASVs were mainly found in the oral and nasal microbiotas. These results thus indicate that despite a common environment and diet, each animal hosted a specific set of bacteria, supporting a tight interplay between each animal and its microbiota. The score of susceptibility to mastitis was slightly but significantly related to the microbiota associated to milk suggesting a link between host genetics and microbiota. Conclusions: This work highlights an important sharing of microbes between relevant microbiotas involved in health and production at the animal level, whereas the presence of common microbes was limited between animals of the herd. This suggests a host regulation of body-associated microbiotas that seems to be differently expressed depending on the body site, as suggested by changes in the milk microbiota that were associated to genotypes of susceptibility to mastitis. [ABSTRACT FROM AUTHOR]

Abstract Background Within complex microbial ecosystems, microbe-microbe interrelationships play crucial roles in determining functional properties such as metabolic potential, stability and colonization resistance. In dairy cows, microbes inhabiting different ecological niches of the udder may have the potential to interact with mastitis pathogens and therefore modulate susceptibility to intramammary infection. In the present study, we investigated the co-occurrence patterns of bacterial communities within and between different niches of the bovine mammary gland (teat canal vs. milk) in order to identify key bacterial taxa and evaluate their associations with udder health parameters and mastitis susceptibility. Results Overall, teat canal microbiota was more diverse, phylogenetically less dispersed, and compositionally distinct from milk microbiota. This, coupled with identification of a large number of bacterial taxa that were exclusive to the teat canal microbiota suggested that the intramammary ecosystem, represented by the milk microbiota, acts as a selective medium that disfavors the growth of certain environmental bacterial lineages. We further observed that the diversity of milk microbiota was negatively correlated with udder inflammation. By performing correlation network analysis, we identified two groups of phylogenetically distinct hub species that were either positively (unclassified Bacteroidaceae and Phascolarctobacterium) or negatively (Sphingobacterium) correlated with biodiversity metrics of the mammary gland (MG). The latter group of bacteria also showed positive associations with the future incidence of clinical mastitis. Conclusions Our results provide novel insights into the composition and structure of bacterial communities inhabiting different niches of the bovine MG. In particular, we identified hub species and candidate foundation taxa that were associated with the inflammatory status of the MG and/or future incidences of clinical mastitis. Further in vitro and in vivo interrogations of MG microbiota can shed light on different mechanisms by which commensal microbiota interact with mastitis pathogens and modulate udder homeostasis.

The aim of the present study was to: 1) check whether it would be possible to detect cows susceptible to mastitis at an early stage of their utilization based on selected genotypes and basic production traits in the first three lactations using ensemble data mining methods (boosted classification tress – BT and random forest – RF), 2) find out whether the inclusion of additional production variables for subsequent lactations will improve detection performance of the models, 3) identify the most significant predictors of susceptibility to mastitis, and 4) compare the results obtained by using BT and RF with those for the more traditional generalized linear model (GLZ). A total of 801 records for Polish Holstein-Friesian Black-and-White cows were analyzed. The maximum sensitivity, specificity and accuracy of the test set were 72.13%, 39.73%, 55.90% (BT), 86.89%, 17.81%, 59.49% (RF) and 90.16%, 8.22%, 58.97% (GLZ), respectively. Inclusion of additional variables did not have a significant effect on the model performance. The most significant predictors of susceptibility to mastitis were: milk yield, days in milk, sire’s rank, percentage of Holstein-Friesian genes, whereas calving season and genotypes (lactoferrin, tumor necrosis factor alpha, lysozyme and defensins) were ranked much lower. The applied models (both data mining ones and GLZ) showed low accuracy in detecting cows susceptible to mastitis and therefore some other more discriminating predictors should be used in future research.

Background: Bovine mastitis is the most common and costly disease of lactating cattle worldwide. Apart from milk somatic cell count (SCC) and somatic cell score (SCS), serum cytokines such as interleukin-17 (IL-17) and interleukin-4 (IL-4) may also be potential indicators for bovine mastitis. The present study was designed to investigate the effects of single nucleotide polymorphisms (SNPs) in bovine IL-17F and IL-17A genes on SCC, SCS and serum cytokines in Chinese Holstein and Inner-Mongolia Sanhe cattle, and to compare the mRNA expression variations of the cows with different genotypes. Results: A total of 464 lactating cows (337 Holstein and 127 Inner-Mongolia Sanhe cattle) were screened for SNPs identification and the data were analyzed using fixed effects of herd, parity, season and year of calving by general linear model procedure. The results revealed that SNP g.24392436C > T in IL-17F and SNP g.24345410A > G in IL-17A showed significant effects on SCC and IL-4 in Holstein (n = 337) and on IL-17 and IL-4 in Sanhe cattle (n = 127). The homozygous GG genotype of SNP g.24345410A > G had significantly higher mRNA expression compared with the heterozygous AG genotype. Conclusions: The results indicate that IL-17F and IL-17A could be powerful candidate genes of mastitis resistance and the significant SNPs might be useful genetic markers against mastitis in both dairy and dual purpose cattle. [ABSTRACT FROM AUTHOR]

Since lactoferrin is acute phase protein and has an exceptional role in defense mechanism of mammary gland, it is considered a candidate gene for mastitis susceptibility in dairy cattle. In this study, blood samples were collected for DNA extraction from fifty Holstein dairy cows in the third lactation season reared under Egyptian conditions assigned into three groups mastitis (n=15), subclinical mastitis (n=20) and healthy (n=15) based on California mastitis test. Moreover biochemical markers for inflammation were determined to detect severity. PCR amplification of a segment of 6th intron of lactoferrin gene yielded a fragment of 301-bp in all animals under study. For revealing polymorphism, DNA sequencing was done for PCR products of lactoferrin gene (301-bp) in only five healthy (resistant) and five affected animals. Results indicated that, association between biochemical data and affections. The PCR-DNA sequencing genetic assessment identified twelve SNPs in the bovine lactoferrin gene and there was association between these identified SNPs and mastitis susceptibility, where ten nucleotide sequence variations for one of the healthy animals were obtained with A166T, T185A, T200C, G230C, A239G, T251G, A254C, A272C, T273C and A296G SNPs (submitted to GenBank with accession number gb|KT159457|. On the other hand, two nucleotide sequence variations for two of the affected animals were obtained with A100G and T275A SNPs. Consequently, the identified SNPs in the bovine lactoferrin gene can be used as marker-assisted selection (MAS) to predict, improve mastitis resistance and minimize incidence of mastitis infection in Holstein dairy cows. [ABSTRACT FROM AUTHOR]

Dairy ruminants experiencing a severe postpartum negative energy balance (NEB) are considered to be more susceptible to mastitis. Although the genetic variability of mastitis resistance is well established, the biological basis of the link between energy metabolism and resistance is mostly unknown. The aim of this study was to characterize the effect of NEB on metabolism and immune response according to the genetic background for mastitis resistance or susceptibility. Fortyeight ewes from high and low somatic cell score (SCS) genetic lines were allocated to 2 homogeneous subgroups 2 wk after lambing: one group (NEB) received an energy-restricted diet to cover 60% of their energy requirements, and the other group received a control (positive energy balance: PEB) diet. Both diets met the protein requirements. After 10 d on either the NEB or PEB diet, all ewes were injected with a Pam3CSK4/MDP solution in one half-udder to induce an inflammatory response. The ewes were monitored for milk production, somatic cell count (SCC), body weight (BW), body condition score (BCS), and blood metabolites. Differential milk cell counts were determined by flow cytometry. Plasma concentrations of glucose, insulin, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHB), and triiodothyronine were determined. Energy restriction resulted in an increased fat:protein ratio in milk and decreased milk yield, BW, and BCS. The NEB ewes had significantly higher NEFA and BHB and lower plasma glucose concentrations than PEB ewes, reflecting a mobilization of body reserves and ketone body synthesis. High-SCS ewes had a higher SCS than low-SCS throughout the experiment, except after the inflammatory challenge, which resulted in similar SCS in all 4 groups. A noteworthy interaction between genetic background and diet was evidenced on metabolic parameters and BW. Indeed, high-SCS ewes subjected to NEB showed greater decrease in BW and increased NEFA and BHB concentrations compared with low- SCS ewes. Thus, NEB in early lactation led to extensive mobilization of body reserves and intense ketone body synthesis in mastitis-susceptible sheep. These results reinforce the hypothesis of a genetic association between mastitis susceptibility and energy metabolism and open the way to further studies on the biological basis for this association. [ABSTRACT FROM AUTHOR]

Backgrounds: Bovine mastitis is a typical inflammatory disease causing seriously economic loss. Genome-wide association study (GWAS) can be a powerful method to promote marker assistant selection of this kind of complex disease. The present study aimed to analyze and identify single nucleotide polymorphisms (SNPs) and candidate genes that associated with mastitis susceptibility traits in Chinese Holstein. Results: Forty eight SNPs were identified significantly associated with mastitis resistance traits in Chinese Holstein cows, which are mainly located on the BTA 14. A total of 41 significant SNPs were linked to 31 annotated bovine genes. Gene Ontology and pathway enrichment revealed 5 genes involved in 32 pathways, in which, TRAPPC9 and ARHGAP39 genes participate cell differentiation and developmental pathway together. The six common genomewide significant SNPs are found located within TRAPPC9 and flanking ARHGAP39 genes. Conclusions: Our data identified the six SNPs significantly associated with SCS EBVs, which suggest that their linked two genes (TRAPPC9 and ARHGAP39) are novel candidate genes of mastitis susceptibility in Holsteins. [ABSTRACT FROM AUTHOR]

The JAK-STAT pathway plays a key role in host immunity. The present study was designed to evaluate the effects of single nucleotide polymorphisms (SNPs) in STAT5A and JAK2 genes on some serum cytokines, mastitis and milk production traits. Two SNPs (SNP1 43046497A/C and SNP2 43047829G/A) in STAT5A, and four SNPs in JAK2 (SNP3 39652267A/G, SNP4 39630048C/T, SNP5 39631044G/A, and SNP6 39631175T/C) were revealed and genotyped in 268 Chinese Holstein cattle. Fixed model was used to analyze the association of SNPs with phenotypes by general linear model procedure of SAS 9.1. SNP1 and SNP4 were significantly associated with IL-6 and IL-17 ( P < 0.05), respectively. In JAK2 gene, SNP3 was highly significant ( P < 0.01) and SNP5 was significant ( P < 0.05) in association with SCC, whereas, the association of SNP6 was found significant ( P < 0.05) with both SCC and SCS. Combination genotype analysis revealed that SNPs in JAK2 gene significantly associated with SCC and SCS were associated significantly with the corresponding phenotypes in combinations as well. The GG genotype of SNP3 individually and in any combination genotypes showed lowest SCC. The dominant effect of SNP1, SNP5 and SNP6 was found highly significant ( P < 0.01) on the corresponding phenotypes (IL-6, SCC and SCS). As for haplotype analysis, two haplotypes were revealed between the two SNPs of STAT5A gene and four haplotypes amongst four SNPs in JAK2 gene; strong linkage disequilibrium (D′ > 0.9) was observed between all these haplotypes. The results imply that the identified SNPs could be powerful markers to select dairy cattle with improved genetic resistance against mastitis. [ABSTRACT FROM AUTHOR]