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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.

International audience; 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. Forty-eight 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), p-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.

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 genome-wide 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. Electronic supplementary material The online version of this article (doi:10.1186/s12863-015-0263-3) contains supplementary material, which is available to authorized users.