MASTITIS RESISTENCE IN HOSTEIN FRIESIANS AND IN RENDENA CATTLE BREEDS

The selective pressure for increased milk production in Holstein Friesian dairy cows has led to their higher propensity to develop diseases in the transition period, including mastitis, when compared to less selected and lesser producing dairy breeds which are typically characterized by a higher resistance to diseases. With the aim of investigating the factors associated to this phenomenon, this study applied a multidisciplinary approach to compare innate immune response patterns, metabolic parameters, milk protein profiles and the milk microbiota in 6 Holstein Friesian and 4 Rendena cows reared in the same farm and under the same management conditions. Quarter milk samples and blood plasma were collected from all cows at dry-off (T1), 1 day after calving (T2), 7-10 days after calving (T3) and 30 days after calving (T4). Quarter milk samples were subjected to bacteriological culture, characterization of the milk microbiota by 16S metagenomics, milk protein profiling by electrophoresis and densitometry, somatic cell counting, measurement of the inflammation marker cathelicidin and assessment of different innate immune-related mediators such as lysozyme, CD45, IL-1b, TNF-a, PTX3, IL-1R8. In parallel, the main inflammometabolic parameters were measured in blood plasma samples. Holstein Friesian cows showed a more severe fat mobilization and systemic inflammatory response at T2 and T3 in comparison with Rendena cows. We also observed a greater muscle mass and an increased amino acid mobilization in Rendena cows immediately after calving compared to Holstein Friesians. Upon bacteriological analysis, contagious bacteria such as Staphylococcus aureus and Streptococcus agalactiae were absent, but significant differences were seen in the general composition of the milk microbiota of the two breeds. Concerning the milk protein abundance profile, pronounced differences were seen in colostrum (T2), with significantly higher amounts of immunoglobulins and other immune-related proteins in Rendena. Adding to this, the expression of innate immune related genes such as PTX-3, IL-1b, TNF-a, as well as the CD45/KRT5 expression ratio in milk cells, indicating the epithelial and leukocyte components, respectively, was lower in Holstein Friesian compared with Rendena at T2. In conclusion, several differences were observed in the two breeds, in spite of the same farming conditions. The observations reported in this work present numerous hints on the factors that may provide autochthonous, more rustic breeds with a higher resistance to disease.