Comparison of milk microbiome biodiversity between Hostein Friesian and an Italian local cattle breed (Rendena). milk metagenome

Animals host a wide diversity of microbial communities on skin, gut, oro-pharyngeal, urinary and genital tracts, that have evolved with them as a result of complex and mutualistic interactions playing crucial roles in their biology and health status. Recently, the mammary gland, previously considered a sterile organ, has also been included among these sites, since that raw milk is an environment that contains diverse and complex microbial population. Due to intramammary infection, mastitis is the most important disease in dairy cows causing economic losses due to fewer milk production, premature culling and costs for veterinary treatment. It is, also, a serious animal welfare issue during the calving period especially for Holstein Friesian breed. This is in contrast with the low prevalence of clinical mastitis in some autochthonous cattle breeds, such as Rendena breed, an indigenous Italian dual-purpose alpine cattle breed with good aptitude to pasture and appreciable functional traits.The aim of this study was to analyse the milk microbiota in 6 Holstein Friesian and 3 Rendena cows in order to better understand the differences in milk microbial composition among calving period between breeds; a total of 4 time points (dry-off (T1), 1 day after calving (T2), 7-10 days after calving (T3) and 30 days after calving (T4)) were considered. Sampling was carried out only on healthy quarters during this physiological transition period, for a total of 117 milk samples, to focus on microbiome changes avoiding shifts due to mastitis.