Farm management risk factors of mastitis for mountain dairy farms in the western Alps

Assistance and veterinary services for dairy farms are scarce in mountain internal areas, because of logistic limitations, inducing a high incidence of diseases on dairy herds, like mastitis. Here, prevention is a key strategy to improve herd’s health and farm efficiency. This study aimed to identify the risk factors of mastitis at a farm management level for mountain dairy herds in the western Italian Alps. Eight dairy farms of Lanzo’s Valleys were selected; 6 of them were transhumant herds. Each farm was visited 3 times: once in spring, twice in summer, 3 to 5 days after transhumance and approximately 1 month later. At each visit, milk samples from individual cow were collected for milk composition, somatic cell count (SCC) and microbiological analysis, focusing on pathogens responsible for mastitis. Simultaneously, on-farm surveys were carried out to collect data on animal characteristics, production, feeding at farm and on pasture, management practices, available infrastructure, workforce, etc. Data from individual animals were averaged at a herd level. A correlation matrix was run on microbiological and farm characteristics and management data. As expected, SCC and contagious pathogens (CnP) were positively correlated (P < 0.01). Both SCC and CnP were positively related to average herd lactation rank (P < 0.05), and negatively with barn oldness (P < 0.01). High SCC and CnP were associated to several variables indicating a highly extensive farm management: a long grazing time per day (P < 0.05); high altitude of grazed plots (P < 0.01); low annual stocking rate (P < 0.01), high pasture and low conserved forages and concentrate proportions in cow diet (P < 0.05). High CnP was also associated to large upland pasture surface (P < 0.05). High SCC was associated to low milk yield/cow*year, low milk yield/ workforce unit, high proportion of hay in winter diet and the time spent by walking during transhumance (P < 0.05). In conclusion, mountain grazing systems with a high degree of extensification (large surface, high altitude, low stocking rate, low milk yield, long cow lifespan, etc.) showed a higher mastitis risk.