Evolution of milk somatic cell count of cows grazing an alpine pasture according to the infection of udder by pathogens

Abstract

The infection of udder by a pathogen and milk somatic cell count (SCC) of 220 quarters from 55 Abondance and Tarentaise cows coming from three Northern Alps herds were analysed three times: in June when cows use a valley pasture before turning to highland pasture and in July and September, respectively at the beginning and the end of highland pasture grazing period. During the three periods, 31% of the experimental quarters were free or infection, 61% were infected by a minor pathogen and 8% were infected by a major pathogen. In quarters infected by a major pathogen, SCC was constantly high (> 1 600 000 cells/ml in the three periods). SCC of uninfected quarters remained below 60 000 cells/ml in the three periods whereas SCC of quarters infected by a minor pathogen averaged 89 000 cells/ml in June and 512 000 cells/ml in September. For the latter, SCC was all the higher as the infection was older. Results are discussed according to the highland grazing conditions that may have had an impact on SCC.