Bilan national des numérations cellulaires dans le lait des différentes races bovines laitières Françaises

Abstract

This paper presents a descriptive overview of milk somatic cell counts in the French dairy cattle breeds. Data originated from the national data base, with complete information since 1995. Cell count level varied according to breeds, and the milk was less concentrated in cells in low producing breeds (Abondance, Simmental Française) than in more high-yielding breeds (Prim'Holstein, Pie Rouge des Plaines). These differences across breeds were still observed for a given production level and, therefore, could not simply be explained by production. Within breed, the lowest producing cows had the highest cell count level. These cows were likely to be infected and their low production probably reflected the depressive effect of infections on milk production. Within breed, cell counts increased with parity. This illustrated the increase in incidence and persistency of intramammary infections with age. The cell counts evolution with days in milk showed a trend inverted to that of milk yield. Except in the beginning of the lactation, this trend likely resulted from a concentration effect due to the change in milk volume over the lactation, as the number of excreted cells was found to be stable after the first two months of lactation. Cell counts were higher in summer and lower in fall, whatever the lactation stage. They also varied among regions. On the other hand, cell count level was stable over time during the last five years and denoted the technical control ability of the farmers.