A survey on milk composition and milk coagulation time

Abstract

A detailed survey was conducted on 41 dairy farms located in the Thônes area (Haute-Savoie) to determine some of the factors in herd management that influence milk quality with respect to cheese making. Farm structures, herd structures and feeding practices were related to the chemical composition of milk and to milk coagulation time. Large variations in milk composition were noted among farms. The difference between values amounted to 6.5 g/kg for milk fat content, 4.0 g/kg for milk protein content and 11 min for milk coagulation time. In winter, low milk protein contents and large monthly variations in milk coagulation times were associated with poor feeding practices. In summer, differences in calving dates explained, to a large extent, the differences observed in milk protein contents. The analysis of individual results measured monthly in a total of 814 cows showed the specific effects of the stage of lactation and of the season on milk composition. In particular, milk coagulation time was minimum (25 min) at the beginning of lactation and maximum (32 min) during the 6th month of lactation. Milk coagulation time was also shown to be maximum in late winter and mid-summer.