A survey on milk composition and butyric acid bacteria in milk

Abstract

A detailed survey has been conducted in the Haute-Loire region on 145 dairy farms that were using grass silage. The structure of the farm and that of the herd, the feeding practices, the milking conditions and the hygiene of the animals were examined. These variables were analyzed in connection with the chemical composition of milk and its contamination with butyric acid bacteria spores. Large variations in milk composition were noted among farms. Differences between extreme values amounted to 6 g/l for milk fat content and to 5 g/l for milk protein content, whereas butyric acid bacteria contamination ranged from 300 to 16 000 spores/I. The variations in milk composition were due mostly to the type of basal diet, the breed, and the calving period. The highest butyric acid bacterial contamination were explained largely by the type of basal diet used (high grass silage diets) and the absence of cleanness of the animals and of the stables. Only a small number of farms was seen to apply the precautions necessary to reduce butyric acid bacterial contamination in milk.