Etude de quelques cas de contaminations microbiennes importantes du lait à la ferme

Abstract

ources of bacterial contaminations of raw milk in the farm The main sources of the bacterial contamination of raw milk have been investigated using a suitable methodology (milking with sterile ustensils, bacteriological rinses of milking plants, milk sampling during milking). This paper deals with a study made in twelve farms where a large and dominant source of contamination was found, i. e. either udder skin, milking machines or cows with mastitis. The microbial "profiles" (i. e. total, psychrotrophic, thermoduric and coliform bacterial counts in milk produced in these farms) seemed to depend on the main source of bacteria e. g. contamination by poorly washed udders was characterized by high total, but low coliform counts, milking machines having defects in design, increased the milk content of both total and coliform bacteria. On the other hand, contamination of milk by poorly cleaned milking machines led to high total and thermoduric counts. This study shows that a bacteriological analysis of milk and the use of characteristic "profiles" may be taken as a useful aid in diagnosing the main cause of milk contamination at the farm