Effect of breed of cow (Friesian and Montbéliarde) on spontaneous and induced lipolysis in milk.

Levels of free fatty acids (FFA) were determined immediately after milking (initial FFA), and after 22 h storage at 4 degrees C, either without (FFA-22) or with a mechanical induction of lipolysis (FFA-22I), in milk from Friesian and Montbéliarde cows in the same herd, at identical stages of lactation and pregnancy and receiving the same feeding regimes. There was no difference between the two breeds in initial FFA and FFA-22 contents whatever the lactation period. This was also true during late lactation when lipolysis was further increased after feeding a poor quality grass silage. The observation that milk FFA-22I content from the Montbéliarde cows was higher than that from Friesian cows in summer, but not in winter, requires cautious interpretation as the activation treatments were not comparable, owing to the different ambient temperatures during activation in these two periods.