“…Lipolytic levels in individual milks may show fluctuations associated with the oestrus cycle, although usually the effect is small. The levels of lipolytic enzymes in milks show a definite relationship with the oestrus cycle, reaching a maximum just before heat (Kelly, 1945;Wells et al 1969) but whether this increases the susceptibility of the milk to lipolysis is uncertain. Also, there are some suggestions in the literature that the actual milking machines, by affecting the hormonal control, may influence the susceptibility of the milk to spontaneous lipolysis.…”