The dry period nutrition of the dairy cow can significantly affect subsequent milk production. It has been suggested that part of this effect can be attributed to the animal's use of labile body protein in support of early lactation nutrient requirements. If this is so, then there may be endocrine changes to signal nutrient partitioning. This experiment was designed to investigate the effect of offering diets differing in protein content during the dry period on changes in the endocrine profiles of animals over that period and during the first 21 weeks of lactation.
Forty-eight multiparous Holstein-Friesian cows were offered one of three different dry period diets for 6 weeks before predicted calving (16 animals per treatment): A) grass silage only, B) a grass silagetoarley straw mix (60:40 on a dry matter basis), or C) grass silage plus 0.5 kg/d high protein maize gluten meal. Diets A, B and C differed in the amounts of protein supplied: medium, low and high respectively. After calving, all animals were offered the same diet of ad libitum grass silage and concentrates at a stepped fixed rate.