Induced lactation in dairy heifers: Effects of bovine somatotropin, time of bovine somatotropin administration, age at induction, and dexamethasone administration

Heifer rearing represents a large cost component of commercial dairying because these animals do not produce milk until approximately two years of age. Inducing heifers into lactation at a younger age would reduce this non&;Holstein heifers were induced into lactation by daily administration of estradiol&;When bST administration began on experimental day 1 with the induction treatment, mean daily milk yield for bST&;Dexamethasone administration (10 mg) on days 1 and 2 of lactation increased initial milk production through 15 DIM, but this did not persist through 305 DIM. Milk yield was 8.6% higher in heifers induced into lactation at 18 months compared to those induced at 14 months of age. This may be due to higher feed intake capacity, greater mammary epithelium, or both.