Hormone Induced Lactation in the Bovine. II. Response of Nulligravida Heifers to Modified Estrogen-Progesterone Treatment

Abstract

Subcutaneous injection of 17/3-estradiol (60 rag/600 kg body weight per day) and progesterone (150 rag/600 kg body weight per day) for 7 days initiated lactation in nulligravida heifers. Lactation was initiated with 17/3-estradiol-progesterone ratios of 1:2.5, 1:2, and 1:1 when constant 17/~-estradiol (60 rag/600 kg body weight per day) was maintained. Varying the dose of 17/3-estradiol (20, 40, or 60 rag/600 kg body weight per day) while maintaining a constant 1713estradiol:progesterone ratio of 1:2.5 also initiated lactation at all rates of 1713estradiol.