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Mammary Gland Growth and the Initiation of Lactation in Dairy Goats¹

Department of Animal Husbandry, Cornell University, Ithaca, New York

ABSTRACT

The efficacy of estradiol, oxytocin, and bovine somatotrophin to initiate lactation in goats with artificially induced mammary gland growth was tested. In a second experiment, the amount of mammary gland growth resulting from the oral administration of diethylstilbestrol (DES) and 6-methyl-17 acetoprogesterone (MAP) was determined.

In the first experiment, the milk production of goats previously treated for 120 days with estradiol and progesterone was not increased by the injections of either estradiol, oxytocin, or bovine somatotrophin. In the second experiment, no marked milk secretion occurred in goats fed DES or MAP for 150 days until a dose of 1.0 mg estradiol had been injected daily for a 7-day period.

The oral administration of DES or MAP alone, or a combination of the two, resulted in some mammary gland growth and milk production, but the production was much lower than that resulting from pregnancy. The combination of both compounds was no more effective than either one alone. The feeding of MAP to goats for the last 60 days of pregnancy resulted in higher levels of milk production for the first 4 wk of lactation, but the difference was not statistically significant (P > 0.10). Thereafter, the milk production was approximately equal in the treated and the normal pregnant groups. The correlation between previous milk production and total alveolar surface area was 0.935.

¹ Supported in part by funds provided by the regional project NE-41, Endocrine Factors Affecting Reproduction and Lactation in Dairy Cattle, a cooperative study by agricultural experiment stations in the Northeastern Region and the Dairy Husbandry Research Branch, ARS, USDA.

² Present address: Endocrinology Research Laboratory, Harvard School of Dental Medicine, Boston, Massachusetts.