ARTIFICIAL INDUCTION OF LACTATION IN BOVINES BY ORAL ADMINISTRATION OF SYNTHETIC OESTROGENS

In the preceding paper [Folley & Malpress, 1944] it has been shown that lactation can be induced in maiden heifers or dry cows by the subcutaneous implantation of tablets of diethylstilboestrol (hereinafter called stilboestrol) or hexoestrol. Dodds, Golberg, Lawson & Robinson [1938] found that stilboestrol was almost as active in the rat, by the vaginal-smear test, when given by mouth as when subcutaneously injected. It was therefore interesting to see whether lactation could be induced in cows and heifers by oral administration of synthetic oestrogens, since the feeding method possesses obvious practical advantages. Induction of lactation in goats by oral administration of stilboestrol was reported by Lewis & Turner [1942]. MATERIAL AND METHODS Experimental animals A series of preliminary experiments was carried out on seven maiden heifers and one heifer (Regality) which had aborted early in pregnancy, each of which re-ceived individual treatment. Four of these (three Shorthorns and one pedigree Guernsey) belonged to this Institute; the other four were Ayrshires belonging t