Some effects of total mastectomy upon subsequent reproductive performance in sows

Six sows were totally mastectomized after the weaning of their second litter and their subsequent reproductive characteristics compared with six intact sows. Mastectomy did not influence the length of the oestrous cycle, the incidence of conception after mating, the length of the gestation or of parturition periods; however the interval between parturition and the first oestrus after parturition was reduced in the mastectomized sows from 7·8 to 5·3 days. During pregnancy, the plasma concentrations of progesterone, oestradiol-17 β, oestrone, oestrone sulphate and growth hormone were unaltered by mastectomy, but the mean plasma concentration of prolactin over the whole of pregnancy was raised from 7·8 to 11·8 mg/ml in the mastectomized sows.Both the control and experimental sows were weaned at parturition and fertility thereafter was poor in both groups. The clearance of progesterone and oestradiol-17 β from the circulation after parturition was examined in three mastectomized and three intact sows weaned at parturition, and compared with four lactating sows; no differences were found.The results indicate that the mammary glands of sows do not influence primary reproductive functions and that the surgical removal of all mammary tissue has no influence on the infertility seen in sows that have been weaned at parturition.