Ovarian and Pituitary Gland Changes in Gilts on Two Nutrient Energy Levels

Abstract

Fifty-two Chester White and Poland China gilts were fed a basal ration (supporting approximately 0.5 kg. gain/day) or a basal ration plus glucose for approximately 14 days prior to slaughter on days 3, 7, 11, 15 or 19 of the third postpuberal estrous cycle. Glucose feeding resulted in greater ovulation rates (when fed for either 12 or 8 days prior to estrus) and in greater bodyweight gains. This treatment also resulted in greater corpus luteum weights and greater luteal progesterone concentrations in gilts killed on days 15 and 19 of the cycle, but had no significant effect on either the number or size of follicles on the days of the cycle studied. Different patterns of pituitary gonadotropin production or release between feed groups were indicated by significant differences in quadratic regressions of gonadotropin estimates on day of the cycle. Residual pituitary FSH activities tended to be lower early in the cycle, higher at mid-cycle and lower late in the cycle in glucose-fed gilts than in basal-fed controls. Residual pituitary LH activities tended to be lower early in the cycle and higher at mid-cycle in basal-fed gilts than in the glucose-fed. The former finding has been interpreted to signify the release of a greater amount of FSH within the few days preceding ovulation in glucose-fed gilts. Cyclic changes in follicular development and residual gonadotropin activities of the anterior pituitary appeared to agree with those reported in previous studies. Poland China gilts tended to have larger follicles than Chester White gilts with the greatest difference (2 mm.) coming at day 19 of the cycle. Chester Whites had smaller weight gains, more follicles?1 mm., higher ovulation rates and lower residual pituitary FSH activities than Poland Chinas. Glucose feeding appeared to lessen the breed difference in residual pituitary FSH activity. Dry anterior pituitary weights were not affected by any of the treatments. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science