Gonadotrophic and Lactogenic Hormone Potencies of Gilt Pituitaries during the Estrous Cycle and Pregnancy

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Abstract
Pituitaries were obtained from gilts slaughtered during estrus, diestrum, early proestrum and at the 25th and 85th days of pregnancy. The FSH potency of the pars anterior 2 days after the onset of estrus was significantly lower than at all other stages studied (P<0.05). There was little difference between the FSH potency at 10 to 12 days after the onset of estrus and that found during early proestrum. The difference between the FSH potency means for early and late pregnancy, as deter- mined by the uterine weight assay, was statistically significant (P<0.05). The higher FSH potency at 85 days of pregnancy does not appear to be in agreement with the estrogen inhibition of FSH production by the pars anterior. Although differences among reproductive stage means in the LH assay were not statistically significant, the average weights of the ventral prostate and seminal vesicles of the assay animals indicate the LH potency is higher in pregnant gilts than in gilts slaughtered during estrus or early proestrum. Significant differences, at the 10% level, in lactogenic hormone potency were found among the reproductive stage means. The lactogenic hormone potency was higher in pregnant gilts than in non-pregnant gilts. An increase in lactogenic hormone potency was found with increases in time after estrus. Copyright © . .

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