Serum progesterone, estradiol-17 beta, and glucocorticoids in the collared peccary during gestation and lactation as influenced by dietary protein and energy.
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Sixteen pregnant collared peccaries were assigned to four experimental diets representing two levels of crude protein and two levels of digestible energy. Serum levels of progesterone, estradiol-17 beta (E2), and glucocorticoids were measured by radioimmunoassay. There was no significant dietary effect (P greater than 0.05) associated with any hormone during gestation. Progesterone did not differ between days 11 and 140 of gestation (X +/- SE = 36.48 +/- 1.11 ng/ml, N = 72), began to decline during the last week prepartum, and continued to decline within 24 hr of birth. Glucocorticoid concentrations remained level throughout gestation (X +/- SE = 6.57 +/- 0.45 microgram/dl, N = 74). E2 levels were low during the first 90 days of gestation, rose significantly (P less than 0.001) from 10.11 +/- 1.73 pg/ml (X +/- SE, N = 8) at Days 81-90 gestation to 49.07 +/- 12.87 pg/ml (N = 3) at 2-4 days prepartum (Days 141-147 of gestation), and declined rapidly to baseline levels within 24 hr of farrowing. Litter size had no effect on progesterone or E2 concentrations. There was no significant dietary effect on litter size or gestation length. During lactation, glucocorticoids and E2 remained stable and did not differ by diet, while progesterone concentrations appeared to be affected by diet. Individuals on the high energy-high protein diet returned to normal ovarian function before animals on the other three diets. Results indicated that the pregnant collared peccary can maintain a reproductive steroid environment that allows for fetal development in the face of moderate caloric or protein restriction and that the lactating peccary can undergo a postpartum ovulation in the presence of good nutrition.
