PSIV-1 Concentrations of follicle stimulating hormone and progesterone in female offspring born to ewes poorly fed during gestation

Abstract The objective of this study was to determine the effects of poor maternal nutrition (restricted- and over-feeding) during gestation on the reproductive efficiency of female offspring. We hypothesized that ewes born to restricted- and over-fed dams would have reduced fertility and decreased concentrations of follicle stimulating hormone (FSH) and progesterone (P4). Multiparous Dorset ewes (F0; n = 46) were fed one of three diets from d 30 of gestation until parturition according to NRC requirements for total digestible nutrients: control- (100%), restricted- (60%), or over- (140%) fed. Resulting female offspring (F1; n = 38) were raised on a control diet and are identified as CON (n = 10), RES (n = 12), or OVER (n = 16) corresponding to diets of their dam. Between 16 and 19 mo of age, the F1 ewes were estrous synchronized by vaginal insertion of a controlled intravaginal drug release device (CIDR) for a 12-d period, followed by a 2 mL (5 mg/mL) intramuscular injection of prostaglandin F2α, and then bred to one of two related rams. Day 0 of gestation was considered when a raddle mark was observed on the rump of the ewe. Time to pregnancy was calculated as the number of days from when the ewes were initially housed with the ram until d 0 of gestation. Based on ultrasounds on d 37 ± 0.77 of gestation, all F1 ewes were identified as pregnant on first service and number of fetuses was recorded and lambs born were counted at parturition. Data were analyzed using RStudio with a significance of P ≤ 0.05 and a tendency of 0.05 P ≤ 0.10. Maternal diet did not significantly affect time to pregnancy, number of fetuses, or number of lambs born (P ≥ 0.13). Blood samples (10 mL) were collected via jugular venipuncture at four timepoints (d -14, -7, 0, 7) corresponding to d 0 of gestation and were analyzed for concentrations of FSH and P4 by enzyme-linked immunoassays in 29 ewes (CON: n = 8, RES: n = 8, OVER: n = 13). The CON ewes had 15.2% less FSH than OVER ewes (P = 0.05) and RES ewes tended to have 14.2% less FSH than OVER ewes (P = 0.08). Concentrations of P4 were not different in F1 ewes (P ≥ 0.14). However, concentrations of P4 in F1 ewes tended to increase (P = 0.08) by 12% from d -14 to d 0, which corresponds with a normal estrous cycle. The increased concentration of FSH in OVER ewes could be due to a dysregulation of FSH. However, those effects may be mitigated at some point in time later in gestation since there were no differences in time to pregnancy nor number of lambs born.