Sex bias of the birth litter affects surge but not tonic LH secretion in gilts

J Anim Sci. 2018 Jun 4;96(6):2195-2203. doi: 10.1093/jas/sky151.

Abstract

The physiology and behavior of gilts that develop in a male-biased litter can differ from gilts that develop in a female-biased litter. We hypothesized that gilts from male-biased litters will have a delayed and attenuated luteinizing hormone (LH) surge, and reduced LH pulse frequency and amplitude compared to gilts from female-biased litters. Gilts were selected at birth from male-biased (>60% males n = 10) or female-biased (>60% females n = 9) litters. From 18 wk of age, detection of puberty using daily boar contact began and their subsequent estrous periods were synchronized with oral progestogen (altrenogest). On day 3 after altrenogest withdrawal, blood samples were obtained from 6 gilts per sex bias group at 10 min intervals from 0900 to 2100 h to determine LH pulse amplitude and frequency. From 0900 on day 4, all 19 gilts were sampled every 4 h until the end of estrus to characterize LH surge dynamics. There were no differences between groups in LH pulse characteristics. Compared to gilts from female-biased litters, the LH surge in gilts from male-biased litters was delayed [56.00 ± 3.32 h vs. 43.11 ± 3.76 h (mean ± standard error of the mean (SEM)), P < 0.05], the duration was decreased [29.78 ± 2.12 h vs. 37.71 ± 1.19 h (mean ± SEM), P < 0.05] and the total secretion as measured by area under the curve was decreased (91.42 ± 9.52 ng/mL vs. 120.28 ± 9.48 ng/mL, P < 0.05). Our results indicate that a male-biased uterine environment has different effects on the tonic secretion of LH than the LH surge, with only some elements of the LH surge being affected.

MeSH terms

  • Animals
  • Behavior, Animal*
  • Environment
  • Estrus / physiology
  • Female
  • Luteinizing Hormone / blood*
  • Luteinizing Hormone / metabolism
  • Male
  • Parturition
  • Pregnancy
  • Progestins / administration & dosage
  • Sex Factors
  • Sexual Maturation
  • Swine / physiology*
  • Trenbolone Acetate / administration & dosage
  • Trenbolone Acetate / analogs & derivatives
  • Uterus / physiology

Substances

  • Progestins
  • altrenogest
  • Luteinizing Hormone
  • Trenbolone Acetate