Postweaning anestrus in the sows: Effect of the low-energy diet during lactation
Khazali, Homayoun
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Permalink
https://hdl.handle.net/2142/19637
Description
Title
Postweaning anestrus in the sows: Effect of the low-energy diet during lactation
Author(s)
Khazali, Homayoun
Issue Date
1992
Doctoral Committee Chair(s)
Bahr, Janice M.
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Neuroscience
Biology, Animal Physiology
Engineering, Biomedical
Language
eng
Abstract
Low energy (LE) intake during lactation results in a delay in the onset of estrus following weaning in primiparous sows. Our first goal was to determine whether LE intake during lactation causes a postweaning imbalance in reproductive and metabolic hormones. Effects of a decreased level of dietary energy intake during lactation on plasma concentrations of estradiol (E$\sb2$), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), growth hormone (GH), thyroxine (T4), triiodothyronine (T3), progesterone (P$\sb4$), cortisol, urea, and glucose were investigated in 16 primiparous crossbred sows. Mean daily concentrations of plasma FSH, E$\sb2$ and LH were lower in LE sows than control (CO) fed sows. Thyroxine concentration was higher in the anestrous sows than the estrous sows during anestrus period. The postweaning high concentrations of T4 in plasma of the LE sows may be one of the factors that mediates the effect of LE diet during lactation on subsequent estrous cycle. The other goal was to determine whether inhibition of gonadotropin releasing hormone (GnRH) and/or LE secretion is the cause for the lower plasma LH concentrations in postweaning anestrous sows. Results suggest that the postweaning decrease of LH secretion caused by LE intake during 28 days of lactation may be mediated through inactivation of the NMA receptors and an increase in the sensitivity of the hypothalamic-pituitary axis to the negative feedback effect of E$\sb2$. The mechanism by which LE diet causes an extended postweaning anestrus may be through an increase in the number of NMA receptors and sensitivity of the hypothalamic-pituitary to negative feedback effect of E$\sb2$ to decrease LH secretion in postweaning anestrous sows. An increase in TRH release as suggested indirectly by the presence of high concentration of plasma T4, may inhibit GnRH release and LH secretion. This suggested mechanism may be a system through which LE diet causes postweaning anestrus in the sow. (Abstract shortened with permission of author.)
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