Sex bias of the birth litter affects surge but not tonic LH secretion in gilts1

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.

Associations between maternal vitamin D status and porcine litter characteristics throughout gestation

“…Previous studies in both mice and pigs have demonstrated effects of intrauterine proximity to male foetuses on foetal growth and morphology [40][41][42][43][44]. Additionally, it is known that sex ratio of a litter has consequences for both gilt and boar postnatal reproductive performance [45][46][47][48][49][50][51][52]. Collectively, given the propensity for sex-biased litters and the strong links between sex of other foetuses within a litter and postnatal success, critical interrogation of the association between vitamin D status and conceptus development in sex biased litters may provide important insights to improve pig production systems.…”

Sex-bias in utero alters ovarian reserve but not uterine capacity in female offspring

“…In the commercial pig a sex-biased in utero environment hormonal environment has been shown to affect several aspects of reproductive function in the offspring. Specifically, females that originate from male-biased litters have fewer teats [8], a lower conception rate at first mating [9], increased sensitivity to gonadotropins [10], and altered LH surge profiles [2], compared to offspring originating from female-biased litters. The cause of these changes in reproductive efficacy remains unclear.…”

“…The Developmental Origins of Health and Disease (DOHaD) describes how the developmental plasticity and in-utero programming of offspring could contribute to susceptibility of a range of adult disease with the maternal intra-uterine hormonal environment has been shown to influence many aspects of offspring development, some of which are sexually dimorphic in nature [1]. Studies specifically investigating the influence of foetal hormones have indicated effects such as endocrine alterations [2], altered physiological development such as delayed lung maturation [3], behavioural changes such as increased aggression [4], and reduced maternal and paternal behaviour [5]. These effects are observed following an androgenisation of the uterine environment in litter bearing species, often caused by disproportionate numbers of males in-utero .…”

Sex bias in utero alters ovarian reserve but not uterine capacity in female offspring

“…The maternal intrauterine hormonal environment has been shown to influence many aspects of offspring development, some of which are sexually dimorphic in nature [ 1 ]. Studies specifically investigating the influence of fetal hormones have indicated effects such as endocrine alterations [ 2 ], altered physiological development [ 3 ], and behavioral changes [ 4 , 5 ]. These effects are observed in litter bearing species following an androgenization of the uterine environment, often caused by disproportionate numbers of males in utero.…”

“…In the commercial pig, a sex biased in utero environment has been shown to affect several aspects of reproductive function in the offspring. Specifically, females that originate from male-biased litters have fewer teats [ 8 ], a lower conception rate at first mating [ 9 ], increased sensitivity to gonadotropins [ 10 ], and altered lutenizing hormone (LH) surge profiles [ 2 ], compared to offspring originating from female-biased litters. The cause of these changes in reproductive efficacy remains unclear.…”