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Melatonin administration during the first half term of pregnancy improves physiological response and reproductive performance of rabbits under heat stress conditions

Nesrein Hashem , Elshymaa Abdelnaby, Mahmoud Madkour, Hossam El-Sherbiny

Abstract

Context. Melatonin may have heat stress alleviating-role during pregnancy. Aims. To investigate the effects of melatonin administration during the first half of pregnancy on heat tolerance capacity and pregnancy outputs of naturally heat stressed rabbits. Methods. Forty female rabbits were stratified equally into two experimental groups and daily received 1 mg melatonin/kg body weight or not (control) for fifteen consecutive days post-insemination. Heat tolerance indices, hormone profile, ovarian structures, and fetal loss were determined. Key results. Treatment with melatonin significantly decreased respiration rate and rectal temperature, improved concentrations of nitric oxide, and tended to decrease malondialdehyde concentrations (P=0.064) compared to control. Melatonin treatment significantly increased concentrations of high-density lipoprotein, estradiol, and progesterone compared to control . No significant differences in the numbers of of visible ovarian follicles, corpora lutea, and total implantation sites on day 18 of pregnancy between both experimental groups. However, melatonin treatment significantly reduced number of absorbed implantation sites and significantly improved amniotic fluid volume and conception rate compared to control. Conclusions. Melatonin administration during the first half term of pregnancy can improve reproductive performance of heat stressed female rabbits. Implications. Melatonin can improve fetal survivability via improving heat tolerance capacity of does and steroidogenesis.

RD23139  Accepted 19 April 2024

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