Effects of Melatonin Administration to Pregnant Ewes under Heat-Stress Conditions, in Redox Status and Reproductive Outcome.

Efterpi Bouroutzika,Mariangela Caroprese,Sotiria Makri,Dimitrios Kouretas,Marios-Lazaros Michailidis,Serafeim Papadopoulos,Ekaterini Theodosiadou,Charilaos Paliouras,Aristidis S Veskoukis,Irene Valasi

doi:10.3390/antiox9030266

Efterpi Bouroutzika, Mariangela Caroprese + Show 8 more

Open Access

https://doi.org/10.3390/antiox9030266

Copy DOI

Journal: Antioxidants	Publication Date: Mar 23, 2020
Citations: 19	License type: CC BY 4.0

Affiliation: University of Thessaly, University of Foggia

Abstract

Heat stress is a known promoter of reactive oxygen species generation, which may compromise pregnancy and foetal development. Melatonin is a pleiotropic molecule that regulates various processes including pregnancy. Thus, it could be used to ameliorate the redox status of pregnant heat-stressed ewes and the outcome of their pregnancy. Sixty-eight ewes participated in the study, which were allocated into two equal groups, i.e., Melatonin (M) and Control (C) group. All ewes were exposed to heat stress from D0 to D120. In both groups, after oestrus synchronization of ewes, rams were introduced to them for mating (D16). In M group, starting with sponges’ insertion (D0), melatonin implants were administered four-fold every 40 days. Pregnancy diagnosis was performed by means of ultrasonography. Daily evaluation of temperature humidity index (THI), rectal temperature, and breathing rate were performed throughout the study. Blood samples were collected repeatedly from D0 until weaning for assaying redox biomarkers. Milk yield was measured thrice during puerperium. The results showed that melatonin administration throughout pregnancy improved the redox status of heat-stressed ewes and increased the mean number and bodyweight of lambs born per ewe, as well as the milk production. Therefore, melatonin may be used as antioxidant regimen in heat-stressed ewes for improving their reproductive traits.

Highlights

During pregnancy, in sheep, both the pregnant ewes and the foetuses are exposed to oxidative stress caused by the increased amount of reactive oxygen species (ROS) [1,2]
We found that melatonin administration in heat-stressed ewes during the peri-conception period led to increased total antioxidant capacity and improved fertility rate, which points out a potential result of the antioxidant effect of melatonin at follicular level and/or early embryonic development
It is indicated that the repeated administration of melatonin throughout the pregnancy period improves the redox status of heat stressed ewes

Summary

Introduction

In sheep, both the pregnant ewes and the foetuses are exposed to oxidative stress caused by the increased amount of reactive oxygen species (ROS) [1,2]. Among them heat stress, may lead to increased ROS production [4,5], which may cause the abortion or development of abnormalities in the foetus [6]. With high direct and indirect solar radiation, wind velocity and relative humidity cause the effective temperature of the environment to often exceed the thermoneutral zone of animals (5–25 ◦ C; [7]), leading to heat stress [8,9]. Heat-stressed animals show reduced feed and water intake, which may in turn alter their endocrinological profile, thereby increasing the energy requirements for maintenance leading to negative impact in the production and reproductive performance of livestock [11,12]. Heat stress has resulted in increased ROS activity in the oviducts and the embryos and in reduced glutathione content in the embryos [13,14]

Objectives

Methods

Conclusion