Pomegranate peels ethanolic extract in free and nanoemulsified forms around mating and early pregnancy differently affect heat tolerance capacity and reproductive performance of ewes under heat stress

Abstract

Global warming is seriously threatening sheep farmings by increasing health problems and decreasing reproductive efficiency. In this study, pomegranate peels ethanolic extract (Ppee), rich in phenolic acids, was prepared in free (Fppee) and nanoemulsified (Nppee, with 18.49 nm–21.8 nm particles size) forms. The protective role of the extracts against heat stress impacts on homeothermy, metabolism and redox status, and reproductive performance of ewes was studied. A total of 36 Barki ewes were synchronized to estrus using two intramuscular injections PGF_2α. On the day of the first PGF_2α, ewes were allocated into three homogeneous experimental groups and received 300 mg/ewe/day Fppee, 300 mg/ewe/day Nppee, or not (control) until day 35 post-mating. The Fppee ewes showed the highest homeothermy in the morning, whereas the Nppee ewes showed the lowest homeothermy in the afternoon (P < 0.001). Both extracts increased plasma total protein, glucose, total antioxidant capacity, and glutathione concentrations (P < 0.001), whereas they decreased plasma urea, cholesterol, and malondialdehyde concentrations compared to control (P < 0.001). The highest and lowest values of these variables were for the Nppee ewes. The Nppee ewes had the significant lowest plasma progesterone concentrations. There were no differences in corpora lutea numbers and diameters. Lambs born to Fppee ewes had the highest birth weights and survivability. In conclusion, supplementing heat-stressed ewes with Fppee improved homeothermy, metabolism, redox status, and lamb weight and survivability without hampering reproductive performance, mainly by decreasing progesterone concentrations as observed in Nppee ewes.