Abstract

Conception rate was affected significantly (P < 0.05) by progesterone + PMSG treatment in summer and insignificantly by supplementation with each of dietary selenium in winter and dietary vitamin A in autumn. When expressing the results in percentages, the highest increase in conception rate was by treatment with progesterone + PMSG in summer (46.91), followed by selenium treatment in winter (7.17) and treatment with vitamin A in autumn (3.01). Meanwhile, lambing rate was insignificantly affected by the three treatments in the three seasons. The highest increase (in lambing rate) obtained was 13.02% in autumn by vitamin A dietary supplementation, followed by selenium dietary supplementation in winter (6.76%) and treatment with progesterone + BMSG in summer (3.83%) respectively. Effects of mating with rams’ dietary supplemented with selenium during winter and summer and with vitamin A during autumn on the studied traits were not significant. The highest increase in conception rate (13.79%) was shown when mating with rams treated with selenium in summer, followed by those treated with vitamin A in autumn (3.63) and by selenium in winter, respectively. In lambing trait, the highest increase was obtained by mating with rams treated with selenium in winter (14.80%), followed by those treated with vitamin A in autumn (11.25%). Housing effects (the housing effect is the difference in perception of warmth or difference in Temperature-humidity index (THI) values between indoors and outdoors) on conception rate were significant (P<0.01 or 0.05) during winter and autumn and insignificantly during summer. In this respect, the conception rate was 32.29% higher in the south than in the north part of the farm in winter. In autumn and summer, the values were 15.38 and 14.02% respectively, higher in the north than in the south part of the same farm. Meanwhile, lambing rate was insignificantly affected by the same factor during the three seasons. Lambing rate was 9.52 and 9.31% higher in the south than in the north part of the farm in winter and autumn, respectively. There were no significant interactions between the factors studied on the traits studied. Therefore, the main factors are reported.

Key words: Ewes reproduction, treatment with selenium in winter, progesterone + BMSG in summer, vitamin A in autumn, housing effect.