Improving reproductive performance of ewes under semi-arid conditions

This experiment was carried out to improve ovulation rate, lambing and twinning rates of Barki ewes by treatment with pregnant mare serum gonadotropin (PMSG) which increases the ovulation rate, this method followed the process of synchronization which can be done through injection of prostaglandin (PGF2a). Increasing the number of lambs born or weaned lambs per each ewe during the year is the principle target to improve reproduction efficiency in this study. This study included two experiments; the first experiment was during the period from October 2007 until June 2008, while the second experiment was during the period from October 2008 until June 2009, in South Sinai Research Station (Ras Sudr), Desert Research Center, Ministry of Agriculture and Land Reclamation, Cairo, Egypt. This station is located at 200 km east of Cairo. In first experiment seventy-five Barki ewes with 3-5 years old and 37.87 ± 4.786 kg average live body weight were used; the ewes were randomly divided into three groups (25 ewes each). All ewes were estrus- synchronized with two intramuscular injections of Synchromate (each of 1 ml solution containing 250 mg Cloprostenol) 11 days apart. Group one served as a control group which received PGF2a treatment only. On the other hand, ewes of group two (treatment 1) were injected by PGF2a as control in addition to intramuscular injection with one dose of PMSG (Folligon-1000 IU) given after the 2nd dose of PGF2a, while ewes of group three ( treatment 2) were injected by PGF2a as control in addition to intramuscular injection with one dose of PMSG (1600 1U) given after the 2nd dose of PGF2a. While the second experiment fifty six Barki ewes were distributedequally into four group ( 14 ewes per each) with live body weight 35.30 ± 4.825 kg. Group 1, ewes were intramuscularly daily injected up to 14 days with l ml progesterone (Prontogest) (each 2 ml Prontogest containing 100 mg progesterone was diluted with 8 ml corn oil), at the last day of injection ewes were injected by 0.5 cm PGF2a. Group 2, ewes were injected similar to ewes in group I, while on day 13; the ewes were injected by 750 IU of PMSG. Group 3, ewes were injected by two injection of PGF2a (1 cm each), 11 days apart. Group 4, was treated as group 3, in addition to PMSG (750 IU) injection given immediately after the second injection of PGF2a. The results showed that, in the first experiment there were slight differences between groups at using hormonal treatment (PGF2a) in response to estrus synchronization. Also, there was no clear effect of hormonal treatment (PMSG) on some reproductive traits (conception rate, lambing rate, twinning rate and weaning rate) although, there was some increase in these traits in group 2 compared to the other groups. Also, there was no detectable effect of hormonal treatment (PMSG) on some productive traits (birth weight, mortality rate, weaning weight and average daily gain). While during the second experiment there were slight differences between groups at using hormonal treatment (P4 and PGF2a) in response to estrus synchronization. Also, there was no clear effect of hormonal treatment on some reproductive traits. Also, there was no detectable effect of hormonal treatment on some productive traits. It could be concluded from plasma progesterone profile that, the accuracy of pregnancy diagnosis in ewes was 100% based on, the plasma progesterone level, when it was 5 ng/ml or above on day 17 post-mating. Effect of ZADO treatment on milk yield of lactating ewes showed no significant differences (P0.05) between control and treatment group. However, treated group recorded the higher average milk yield by 13.6 % (559.8 vs. 483.5 ml). Also the effect of ZADO treatment on milk composition was non significant (P0.05). Differences in plasma T 3 and T4 concentrations were not significant (P0.05) due to ZADO treatment.