Abstract
Purpose: The objective of the present study was to compare the reproductive performance in synchronized and spontaneous estrus sheep raised under farm conditions. Subjects and Method: Two hundred Karadi and Two hundred Awassi were used in this study. Of each breed, 100 ewes were allowed to come in estrus spontaneously and the other 100 ewes were synchronized using intravaginal sponges (ESPONJAVET, HIPRA, Amer, Girona, SPAIN). Ewes were injected with intramuscular injection of 500 IU of PMSG when sponges were removed on day 14. Results: This study revealed that estrus synchronization had a higher rate of lambing (P=0.014), twining (P<0.001), dystocia (P=0.024), and barrenness (P=0.012) in Karadi ewes. Estrus synchronization also had a significantly higher rate of lambing (P=0.018), twining (P=0.017), abortion (P<0.001), barrenness (P=0.012) and productivity (P=0.010) in Awassi ewes. the result of the current study shows that the barrenness rate was higher in spontaneously ovulated ewes compared to synchronized Awassi ewes. The result of the current study shows that the abortion rate was higher in spontaneous ewes compared to synchronized ewes. The twinning rate was higher in synchronized compared to spontaneous Karadi ewes. Conclusion: In both breeds, synchronized ewes had higher reproductive efficiency compared to ewes that had spontaneous estrus.
Highlights
There has been an increasing interest in the understanding of the influence of some factors on productivity efficiency in sheep
Regarding the effect of spontaneous and synchronized on reproductive efficiency in Karadi sheep, the rate of lambing (P = 0.014), twining (P < 0.001) and dystocia (P = 0.024) were higher in synchronized ewes compared to spontaneous ewes (107 vs 84%, 25.88 vs 7.69% and 4.7 vs 1.0%, respectively)
The results show no differences in the rate of fertility (P = 0.192), conception (P = 0.297), litter size or prolificacy (P = 0.415), dystocia (P = 107) and lamb mortality rate from birth to weaning (P = 0.174) between synchronized Awassi ewes and spontaneous Awassi ewes (Table 2)
Summary
There has been an increasing interest in the understanding of the influence of some factors on productivity efficiency in sheep. To maintain high reproductive performance in Karadi and Awassi sheep flocks under traditional conditions, identifying factors that influence reproductive efficiency is critically important (Juma & Alkass, 2005; Lafi et al, 2009; Zebari et al, 2018). Intravaginal progestogen sponges, followed by pregnant mare serum gonadotropin (PMSG) injection were applied to ewes to synchronize estrous (Mutiga & MukasaMugerwa, 1992) and to improve the ovulation rate (Tetsuka et al, 1988). Intravaginal progestogen sponges are usually inserted over a period of 12-14 days followed by injection of PMSG, especially during the non-breeding season in sheep (Wildeus, 1997; Ungerfeld & Rubianes, 2002). Conception rate (Alkass & Abdulkareem, 2004; Zebari, 2019), litter size or percentage of lambs born to ewe lambed (Abdulkareem & Eidan, 2014), the number of ewe lambed, abortion, parturition dystocia and mortality rate after birth are considered the main aspects in sheep reproductive performance (Evans, 2003)
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