A meta‐analysis of the effects of synchronization protocols applied to sheep in Turkey on pregnancy rates during breeding and non‐breeding seasons

Abstract

This study aimed to determine common pregnancy rates and effect sizes with metaanalysis of studies investigating the effect of different synchronization protocols applied to sheep during breeding and non-breeding seasons on pregnancy rates. Common pregnancy rates were estimated by coalescing pregnancy rates of studies performed independently, and heterogeneity between the studies was investigated. The meta-analysis included 24 studies that determined pregnancy rates in 78 different groups consisting of 1934 sheep with five different synchronization protocols in Turkey between 2001 and 2020. Among the different synchronization methods, the P4+PMSG group (90.37%) during the breeding season and P4+PGF2α (69.77%) and P4 (68.75%) groups during the non-breeding season showed the highest pregnancy rate. Also, the effect size of P4+PMSG application during the breeding season was calculated as 0.934 (95% confidence interval: 0.901-0.967), and the effect size of P4+PGF2α application during the non-breeding season was calculated as 0.709 (95% confidence interval: 0.406-1.013). To conclude, the combination of P4+PMSG during the breeding season and progestogen and other hormone applications during the nonbreeding season are the most effective methods for estrus synchronization and for achieving the desired pregnancy rates.

The Role of Certain Specific Hormonal Treatments in Estrus Synchronization of Ewes: A mini Review

“…The pineal gland secretes the hormone melatonin, and its concentration level rises during the dark period; increased secretion of the hormone melatonin is responsible for inducing ovarian cycles in ewes [65], and continuous administration of the hormone leads to inducing the reproductive season by affecting the hypothalamus gland to secrete the release GnRH hormone and thus the secretion of the hormones LH and FSH from the anterior lobe of the pituitary gland [66]. Treatment of ewes with melatonin improved the reproductive performance of domestic ewes by increasing the fertility rate and the number of additional pregnancies [67].…”

Türkiye’de IBR ve BVD hastalıklarının meta-analiz incelemesi

“…Even though meta-analysis is particularly suitable for serial controlled experimental studies, it is used in observational studies as well. Meta-analytical studies also have been conducting in Turkish veterinary obstetrics and gynaecology studies from time to time (4,12).…”

Effects of selenium, vitamin E, and β-carotene administration on fertility of Awassi ewes synchronized for estrus in non-breeding season

“…A meta-analysis study conducted in Turkey discovered that pregnancy rates were lower in progesterone + PMSG based estrus synchronization protocols (59.36 %) used in non-breeding season compared to the reproductive period (90.37%). The deep anestrus in animals, diminished hormonal effects, and low ovarian activity are the causes of the low pregnancy rates during the non-breeding season (Arikan et al, 2021). The ovarian follicle population in sheep is known to be highly sensitive to dietary intake, and it has been reported that dietary manipulations can increase both folliculogenesis and ovulation (Scaramuzzi et al, 2006).…”