Genetic analysis of reproductive characteristics in Iran-Black sheep

Abstract

This study was conducted to estimate genetic parameters and trends for reproduction traits using data collected at the breeding station of Iran-Black sheep during 1980 to 2004. The traits included in the analyses were litter size at birth (LSB) and weaning (LSW) and litter mean weight per lamb born (LMWLB) and weaned (LMWLW) as basic traits, and total litter weight at birth (TLWB) and weaning (TLWW) as composite traits. Direct heritability estimates for LSB, TLWB, LMWLB, LSW, TLWW and LMWLW were 0.11, 0.07, 0.33, 0.08, 0.09 and 0.11, respectively. The permanent environmental effects had significant impact on all traits and ranged from 0.05 to 0.16. Effect of service sire was highly significant (p < 0.01) for all traits except LMWLW. Estimates of genetic correlations ranged from -0.76 (LSB-LMWLB) to 0.98 (LSB-LSW). Phenotypic and environmental correlations were generally lower than those of genetic correlations. Environmental correlations ranged from -0.55 (LSW-LMWLW) to 0.99 (LSB-LSW). Also, the estimated correlation for the effect of service sire ranged from -0.77 (LMWLB-TLWW) to 0.96 (LSB-LSW and LSB-TLWW). The results suggest that selection based on TLWB could be more effective than the other traits to enhance reproductive performance in Iran-Black ewes.

Estimation of Repeatability and the Most Probable Producing Ability (MPPA) Based on Birth Weight and Weaning Weight for Ranking of Sapudi Sheep

“…Genetic and environmental factors influence birth weight characteristics of Sapudi lambs; permanent factors constitute 10.8%, while temporary environmental factors constitute 89.2%. The repeatability value of birth weight obtained from the results of this study is almost the same (low category) when compared to that reported in lambs, namely 0.118 (Piwczyński et al, 2011), 0.13 (Ozturk et al, 2018), and 0, 19 (Yafarivard et al, 2015 but lower than the Iranian lamb of 0.27 including the medium category (Baneh et al, 2019).…”

Effect of Dry Season Supplementary Feeding and Parity on Performance of Desert Sheep in North Kordofan State, Sudan

“…Also [43] reported that the fertility rate was lower in 1.5-year-old ewes than in older ewes. Same results were obtained by [45] reported that decreasing reproductive performance after approximately five parities can be explained by an increase in twinning rate and conception rate with age.…”

“…[30] reported a greater effect of ewe live weight on reproductive performance in younger ewes than older ewes. Also [43][44][45][46][47][48][49][50][51][52][53][54][55][56], who showed that litter size was more in the protein supplement group than the control group (no supplements of protein). Increasing the pre mating weight ewes could increase the pregnancy rate and multiple births [10,11,39].…”

A study on the genetic and phenotypic factors affecting specific ewe productivity traits in Sangsari sheep

“…In addition, genes that increase TLWB may also increase the mother's milk and mothering abilities, since the lamb's weaning weight depends on the ewe's maternal ability besides its genotype. The r p values ranged from − 0.19 for LSB-LMWLW to 0.66 for LSB-LSW, and these ndings are according to previous studies(Mohammadi et al, 2013;Eteqadi et al, 2017;Baneh et al, 2020). Some of the studied reproductive traits show a medium and positive phenotypic correlation, suggesting that environmental factors that enhance one trait may also positively impact other traits.…”

“…, and Iran-Black(Baneh et al, 2020) sheep populations. Our analysis indicates that the estimated service sire effect ranges from 0.012 to 0.039, as reported by scholarly sources(Mohammadi et al, 2015;Amiri Roudbar et al, 2018).…”