Estimation of co-variance components, genetic parameters, and genetic trends of reproductive traits in community-based breeding program of Bonga sheep in Ethiopia

Abstract

Objective: The objectives of the study were to evaluate reproductive performance and selection response through genetic trend of community-based breeding programs (CBBPs) of Bonga sheep.Methods: Reproduction traits data were collected between 2012 and 2018 from Bonga sheep CBBPs. Phenotypic performance was analyzed using the general linear model procedures of Statistical Analysis System. Genetic parameters were estimated by univariate animal model for age at first lambing (AFL) and repeatability models for lambing interval (LI), litter size (LS), and annual reproductive rate (ARR) traits using restricted maximum likelihood method of WOMBAT. For correlations bivariate animal model was used. Best model was chosen based on likelihood ratio test. The genetic trends were estimated by the weighted regression of the average breeding value of the animals on the year of birth/ lambing.Results: The overall least squares mean±standard error of AFL, LI, LS, and ARR were 375± 12.5, 284±9.9, 1.45±0.010, and 2.31±0.050, respectively. Direct heritability estimates for AFL, LI, LS, and ARR were 0.07±0.190, 0.06±0.120, 0.18±0.070, and 0.25±0.203, respectively. The low heritability for both AFL and LI showed that these traits respond little to selection programs but rather highly depend on animal management options. The annual genetic gains were –0.0281 days, –0.016 days, –0.0002 lambs and 0.0003 lambs for AFL, LI, LS, and ARR, respectively.Conclusion: Implications of the result to future improvement programs were improving management of animals, conservation of prolific flocks and out scaling the CBBP to get better results.

Productive and reproductive performance of Dawuro highland sheep managed under community-based breeding program in Ethiopia

“…Similarly, lambing year and site effect were significant effects (p<0.01) on litter size. Significantly higher litter size was observed in 2018.The current LS of 1.67±0.04 litter/ewe is much higher than several previous authors of [ 13 , 16 , 22 ]. However, [ 23 ] reported 1.82 litter/head/ewe which is higher than the current finding for the Moroccan D’man sheep breed.…”

Growth rate and efficiency-related traits in Kermani lambs: estimations of (co)variance components and genetic parameters

“…The xed effect of birth year on all studied traits was signi cant (P < 0.01). Likely, differences in agro-climatic conditions, management practices, and pasture quality and quantity play a major role in explaining why the birth year has a signi cant effect on the traits analyzed(Tesema et al, 2021;Areb et al, 2021).…”

Prediction of reproductive performance of ewes based on the early production data, ewe birth rank, dam age, and dam birth rank

“…This may be because some of the variations in lambing intervals are repeatable, so ewes with short first lambing intervals lambed more frequently than ewes with long first lambing interval. Areb et al (2021) found the repeatability of the lambing interval in Bonga sheep to be as high as 0.57. They concluded that selection decisions could be made based on the early reproductive performance indicators.…”