VARIANCE COMPONENTS ESTIMATE USING BAYESIAN METHODS FOR LITTER SIZE AND TOTAL LITTER WEIGHT AT BIRTH IN SOHAGI SHEEP | ||
| Egyptian Journal of Animal Production | ||
| Volume 62, Issue 3, September 2025, Pages 179-187 PDF (552.12 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejap.2025.394473.1115 | ||
| Authors | ||
| Ahmed Elnahas1; Reda Elsaid* 2 | ||
| 1Animal Production Department, Faculty of Agriculture, Sohag University, Egypt | ||
| 2Department of Sustainable Development, Environmental Studies and Research Institute (ESRI), University of Sadat City, Menofyia, Egypt | ||
| Abstract | ||
| This study aimed to estimate variance components for litter size (LS) and total litter weight at birth (TLW) in Sohagi sheep using Bayesian methods. Data were collected from 2003 to 2022 at the experimental farm of Sohag University, which included records from 1,464 ewes, the offspring of 51 sires and 325 dams, to assess the influence of various environmental factors on these traits. The average LS and TLW were 1.25 ± 0.01 lambs and 3.74 ± 0.03 kg per ewe, respectively. To estimate the posterior means and standard deviations of genetic parameters for LS and TLW, univariate linear, univariate threshold, bivariate linear, and bivariate threshold linear models were employed using GIBBSF90+. For LS, heritability estimates ranged from 0.10 (univariate linear model) to 0.21 (univariate threshold model), while repeatability ranged from 0.13 to 0.26, following a similar pattern. For TLW, heritability estimates varied from 0.04 (univariate linear model) to 0.07 (bivariate threshold linear model), with repeatability estimates also showing a similar trend, ranging from 0.10 and 0.13. The bivariate threshold linear model indicated a high genetic correlation of 0.98 and a phenotypic correlation of 0.94. Additionally, the bivariate linear model showed strong positive correlations, with genetic and phenotypic values of 0.99 and 0.87, respectively. For LS, Spearman rank correlations between breeding values obtained from four models demonstrated consistent animal rankings across different statistical approaches. Based on these findings, we propose a selection index that incorporates both LS and TLW traits to enhance genetic evaluation strategies in Sohagi sheep. | ||
| Keywords | ||
| Sohagi sheep; Litter size and total litter weight at birth; Linear and threshold models; Genetic parameters | ||
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