The objective of this study was to estimate the genetic parameters, genetic trends and inbreeding levels for growth traits of Doyogena sheep managed under community-based breeding program. Records used in the study were collected over a period of 6 years (2013-2018).A total of 2990 birth weight (BWT), 2121 three-month weight (WWT), 1303 six month weight (6WT), 2098 average daily gain from birth to weaning (ADG0-3), 1287 average daily gain from weaning to 6-month age (ADG3-6), and 1293 average daily gain from birth to 6-month age (ADG0-6) were used. Variance components and genetic parameters were estimated with univariate analysis by fitting restricted maximum likelihood methods using WOMBAT software. Six different animal models were fitted by including or excluding maternal effects. Multivariate analysis was applied for correlation estimates. The overall least squares means ± standard errors (LSM±SE) of lamb body weight for BWT, WWT and 6WT were 3.05±0.02 kg; 14.8±2.49 kg and 22.0±0.22 kg respectively. The overall LSM±SE of ADG0-3, ADG3-6, and ADG0-6 in gram were 130.4±2.27, 80.6±3.62 and 106.2±1.7 respectively. Based on the best fitted univariate models, direct heritability estimates, for BWT, WWT, 6WT, ADG0-3, ADG3-6 and ADG0-6 were 0.33±0.06, 0.31±0.06, 0.14±0.06, 0.13±0.04, 0.11±0.07, and 0.023±0.05 respectively. The maternal heritability estimates for BWT and WWT were 0.24±0.12 and 0.6±0.07 respectively. BWT has weak genetic correlation with all other traits while genetic correlations between WWT and 6WT was higher (r=0.52±0.09). Genetic changes over the selection period was s0.00085 kg,0.30 kg,0.15 kg, 2.56gm, -0.37gm,0.09 gm, for BWT, WWT, 6WT, ADG0-3, ADG3-6, and ADG0-6, respectively. Genetic parameter estimates and genetic trend over years suggested that the genetic selection can lead to improvement of Doyogena sheep breed under the ongoing community-based breeding programs. Thus, continuation of selection therefore recommended for bringing further improvement.
Figures & Tables
Figure 1. Annual mean of inbreeding