Estimation of genetic parameters and genetic trends for biometric traits in Moghani sheep breed

Abstract

The present study aimed to estimate the genetic parameters as well as genetic trends for biometric traits in Iranian Moghani-sheep breeds. The data set consisted of 15115 biometric records from 3702 individual progenies of 499 sires and 3203 dams, which involved a period of 15 years of time (1996–2011). The records were extracted from Moghani sheep breeding and raising station. The studied traits were: height at withers (HW), height at rump (HR), body length (BL), heart girth (HG) and leg circumference (LC). variance components and genetic parameters were estimated with single and five-trait analysis using restricted maximum likelihood (REML)-methods and WOMBAT software. Six different animal models were fitted to the traits, with the best model for each trait determined by Akaike Information Criterion (AIC). All traits were significantly influenced by year of birth, month of birth, sex of the lamb and birth type (P<0.01). The breeding values were compared across years of birth with respect to the genetic trends. Direct heritabilities using single trait analysis were estimated 0.10 for HW, 0.11 for HR, 0.16 for BL, 0.11 for HG and 0.23 for LC. Using bivariate analysis, the estimates of additive genetic correlations were ranged from −0.55 (between BL and LC) to 0.99 (between HW and HR). Estimates of breeding value by year of birth for all traits were fluctuated throughout the period of study. Estimates of genetic parameters as well as the estimates of breeding values suggested that the genetic selection can lead to a significant genetic improvement of the Moghani sheep.