Investigation of Genetic, Phenotypic and Environmental Trends for Biometric Traits in Makuie Sheep

In this research, investigation of genetic, phenotypic and environmental trends of biometric traits in Makuie sheep was performed using collected data from 1989 to 2012 at Makouei sheep breeding station. Estimation of trends was performed by multivariate animal model using the DFREML software. Genetic, phenotypic and environmental trends were estimated by regression of breeding values average, phenotypic values average and average of difference between breeding values with phenotypic values on birth year, respectively. Results showed that heritability estimates for biometric traits including height at withers, height at rump, body length, heart girth and thigh circumference were 0.23±0.05, 0.25±0.05, 0.19±0.04, 0.28±0.05 and 0.06±0.04, respectively; and the highest genetic and phenotypic correlations were between height at withers and height at rump traits (0.98 and 0.93, respectively). Genetic trends of mentioned traits were 0.25±0.07, 0.26±0.07, 0.59±0.05, 0.22±0.09 and 0.23±0.03 cm; phenotypic trends were 0.08±0.08, 0.07±0.05, 0.39±0.06, -0.23±0.16 and 0.08±0.05 cm and environmental trends were -0.16±0.06, -0.15±0.06, -0.20±0.06, -0.45±0.15 and -0.16±0.04 cm, respectively. Total genetic improvement after 24 years was low and the highest improvement was observed in body length and chest girth traits therefore, it can be concluded that despite the positive genetic trend, selection in this herd were not based on breeding value and regular plan.