Study of the environmental, genetic and phenotypic trends for pelt traits and body weight traits in Zandi sheep

Abstract

In this study, the data of body weights and pelt records of Zandi sheep kept at the Khojir national park breeding station of Iran were used to estimate phenotypic, genetic and environmental trends for birth weight (BW), 3 months weight (3MW), 6 months weight (6MW), yearling weight (YW), curl type (CT), pattern score (PS) and Luster (Lu) of pelt. Data were analyzed for each trait using derivative-free REML procedures under a univariate animal model. Genetic, phenotypic and environmental trends were estimated by regression of the estimated mean of breeding values, phenotypic mean and difference between estimated mean of breeding values and phenotypic mean on birth year, respectively. The average additive direct genetic trends for BW, 3MW, 6MW, YW were 0.001±0.001, 0.034±0.004, 0.028±0.007 and 0.024±0.004 g/year and for CT, PS and Lu were 0.006±.002, 0.001±0.002 and 0.002±0.004, respectively. Although selection for body weight traits was effective and significant genetic improvements were obtained, limited genetic improvement in the pelt traits were detected. © 2013 Taylor & Francis.