Genetic trends for some productive traits of Lohi sheep in Pakistan

Data on performance records on birth weight, weaning weight and yearling weight of Lohi sheep maintained at Livestock Production Research Institute (LPRI), Bahadurnagar, Okara during a period 1990-2008 were used in the present study. Birth, weaning and yearling weight (kg) averaged as 2.79 plus minus 0.05, 18.44 plus minus 0.31 and 36.70 plus minus 0.33, respectively. The effect of year and season of birth, sex, type of birth and age of dam was studied by least square analysis of variance using Harvey's Mixed Model Least Square and Maximum Likelihood (LSMLMW) Computer Program. Birth weight varied significantly for all factors while significant effect of year of birth and season of birth was found on weaning weight. However, the differences due to sex, type of birth and age of the dam were non significant. Effects of year of birth, season of birth and age of dam on yearling weight were found significant. Heritability was estimated using Restricted Maximum Likelihood (REML) procedure under animal model. Low estimates of heritability (0.11 plus minus 0.03, 0.08 plus minus 0.03, 0.10 plus minus 0.05) for birth, weaning and yearling weights, respectively were observed. Estimated breeding values (EBVs) for birth weight, weaning weight and yearling weight for the males ranged from 0.26 to 0.33, -1.12 to 1.30 and -1.55 to 1.51 and for females -0.25 to 0.27, -0.99 to 1.05 and -1.26 to 1.46 respectively. However, overall EBVs ranged between -0.25 to 0.33, -0.99 to 1.30 and -1.26 to 1.51, respectively. The results showed the decreasing genetic and static phenotypic trends for birth weight where as, the genetic and phenotypic trend for weaning weight showed increasing trend. No specific genetic and phenotypic trend was observed for yearling weight.