Estimates of phenotypic, genetic and environmental trends in a flock of nali sheep

The present study was undertaken for estimating annual rate of change in flock of Nali sheep during 1978 to 1998 by using data on 547 lambs for production and reproduction traits of 35 progeny sires in relation to phenotypic, genetic and environmental factors. The annual change in estimates of phenotypic trends were significant (P<0.05) for weaning weight (−0.72 ± 0.032 kg, preweaning gain (−0.776 ± 0.373 g), grease fleece weight (−0.013 ± 0.006 kg) and medullation percentage (0.483 ± 0.187), whereas estimates of birth weight, six month weight, post weaning gain and fibre diameter did not change significantly. The estimates of annual rates of environmental progress were non-significant in both methods except for pre-weaning gain. The results indicated that selection was not effective in bringing desired genetic improvement in this flock.