Heritability estimates of some growth traits of Hissardale sheep in Pakistan

Hissardale breed of sheep having 7/8 Merino and 1/8 Bikaneri inheritance kept at the Livestock Experiment Station, Jahangirabad, district Khanewal (Pakistan) was used in the present study. Data on 5 260 birth records of 1179 Hissardale sheep during 1978-95 were analysed using Harvey's mixed model least-squares and maximum likelihood computer programme. The objective was to evaluate the performance and estimate the heritability of growth traits of Hissardale sheep. The average birth weight, 60- day and 90-day weights were 4.0 +/- 0.51, 11.5 +/- 2.13 and 15.5 +/- 3.06 kg respectively. The weaning weight averaged 20.1 +/- 3.86 kg. Pre-weaning average daily gain was 135 +/- 0.04 g. The age at first service and age at first lambing averaged 593.3 +/- 265.87 and 746.9 +/- 266.0 days respectively. The heritability estimate of birth weight, 60-day and 90-day weight, weaning weight and pre-weaning average daily gains were 0.08 +/- 0.02, 0.12 +/- 0.03, 0.16 +/- 0.03 and 0.10 +/- 0.03, 0.11 +/- 0.03 respectively. The heritability estimates for both the age at first service and age at first lambing were quite high (0.44 +/- 0.1 1) meaning that these 2 traits were largely controlled by additive gene action. The low estimates of heritability for various performance traits indicated large environmental variances.