Effect of breed and some non-genetic factors on growth performance of sheep under temperate conditions of Kashmir

Abstract

The data pertaining to 4849 birth records spanning over a period of 21 years (1997–2017) of different genetic groups were collected from Mountain Research Centre for sheep and goat Station (MRCSG), Shere Kashmir University of Agricultural Science and Technology, Kashmir (SKUAST-K), Shuhama, Kashmir to investigate the effects of genetic group and non-genetic factors on growth performance of Bakarwal, Corriedale, Hampshire x Corrriedale Cross, Hampshire, Non-descript x Corriedale Cross, Non-descript x Polled Dorset Cross, Polled Dorset x Corriedale, Polled Dorset and South down sheep genetic groups. The non-genetic factors considered were period of birth sex of lamb whereas the growth profile traits considered were birth weight (BW), weaning weight (W3), six months body weight (W6), yearling body weight (W12), average daily gain from birth to weaning (ADG1), metabolic mass at weaning (W30.75), Kleiber ratio from birth to weaning (KR1), average daily gain from weaning to yearling age (ADG2), metabolic mass at yearling age (W120.75) and Kleiber ratio from weaning to yearling age (KR2). The overall least-squares means for BW, W3, W6, W12, ADG1, W30.75, KR1, ADG2, W120.75 and KR2 were 3.47 ± 0.04 kg, 13.30 ± 0.15 kg, 18.13 ± 0.19 kg, 23.79 ± 0.25 kg, 107.58 ± 1.54 g/day, 6.93 ± 0.06 kg, 15.20 ± 0.12, 37.21 ± 0.86, 10.81 ± 0.09 and 3.37 ± 0.06, respectively. The effect of genetic group and period was highly significant (p < 0.01) on all the traits under study whereas effect of sex was significant (p < 0.05) on BW, W3, W6, W12, ADG-1, ADG-2, W30.75 and W120.75 with sexual dimorphism of 1.03, 1.08, 1.09, 1.06, 1.03, 1.05, 1.07, 1.09, 1.05 and 1.04 for BW, W3, ADG1, W30.75, KR1, W6, W12, ADG2, W120.75 and KR2, respectively. The effect of interaction of genetic group and period of birth was highly significant (p > 0.01) whereas the effect of interaction of sex and period of birth was significant (p > 0.05) on all the traits under study. The effect of interaction of genetic group and sex was significant on BW, W3, ADG1 and W30.75 only. Pre-weaning average daily gains (ADG1) and Kleiber ratio (KR1) were higher than post-weaning average daily gains (ADG2) and Kleiber ratio (KR2), respectively in all genetic groups. Whereas the metabolic mass at weaning (W30.75) was lower than metabolic mass at yearling age (W120.75) in all genetic groups. The non-genetic factors of sex and period were observed to be important sources variation in the growth performance of sheep. The study concludes that Hampshire x Corrriedale cross outperformed other genetic groups with respect to ADG2 and W12. Further, environment plays significant role in performance of genotype. Hence, Hampshire x Corrriedale cross should intersemated to produce and evaluate F2 generation for post-weaning growth rate.