Genetic evaluation of growth performance in Corriedale sheep in J&K, India

Abstract

The data pertaining to 6874 lambs born to a total of 145 sires spanning over a period of 49 years (1969–2017) were collected from Mountain Sheep and Goat Research Station, SKUAST-K, Shuhama, Kashmir for a comprehensive evaluation of the growth performance of Corriedale sheep under Indian (temperate) conditions to assess the random effect of sire and fixed effects of period, sex, and type of birth on its performance. All the 145 sires, during the study period, were selected from within the farm. Evaluation was done for 11 performance traits viz: birth weight (BW), weaning weight (WW), six months body weight (SMW), nine months body weight (NMW), yearling body weight (YBW), average daily gain from birth to weaning (ADG-1), metabolic mass at weaning (WW0.75), Kleiber ratio from birth to weaning (KR-1), average daily gain from weaning to yearling age (ADG-2), and metabolic mass at yearling age (YBW0.75) and Kleiber ratio from weaning to yearling age (KR-2). The overall least-squares means for BW, WW, SMW, NMW, YBW, ADG-1, WW0.75, KR-1, ADG-2, YBW0.75 and KR-2 were 3.66 ± 0.02 kg, 13.48 ± 0.14 kg, 18.79 ± 0.25 kg, 21.96 ± 0.19 kg, 25.23 ± 0.19 kg, 109.0.21 ± 1.56 gm/day, 7.01 ± 0.06 kg, 15.29 ± 0.10, 41.49 ± 0.42 gm/day, 11.23 ± 0.07 kg and 3.64 ± 0.29, respectively. The effect of sire and period was significant (p < 0.01) whereas effect of birth type was non-significant on all the traits. The effect of sex of animal was significant on growth performance traits and males were heavy at all age than females. The heritability estimates ranged from low to high indicated low to genetic variability. The genetic and phenotypic correlations between different traits also range from low to very high. The average breeding values of sires were 3.69 ± 0.02 kg, 13.46 ± 0.09 kg, 18.41 ± 0.15 kg, 21.73 ± 0.12 kg, 25.12 ± 0.12 kg, 108.66 ± 0.93 gm/day, 7.01 ± 0.03 kg, 15.24 ± 0.07, 41.75 ± 0.33 gm/day, 11.22 ± 0.03 kg and 3.67 ± 0.02 for BW, WW, SMW, NMW, YBW, ADG-1, WW0.75, KR-1, ADG-2, YBW0.75 and KR-2, respectively. The negative phenotypic and genetic trends were observed for all traits except KR-2. The environmental trend was positive for SMW, NMW, YMW, ADG-1 and KR-2. The results indicate selection based on SMW may improve growth performance in this flock as the trait has high heritability and positive genetic and phenotypic correlations with other body weight and growth performance traits. An optimal strategy for selection considering both genetic merits and coancestry of mates (avoiding close breeding) may be adopted which is also in consonance with the current breeding policy of the J&K.