Estimation of co (variance) components and genetic parameters for growth and feed efficiency traits in Jamunapari goat

Jamunapari goat is majestic dual purpose goat adapted to semi-arid climate in India. The aim of the present study was to assess the genetic potential of Jamunapari goat and design breeding program based on growth and feed efficiency traits. A total of 8763 animals descended from 1845 dams and 339 sires between 1982-2019 (37 years) at ICAR-Central Institute for Research on Goats, Makhdoom were used for the analysis. The effect of period and season of kidding, sex, type of birth and weight of doe at kidding was significant on live weights, average daily gains (ADG) and Kleiber ratio (KR). The estimates of genetic parameters were obtained for these traits by univariate and bivariate animal models using the average information restricted maximum likelihood (AIREML). Average inbreeding coefficient for the pedigree (N = 9418) was 0.83 % and amongst inbred animals (N = 3751), it was 2.045 %, indicating that the scientific mating could keep the inbreeding within normal limits in a nucleus flock. Genetic analysis revealed that the inclusive model for direct effect of animal and dam and their covariance and permanent environment of dam was best for birth weight (BW), however the model with direct effects of animal and dam along with their covariance was best for all other traits. Early growth traits were having significant maternal effect that faded as the age advanced. Correcting for maternal effects was essential to obtain unbiased estimated of heritability using univariate analysis. Moderate estimates of the heritability (h2) were obtained using multivariate analysis. The estimates were 0.17 +/- 0.02, 0.19 +/- 0.01, 0.20 +/- 0.02, 0.16 +/- 0.02, 0.17 +/- 0.02, 0.20 +/- 0.02, 0.14 +/- 0.02, 0.13 +/- 0.02, 0.22 +/- 0.02, 0.14 +/- 0.02 and 0.18 +/- 0.02 for birth weight (BW), three month weight (3 MW), six month weight (6 MW), nine month weight (9 MW), twelve month weight (12 MW), ADG1 (birth to 3-month), ADG2 (three to six month), ADG3 (six to 12-month), KR1 (ADG1/3 MW0.75), KR2 (ADG2/6 MW0.75) and KR3 (ADG3/12 MW0.75), respectively. Results for multivariate analysis were similar but little better as compared to estimates from univariate analysis, provided we accounted for maternal effect appropriately. Moderate h2 estimates augurs the scope for selection of Jamunapari goats for growth and feed efficiency traits. The high and positive genetic and phenotypic correlations between post-weaning weights indicate that early selection of Jamunapari goat by reducing age at selection from 9-month to 6-month is possible owing to lower GxE and higher chances of retaining ranks by animals in adulthood. ADG and their corresponding KR have high genetic correlations and thus kids can be indirectly selected for higher feed efficiency. The selection index combining live weight at 6-month and post-weaning KR will be useful for early selection of Jamunapari goat.