Influences of maternal factors on the estimate of genetic parameters for goat feed efficiency traits

The objective of the present study was to estimate the genetic parameters for the feed efficiency traits in Barbari goats. The data records of 9332 progenies born to 413 sires and 2580 dams were collected with respect to the average daily weight gain (ADG), i.e., ADG1 (birth to weaning), ADG2 (weaning to 6 months), ADG3 (6 to 12 months), as well as derived trait Kleiber ratio (KR), i.e., KR1 (ADG1/3MW^0.75), KR2 (ADG2/6MW^0.75), and KR3 (ADG3/12MW^0.75). The data were corrected for fixed covariates like period of kidding, the season of birth, sex, type of birth, and parity. Univariate and multivariate animal models with an average information function of restricted maximum likelihood (REML) were used to estimate genetic factors for these traits. The best model was evaluated based on the likelihood ratio test. The direct heritability estimates were 0.21 ± 0.03, 0.17 ± 0.03, 0.23 ± 0.04, 0.22 ± 0.04, 0.16 ± 0.04, and 0.26 ± 0.04 for ADG1, ADG2, ADG3, KR1, KR2, and KR3, respectively. However, they were inflated due to high and negative estimates of covariance between direct animal and maternal genetic effects. Moderate estimates of heritability augur the scope for improvement for feed efficiency traits. The maternal genetic effects (m²) significantly contributed to 3-12% of the total phenotypic variance. The realized heritability of mass selection, which takes into account direct and maternal genetic variance together, shows a low to moderate estimate of genetic variance for ADG and KR. The genetic correlation ranged from - 0.48 ± 0.11 (ADG1-KR3) to 0.95 ± 0.00 (ADG1-KR1), phenotypic correlation ranged from - 0.28 ± 0.01 (ADG2-KR3) to 0.94 ± 0.01 (ADG1-KR1), maternal genetic correlation ranged from - 0.22 (KR2-KR3) to 0.96 (ADG1-KR1) and - 0.69 (ADG1-KR3) to 0.95 (ADG1-KR1) for the maternal permanent environment, respectively. Kids can be indirectly chosen for higher feed efficiency since ADG and their associated KR have substantial genetic correlations. It is suggested that the KR should be used as a selection criterion for Barbari goats for improving feed efficiency.