Direct and maternal genetic effects of growth traits for Sanjabi sheep

Abstract

Introduction: Estimation of genetic parameters for economic traits has a practical and
prerequisite role for the implementation of animal breeding programs. Therefore, the aim of
current study was to evaluate direct and maternal genetic effects for growth traits of Sanjabi
sheep.
Materials and Methods: Used data was related to Sanjabi herd of Mehregan station in 2016
to 2021. For the traits, 6 animal models differed on maternal genetic abd permanent
environmental effects were taken into accounts. Proper model was identified for the final trait
analysis based on a comparison of the log likelihood ratio and the Akaike criterion.
Results: Significant model for birth, 3 and 6 months’ weights, daily weight gain from birth to
3 and 3 to 6 months, and kleiber ratios from birth to 3 and 3 to 6 months was 2, 2, 2, 5, 5, 2 and
5, respectively (P<0.05). Direct heritabilities based on appropriate model for birth, 3 and 6
months’ weights, daily weight gain from birth to 3 and 3 to 6 months, and kleiber ratios from
birth to 3 and 3 to 6 months were 0.05, 0.103, 0.182, 0.422, 0.004, 0.135 and 0.001,
respectively. Also, maternal heritabilities for birth, 3 and 6 months’ weights, daily weight gain
from birth to 3 and 3 to 6 months, and kleiber ratios from birth to 3 and 3 to 6 months were
0.122, 0.191, 0.166, 0.087, 0.024, 0.156 and 0.004, respectively. The ratio of maternal
permanent environmental effect on phenotypic variance for daily weight gain from birth to 3
and 3 to 6 months, and kleiber ratio from 3 to 6 months were 0.088, 0.001, and 0.016,
respectively.
Discussion: Estimated direct heritabilities were moderate to high, representing ability for
response to selection. Maternal effects, genetic and permanent environmental, were significant.
Neglecting maternal effects in the final model of analysis make the genetic parameters
overestimated. Estimated heritabilities showed that growth traits of Sanjabi sheep can response
to selection.