DIRECT AND MATERNAL COMPONENTS OF VARIANCE FOR RELATIVE GROWTH RATE IN NILAGIRI AND SANDYNO SHEEP
Loading...
Date
2015-08
Journal Title
Journal ISSN
Volume Title
Publisher
Indian Society for Sheep and Goat Production and Utilization
Abstract
A study was conducted to estimate genetic parameters of relative growth rate (RGR) and
explore the possibility of its use as a selection criterion in Nilagiri and Sandyno sheep. RGRfor the
pre-weaning (birth to 3 months, n=6504) and post-weaning (3-6, 6-9, 9-12 and 3-12 months,
n=4309, 3267, 2978 and 3257, respectively) periods were studied. The maximum RGR was
noticed for the pre-weaning period and least during the latest age interval from 9 to 12 months. The
ability of the trait to adjust for body size was evident from the effects of litter size, breed and age of
dam on the trait. An animal model, including maternal effects was used to obtain REMLestimates
of (co)variances. Maternal genetic effects and inbreeding were not significant for RGR at any of
the age intervals. Moderate estimates of heritability were obtained for pre-weaning RGR, with
values of 0.126 and 0.103 for Nilagiri and Sandyno sheep, respectively.Among the post-weaning
RGR, the age interval 3-6 months showed moderate value (0.140) in Nilagiri sheep. Post-weaning
RGR for other intervals in Nilagiri and all intervals in Sandyno sheep showed negligible to low
heritability estimates. The genetic correlations between pre-weaning RGR and body weight traits
were high and positive in Nilagiri sheep. The estimates for the breed were found to decrease with
age. Moderate heritability for pre-weaning RGR and high genetic correlation of the trait with other
body weight traits provide scope for indirect selection using the trait in Nilagiri sheep. The result of
the study supports the fact that RGR is able to adjust growth curve in such a way as to improve
growth without affecting mature body size.
Description
TNV_IJSR _2017_22(1) _16-21
Keywords
Small Ruminants