Assessment of growth and population structure revealed sufficient genetic diversity among lambs of Mecheri sheep in Tamil Nadu, India
Loading...
Date
2022-07
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
This study was designed to evaluate various genetic parameters for growth characteristics, genetic progression,
and to find out the genetic constitution of a population of Mecheri sheep, a tropical breed native to Tamil Nadu,
southern India. Data for this study were various records from 2768 lambs, which were a result of mating of 110
sires and 748 dams during a period of 10 years, between 2010 and 2019. Among the evaluated traits included
body weights at various stages of growth such as birth weight (BWT), as well as weight at weaning (WWT), at 6-
months (6WT), at 9-months (9WT), and at one-year-old (12WT). Estimated genetic parameters included additive
direct and maternal heritabilities and genetic correlations, genetic changes, inbreeding, and generation interval.
Among the software required for various analyses were the ENDOG (version 4.8) and Restricted Maximum
Likelihood (REML). Mean ( ± SE) values of weight at birth and at 12 months were 2.37 ± 0.02 and 21.34 ± 0.34
kg respectively. Direct heritability values estimated at birth, six months, as well as 12 months were respectively
0.14 ± 0.05, 0.07 ± 0.03, and 0.08 ± 0.03. Maternal heritability value for BWT was 0.28 and whereas low and
varied values between 0.03 and 0.05 were obtained for both weaning and post-weaning traits. Overall, genetic
improvement was low at birth (− 0.0025 kg) and highest (0.1314 kg) around weaning age. Average inbreeding
coefficient value was 0.16 % and the effective population size of founders was 100.35, while mean generation
interval ( ± SE) was 3.44 ± 1.15 years. Effective number of founders was 18.01 % and indicates that Mecheri
sheep have their origin from a moderate genetic base. The observed f e /f a ratio was 1.00 and is linked to presence
of sufficient founding ancestors, less bottlenecks, and possibly implementation of rotational mating scheme at the
farms. In summary, our study revealed that there are high correlations between WWT and post-weaning weights.
Based on heritability values, the WWT could be used as an important trait which can facilitate improvement in
body weight of Mecheri lambs. Further, the present genetic parameter values for different variables advocates
that the genetic progress for body weight at various stages of growth is feasible in Mecheri sheep thorough
genetic selection strategies. We conclude that sufficient genetic diversity is maintained within Mecheri sheep.
Description
Journal Article
Keywords
Mecheri sheep, Genetic evaluation, Genetic trends, Inbreeding, REML analysis