Genetic evaluation of growth in farmers’ flocks of Madras Red sheep under long-term selection in a group breeding scheme
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Date
2018-04
Journal Title
Journal ISSN
Volume Title
Publisher
Akinik Publications
Abstract
The Network Project on Sheep Improvement (NWPSI)–Madras Red field unit is a group breeding scheme involving 198 farmers’
flocks of Madras Red sheep in which selection for growth traits and rotation of rams have been practised for over two decades.
Growth data collected from these flocks were used to evaluate the performance and understand the direct and expected responses
to selection based on genetic parameters. The body weight at birth (BW), weaning weight (WW), 6-month weight (6W), 9-month
weight (9W), 12-month weight (YW), pre-weaning average daily gain (ADG1, birth to 3 months), post-weaning ADG2 (3–
6 months), ADG3 (6–9 months), ADG4 (9–12 months) and ADG5 (3–12 months) were 2.67, 10.05, 14.56, 18.36, 21.36, 80.13,
49.05, 43.00, 34.21 and 41.18 g, respectively. Univariate analyses were carried out using animal and sire models to estimate
variance components. Heritability obtained from animal model for BWwas 0.36 and the values for other body weight traits were
almost unity. Heritability estimate for pre-weaning ADG1 was 0.31. Very high genetic variability was observed in spite of
long-term selection and this sustenance of variability is one of the main advantages of a group breeding scheme, combining
several flocks of smaller size. An increasing genetic and phenotypic trend was noticed for almost all the traits studied. The
expected responses calculated based on genetic parameters also indicated scope for improvement.
Description
TNV_TAHP_2018_50(7)1463-1471
Keywords
Veterinary Science