GENETIC ARCHITECTURE OF CHHOTANAGPURI SHEEP IN CONTEXT TO ITS FECUNDITY
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Date
2013
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Birsa Agricultural University, Kanke, Ranchi, Jharkhand
Abstract
The present study was conducted to study polymorphism of FecB genes and
ascertain genotypes of Chhotanagpuri lambs on the basis of alleles of FecB gene with
objectives to estimate the effects of genotypes and some non- genetic factors on growth
in terms of absolute body weights of lambs from birth to 52-week of age as well as
variation in growth rate in terms of average daily gain in weight during different periods
of growth. Attempts were also made to study relationship of ewe’s weight at lambing
with growth of their lambs as well as among body weights at different stages of growth
from birth to 52-week of age. Regression equations with their coefficient of
determination were also developed to predict body weight at later stages of life on the
basis of earlier weights.
The findings of this study are being summarized as follows:
(1) Six single strand conformation polymorphism variants of FecB gene were obtained
at Locus-1 and Locus-2.
(2) AT Locus-1, the genotype frequency of AA was highest (0.424) followed by AB
(0.326) and BB (0.250) .revealed that the frequency of A and B alleles were 0.587 and
0.413, respectively.
(3) Locus-2, the genotype frequency of CD was higher (0.402) followed by CC (0.381)
and DD (0.217), indicating that the frequency C and D were 0.587 and 0.418,
respectively.
(4) Genotypes at Locus-1 had significant effect on body weights of lambs from 8th week
of age to 52nd week of age, though the variations in birth weight and weight at 4th week
due to it was not significant.
(5) Lambs with BB genotype at Locus-1 had better growth rate up to 52-wk of age than
those with AA and AB genotypes.
(6) Growth of lambs remains unchanged due to genotypes at Locus 2, though lambs of
CC genotype had better growth than CD and DD genotypes.
(7) Body weights of lambs from 4th week onwards varied significantly due to dam’s
weight at lambing.
(8) Lambs of heavier dams continued to weigh more than those of lighter dams till 52-
wk of age.
(9) Birth weight of lambs had significant effect on their growth up to 52-week of age.
Lambs born with higher birth weight at grow faster rate than those born having lower
birth weight particularly during pre-weaning period i.e up to 12-week of age.
(10) Average Daily Gain (ADG) in body weight of lambs was maximum (81.64±3.83
g/day) irrespective of genotypes.
(11) ADG declined with the advancement in age.
(12) Lambs with BB genotype at Locus had better growth rate in terms of ADG than
those of AA and AB at this locus
(13) Lambs with higher birth weight had better ADG particularly during pre-weaning
period.
(14) Dam’s weight at lambing had positive and significant phenotypic association with
body weight of their lambs up to 52 – week of age.
(15) Phenotypic association among body weights at various stages of growth were
positive and significant, though the magnitude of relationship declined with the increase
in gap between two weights taken.
Regression study revealed that the body weight at growth could be predicted with
moderately higher accuracy on the basis of preceding weight
The following conclusions have been drawn:
(1) Chhotanagpuri lambs with BB genotypes should be selected for better growth.
(2) Breeding program should be designed to increase the frequency of ‘B’ allele among
individuals in a flock of Chhotanagpuri sheep.
(3) Lambs with high birth weight should be cared properly particularly after weaning at
12-wk of age for better post-weaning growth.
(4) Keeping in view the positive association of dam’s weight at lambing on growth of
their lambs up to 52-week of age the ewes particularly during advance stage of
pregnancy should be fed properly and cared properly for improving birth weight of
lambs and its growth.
(5) Lambs could be selected on the basis of weight at at birth and 12-wk of age for
better growth and more meat yield.
(6) Polymorphism of FecB gene should be studied with a large number of primers to
derive valid conclusion in context of fecundity.
Description
GENETIC ARCHITECTURE OF CHHOTANAGPURI SHEEP IN CONTEXT TO ITS FECUNDITY