GENETIC EVALUATION OF GROWTH TRAITS USING RANDOM REGRESSION MODELS IN JERSEY CROSSBRED CATTLE
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Date
2022-04
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
A total of around 34,726 number of body weight records of 7363 animals,
belonging to 108 sires and 7363 dams with known history and pedigree having
minimum 3 number of records per each animal were considered. The data was recorded
on body weight at repeated intervals from birth to 54 months of age i.e. BW0, BW6,
BW12, BW18, BW24, BW30, BW36, BW42, BW48 and BW54 and were subjected to
random regression analysis for additive genetic, individual permanent environmental,
maternal genetic and maternal permanent environmental effects by using different
Legendre polynomials like quadratic, cubic and quartic etc.
Preliminary analysis revealed that all fixed effects included in the study were
having significant (P98% and 1.26% of total genetic variation, whereas 3rd Eigen function
was zero.
The direct genetic heritability estimates obtained for BW0, BW6, BW12, BW18,
BW24, BW30, BW36, BW42, BW48 and 54 months of age were 0.03±0.01, 0.09±0.03,
0.17±0.03, 0.09±0.02, 0.18±0.05, 0.22±0.07, 0.21±0.07, 0.21±0.07, 0.23±0.09 and
0.26±0.10 respectively. The heritability value for individual permanent environmental
variance was found to be low (0.01±0.10) at birth and high (0.44±0.13) at 54 months of
age. The heritability estimates for maternal effects m2 & c2 were found to be similar and
low (0.01 to 0.03) across the ages.
The direct genetic correlation of birth weight was found to be negatively
correlated with BW6 (-0.71±0.29), BW12 (-0.47±0.26), BW18 (-0.22±0.13) and
positively correlated with BW24 (0.02±0.03), BW30 (0.12±0.04), BW36 (0.22±0.04),
BW42 (0.29±0.05), BW48 (0.34±0.05) and BW54 (0.39±0.06).
The animal permanent environmental correlations between body weight at
different ages showed strong positive relationship with a range of 0.18±0.06 (BW0 and
BW54) to 1.0±0.0 (BW30 and BW36; BW36 with BW42, BW48 and BW54; BW42
with BW48 and BW54; BW48 and BW54). The estimates of maternal genetic and
maternal permanent environmental correlations showed a similar pattern of negative
correlation of birth weight with body weight at different ages (-0.69±0.02 to -0.35±0.03)
and (-0.76±0.02 to -0.48±0.22). The average breeding value for birth weight was found
to be 23.24 kg, which improved to 321.10 kg at 48 months of age. Maximum breeding
value (333.49 kg) was recorded at 42 months of age.
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