GENETIC STUDIES ON THE PERFORMANCE OF CROSSBRED PIGS

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Date
2008-10
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT : Data on 2,909 pigs belonging to 50 and 75% Large White Yorkshire (LWY)-desi crossbreds maintained at All India Coordinated Research Project on Pigs, Tirupati and born during 2000 to 2008 were utilized for the present study. Genetic group had no significant effect on gestation period and litter traits while period and season of birth had significant effect except the non-significant effect of season on litter weight at birth. The overall least-squares means for gestation period, litter size at birth (LSB) and weaning and litter weight at birth and weaning were 111.49 ± 0.34 days, 6.78 ± 0.11 and 6.22 ± 0.11 piglets and 7.53 ± 0.12 and 60.77 ± 1.00 kg, respectively. Rainy season was found to be the favorable season of birth for litter size and weight at weaning. Genetic group, period and season of birth and LSB in general, affected all the body weights highly significantly. The overall least-squares mean body weights were 1.11 ± 0.01, 2.16 ± 0.01, 3.20 ± 0.02, 4.32 ± 0.02, 5.44 ± 0.03, 6.52 ± 0.04, 7.65 ± 0.04, 8.79 ± 0.05, 10.13 ± 0.06, 14.40 ± 0.13, 20.38 ± 0.22, 27.41 ± 0.41, 34.68 ± 0.47, 44.08 ± 0.53 and 52.37 ± 0.56 kg at birth, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 28 and 32 weeks age, respectively. The overall least squares mean ADGs during 0 and 1, 1 and 2, 2 and 3, 3 and 4, 4 and 5, 5 and 6, 6 and 7, 7 and 8, 8 and 12, 12 and 16, 16 and 20, 20 and 24, 24 and 28, 28 and 32, birth and 8 and 8 and 32 weeks were 0.149 ± 0.002, 0.148 ± 0.002, 0.158 ± 0.002, 0.161 ± 0.002, 0.154 ± 0.002, 0.161 ± 0.002, 0.165 ± 0.003, 0.191 ± 0.003, 0.14 ± 0.003, 0.20 ± 0.004, 0.23 ± 0.01, 0.23 ± 0.01, 0.26 ± 0.01, 0.27 ± 0.01, 0.161 ± 0.001 and 0.26 ± 0.004 kg, respectively. In general, 75% LWY has recorded higher body weights and ADGs. Body weights and ADGs of piglets born in rainy and winter seasons were higher during pre- and post weaning ages, respectively. Pigs from smaller litters had significantly higher body weights and ADGs than those from larger litters. Heritability of gestation period in 75% LWY group was 0.08 ± 0.29. Heritability for litter traits ranged from 0.30 ± 0.30 to 0.87 ± 0.31in 50% and 75% LWYcrossbred pigs. Heritabilities for pre-weaning body weights varied from 0.53 ± 0.11 to 0.96 ± 0.15 and those of post weaning body weights were beyond normal range. Heritabilities of ADGs varied from 0.07 ± 0.15 to 0.90 ± 0.27. Genetic, phenotypic and environmental correlations ranged of gestation period with litter traits ranged from -0.49 ± 0.31 to -0.05 ± 0.85, -0.18 ± 0.07 to -0.04 ± 0.07 and -0.15 to 0.18 while those among litter traits were all positive and high. Genetic and phenotypic correlations among body weights were mostly positive and medium to high. Phenotypic correlation of BW0 with all the post weaning body weights were negative and low in magnitude in 50% LWY genetic group. Correlations among average daily gains were very low and without any trend. In conclusion, the effects of genetic group, period and season of birth and litter size at birth were significant on litter size and weight at weaning, body weights and daily gains. Heritabilities for body weights and daily gains were moderate to high with positive correlations among body weights and among ADGs indicating a substantial scope for genetic improvement by selection with optimum management.
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