GENETIC STUDIES ON THE PERFORMANCE OF CERTAIN BROILER RABBIT BREEDS
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Date
2007-10
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT :
The present study was conducted on New Zealand White (NZW), Grey Giant (GG), Soviet Chinchilla (SC), Flemish Giant (FG), Californian White (CW) purebreds and two synthetics - APAU Fawn (FN) and APAU Black (BL) bunnies born during November 2006 and July 2007 in the “Rabbit Production for Meat” scheme, Department of Animal Genetics and Breeding, College of Veterinary Science, Hyderabad. Bunnies were reared under cage and deep litter system.
The overall least-squares mean litter size at birth and weaning and litter weight at birth and weaning were 6.18 ± 0.28 and 3.75 ± 0.23 bunnies and 305.16 ± 13.75 and 1190.93 ± 56.92 g, respectively. Winter proved to be the favorable season of birth for litter traits.
The overall least-squares mean body weights were 50.00 ± 0.59, 104.52 ± 1.89, 175.10 ± 3.28, 239.50 ± 6.11 and 354.07 ± 9.19 g at birth, 1 2, 3 and 4 weeks age, respectively. In general, BL bunnies and those born in rainy season recorded significantly higher pre-weaning body weights. Mean body weights from birth to 3 weeks of age declined as the LSB increased.
The overall mean body weights at 6, 8, 10, 12, 14 and 16 weeks of age were 551.89 ± 16.84, 684.30 ± 19.68, 856.37 ± 23.33, 1018.79 ± 28.83, 1207.18 ± 31.98 and 1352.84 ± 37.93 g, respectively. The FG rabbits have recorded significantly higher weights up to 8 weeks age. Post weaning body weights of bunnies born in winter were higher. The litter size classes 1-3 and 4-6 recorded higher body weights. The overall least square mean ADGs during 5-6, 7-8, 9-10, 11-12, 13-14 and 15-16 weeks were 17.55 ± 1.04, 9.06 ± 0.73, 10.91 ± 0.80, 10.46 ± 0.94, 14.47 ± 0.90 and 10.98 ± 1.0 g, respectively. Genetic group, rearing system and season had significant influence. The overall least-squares mean lactation milk yield was 1116.21± 98.28 g. Does kindled during February and those with a LWB of >250 g. recorded significantly higher milk yield. The mean daily milk yield ranged from 61.2 ± 2.1 to 73.3 ± 2.1.
The effect of genetic group and season of birth was significant on feed intake and feed efficiency but not on weight gain. The overall least-squares means for pre-slaughter weight, dressed weight, dressing percentage, forecut, midcut, hindcut, head and feet, pelt, edible offals, inedible offals and length of caecum were 1451.14 ± 63.04 g, 695.33 ± 39.18 g, 46.69 ± 0.86, 245.73 ± 12.14 g, 174.41 ± 12.95 g, 275.19 ± 14.81 g, 193.79 ± 6.33 g, 141.11 ± 8.93 g, 57.44 ± 2.81g, 303.19 ± 11.47 g and 43.38 ± 0.85 cm, respectively. Length of caecum was significantly lower in CW rabbits. Most carcass traits studied were significantly higher in males and in those born in winter season. Rearing system had a significant influence on the length of caecum only.
The overall least-squares means for dry matter, total ash, protein, fat and cholesterol in rabbit meat were 24.3%, 1.3%, 20.3 g%, 4.1% and 0.1mg%, respectively. Heritability estimates for litter traits were beyond the normal range. Heritability estimates of the pre and post weaning body weights, post weaning ADGs and carcass traits that could be computed varied from 0.11 ± 0.69 to 0.98 ± 1.94. The genetic and phenotypic correlations ranged from -0.04 ± 1.75 to 0.98 ± 0.02 and 0.45 to 0.97 among post weaning body weights, -0.21 ± 0.33 to 0.54 ± 0.27 and -0.09 to 0.25 among post weaning ADGs, respectively
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