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Kerala Veterinary and Animal Sciences University, Wayanad

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20121
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Subject: Animal Genetics and Breeding × Author: AJEESH MATHEW × Type: Thesis × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    PERFORMANCE OF SOVIET CHINCHILLA RABBITS IN HIGH RANGE CONDITIONS OF KERALA
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD, 2012) AJEESH MATHEW; Bindya Liz Abraham
    A low rate of kindling per year as well as a low growth rate, high feed consumption and non availability of good quality breeding stock are identified to be the major constraints of rabbit breeding in Wayanad district which harbours a major proportion of Soviet Chinchilla rabbitaries in Kerala. Hence, a genetic evaluation of the litter, growth, feed and carcass traits of a Soviet Chinchilla population was undertaken in the present study at the rabbit unit of College of Veterinary and Animal Sciences, Pookode, Wayanad for formulating suitable rabbit breeding strategies for these high range conditions. Data on litter size and weight at birth, 21 days and at weaning, fortnightly body weights, daily feed intake and carcass traits belonging to 128 progenies born out of 22 kindlings of four sires and six dams of Soviet Chinchilla from six to 20 weeks of age, maintained at the Instructional rabbit unit of College of Veterinary and Animal Sciences, Pookode, Wayanad, during 2009 - 2011 were generated. The effect of parity, sex, litter size at birth and season of kindling on these traits were studied using Least squares analysis of variance and genetic parameters like heritability and genetic, phenotypic correlations were estimated using paternal half-sib correlation method. The mean litter sizes at birth, 21days and weaning in Soviet chinchilla under the present study were 5.85 ±0.416, 4.80 ±0.32 and 4.28 ±0.37 and the mean litter weights during same periods were 332.79 ±18.63g, 1592.09 ±18.63g and 2582.58 ±278.19 g respectively. The effect of parity was not significant on litter traits. Average daily gain showed an increasing trend from six to 10 weeks of age and a declining one during next two fortnights from 11-14 weeks of age. The effect of sex was not significant on average daily gain, fortnightly body weights and feed conversion ratios at any stage studied. The effect of season of birth was highly significant on average daily weight gains at eight to 10 weeks of age. The effect of litter size at birth was significant during 6-8, 8-10, 12- 14 and 14-16 weeks of age. A substantial and faster increase in body weights was noticeable from 6 - 12 weeks of age over the fortnights while it was nominal beyond 14 weeks of age. The effect of season was significant on all body weights except those at end of eight and 20 weeks of age (P≤0.05). The effect of litter size at birth was significant on body weights at six, eight, 16 and 18 weeks of age (P≤0.05). Winter-born bunnies had highest daily gains as well as fortnightly body weights at all stages from six to 20 weeks of age. Similarly, animals born in four- sized litters tended to be heavier with higher daily gains than those from larger litters. Highest feed conversion efficiency was observed during 8-10 weeks of age wherein the feed conversion ratio was the least (4.60 ±0.26).Season of birth was significant on feed conversion ratio during initial periods from six to 10 weeks of age (P≤0.01). Maximum feed efficiency was observed in winter-born bunnies which showed minimum feed conversion ratios. Effect of litter size at birth was significant for the feed conversion ratio during eight to 10 weeks of age (P≤0.05). Least feed conversion ratios were observed in bunnies hailing from small foursized litters. The effect of sex on carcass yield was significant in the population and males had better carcass yield than females (P≤0.05). The heritability estimates for litter size and weight at birth (0.35 and 0.79) as well as for body weights at six (weaning), 10 and 12 weeks of age were medium to high (0.38 to 0.58) indicating a high scope for genetic improvement of these traits through judicious selection. Feed conversion ratios at 10-12 weeks of age were also highly heritable (0.99). Heritability estimates of litter size and weight at weaning as well as body weights at 16 to 20 weeks and feed conversion ratios above12 weeks of age were more than unity due to low sample size and consequent sampling error. Phenotypic correlations among litter traits were positive and medium, ranging from 0.412 to 0.902. Positive medium and reliable phenotypic associations were observed for the individual weaning weight at six weeks of age with those at 10 and 12 weeks of age (0.46 and 0.48). The phenotypic correlations among the feed conversion ratios were generally low, negative and imprecise. The increasing trend of positive, medium to high phenotypic correlations of fortnightly body weights from eight to 20 weeks of age with the carcass yield (0.29 to 0.72) indicated a phenotypic tendency of higher body weights to contribute to higher carcass yield. The genotypic correlations among majority of the litter traits could not be estimated or beyond unity. The genetic correlations of the weaning weight at six weeks with those at 10 and 12 weeks were positive and beyond unity offering a scope for a stronger genetic dependency between the traits. The genetic correlations of FCR (8-10) with FCR at later stages were positive and above unity. The genotypic correlations of fortnightly body weights from eight to 20 weeks of age with the carcass yield could not be estimated. In overall, the present study has thrown light on the following characteristics of the Soviet Chinchilla population reared in the sub tropical high range conditions: Progenies from four sized litters displayed an optimum performance in traits of broiler importance like body weights, average daily gain and feed efficiency. Winter born bunnies performed better in all these traits indicating winter to be the most ideal season, conducive for kindling and early growth in this population reared in the subtropical high range conditions. The substantial and faster increase in body weights noticeable from six to 12 weeks of age indicated that this was the most important stage of growth in Soviet Chinchilla in sub tropical climatic conditions. Heritability estimates for body weights at six (weaning), 10 and 12 weeks of age were medium to high heritable indicating a high scope for genetic improvement of these traits through judicious selection. Early selection for individual weaning weight at six weeks may improve subsequent body weights at 10 and 12 weeks of age which are supposed to be the ideal marketable ages for broiler rabbits. The positive genetic correlations between feed conversion ratios at 8-10 weeks and 10-12 weeks of age also hold the scope for a genetic improvement of feed efficiency through an early selection for FCR. Therefore it can be concluded that there exists the possibility of genetic improvement in litter traits, individual weaning weight at six weeks of age, body weights at 10 and 12 weeks of age and feed efficiency at 10 and 12 weeks of age in the population son account of their medium to high heritability estimates and genetic correlations, through a systematic selection of sires.