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Theses

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1980 - 19832
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Subject: Animal Genetics and Breeding × End date: 1999 × Start date: 1980 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Studies on certain genetic and nongenetic factors affecting birth weight and growth rate malabari and crossbred goats
    (Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1980) Raghavan, K C; KAU; Krishnan Nair, B R
    The data on 1227 kids belonging to Malabari (309) Saanen x Malabari (389) and Alpine x Malabari (309) genetic groups born and brought up at the All India co – ordinated Research Project on Coats, Kerala Agricultural University, Mannuthy during the period from April 1974 to March 1979 were utilised to study the effects of various genetic and non genetic factors on body weight at different ages. Crossbred goats, S x M and A X M, registered higher weights at birth, at one month, at four months and at one year than the local Malabari goats. District sexual dimorphism in body weights at different ages could be observed in crossbred goats. Litter size significantly affected birth weight and weight at one month. Sason of birth had only non significant influence on weights at birth and that at one month, though the effect was significant on 4 month’s and one year weights. Even though the effect of gestation length undergone by kids was a significant source of variation for weights at birth alone in Saanen x Malabari and Alpine x Malabari kids, the same had significant effect on body weights at birth and at one month in Malabari. Significant effects of dam’s weight at kidding on weights at birth, one month and four months in Malabari ; at birth and a one month in Alpine x Malabari and at birth alone in Saanen x Malabari could be observed. Sire effect was significant on body weights at one month, 4 months and one year in Malabari, at birth and one year in Alpine x Malabari and one year alone in Saanen x Malabari. The growth rate was found to be highest in A x M upto four months of age and afterwards upto one year S X M showed highest rate of gain. The effect of genetic group on growth rate was found to be significant during all the periods of growth. The heritability estimate for weight at birth was near to zero. The h2 estimates were seen getting higher as the age advanced. Genetic correlations between body weights at different ages were found to be fairly high. But the phenotypic correlations between weight at different ages were found to be highly variable. Twins were more than singles in all the genetic groups and the secondary sex ratio was found to be 50:50. The results of the study indicated that crossbreeding of local goats with exotic breeds, Saanen and Alpine, is the desirable breeding plan to accomplish the improvement of body weight in goats, at different ages.
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    ThesisItemOpen Access
    Inheritance of chick weight and egg production in white leghorn birds
    (Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy, 1983) Rose Job, T; KAU; Sosamma, Ipe
    A research work was undertaken in two strains of White Leghorn birds to study the inheritance of chick weight and egg production. The birds maintained at the poultry farm under All India Co – ordinated Research Project on Poultry for Eggs, Mannuthy were utilized for the study. The mean values for six – week body weight (g), eight week body weight (g) and egg production upto 280 days of age (number) were 319.4 + 1.4, 452.9 + 1.8 and 71.5 + 0.4 for N strain and 351.2 + 1.7, 513.7 + 2.2 and 80.6 + 0.5 for P strains. Least squares analysis for effect of generations and hatches within generations were carried out. Generation effects were significant for the three characters in both the strains. Effect of hatches within generations were also found to be significant except for egg production in first generation batches and for six – week body weight in second generation hatches in N strain. The data were adjusted for the generation and hatch effects. Adjusted data were used to estimate heritability, genetic, phenotypic and environmental correlations. The heritability estimates in N strain were 0.223 + 0.112, 0.642 + 0.078 and 0.433 + 0.099 for six – week body weight 0.278 + 0.108, 0.372 + 0.068 and 0.325 + 0.095 for eight – week body weight and 0.219 + 0.095, 0.379 + 0.077 and 0.298 + 0.095 for egg production based on sire, dam and sire + dam components of variance respectively. The respective estimates in P strain were 0.405 + 0.110, 0.341 + 0.103 and 0.373 + 0.101 for six – week body weight, 0.354 + 0.110, 0.443 + 0.094 and 0.398 + 0.118 for eight – week body weight and 0.530 + 0.102, 0.230 + 0.130 and 0.380 + 0.131 for egg production. The genetic correlation estimates between six – week and eight – week body weight were found to be high and positive in both the strains. The phenotypic correlations were also found to be positive but lower compared to genetic correlation and similar in both the strains. The environmental correlations had also been positive though of still lesser magnitude in both the strains. In general, the correlation estimates between chick weights and egg production were found to be very low in both the strains. The results were not suggestive of any strong relationship between chick weights and egg production. Out of these three characters, only egg production deserved consideration in selection as chick weight in White Leghorns cannot be considered as an economic trait. It was estimated that an improvement of 7.57 eggs per generation could be expected in both the strains for standard deviations of 16.04 and 15.41 and heritabilities of 0.219 and 0.230 in N and P strains respectively, when selection of males is 8.5 per cent and females 16 per cent.