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Rajasthan University of Veterinary and Animal Sciences, Bikaner (2017)

GENETIC ANALYSIS OF WOOL TRAITS AND ITS ASSOCIATION WITH KERATIN GENES IN MAGRA SHEEP

HARVINDER SINGH

Titre : GENETIC ANALYSIS OF WOOL TRAITS AND ITS ASSOCIATION WITH KERATIN GENES IN MAGRA SHEEP

Auteur : HARVINDER SINGH

Université de soutenance : Rajasthan University of Veterinary and Animal Sciences, Bikaner

Grade : Doctor of Philosophy (PhD) Animal Genetics and Breeding 2017

Résumé partiel
The objectives of the present study were to estimate the mean performance of wool traits along with the effect of genetic and nongenetic factors affecting them, estimation of genetic and phenotypic parameters both by sire and animal models, to identify the polymorphism of keratin genes (KIF- I and KAP 11-1 genes) in Magra sheep and to find association of keratin genes with wool traits. Data and blood samples for the present study were collected from the farm of Magra sheep, maintained at arid region campus, Central Sheep and Wool Research Institute (ICAR- CSWRI), Bikaner, Rajasthan. The overall least-squares means were observed to be 690.50 ± 4.713, 754.83 ± 5.571 and 670.93 ± 5.386 g for greasy fleece yield at first, second and third clip, respectively. The overall least-squares mean for staple length, crimp frequency, fibre diameter, pure, hetro, hairy and medullated fibres were estimated as 6.26 ± 0.039 cm, 0.92 ± 0.010 per cm, 33.31 ± 0.131 μ, 54.74 ± 0.593 %, 33.25 ± 0.416 %, 12.01 ± 0.291 % and 45.26 ± 0.593 %, respectively. The effect of sire was observed to be highly significant (P≤ 0.01) on all the wool traits under study. The effect of period of shearing was found highly significant (P≤ 0.01) for all the wool traits except at greasy fleece yield at third clip and fibre diameter. The effect of sex was found highly significant (P≤ 0.01) on greasy fleece yield at different clips and crimp frequency ; and significant (P≤ 0.05) on fibre diameter. The effect of season of birth was found highly significant (P≤ 0.01) for all the wool traits except for pure, hetro and medullation percentage. The regression of lamb’s age at shearing had highly significant (P≤ 0.01) effect on greasy fleece yield at different clips, crimp frequency and hetro fibres ; and significant (P≤ 0.05) effect was found on medullation percentage. Heritability estimates for greasy fleece yield at first, second and third clip were estimated as 0.68 ± 0.083, 0.81 ± 0.095 and 0.66 ± 0.150, respectively, using sire model and 0.25 ± 0.037, 0.24 ± 0.039 and 0.32 ± 0.075, respectively, using animal model. The estimates of heritability for staple length, crimp frequency, fibre diameter, pure, hetro, hairy and medullated fibres were estimated as 0.52 ± 0.085, 0.20 ± 0.055, 0.18 ± 0.052, 0.41 ± 0.073, 0.33 ± 0.066, 0.53 ± 0.082 and 0.44 ± 0.075, respectively, using sire model and 0.31 ± 0.046, 0.09 ± 0.033, 0.14 ± 0.035, 0.40 ± 0.046, 0.28 ± 0.044, 0.41 ± 0.045 and 0.41 ± 0.046, respectively, using animal model. Fitting six different animal models with various combinations of direct and maternal effects showed that there was no or very low evidence of the maternal genetic and maternal permanent effect for all the wool traits under study. Using sire model, genetic correlations among different wool production traits ranged from 0.33 to 0.87, and that of wool quality traits ranged from -1.00 to 0.93 ; and phenotypic correlations ranged from - 0.01 to 0.09 and -1.00 to 0.89, respectively for wool production and wool quality traits, respectively

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