Crossbreeding Effects for Wool Quality Traits of Sheep

摘要

Crossbreeding effects for wool quality traits viz. grease fleece weight (kg), staple length (cm),rnaverage fibre diameter (U) and modulation percentage were estimated using the Dickerson’s andrnKinghorn’s models. The data analyzed involved 15 genetic groups including Nali purebred, F1’s ofrntwo and three breeds, F2’s and reciprocal crossbred obtained from the crossing of Nali (N), Merinorn(M) and Corriedale breeds during 1980-96. Nali and Corriedale breeds had non significant negativernadditive genetic effects (Dickerson’s model) on grease fleece weight, while effects of Corriedale werernnegative for staple length only from both models. In general additive genetic effects of all threernbreeds were non significant for all the wool traits except modulation percentage. Non significantrnheterosis and recombination effects (epistatic loss) were statistically non significant estimated fromrnboth models. However, the estimates of crossbreeding effects varied between the models both inrnmagnitude as well as in direction barring few exceptions. Undesirable positive heterosis was foundrnfor all types of combinations involving three breeds. Results on linear contrasts comparison ofrnvarious genetic group means revealed that both two breed and three breed crosses were superior tornNali breed for all the wool quality traits. Fibre diameter of MN crossbreds was significantly less thanrnCN crossbreds. Results also indicated that as the inheritance of Nali breed in a cross is decreased, thernmodulation percentage decrease that is desirable. Inter se mating of crossbreds (two breed, threernbreed) has not resulted in decline in the wool quality traits. These results are of indicative of the factrnthat the synthetic population derived from three breeds can be stabilized easily for wool traits.