Association of Linear Body Measurements with Age at First Lambing in Sheep

摘要

Age at first lambing and growth rate are important economic traits in sheep production. Harnali is a new synthetic strain of sheep developed for superior carpet wool, better growth and adaptability. Data recorded on 349 Harnali animals for Body length (BL), Body height (BH), Heart girth (HG), Paunch girth (PG), Tail length (TL), Head circumference (HC), Ear length (EL), Ear width (EW), Face length (FL) and Age at first lambing (AFL) were analysed to study the association of body measurements with age at first lambing. The mixed linear model methodology with dam-s weight at lambing as covariate was used to study the effect of non-genetic factors on body measurements and age at first lambing. Genetic parameters were estimated by paternal half sib correlation method using sire components of variance and covariance and backward stepwise regression procedure was utilized to develop prediction equations. High heritability estimates were obtained for BL, BH, HG, TL, HC, EL, EW and FL while moderate estimate was obtained for PG and AFL. The phenotypic correlations of various linear body measurements with AFL were quite varying in magnitude ranging from -0.01-0.01 to 0.13-0.02. BL was found to have the highest phenotypic correlation with AFL (0.13-0.02). The genetic correlations of BL, TL, EL and EW with AFL were estimated as 0.39-0.14, 0.16-0.15, 0.19-0.16 and 0.17-0.16, respectively. The various combinations of linear type traits to predict AFL were found to have coefficient of determination as high as 0.085. The phenotypic and genetic correlations of AFL with body measurements indicated that body length of animal is directly related to its age at first lambing and ear length which can be used as a tool for selection of early lambing animals.