ESTIMATION OF HERITABILITY AND BREEDING VALUES FOR SOME WOOL TRAITS IN BARKI SHEEP, USING SINGLE AND MULTIPLE TRAITS ANIMAL MODELS IN COMPARISON WITH SIRE MODELS

SUMMARY
The present study was undertaken to evaluate some wool traits using animal versus sire model as well as analyzing single trait versus multiple traits in order to obtain accurate estimates of genetic parameters in Barki sheep. This study utilized 937 Barki fleeces obtained from animals raised in three Barki sheep flocks located at the north western desert. Wool samples taken from these animals were used to assess kemp score, KS, handle grade, HG, lustre grade, LG and measure staple length, STL. Results indicated that Barki wool has slightly more than average kemp fibres and tend to be more than average softness and lustrous with an average staple length of 10.31 cm. Heritabilities obtained from single and multiple-traits analysis using animal and sire models were estimated for KS (ranged from 0.58 to 1.00), HG (ranged from 0.50 to 0.71), LG (ranged from 0.61 to 1.00) and STL (ranged from 0.62 to 0.80). Estimates of h2 obtained from single trait analysis were consistently higher than those obtained from multiple traits analysis using animal model. Moreover, the standard errors for heritability estimates obtained from sire model were obviously lower than those obtained from animal model. The present study revealed that sire model, particularly with the multiple traits analysis, is probably more adequate than animal model for estimating h2 of the studied traits. The range of estimated breeding values (EBV's) was wider when estimated from animal model and from multiple traits analysis compared with the corresponding values obtained from sire model and from single trait analysis, respectively. Using animal model, particularly with the multiple trait analysis, for estimating BV's showed higher genetic diversity compared with sire model which would lead to a rapid genetic gain in the future generations.