كليدواژه :
پارامترهاي ژنتيكي , Baluchi sheep , وزن بدن , genetic parameters , مدل تابعيت تصادفي , body weight , Random regression model , گوسفند بلوچي
چكيده لاتين :
Random regression models have been used increasingly to estimate genetic parameters and to predict breeding values, due to their relative advantages as compared to the animal models. These models are used when repeated measurments of a trait during different times are available. The objective of this study was to estimate genetic parameters of body weight traits at different ages using random regression in Baluchi sheep breed, in Abbass-Abad station. A total of 38659 test day records of 12328 animals were used. Random regression models with additive genetic and permanent environmental effects of order 3, 4 and 5 were fitted. Results indicated that the 5th order was more appropriate than others. Heritability of body weight at birth, 45, 60, 90, 120, 150, 180, 210, 320 and 360 days were estimated 0.46, 0.43, 0.42, 0.45, 0.51, 0.54, 0.47, 0.35, 0.33 and 0.34 respectively. Heritability of body weight (except birth weight) increased with increase in the age of animals up to 150 days and decreased next to 150 days (model 3), but in models 1 and 2, heritability of body weight increased with increase in the age of animals up to 360 days. Genetic correlations between body weight measurements at closer ages were higher. In general the results obtained suggest that body weight measurement at later stages of life were different than the measurements taken at earlier stages and that some different genes might be affect body weight gain at older ages.
