Genetic Analysis of Pre-Weaning Growth Traits of Anglo-Nubian and Baladi Kids التحلیل الوراثی لصفات النمو قبل الفطام للجدیان الأنجلونوبیان والبلدی

Abstract

Data representing 592 Anglo-Nubian and 347 Baladi kids born at Alexandria University Experimental Station, between 1997and 2014 were utilized in this investigation to estimate genetic parameters, breeding values and genetic trends of birth weight (BW), weaning weight (WW) and average daily gain (ADG) from birth to weaning. The analysis of variance indicated that the overall means of BW, WW and ADG of Anglo-Nubian kids were 2.54 kg, 13.12 kg and 86.8 g, while the corresponding values for Baladi kids were 2.27 kg, 10.21 kg and 64.9 g, respectively. The effect of season and year of birth, sex of kid, type of birth and parity on all traits were significant (P<0.01or P<0.05) except for the effect of parity on WW and ADG of Baladi kids which were not significant. Genetic parameters and breeding values for the studied traits were estimated for each breed separately using Wombat program, fitting multivariate animal models. Estimates of the direct heritability (h 2 a ) were 0.097, 0.109 and 0.095 for BW, WW and ADG of Anglo-Nubian kids, respectively. The corresponding values for Baladi Kids were 0.060, 0.280 and 0.292for the respective traits. Estimates of the maternal heritability (h 2 m ) were 0.238, 0.106 and 0.097 for BW, WW and ADG of Anglo-Nubian kids, respectively. The corresponding values for Baladi Kids were 0.045, 0.178 and 0.162 for the respective traits. Estimates of the fraction of variance due to maternal permanent environmental effects (c 2 ) were 0.488, 0.057 and 0.066 for BW, WW and ADG of Anglo-Nubian kids, respectively. The corresponding values for Baladi kids were 0.295, 0.038 and 0.021 for the respective traits. These results indicate that maternal effect is an important source of variation for pre-weaning growth traits of kids of both breeds. The genetic correlations (r g ) among growth traits of both breeds were significant (P<0.01), ranging from 0.677 to 0.999. These high and positive correlations indicate that selection for any of growth traits can lead to positive genetic progress in the others. The maternal genetic correlations (r m ) were low to high, being 0.329, 0.061 and 0.962 between BW and WW, between BW and ADG and between WW and ADG of Anglo-Nubian kids, respectively. The corresponding values for Baladi kids were 0.347, -0.027 and 0.919. The maternal permanent environmental correlations (r c ) among growth traits of Anglo-Nubian kids were considerably high and ranged from 0.925 to 0.999, the respective values for Baladi kids were close to unity. The phenotypic correlations (r p ) were 0.393 and 0.240 between BW and each of WW and ADG of Anglo-Nubian kids, while the value between WW and ADG was greatly higher being 0.962. The corresponding values in the case of Baladi kids were close to unity. The breeding values for BW, WW and ADG of Anglo-Nubian bucks varied between -0.131 and 0.324 kg, between -0.591 and 1.818 kg and between -4.64 and 12.27 g, respectively, the corresponding values for Baladi bucks were between -0.144 and 0.112 kg, between -2.277 and 1.205 kg and between -18.08 and 9.2...