Selection Responses for Augmenting Early Growth Rate in Japanese Quail

Abstract

Throughout a selection experiment, which extended over five generations: the base and four generations of selection for augmenting early growth rate (GR) during the period from hatch to 21 days of age in Japanese quail, a total number of 8724 birds were used: 1726 in the base population, 5176 for the selected line (HGR 1-21 ) and 1822 for the control line. The most important results obtained as follows: Genetically, heritability (h 2 ) for all body weights (BW) showed moderate h 2 ranged from 0.19 to 0.29. The GR 1-21 positively correlated with all body weights weekly measured except BW at hatch (BW 1) with genetic correlations (r g ) ranged from 0.06 to 0.47, and a wide range of phenotypic correlation (r p ) ranged from 0.18 to 0.52. The GR during different periods of growth had medium h 2 ranged from 0.17 to 0.28 and showed a wide range of moderate to high r g with the selection criterion (0.15 to 0.70) and had a broader range of r p ranged from 0.03 to 0.67. The HGR 1-21 line in the 4 th generation had the best growth performance for each of BW 7 , BW 21 , BW 28 , GR during the periods 1-7, 1-14, 1-28 and 1-35 days of age with significant differences. The realized cumulative response after four generations of selection was 0.063 (6.30%) for GR 1-21 , the cumulative correlated responses for BW s and GR s ranged from 1.19,g to 23.94,g and from 3.10% to 17.00%, respectively. So, the current study aimed to evaluate the effectiveness of the selection program through estimation of direct and correlated responses to selection for fast GR 1-21 , and determination of correlations between selection criterion and either body weights at different ages or GRs during different growth periods for Japanese quail.