ABSTRACT

This research investigated the phenotypic and repeatability estimates of linear body and egg quality traits of Sigmoid strain of Japanese quail. A total of 100 experimental breeders of' Japanese quails were obtained from the Michael Okpara University's Poultry Farm Unit. The laying birds (6-8 weeks old) were replicated five times, that is, 20 birds per replicate, with the ratio of 5 male to 15 female, in a Completely Randomized Design (CRD). Data were collected for egg quality traits as well as body weight and linear body traits fortnightly for six weeks. Data collected were subjected to Pearson correlation test using Statistical Software Package for Social Scientists (SPSS) version 16 (2006) in order to determine the phenotypie correlations among body weight and linear body traits, external egg quality traits and internal egg quality traits in three lines of the Japanese quail. Repeatability estimate was also carried out using intraclass correlation coefficient. Result of the phenotypic correlation for the linear traits showed significant correlations in the Heavy line between body weight vs shank length (0.732), body weight vs keel length (0.676), breast width vs shank length (0,682) In the Medium line, significant correlations were observed between breast width vs shank length (0.674), body weight vs keel length (0.8 16), body weight vs wing length (0.696). wing length vs keel length (0.623); whereas, in the Light line, significant correlations were observed between the body weight vs breast width (0.722), body weight vs shank length (-0.779). breast width vs shank length (-0.647), body weight vs keel length (0.875). breast width vs keel length (0.928). The three lines showed similarity in the significant positive associations between body weight and keel lengths but showed variations in other associations. The external egg quality traits portrayed significant associations between egg weight vs egg length (0.730), egg surface area vs shape index (-0.895). The internal egg quality traits portrayed significant positive correlations between albumen height vs Haugh unit (0,955) and yolk height vs yolk index (0.932). Body weight was highly repeatable in the Heavy line whereas, shank length decrease progressively and these distinguished it from the other line in this study. In the Medium line, the repeatability of keel length improved over time and that of' breast width decreased progressively. Wing length maintained high repeatability in the Light line. The repeatability estimates in the other traits in each line showed inconsistent variations. In conclusion crossbreeding of the Japanese quail used in this study with an exotic breed with proven higher genetic potential is suggested for improving the association studies and the repeatability estimates. More so, subsequent research should attempt to increase the population of study triple the number used in this study for a more reliable repeatability estimate.