Egg quality traits, phenotypic correlations, egg and yolk weights prediction using external and internal egg quality traits of Japanese quails reared in Calabar, Nigeria

Three hundred freshly laid eggs collected from 12 weeks old brown Japanese quails on deep litters fed 18% CP and 2700 kcal ME/kg ration and water ad libitum. External egg quality traits measured included egg (weight and width) and yolk (weight, height and width). Data collected were used to estimate descriptive statistics, phenotypic correlations and to predict egg and yolk weights. Results of phenotypic correlation of external egg traits investigated expressed mostly non-significant (p>0.05) both positive and negative low values with the exceptions of two higher, negative significant (p<0.01) correlations observed between egg weight and egg length (r= – 0.721) and egg weight and shell thickness (r= – 0.616). Similarly, results of phenotypic correlations of internal egg traits expressed mostly non-significant (p>0.05) both positive and negative low values with the exceptions of very high negative correlation coefficient (r= – 0.802) between yolk weight and albumen width and moderate negative correlation coefficient (r= – 0.561) between albumen height and albumen width. The only moderate positive significant correlation (r=0.519) obtained in this study was between yolk weight and albumen height. The regression estimates of parameters and coefficient of determination for simple (one trait) and multiple (two traits and for predicting egg and yolk weight sh6wed very low non-significant associations/interrelationship. But with three to five traits fitted into the multiple linear regression equations, highly significant (p<0.001) associations/interrelationships were obtained for egg and yolk weights. Egg and yolk weights can be predicted using external and internal egg traits measurements with two external traits (egg length and egg width) and two internal traits (albumen height and albumen width) best predicted egg and yolk heights respectively.