Purebred and crossbred performances from a Japanese quail line with very small body size

Abstract

In this study on Japanese quail, heterosis for weight, growth rate, and fitness traits were estimated and growth curves were fitted to traits and were compared. Crossing (SR) was performed between females of a very small line (SS) which was selected for low body weight at the age of six weeks and males of a randombred population (RR) from the same origin. Heterosis for female body weight was observed at 4 and 6 weeks of age, but it was not significant for adult size in males and females. The four growth curve models of Brody, Logistic, Gompertz and Bertalanffy were compared and the Gompertz model was the most suitable. Heterosis by the Gompertz model was negative for the age at the point of inflexion and the age at the 90% body weight of the asymptote in both sexes, but it was larger for the second trait. There was no heterosis for fertility and viability from 6 weeks up to 100 days of age in the female, but it was significant for hatchability and survival rate up to 6 weeks of age. Large heterosis was found for the age at first egg, the number of eggs and the total egg weight up to 100 days of age. However, the average egg weight of SR was lighter than that of RR, showing no heterosis.