Relationship between Maternal Breeding Values of Day Old-Chick Weight and Egg Quality and Quantity Traits in a Commercial Broiler Line

The purpose of this study was to investigate the relationship of maternal breeding values of the weight of day-old chick chicks in a commercial broiler line with egg traits including yolk fatty acids. Maternal breeding values of 63 hens of known pedigree were estimated through an animal model, containing direct additive genetic effect, maternal additive genetic effect, maternal common environmental effect and covariance between direct and maternal additive genetic effects, through DFREML program employing 6476 records of day-old chick weights. Hens were divided into 3 genetic groups (low, LGG; medium, MGG; and high, HGG) on the basis of estimated maternal breeding values. From the hens, 126 eggs (2 eggs from each hen) were collected at 32 weeks of age for an assessment of egg quality and quantity traits (egg weight, shell thickness, shell strength, shell weight, yolk weight, yolk percentage, albumin weight and albumin percentage) as well as yolk fatty acids (palmetic, palmitoleic, estearic, oleic, linoleic and linolenic acids). Analysis of variance was carried out through GLM procedure and differences among the means evaluated using Tukey method. Egg, shell, yolk, and albumin weights as well as albumin percentage were higher (p<0.05) for HGG than for MGG and LGG. However, yolk percentage mean decreased as maternal breeding values increased. With the as fitting egg weight as a covariate, the differences among the means in the 3 genetic groups were not found as significant. The results indicated that egg weight accounts for a considerable part of variability of all traits. The MGG had the higher and the HGG a lower mean of yolk fatty acids, but the differences were not significant.