Effects of the dwarfing gene (dw) on egg weight, chick weight, and chick weight: egg weight ratio in a commercial broiler strain.
The effects of the dwarfing gene (dw) on egg weight, chick weight, and chick weight: egg weight ratio were studied. Egg weights prior to setting and subsequent chick weights were determined on 1842 chicks from standard-sized broiler dams and 1694 chicks from closely related dwarf dams. Egg weight means were 67.3 and 63.0 g for standard and dwarf dams, respectively. Chick weights expressed as percentage of egg weight were 68.4 and 67.3% for standard and dwarf dam chicks, respectively. Both egg weight and chick weight: egg weight ratio differences were highly significant (P less than .01). Percent hatch weights of male and female chicks, 68.0 and 67.7%, respectively, were also significantly different (P less than .05). Regression analysis of egg weight on chick weight estimated the overall equation: chick weight = -6.13 g + .78 X egg weight. A significant positive linear relationship between chick weight: egg weight ratio and egg weight was detected; males increased more than females and dwarf dam chicks more than standard dam chicks. This suggests that chicks from large eggs utilize egg nutrients more efficiently than those from small eggs. Because the larger eggs come from larger hens, it is speculated that there may be a genetic basis to this phenomenon. It was concluded that egg weight, sex, and dam type each significantly contributed to the variability in chick weight and chick weight: egg weight ratio.
D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology; D004531:Eggs; D005260:Female; D005796:Genes; D005838:Genotype; D008297:Male; D012044:Regression Analysis; D012737:Sex Factors