Growth and organ differences between chicken lines selected for divergent growth rates

Feierstein, Erika
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University of Delaware
Selecting chicken for enhanced meat production has altered the relative growth of organs in modern broiler lines, when compared with heritage lines. In this five week study, we compared the growth and feed efficiency of a heritage line, UIUC, with a modern production line, Ross 708. During this period, the body mass and feed efficiency of the modern strain was higher than that of the heritage line, indicating that the Ross 708 birds are more efficient at converting feed to body mass. The relative growth of the breast, heart, liver and intestine were also compared during these five weeks. The breast muscle of the heritage line constituted 9% of the total body mass at five weeks, while the breast mass of the modern line comprised 18% of the total body mass. In contrast, the relative size of the heart decreased after day fourteen in the modern line, suggesting that selection for increased breast muscle has translated to decreased relative heart muscle mass. The mass of the liver reached its peak earlier in the modern line than the heritage line, possibly improving nutrient utilization. Finally, the jejunum and ileum segments of the intestine were 20% longer in the modern line, indicating a potential increase in nutrient absorption.