Human selection and trait evolution in the chicken a concentration on the developmental anatomy of the small intestine
University of Delaware
Since the early 20th century, the poultry industry has influenced the growth of broiler chickens significantly through the implementation of highly selective breeding programs which focused primarily on breast muscle deposition, feed efficiency, and growth rate. In this study, the morphological differences between a modern broiler line (Ross708) and a line maintained from the early 20th century (Heritage) were compared. The purpose of the study was to determine if the selection for breast muscle, feed efficiency, and growth rate resulted in an increase in intestinal mass, length, cross-sectional area and villus length to allow for more surface area in order to increase absorption and therefore increase efficiency. Both lines were grown in identical batteries with ad libitum access to feed and water and continuous lighting. Samples were taken of the duodenum, jejunum and ileum intermittently over a 35-day period. The data showed a significant increase in overall jejunum and ileum masses, lengths, cross-sectional areas, and villus lengths from the Heritage to the Ross708 line. The differences within the duodenums of the two lines were not as drastic as seen in the aforementioned sections. The data from this study suggested that the selective breeding in the poultry industry targeted the growth patterns of the small intestine, specifically the jejunum and ileum, by increasing the overall surface area.