Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/1996
Publication Date: N/A
Interpretive Summary: Turkeys that are genetically selected for faster growth rate or increased egg production were compared to the parent lines from which they were derived to see if the ability of the immune system to respond to stimulation was effected by the selection. Two commercial turkey lines, also selected for fast and profitable growth, were also tested. Turkeys selected for fast growth rate had decreases in some of the responses measured and increases in others, suggesting that selection for rapid growth does affect the turkey's immune system. This information may be important in the study of turkey diseases which may be related to a relative inability to respond to infection.
Technical Abstract: Selection of poultry for fast growth rate is often accompanied by a reduction in specific immune responses or increased disease susceptibility. In this study 17-wk-old male turkeys from each of four closed genetic lines, a randombred control (RBC) line and its subline (F) selected for increased 16-wk BW and another RBC line and its subline (E) selected for increased egg production, were tested for in vivo response to toe-web inoculation with phytohemagglutinin-P (PHA-P), in vitro response of lymphocytes in whole blood to PHA-P and conconavalin-A (Con-A), hemolytic complement activity, differential white blood cell counts, hematology, and serum chemistry valves. Fifteen male turkeys from each of two commercial lines, Com A and Com B, were also tested. The large-bodied F-line birds had a lower toe-web response to Pha-P, lower lymphocyte counts, and lower relative spleen weights than their smaller parent line. Body weights, total lerythrocyte counts, blood urea nitrogen (BUN) levels, and in vitro mitogenic response to PHA-P and Con-A were higher in the F-line birds. Line E had lower hemolytic complement levels, lower relative spleen and relative bursal weights, and a higher in vitro mitogenic response to PHA-P than its parent line. The Com B line had a lower toe-web response to PHA-P, and lower serum levels of gamma-glutamyltransferase and bilirubin than Com A. Com B had higher total RBC counts and higher levels of alanine aminotransferase (ALT) than Com A. These results support the concept that some changes in the cell-mediated immune response, as well as other physiological changes that may potentially affect immune response, appear to accompany selection for faster growth.