Parasitic infection can prove to be detrimental to the condition, reproductive fitness, and survival of the host organism. During infection, an organism experiences trade-offs between functions such as growth, reproduction, and immunological activity as a result of limited resources. When challenged by infection, wild turkeys, adapted for survival, should fight the infection rather than invest in growth. Because domestic turkeys have been artificially selected to grow rapidly, I hypothesized that they would invest in growth rather than immunocompetence. To test this hypothesis, I infected domestic turkeys with coccidia and measured components of growth and immunocompetence. Turkeys were infected with the protozoan parasite Eimeria. Blood samples were collected prior to inoculation and both one and two weeks following inoculation. The weight and tarsus length of each turkey were also measured at the time of blood collection. Levels of plasma immunoglobulins were measured using agarose gel electrophoresis and digital densitometry. Domestic turkeys infected with coccidia experienced a trade-off between growth and immunoglobulin production, although not all individuals invested in growth. Studies such as this provide insight into how natural selection has molded the trade-off between growth and immunocompetence during infection
