Characterization of the growth response obtained from Eimeria acervulina infection in chicks fed lysine-deficient diets.

Five assays were conducted with crossbred chicks to define the gain and feed efficiency response elicited when chicks fed lysine-deficient diets are infected with Eimeria acervulina. Crystalline amino acid diets that were either severely deficient in lysine (.12 or 20%) or adequate (.91%) were fed in the presence or absence of E. acervulina infection in the first four assays. In Assay 5, intact protein-based diets (corn-corn gluten meal) containing either .43 or 1.44% lysine were used to study the effects of lysine status on morbidity caused by E. acervulina infection. The infection was produced by crop intubating 1 X 10(6) sporulated E. acervulina oocysts either every other day in Assays 1, 2, and 5, or once at assay initiation in Assays 3 and 4. At deficient levels of dietary lysine, chicks by Day 6 after inoculations commenced exhibited marked gain and feed efficiency responses to E. acervulina inoculation. The same inoculation regimen in chicks fed diets adequate in lysine resulted in marked depressions in gain and feed efficiency. Monensin feeding diminished but did not entirely eliminate the inoculation response in lysine-deficient chicks. Throughout the assays, typical duodenal lesions were evident in infected chicks at necropsy, and dietary lysine status appeared to have no effect on the severity of lesions.