A Mechanism of Interaction between Dietary Protein Levels and Coccidiosis in Chicks

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Abstract
Chicks were used to study a mechanism of interaction between dietary protein levels and coccidiosis. The results of the study indicate mortality from coccidiosis is less among groups of chicks fed a protein-free diet for 48 hours, or a 5% protein diet for 14 days before inoculation with coccidia, than among chicks fed a 20% protein diet. Starvation had the same effect as the protein-free diet. Observation of gross cecal lesions also indicates less infection in chicks fed a protein-free diet than in chicks fed a 20% protein diet. Low protein diets also reduced intestinal trypsin activity. A positive correlation was shown between dietary protein level and intestinal trypsin activity and between intestinal trypsin activity and degree of infection of chicks with coccidiosis. Addition of trypsin to the inoculum of the chicks fed a protein-free diet resulted in an infection as severe as when the chicks were fed a 20% protein diet. Since trypsin has been found to be essential for the establishment of coccidiosis infection, it is proposed that the effect of low protein diets in decreasing the severity of coccidiosis is due to the effect of these diets on intestinal trypsin activity.