Dietary protease can alleviate negative effects of a coccidiosis infection on production performance in broiler chickens

Two experiments were conducted to determine the effect of dietary protease on coccidiosis infection, production performance, the intestinal mucus layer thickness, and brush border enzyme activity using broilers challenged with Eimeria spp. laboratory isolates (Eimeria acervulina, E. maxima and E. tenella). In the first study the protease was supplied at a concentration of 2.5 × 104 amylase-DU per kg feed. Broiler chickens were housed in cages and were infected at 10 days of age with 104.0 E. acervulina, 103.8 E. maxima or 103.3 E. tenella sporulated oocysts. Coccidial lesion scores, oocysts shedding, sporulation assessment and daily weight gain were used as parameters to quantify the effect of the protease. In the second study the effects of the protease (supplied at a concentration of 2.5 × 104 amylase-DU per kg feed) on the thickness of the mucus adherent layer and sucrase-isomaltase activity (SIA) of three regions (duodenum, jejunum and caecum) of the intestinal tract were determined. In experiment 1, no significant interaction between dietary enzyme supplementation and single Eimeria spp. challenge was observed on body weight gain. However, protease addition to the diet resulted in a significant (P=0.046) higher weight gain after comparing all supplemented and non-supplemented groups. E. maxima infected chickens showed a significant lower body weight gain in comparison with the other Eimeria infected groups. Coccidial lesions were not significantly affected by the dietary protease supplementation, despite the slight tendency to a higher lesion score for E. acervulina on the enzyme supplemented diets. In experiment 2, it was shown that the adherent mucus layer of the duodenum (P<0.001), jejunum (P<0.001) and caeca (P=0.005) was significantly thicker in birds fed the enzyme-supplemented diet. The sucrase-isomaltase activity (SIA) in mucosal scrapings of the jejunum was significantly lower (P=0.005) in birds fed the enzyme supplemented diet, indicating a higher villus turnover rate. In conclusion, our data suggest that dietary supplementation with a protease reduced the negative impact of a coccidiosis infection on body weight gain of broilers, although the coccidial lesions and oocyst excretion remained unaffected.