Enhancement of resistance to coccidiosis and necrotic enteritis in broiler chickens by dietary muscadine pomace.

Muscadine pomace (MP), a by-product of the production of wine and juice from Vitis rotundifolia, was dried and tested in chickens for effects on primary resistance to coccidiosis, development of protective immunity after vaccination with live coccidia, and resistance to necrotic enteritis (NE) caused by the joint action of Clostridium perfringens and coccidia. To test primary resistance to coccidiosis, 2-wk-old chicks were given 2% or 5% MP in the diet and inoculated with Eimeria acervulina and E. maxima. Birds given MP at either level had significantly (P < 0.05) lower lesion scores at 7 days postinoculation, in comparison with control birds, although weight gains were statistically similar. Broiler chickens were given 2% or 5% MP and grown to 42 days to test the palatability of MP. Birds given 2% MP in feed grew similarly to untreated controls, but birds given 5% had poorer average live weight. This suggested a negative effect on feed intake at the higher level. The effects of dietary 0.5% or 2.0% MP on immune protection were tested after live coccidiosis vaccination in the hatchery. Chicks were removed from each pen at 21 days of age and challenged with E acervulina, E. maxima, and E. tenella. Resistance to infection was improved by MP as suggested by significantly (P < 0.05) lower lesion scores 7 days postchallenge, and improved weight gains in comparison with immunized control birds that did not receive MP. At 42 days of age, birds given MP had higher average live weights than controls, although feed efficiency was not affected. An established model was used to study the effect of MP on NE in broiler chickens. Chicks were inoculated with live coccidia at 14 days of age and dosed orally with live cultures of C perfringens on day 19, day 20, and day 21. Enteritis caused 48% mortality in the first study and 67% mortality in the second study. Dietary MP at 0.5-2.0% significantly (P < 0.05) reduced mortality in both experiments; improved weight gain relative to the unmedicated, infected control; and reduced lesion scores at necropsy. Overall, the results of six experiments suggested that MP given in the diet at 0.5% or higher had a positive effect on primary resistance and development of acquired resistance to two severe intestinal diseases in chickens.