Influence of feeding crimped kernel maize silage on the course of subclinical necrotic enteritis in a broiler disease model

摘要

This experiment was carried out with 375 male broilers(Ross 308) from days 1 to 28 to evaluate the influence of crimped kernel maize silage(CKMS) on the manifestation of subclinical necrotic enteritis,microbiota counts, organic acid production and relative weights of gastrointestinal segments. A necrotic enteritis disease model was applied. Birds were allocated into 3 different dietary treatments: a maizebased feed(MBF, control diet), and 2 diets supplemented with 15%(CKMS15) or 30%(CKMS30) of crimped ensiled kernel maize. The disease model involved a 10-time overdose of an attenuated live vaccine against coccidiosis given orally on day 17, followed by oral inoculation of Clostridium perfringens Type A(S48,10~8 to 10~9 bacteria/bird) twice daily on days 18,19, 20 and 21. Scoring of intestinal lesions was performed on days 22, 23, 25 and 28. Ileal and caecal digesta samples were collected for the quantification of selected bacterial groups and organic acids. The results showed that there was no effect of dietary treatments on small intestinal lesion scores(P> 0.05). Lesions scores peaked on days 23 and 25 and decreased again on day 28(P = 0.001). No effect of age on microbiota counts was observed, but feeding of CKMS30 reduced the number of coliforms in ileal contents(P = 0.01). Dietary treatments did not affect organic acid concentrations in ileum and caeca, but there was an effect of age; butyric acid was higher on days 22, 23 and 25 than on day 28(P = 0.04). Acetic acid and propionic acid concentrations in caeca were the highest on days 22 and 28 but the lowest on days 23 and 25. Relative gizzard and caeca weights were increased, and relative ileum weights were decreased when birds were fed CKMS30(P < 0.05). In conclusion, the inclusion of CKMS in broiler diets had no effects on the course of necrotic enteritis but had potential benefits in terms of inhibition of potentially harmful microorganisms.