Effects of whole wheat dilution v. substitution on coccidiosis in broiler chickens.

To test the hypothesis that inclusion of whole cereals in the diet of broiler chickens reduces the severity of a coccidial infection, the effects were investigated, in birds infected with Eimeria acervulina, of feeding a complete pelleted control food, the control food diluted with whole wheat (400 g/kg), or a diet in which ground wheat in the pellets was substituted with whole wheat (400 g/kg) so as to achieve the same composition as the control diet. In the weeks prior to and after infection, (days 14--20 and days 21--27), no significant differences in performance were observed between birds fed the complete pellet and substituted feeds. Birds fed the diluted feeds had significantly lower gains per unit of feed and numerically lower weight gains than the birds fed the control and substituted feeds during this period. No significant differences in performance were observed between treatments from days 28--34. Diluting feeds with whole wheat (400 g/kg) significantly increased ileal digesta viscosity levels, compared with feeding the control and substituted feeds in birds dissected on day 21, although no significant differences in digesta viscosity levels were observed in birds dissected on day 35. Whole wheat feeding, either by dilution or substitution, significantly increased gizzard sizes in birds dissected on day 21 and day 35. Neither dilution nor substitution of feeds with whole wheat (400 g/kg) significantly affected the level of an Eimeria acervulina infection, as measured by daily and total faecal oocyst yields.