Effects of whole wheat feeding on the development of coccidial infection in broiler chickens until market-age

Abstract

An experiment was performed to assess the effect of feeding whole grain to poultry infected with coccidiosis. At the age of 7 d, whole wheat and a pelleted protein concentrate (WP) were given to broiler chickens and compared to chickens fed a complete ground and pelleted diet (C). At 22 d of age, each dietary treatment was divided into four groups, one uninfected control and the others inoculated each with one species of coccidia infecting different parts of the gut: Eimeria acervulina (duodenum), Eimeria maxima (jejunum and ileum) and Eimeria tenella (caeca). The effects of diets were assessed on growth performance until market-age, coccidial development criteria, and the faecal microflora. In uninfected birds, the WP diet led to a higher feed conversion efficiency from 7 to 28 d of age and to a more beneficial microflora (higher counts of lactobacilli and lower counts of coliform bacteria) at 22 d compared to the C diet. However, after experimental infection with each Eimeria species, bird performance was more affected with the WP diet than the C diet. During the acute phase of the disease, whole wheat led to a lower weight gain than the C diet: 17 ± 7 g/d versus 47 ± 7 g/d with E. acervulina (3–5 d post-inoculation, d PI), 16 ± 11 g/d versus 73 ± 7 g/d with E. maxima (4–7 d PI), 13 ± 12 g/d versus 71 ± 5 g/d with E. tenella (4–6 d PI). During the recovery phase, similar weight gains were found for both diets, whatever the Eimeria species. The decrease in serum coloration with E. maxima was higher in WP than C-fed birds. E. tenella led to a decrease in haematocrit only in WP-fed birds. The serum IgG antibody response to E. acervulina and E. tenella was higher in birds fed the WP than the C diet. The total oocyst excretion was similar between the two diets with E. acervulina, slightly higher with E. maxima (×1.5), and 10 times higher with E. tenella in WP- than C-fed birds. After coccidial infection, no effect on the microflora was observed in C-fed chickens, while in WP-fed chickens Escherichia coli counts were increased compared to their uninfected counterparts. Although whole wheat feeding appeared beneficial for uninfected chickens, after an experimental inoculation with coccidia this mode of feeding led to detrimental effects compared to the same diet with ground wheat.