Effects of hen age, Bio-Mos,® and Flavomycin® on poult susceptibility to oral Escherichia coli challenge

The effects of hen age, Escherichia coli, and dietary Bio-Mos(R) and Flavomycin(R) on poult performance from 1 to 21 d were studied. Day-of-hatch BUTA (BIG-6) male poults were gavaged orally (1 mt) with approximately 10(8) cfu/mL E. coli composed of four serotypes or sterile carrier broth. A mixture of the same E. coli cultures was added to the poults' water troughs to attain a concentration of approximately 10(6) cfu/mL on a weekly basis to ensure a continuous bacterial challenge. Within each E. coli split plot treatment group, poults from hens of different ages (33 and 58 wk of age) were fed diets containing Bio-Mos(R) (1 g/kg feed), Flavomycin(R) (2.2 mg active ingredient/kg feed), Bio-Mos(R) plus Flavomycin,(R) or a control diet, in a randomized complete block design. This experiment yielded eight treatments per challenge group. At Weeks 1 and 3, eight birds from each treatment from the E. coli challenged and unchallenged groups were randomly chosen for bacterial sampling of liver and intestinal tissue for coliforms, aerobic bacteria, and Lactobacillus spp. E. coli isolates from tissue samples were O serotyped. During E. coli challenge, dietary Bio-Mos(R) and Flavomycin(R) improved poult BW and BW gains (P less than or equal to 0.05). When poults were not challenged with E. coli, poults from old hens had improved BW and cumulative BW gains over poults from young hens (P less than or equal to 0.05). Cumulative 3-wk BW gains for unchallenged poults from young hens were improved by Bio-Mos(R) and Flavomycin(R) (P less than or equal to 0.05) alone and in combination when compared to the control diet. Two of the four E. coli serotypes administered were recovered. Several serotypes were recovered that were not administered. It may be concluded that dietary BioMos(R) and Flavomycin(R) can improve the overall performance of poults, especially when they are faced with an E. coli challenge.