The influence of complex carbohydrates on Salmonella typhimurium colonization, pH, and density of broiler ceca

Salmonella typhimurium colonization, pH, and density of ceca were measured in 3-, 5-, and 6-wk-old broilers fed either a control ration or rations with added fructooligosaccharides (FOS) or lactose derivatives (LD). The purpose was to compare dietary crude FOS from Jerusalem artichokes with refined FOS and two LD for ability to reduce Salmonella colonization as determined by semi-quantitative procedures. Chicks were challenged commencing at 5 d, by exposure to chicks orally infected with S. typhimurium. With the exception of chicks fed crude FOS, the high prevalence of Salmonella infection at 3 wk declined as chicks aged. At 6 wk, broilers fed crude FOS had higher Salmonella counts than all other broiler groups, whereas broilers fed refined FOS had lower infections than control broilers. The decline of Salmonella infection of broilers fed either refined FOS or LD ceased after dietary additives were discontinued at 5 wk of age. At 6 wk, infection rates of the latter groups were at least as high as those of control broilers. Both FOS and LD reduced cecal pH and density. Broilers fed the control ration had higher pH at 5 and 6 wk and higher cecal densities at 3 and 5 wk than those of broilers fed rations containing 5% (wt/wt) carbohydrates. Treatment differences for cecal pH and density disappeared within 1 wk of withdrawal of carbohydrates from 5-wk-old broilers. No consistent effect of cecal pH and density on Salmonella infection was observed. Density was dependent on cecal volume, and at 6 wk of age, on broiler size.