Feeding two single strain probiotic bacteria and wheat bran failed to modify the production traits but altered some gut characteristics in broiler chickens

The effects of a single strain lactic acid producing bacteria (LAB) (Lactobacillus farciminis 5x10(9) CFU/kg) and a single strain butyric acid producing bacteria (BAB) (Clostridium butyricum 2.5x10(9) CFU/kg) with or without wheat bran supplementation (WB), were investigated on the production traits and on several gut characteristics of broiler chickens. In total, 576 male Ross 308 day-old chickens were divided into 24 floor pens and fed a corn-soybean based control diet (C) and five other probiotic or wheat bran supplemented diets (LAB, BAB, LAB+WB, BAB+WB, C+WB) in 4 replicates. The wheat bran content of the starter, grower and finisher diets were 3, 6 and 6%, respectively. During the 37 day long fattening period, growth rate, feed intake were recorded and feed conversion was calculated. At the end of the trial, 8 chickens per treatment were slaughtered and the following parameters investigated: trypsin, lipase and amylase activity of the jejunal chyme, ileal histomorphology and Lactobacillus load. None of the treatments resulted significant differences in the production traits (P>0.1). BAB supplementation tended to decrease digestive enzyme activity. Feeding WB in all combination increased crypt depth (P=0.002), ileal muscle layer thickness (P=0.001) and decreased the villi: crypt ratio (P=0.037) in the ileum.