Feeding decreasing levels of a probiotic, Bio Poul®, with age on growth performance, immune response and intestinal morphology of broiler chickens

This experiment was performed to investigate the effects of decreasing levels of a commercial probiotic, Bio Poul®, on performance, immunological response and intestinal morphology of broiler chickens. A total of 256 one-day old broiler chicks was allocated to a completely randomized design with four treatments including 1) control treatment, 2) birds fed diets including 300 (1 to 10-day old), 200 (11 to 24-day old) and 100 (25 to 42-day old), grams probiotic, Bio Poul® per ton of feed, 3) birds fed diets including 150 (1to 10-day old), 100 (11 to 24-day old) and 50 (25to 42-day old), grams probiotic, Bio Poul® per ton of feed, 4) birds fed diets including a fixed level of 300 grams probiotic, Bio Poul per ton of feed. Results showed that, none of the probiotic treatments have effect on feed intake, weight gain and feed conversion ratio. The effect of treatments was significant on the percentage of hematocrit (P<0.05) while this parameter is higher in the birds fed with treatment 2. Antibody production level against sheep red blood cells were not affected by treatments (P<0.05). The duodenum part of intestine significantly was changed in term of goblet cells number on Villi (P<0.05), as well as the number of goblet Villi per 100 micrometers in length by BioPoul® treatment (P<0.01). Villi thickness in the area of the ileum significantly was changed by treatments (P<0.05). The highest of Villi thickness was observed in control group, whereas there were not significant differences between the other treatments receiving probiotics.