ABSTRACT
A total of 360 one-day-old Cobb 500 chicks were randomly distributed in a completely randomized design according to a 3×2 factorial arrangement, consisting of three levels of dietary crude protein (100, 90 and 85% of NRCrecommended levels) and a feed additive (with or without feed additive). A blend of a commercial probiotic and a prebiotic were used as feed additives. Each treatment had four replicates of 15 birds each. Prebiotic and probiotic were added to the starter (days 1 to 21) and finisher (days 22 to 42) diets according to the manufacturer´s recommendations. The findings indicated that significant differences were not observed between 100 and 90% NRC for broiler performance (body weight, body weight gain, feed intake and feed conversion ratio) throughout the experiment, while the birds fed the diets containing 85% NRC had poorer performance than those fed 100% (p<0.05). Feed additives had no significant effect on broilers performance. There was no significant interaction between protein level and feed additive for performance. Dietary inclusion of feed additives had no significant effect on cecal lactobacillus and Escherichia coli counts at 21 days of age, while, at 42 days of age, feed additive increased lactobacillus and decreased the counts of Escherichia coli (p< 0.05). In conclusion, according to the findings of the current experiment, dietary crude protein could be reduced by 10%, without negative effect on broiler performance. Supplementation with feed additives had no significant effect on broiler performance, but beneficially influenced cecal bacteria counts at 42 days of age.
Keywords:
Broiler; low protein diet; prebiotic; probiotic