Since the ban of using antibiotic growth promoters (AGPs) in livestock in several countries, probiotics have been considered as possible alternative. Spore forming bacteria that belong to Bacillus species are one of those probiotics selected for their ability to resist adverse environmental and nutritional conditions such as, low pH in the stomach and high temperature of the feed manufacturing process. Our study aims at comparing the effects of two doses of a Bacillus-based-probiotic product (BP) on broilers growth performance. A total of 840 broiler chickens (1-day old, Ross 308, male) were randomly allocated to one of 3 dietary treatment groups, with 8 replicate pens per treatment and 35 birds per pen. The birds were fed one of three dietary treatments: (T1) control with no BP, (T2) control + log 4.5 CFU/kg BP, (T3) control + log 5 CFU/kg BP, for a period of 42 days divided in 3 phases: (i) starter (0-14), (ii) grower (15- 28) and (iii) finisher (29-42). During the starter phase, both birds from T2 or T3 gained significantly more weight (14.5% and +6%, respectively) and consumed more feed (+10% and +4%, respectively) than birds from T1 (P < 0.0001). During the grower phase, birds from T3 gained more weight (1003,5 g) than T1 (814.2 g) and consumed significantly also more feed (1459.9 g) than control group (1261.3 g). During the finisher phase, no significant difference in weight gain or in feed intake was recorded between treatments. Overall (d 0-42), birds fed with BP resulted with higher body weight gain (P < 0.0087) and consumed more feed compared to control group T1 (P < 0.0121) without any difference between T2 and T3. No effect was observed on FCR during the overall period. To conclude, supplementation of diets with either log 4.5 or log 5 CFU/kg of feed of a Bacillus-based probiotic increased body weight gain of broilers and feed intake over the 42-day study as compared to its control.
Key Words: Probiotic, Bacillus, Broiler, Feed Intake, Growth