Could benzoic acid and amylase replace an antibiotic in chicken feed without reducing growth?

Details

The study evaluated the acidifier benzoic acid (BA), amylase (AL) and their combination as antibiotic substitutes, examining growth performance, antioxidation, nutrient digestion and gut microbiota in yellow-feathered broilers.

A total of 1,440 broilers, aged 21 days, were randomly allocated to six treatments. The control group (CON) received a basal diet. The other five groups received the basal diet supplemented with zinc bacitracin (antibiotic, AT, 40 mg/kg), BA (2,000 mg/kg), low-level AL (AL-L, 300 mg/kg), high-level AL (AL-H, 500 mg/kg), or the combination of BA and AL-H (BA+AL-H). The trial ran from 21 to 63 days of age. At its end, the experimental birds were killed, and blood samples were then collected from two birds per pen. Bird weight, feed intake and survival rate were recorded on a pen basis.

Growth performance was not significantly affected by AT, BA, AL-L, AL-H or BA+AL-H. All supplemented treatments reduced plasma uric acid (UA) compared with CON; AT, BA, AL-H and BA+AL-H also lowered plasma AKP activity. BA reduced plasma LDH activity.

In the jejunal mucosa, BA, AL-L, AL-H and BA+AL-H increased Na+K+-ATP activity. Mucosal T-AOC activity increased with AL-L supplementation, while mucosal CAT activity increased with AT supplementation. In the cecal contents, BA+AL-H reduced the relative abundance of Escherichia coli (E. coli). All supplemented treatments except AL-H increased the relative abundance of Lactobacillus.

The authors concluded that dietary AT, BA, AL-L, AL-H or BA+AL improved antioxidant capacity, nutrient digestion and gut microbiota composition. No significant differences were observed in the tested variables between AT and the other treatments, indicating that BA, AL and their combination may be alternatives to dietary zinc bacitracin. The authors identified dietary supplementation with 500 mg/kg AL and 2,000 mg/kg BA as an optimum dose.