Humic substances as an alternative to performance-enhancing antimicrobials

The use of humic substances (HS) in agriculture is promising, as this fraction of organic matter can benefit the growth and development of plants and animals, promoting sustainability. This study aimed to evaluate the impact of different diets in broiler chickens with HS on zootechnical indicators such as feed consumption, weight gain, feed conversion, feed efficiency, small intestine weight and size, carcass yield, average bird weight, mortality and breeding viability during the period from 11 to 42 days of age, with eight experimental diets. The experiment followed a randomized block design with four replications for each treatment, totaling 32 experimental units consisting of 10 birds each, totaling 320 birds. The experimental diets were: Diet 1: basal diet; Diet 2: basal diet + 40 mg of HS; Diet 3: basal diet + 80 mg of HS; Diet 4: basal diet + 160 mg of HS; Diet 5: basal diet + 320 mg of HS; Diet 6: basal diet + 640 mg of HS; Diet 7: basal diet + 1280 mg of HS; Diet 8: basal diet + 366 g.ton-1 of performance-enhancing antibiotic - zinc bacitracin at 15%. HS can be used as a feed additive for broilers, especially in the starter phase (11-21 days of age), with the most effective concentration for productive performance being 40 mg kg-1, and can adequately replace traditional antimicrobials.