Enhancing Broiler Production With Humic Acid and Probiotics: Effects on Growth Performance, Carcass Traits, Immune...

Humic acid and probiotics are increasingly used as natural alternatives to antibiotic growth promoters in poultry production. Humic substances have been reported to support nutrient absorption and gut health, while probiotics enhance microbial balance and immune function.

This study aimed to evaluate the individual and combined effects of humic acid and probiotics on growth performance, carcass characteristics, immune parameters, caecal bacterial populations (Escherichia coli, Salmonella spp., and Lactobacillus spp.), and the financial feasibility of broiler production.

A total of 195 one-day-old Lohmann Meat (Indian River) broiler chicks were allocated in a completely randomized design with five dietary treatments and 3 replicates of 13 birds each. Dietary treatments were as follows: a basal diet (control), a basal diet with 0.05% humic acid, a basal diet with 0.10% humic acid, a basal diet with 0.02% probiotics, and a basal diet containing both 0.05% humic acid and 0.02% probiotics.

Dietary inclusion of humic acid or probiotics did not significantly affect (p > 0.05) body weight gain, feed intake, or feed conversion ratio at 28 days (market age), but significant improvements were observed at 7, 14, and 21 days. However, the combined supplementation of 0.05% humic acid and 0.02% probiotics significantly improved several carcass traits (thigh, drumstick, back, wing, and liver weights), reduced caecal pathogenic bacteria (E. coli and Salmonella spp.), increased beneficial Lactobacillus spp., and enhanced immune parameters (higher lymphocyte percentage and lower white blood cell counts) compared to the control (p < 0.05). Hematological values remained within normal physiological ranges across all treatments. Economic analysis revealed that the combined supplementation group recorded the highest net present value (176.44 USD), internal rate of return (43.51%), and benefit-cost ratio (1.22), and the shortest payback period (1.93 years).

Overall, this study demonstrated that dietary supplementation with humic acid and probiotics, particularly in combination, improved carcass traits, reduced pathogenic bacterial loads, enhanced selected immune parameters, and increased economic returns without affecting growth performance at 28 days.