ABSTRACT Background Restrictions on antibiotic growth promoters in poultry production have driven the search for safe, natural alternatives. Organic acids, herbal additives and spirulina are promising options due to their antimicrobial, antioxidant and growth‐enhancing effects. Objectives The purpose of this experiment was to evaluate the effects of formic acid (FAc), herbal mixture (HMX) and spirulina powder (SPI) as potential antibiotic alternatives in broiler diets, specifically examining their impact on growth, carcass characteristics, blood biochemistry and intestinal microbial count. Methods Six replicates of ten unsexed chicks per group comprised the eight experimental groups to which 480 one‐day‐old Ross 308 broiler chicks were randomly assigned. The treatments were as follows: T1 (control); T2 (0.5 g Colistin antibiotic/kg diet); T3 (2 cm 3 FAc/kg diet); T4 (4 cm 3 FAc/kg diet); T5 (2 g HMX/kg diet); T6 (3 g HMX/kg diet); T7 (0.5 g SPI/kg diet); and T8 (1 g SPI/kg diet). Results Significant differences were detected in daily body weight gain (DBWG) and live body weight (LBW), with the spirulina‐treated groups (T7 and T8) showing the highest values. Also, significant influences on feed intake (FI), feed conversion ratio (FCR) and performance index (PI), with the HMX groups showing the most favourable FCR and the highest PI. Blood biochemistry and antioxidant markers were influenced by the HMX and SPI treatments. The SPI groups showed reduced liver enzyme levels, while the HMX groups demonstrated improved protein profiles and enhanced antioxidant enzyme activity. Microbial analysis revealed that FAc and HMX treatments led to a reduction in pathogenic bacteria, with T3, T4 and T5 showing the lowest levels of Escherichia coli and Salmonella . Conclusion These results suggest that FAc, HMX and SPI are promising dietary supplements for enhancing both the broiler chickens' growth rates and general health.
Ashour et al. (2026) studied this question.