In Vitro Study of Curcuma, Honey, and Probiotics Combination as Candidates for Feed Additives to Replace Growth Promoter Antibiotics (AGP)

Growth Promoter Antibiotics are used to prevent disease and promote growth and production in poultry. Repeated administration of feed can have a micro-organic resistance effect, accumulation of antibiotic residues in animal and environmental products and imbalance of normal micro-flora in the intestine. The antibacterial and carbohydrate content of some natural ingredients can be potential as a replacement candidate for AGP. This study aims to determine the role of a combination of curcuma, honey, and probiotics (Bacillus subtilis and Lactobacillus acidophilus) as AGP candiate in vitro. The antibacterial activity of the combination of curcuma and honey against pathogens (E. coli) and their use against probiotics was tested by disk diffusion method, while the calculation of optical density values to determine the minimum inhibitory concentration and minimum bactericidal concentration was carried out on E. coli. The inhibition ability of probiotics against pathogens is also done by the disk diffusion method. The disk diffusion test results showed the best combination of 25% curucuma aquades extract+100% Lombok honey with inhibition zone diameter (8.53 ± 0.03). Optical density values indicate this combination is able to inhibit and kill E. coli (DO 0.00 ± 0.002) and supports the growth of B. subtilis (DO 0.18 ± 0.002) and L. acidophilus (DO 0.25 ± 0.005) significantly better than positive control. MIC value of curcuma aquades extract and honey combination against E. coli is curcuma aquades extract 3.13%+Lombok honey 25%, and MBC value is curcuma aquades extract 6.25%+Lombok honey 25%. The combination of B. subtilis and L. acidophilus probiotics showed the largest inhibitory zone diameter against E. coli pathogen (7.30 ± 0.02 mm) compared to individual colonies. The combination of curcuma and honey, in addition to inhibiting also able to kill pathogens and support the growth of probiotics, so this formula can be used as one of the replacement candidates for AGP.