Comparative Assessment of Autochthonous Probiotic Lactic Acid Bacteria on Growth Performance, Blood Biochemistry, and Intestinal Microbiota of Broiler Chickens in Côte d'Ivoire

Antimicrobial resistance is accelerating the search for sustainable alternatives to growth-promoting antibiotics (GPAs) in tropical poultry farming. The objective of this study was to evaluate three indigenous strains of lactic acid bacteria (LABs): Enterococcus faecium JK96, Pediococcus acidilactici JK148, and Lactobacillus pentosus JK151, isolated from the gastrointestinal tract of free-range, native Ivory Coast chickens, as probiotic candidates for commercial broiler production. To this end, in a 42-day completely randomized trial, 480 one-day-old Cobb 500 broiler chicks were divided into six treatment groups: three individual probiotic strains, a combination of several strains (1:1:1), an antibiotic growth promoter (Tylo-dox), and an untreated control group. Each group consisted of two pens of 40 chickens each. Freeze-dried probiotic powders (viable cell count: ~1.0 × 10¹⁰ CFU/g) were administered daily in drinking water at a rate of 0.5 g per 10 L. Growth performance, blood biochemical parameters, and intestinal microbiota were assessed in 42-day-old chickens. The results of this study showed that probiotic supplementation significantly improved average daily gain (ADG) and feed conversion ratio (FCR) compared to the control and antibiotic-treated groups. The Lactobacillus pentosus JK151 strain achieved the highest ADG on day 28 (108.27 g/day vs. 83.83 g/day in the control group), maintained an FCR below 2.0 throughout the finishing period, and exhibited no cumulative mortality, compared to 5.0% in the antibiotic-treated group. No significant differences were observed in serum biochemical parameters (glucose, total protein, albumin, triglycerides, cholesterol, uric acid, alkaline phosphatase) or carcass characteristics between treatments (p > 0.05), thus confirming the physiological safety of all tested strains. All probiotic groups significantly reduced the intestinal bacterial load of Escherichia coli (1.38-9.54 × 10⁷ CFU/g) compared to the untreated control group (9.81 × 10⁹ CFU/g) and the antibiotic-treated group (1.10 × 10⁹ CFU/g), without significantly altering the total mesophilic aerobic flora or lactic acid bacteria populations. Notably, the antibiotic-treated group exhibited a higher bacterial load of E. coli than the control group, These results demonstrate that indigenous strains of lactic acid bacteria, in particular L. pentosus JK151, are effective, safe and locally adapted alternatives to growth-promoting antibiotics (GPAs) for sustainable broiler chicken production in Côte d'Ivoire.