Background and Aim: Natural feed additives are important for broiler sustainability during the post-antibiotic era. This study aimed to evaluate the possible effects of the dietary supplementation of Lactobacillus casei-fermented mixture of red rice and aromatic ginger (FERMIX) on growth, blood profiles, intestinal bacterial content, and morphological measurements of broilers.

Materials and Methods: Two hundred broiler chicks were allotted to four groups with five replications, including CONTROL (chicks provided with basal feed), FERMIX025 (basal feed supplemented with 0.25% FERMIX), FERMIX050 (0.50% FERMIX), and FERMIX100 (1.00% FERMIX). FERMIX is an anaerobic fermentation product from a mixture of red rice flour and aromatic ginger using L. casei. Blood, organs, digesta, and carcass were collected on day 35.

Results: Final body weight, weight gain, feed intake, and feed conversion ratio did not differ (p>0.05) across treatments. FERMIX at 0.5% increased (p<0.05) spleen relative weight. Liver weight was lower (p<0.05) in broilers fed with 1% FERMIX. The liver weight linearly reduced (p<0.05) with the increased FERMIX levels. FERMIX at 0.25% elevated (p<0.05) broiler drumsticks' yield than that in other groups. Erythrocytes, hemoglobin, packed cell volume, and plasma total protein levels were quadratically higher (p<0.05) in FERMIX050 treated than in other groups. Increased FERMIX levels resulted in a linear decrease (p=0.08) in ileal lactose-negative Enterobacteriaceae counts. Villi height/crypt depth (CD) ratio was quadratically higher (p<0.05) in the duodenum of broiler supplemented with 0.5% FERMIX. The jejunal CD was quadratically lower (p<0.05) in FERMIX050 than in other groups.

Conclusion: Although it did not influence growth, dietary FERMIX, especially at 0.5%, improved immune competencies, physiological conditions, and health of broilers' intestine.

Keywords: broiler, fermentation, health, phytogenic, prebiotic, probiotic.