Mixed Solid-State Fermentation of Okara and Copra Meal by Probiotics with Non-Starch Polysaccharide Enzymes and Its Effects on the Growth Performance and Ileal Microbiota in Broilers

With the global shortage of feed ingredients, the use of agricultural by-products has become an alternative to animal feed. Okara, a by-product of soymilk and tofu processing, is high in nutrients but contains non-starch polysaccharides (NSP) and has a high-water content, which are disadvantages in animal feed. Herein, we mixed okara and copra meal (CM) with probiotics (<i>Lactobacillus</i> species and <i>Clostridium butyricum</i>) and NSP enzymes (NSPases) for solid-state fermentation (SSF) to enhance okara feed value; the optimal parameters of fermented okara and CM (FOCM) and their effects on broiler growth performance and ileal microbiota were investigated. The result showed that FOCM in combination with NSPases and probiotics at 55% of the initial moisture content and 60 h fermentation time at 37 °C were able to degrade NSP and reduce sugar content. After fermentation, the total viable counts, lactic acid, and butyric acid contents in the FOCM were 8.6 log CFU/g, 3.7%, and 17.15%, respectively. During the fifth week of the feeding period and over the whole feeding period, broilers fed with 1.25% and 2.5% FOCM had a better feed conversion ratio (<i>p</i> < 0.05); both groups increased the duodenal villus length (<i>p</i> < 0.05). Further microbiome analysis suggested that FOCM significantly increased the abundance of the phylum Firmicutes and reduced the abundance of <i>Escherichia-Shigella</i> in the ileal content (<i>p</i> < 0.05). Collectively, supplementation of probiotics and enzymes during SSF was found to be effective in enhancing the nutritional value of FOCM. Moreover, dietary supplementation of FOCM improved the broiler feed conversion ratio, gut morphology, and ileal microbiota.