Evaluation of ensiled soy sauce by-product combined with several additives as an animal feed

AIM: The present experiment aimed to evaluate the use of different additives, i.e., lactic acid bacteria (LAB) inoculant, tannin extract, and propionic acid, on the chemical composition, fermentative characteristics, and in vitro ruminal fermentation of soy sauce by-product (SSB) silage. MATERIALS AND METHODS: SSB was subjected to seven silage additive treatments: Fresh SSB, ensiled SSB, ensiled SSB+LAB, ensiled SSB+2% acacia tannin, ensiled SSB+2% chestnut tannin, ensiled SSB+0.5% propionic acid, and ensiled SSB+1% acacia tannin+1% chestnut tannin+0.5% propionic acid. Ensiling was performed for 30 days in three replicates, and each replicate was made in duplicate. The samples were evaluated for their chemical composition and silage fermentation characteristics and were tested in an in vitro rumen fermentation system. RESULTS: In general, the nutrient compositions did not differ among the tested SSBs in response to the different additives used. The addition of tannins, either acacia or chestnut, and propionic acid significantly decreased the pH of the ensiled SSB (p<0.05). The addition of several additives (except LAB) decreased the ammonia concentration in SSB silage (p<0.05). The total volatile fatty acids in the in vitro rumen fermentation profile of the ensiled SSB were not significantly altered by the various additives applied. The addition of some additives, i.e., ensiled SSB+LAB and ensiled SSB+2% acacia tannin, reduced the digestibility values of the SSB (p<0.05). Different silage additives did not significantly affect methane production, although the addition of acacia tannins tended to result in the lowest methane production among treatments. CONCLUSION: The use of additives, particularly 2% acacia tannins, can reduce proteolysis in SSB silage.