Effects of brewers’ spent grains on fermentation quality, chemical composition and in vitro digestibility of mixed silage prepared with corn stalk, dried apple pomace and sweet potato vine

Abstract

The experiment was conducted to evaluate the effects of brewers’ spent grains (BSG) on the fermentation quality, chemical composition and in vitro parameters of mixed silage prepared with corn stalk, dried apple pomace and sweet potato vine. In the experiment, a ternary mixture of corn stalk, sweet potato vine and dried apple pomace (50/30/20) was ensiled with 0%, 10%, 15% and 20% BSG on a fresh weight (FW) basis for 1, 3, 5, 7, 14 and 30 days, respectively. The application of BSG significantly (p<.05) increased lactic, acetic and total volatile fatty acids content, and significantly (p<.05) decreased pH, lactic acid/acetic acid, ammonia nitrogen, dry matter and water-soluble carbohydrates content during ensiling. None or tiny amounts of propionic and butyric acid were detected in all silages. Compared with the control, higher (p<.05) Flieg points, crude protein content and lower (p<.05) neutral detergent fibre, acid detergent fibre, cellulose and hemicellulose content were found in BSG-treated silages on day 30 of ensiling. After 72 h of incubation, the application of BSG significantly (p<.05) increased the cumulative gas production, potential gas production, in vitro dry matter, crude protein digestibility and metabolisable energy. The 20% BSG silages had better fermentation quality and higher in vitro digestibility, as indicated by higher lactic acid content, in vitro dry matter, crude protein digestibility, metabolisable energy, lower pH, and lower ammonia nitrogen content than other silages. The application of 20% BSG was recommended to ensure good quality silages. Highlights Ensiling in the form of mixed silages is a good way to consume largely agro-food by-products. Reducing the energy waste and environmental pollution caused by high-quantity agro-food by-products. 20% brewers’ spent grains application had positive effects on in vitro parameters.