Effect of additives on fermentation characteristics, nutrient values and in vitro fermentation profile of Neolamarckia cadamba leaf silage

Abstract

This study was designed to investigate the effects of additives on the ensiling characteristics of Neolamarckia cadamba leaf (NCL) silage. The NCL were allocated to six ensiling treatments, namely control (C-S), uncompacted (UC-S) (negative control), with the addition of sodium sulphite (S-S), with propionate (P-S), with citric acid plus sodium acetate (CA-S), and with glucose (G-S). Fermentation parameters, chemical compositions and in vitro fermentation profile of the silages were investigated after 60 days' storage. Compared with the control, the application of additives improved dry matter recovery (DMR), while UC-S had a poorer DMR. All the silages increased in pH value and acetate content, except for P-S. Lactate concentration was higher in S-S and G-S, and lower in UC-S, P-S, and CA-S. P-S, CA-S, and G-S had increased water soluble carbohydrate (WSC) concentrations. Soluble crude protein was higher in UC-S and CA-S. All the treated silage had greater gas production at slower rates, except for S-S. The fermentation of S-S, P-S and CA-S resulted in higher content of short-chain fatty acids and microbial crude protein relative to UC-S. S-S (38.82%) and CA-S (37.89%) had higher organic matter digestibility relative to the control (36.43%). S-S (42.80%) and P-S (43.99%) had higher crude protein digestibility, which was lower in UC-S (30.73%) when compared with the control (37.74%). There was no difference in the predicted available energy of these silages. The low ammonium nitrogen ratio and the high proportion of true protein inferred that protein was well preserved in these silages, even the uncompacted silage. These results suggest that sulphite and organic acids, such as propionate and citrate, could be an option to improve the feed quality of NCL silage, and its great protein conservation deserves more attention.