Effects of citric acid residue and lactic acid bacteria on fermentation quality and aerobic stability of alfalfa silage

Abstract

An experiment was conducted to investigate the effects of citric acid residue (CAR) and lactic acid bacteria (LAB) on fermentation quality and aerobic stability of alfalfa silage. Alfalfa was treated as follows: (1) control without additive (CON); (2) LAB (L); (3) 12 g/kg CAR (C); (4) 12 g/kg CAR + LAB (CL) and fermented for 3, 6, 9, 15, 30 and 45 days. The residual silages ensiled for 45 days were evaluated for aerobic stability. The results showed that addition of CAR with or without LAB inoculant decreased pH, acetic acid, ammonia nitrogen , neutral detergent fibre, hemicellulose contents and Enterobacteriaceae counts (p < .05) and increased dry matter and lactic acid contents (p < .05) after 45 days of ensiling. Whereas, the lower lactic acid and higher acetic acid contents were observed in L silages (p < .05) after 45 days of ensiling. During aerobic exposure, L and CL silages remained stable in pH, lactic and acetic acid contents, while the control and C silages showed higher pH, yeast and mould counts and lower lactic and acetic acid contents. Compared with the control, L and CL improved aerobic stability, whereas the poorer aerobic stability was shown in C silages (p < .05). In conclusion, applying a combination of CAR and LAB inoculant improved both fermentation quality and aerobic stability of alfalfa silage. Highlights Citric acid residue (CAR) was compared with a lactic acid bacteria (LAB) inoculant in ensiling alfalfa. The CAR improved fermentation quality compared to control and LAB treated silages. Aerobic stability improved when CAR was used in combination with LAB but not when used alone.