Effects of Ferulic Acid Esterase-Producing Lactic Acid Bacteria and Storage Temperature on the Fermentation Quality, In Vitro Digestibility and Phenolic Acid Extraction Yields of Sorghum (Sorghum bicolor L.) Silage

Two lactic acid bacteria (LAB) strains with different ferulic acid esterase (FAE) activities were isolated: Lactobacillus farciminis (LF18) and Lactobacillus plantarum (LP23). The effects of these strains on the fermentation quality, in vitro digestibility and phenolic acid extraction yields of sorghum (Sorghum bicolor L.) silage were studied at 20, 30 and 40 degrees C. Sorghum was ensiled with no additive (control), LF18 or LP23 for 45 days. At 40 degrees C, the lactic acid content decreased, whereas the ammonia nitrogen (NH3-N) content significantly increased (p < 0.05). At all three temperatures, the inoculants significantly improved the lactic acid contents and reduced the NH3-N contents (p < 0.05). Neither LP23 nor LF18 significantly improved the digestibility of sorghum silages (p > 0.05). The LP23 group exhibited higher phenolic acid extraction yields at 30 degrees C (p < 0.05), and the corresponding yields of the LF18 and control groups were improved at 40 degrees C (p < 0.05). FAE-producing LABs might partially ameliorate the negative effects of high temperature and improve the fermentation quality of sorghum silage. The screened FAE-producing LABs could be candidate strains for preserving sorghum silage at high temperature, and some further insights into the relationship between FAE-producing LABs and ensiling temperatures were obtained.

Automated summary

Two lactic acid bacteria strains, LF18 and LP23, with different ferulic acid esterase activities were isolated and studied for their effects on sorghum silage fermentation quality, digestibility, and phenolic acid extraction yields at 20, 30, and 40 degrees C. The inoculants significantly improved lactic acid contents and reduced NH3-N contents at all three temperatures. While neither LP23 nor LF18 significantly improved digestibility, LP23 showed higher phenolic acid extraction yields at 30 degrees C, and LF18 and control groups had improved yields at 40 degrees C. The FAE-producing LABs could potentially ameliorate negative effects of high temperature and improve fermentation quality of sorghum silage.