Study on the nutritional value and ruminal degradation characteristics of fermented waste vinegar residue by N. sitophila.

Chemical composition and rumen degradability of waste vinegar residue (WVR) as roughage feed used for mutton sheep were evaluated in this work. Compared with the unfermented WVR, the WVR fermented by N. sitophila had more (P < 0.01) ash, crude protein (CP), and true protein (TP), less (P < 0.01) ether extract (EE), and significantly more carotenoid by about 27 times. But the contents of dry matter (DM), crude fiber (CF), neutral detergent fiber (NDF), and acid detergent fiber (ADF) had no obvious differences (P > 0.05) between unfermented and fermented WVR. The results suggested that the nutritional value of fermented WVR was higher for mutton sheep as roughage feed than that of unfermented WVR. The effective degradability (ED) of DM was higher (P < 0.05) in sheep with fermented WVR-based diet. The ED of CP and NDF of fermented WVR was reduced (P < 0.01) compared with the unfermented WVR. The results further suggested that the fermentation improved the degradability of WVR, and the rumen degradability of protein by ruminal flora decreased in fermented WVR, saving more protein for the sheep post-ruminal digestion and absorption. Furthermore, the results presented here clearly indicated the potential of fermented WVR by N. sitophila as an unconventional and functional feedstuff with rich carotenoid for ruminants, which could reduce WVR discharge in vinegar brewing industry and improve ruminant production. This work laid a foundation for the development of ruminant carotenoid functional feed.