Abstract
This study aims to investigate the effect of varying addition levels of corn steep liquor (CSL) on the fermentation quality, bacterial community, and ruminal degradation rate of corncob silage. The experiment included a control group (CON) and four treatment groups: L1 with 5% CSL (50 g·kg(-1) fresh matter), L2 with 10% CSL (100 g·kg(-1) fresh matter), L3 with 15% CSL (150 g·kg(-1) fresh matter), and L4 with 20% CSL (200 g·kg(-1) fresh matter). The water content was controlled at 65% during fermentation for a period of 45 days. The results showed that the addition of CSL significantly increased the contents of dry matter (DM), crude protein (CP), and lactic acid (LA), while decreasing the pH, neutral detergent fiber (NDF), acid detergent fiber (ADF), and ammonia nitrogen (NH(3)-N). Furthermore, the addition of CSL altered the relative abundance of microbial genera. While Pediococcus was the dominant bacterium in the CON group, Lactobacillus became the prevalent species upon the addition of CSL, and its relative abundance increased in accordance with the supplemental amount. These findings suggest that CSL provides a favorable environment for lactic acid bacteria. It is worth noting that CSL addition did not significantly alter the phylum-level bacterial community structure. The dominant bacterial taxa across all treatments were Bacillota, Proteobacteria, and Bacteroidota, with their cumulative relative abundance accounting for over 95%. The rumen degradation of the tested feedstuff was determined using the in situ nylon bag method. Results revealed that incorporating CSL into corncob silage significantly enhanced the effective degradation rates of DM, CP, NDF, and ADF in the rumen of Kazakh sheep. Specifically, the effective degradation rate of DM in the CON group was only 49.10%, which increased to 53.12% following the addition of 20% CSL, along with corresponding improvements in the degradation rates of CP, NDF, and ADF. In summary, as a valuable feed additive, corn steep liquor supports the proliferation of beneficial microorganisms in fermentation systems by supplying essential growth substrates. Additionally, it improves the nutritional balance of corncob feed and further enhances the absorption and utilization of nutrients from this feed by animals.