Effects of Moisture Content and Silage Starter on the Fermentation Quality and In Vitro Digestibility of Waxy Corn Processing Byproduct Silage

We investigated the effects of the moisture content and silage starter preparation on the fermentation quality, nutritional value, and in vitro digestibility of waxy corn processing byproducts and rice bran (WRB) mixed silage and waxy corn processing byproducts and rice polished powder (WRPP) mixed silage. Two mixed silages with 55%, 60%, and 65% moisture content (MC) were set up without any additives (control) or with former Lactobacillus (L), and opened on the 60th day after storage the fermentation quality, nutritive value, and in vitro digestibility of the silages in each treatment. The optimal formulation of high-quality waxy corn processing byproduct (WCPP) silage was screened to provide a reference and theoretical basis for the further development and utilisation of WCPPs. The results showed that the proportions of ammonia nitrogen to total nitrogen (AN/TN) and acid detergent lignin (ADL) significantly decreased with a decreasing MC, whereas the levels of lactic acid (LA), crude protein (CP), dry matter (DM), and in vitro crude protein digestibility (IVCPD) significantly increased (<i>p</i> < 0.05) for both mixed silages with L. After treatment with 60% MC, the content of neutral detergent fibre (NDF) was significantly lower, and the CP content was significantly greater in the WRB mixed silage treated with L (<i>p</i> < 0.05). With 55% MC, the addition of L not only reduced the pH and AN/TN ratio of the two mixed silages but also significantly improved their in vitro digestibility (<i>p</i> < 0.05). Studies have shown that reducing the MC of silage raw materials and adding L allows for the preparation of high-quality silage.