Effects of different supplemental calcium propionate levels on corn stover silage fermentation quality and bacterial community diversity, and their impacts on growth performance, metabolism, and blood biochemical indices of Hu lambs

Introduction Limited attention has been paid to the use of calcium propionate (CaP) as a silage additive for corn stover preservation, especially in integrated trials that include both fermentation quality and feeding performance evaluation. This study investigated the effects of calcium propionate (CaP) supplementation on corn stover silage quality and its subsequent impact on Hu lambs’ growth performance. Methods The ensiling experiment used a single-factor completely randomized design with five treatments: control (CK, no additive) and 0.1% (CaPA), 0.2% (CaPB), 0.3% (CaPC), and 0.4% (CaPD) CaP (fresh matter basis), ensiled for 30 days. According to the ensiling results, 0.2% CaP was selected for the feeding trial. Thirty growing Hu lambs were randomly assigned to three diets: corn stover (CS), untreated corn stover silage (CSS), and 0.2% CaP-treated silage (CaP-S). Results Compared with CK, CaP supplementation significantly improved fermentation quality by lowering pH ( P 0.05), increasing lactic acid, total acids, acetic acid, and propionic acid concentrations ( P 0.05), and reducing butyric acid ( P 0.05). The 0.2% CaP treatment (CaPB) increased crude protein content by 12.85% relative to CK ( P 0.05). Microbial analysis showed that CaP decreased bacterial alpha diversity ( P 0.05) and enriched beneficial taxa such as Firmicutes, Lactobacillaceae, and Weissella. In the feeding trial, the CaP-S group showed 34.69% higher average daily gain ( P 0.05) and 25.76% lower feed-to-gain ratio ( P 0.05) than the CS group. Apparent crude protein digestibility was also significantly higher in the CaP-S group than in the CS and CSS groups ( P 0.05). Discussion In conclusion, adding 0.2% CaP to corn stover silage optimizes fermentation, reshapes the microbial community, and enhances growth performance and nutrient utilization in Hu lambs. These findings provide lamb farmers, especially those in regions with limited high-quality forage, a practical and low-cost strategy to upgrade abundant crop residues into improved feed, supporting more sustainable and economically viable lamb production.