Grapevine branch and leaf silage (GBLS), a polyphenol-rich unconventional forage, exhibits antimicrobial and antioxidant properties that can benefit animal health and productivity. A total of 60 healthy six-month-old Kazakh rams (43.29 ± 4.55 kg, p > 0.05 for initial body weight among groups) were randomly assigned to three dietary groups, each consisting of four replicates with five rams per replicate. The control group (CK) was fed a basal diet based on whole-plant corn silage, whereas the experimental groups received diets in which 50% (GBLS50%) or 100% (GBLS100%) of the corn silage was replaced with GBLS. A 10-day adaptation period preceded the 90-day formal feeding trial. Results showed a significant quadratic response for average daily gain (ADG) and average daily feed intake (ADFI) across GBLS substitution rates (p < 0.05), with the 50% level yielding the highest values. Specifically, ADFI at the 50% replacement level was significantly higher than that of the control (p < 0.05), confirming an inverted U-shaped response with 50% as the optimal substitution rate. However, in-depth analysis of serum biochemical parameters revealed that GBLS supplementation significantly reduced serum concentrations of total cholesterol, triglycerides, urea nitrogen, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA), while significantly increasing levels of immunoglobulins (IgA, IgM, IgG), superoxide dismutase (SOD), and catalase (CAT) (p < 0.05). Rumen fermentation analysis showed that the GBLS50% group had significantly lower concentrations of acetate, butyrate, and total volatile fatty acids (VFA) (p < 0.05). In the rumen microbiota study, no significant differences were observed in alpha or beta diversity or at the phylum level between groups (p > 0.05); however, the abundance of Lactobacillus gasseri was significantly reduced in the GBLS50% group (p < 0.05). Metabolomic profiling identified 43 significantly altered metabolites—27 upregulated (e.g., PE (18:1(9Z)/0:0) and 12,14-pentacosadiynoic acid) and 16 downregulated (e.g., deoxyadenosine). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis highlighted purine metabolism as a significantly altered pathway (p < 0.05), providing insight into the potential metabolic mechanisms underlying the physiological effects of GBLS in rams. In conclusion, replacing 50% of whole-plant corn silage with grapevine branch and leaf silage improves growth performance trends and significantly enhances immunity and antioxidant capacity in Kazakh rams.

This study evaluated the effects of replacing whole-plant corn silage with cotton stalk and sugar beet pulp mixed silage at 0, 30, 60, or 90% on growth performance, serum parameters, and rumen characteristics in Suffolk ram lambs, addressing the lack of systematic research on moderate-to-high replacement ratios in sheep diets. Eighty-four 4-month-old ram lambs (32.36 ± 2.92 kg) were assigned to four treatments (3 pens/treatment, 7 lambs/pen) for a 120-day trial after a 15-day adaptation. Based on the growth performance and serum parameter results, the control and 60% replacement groups were selected for further analysis of rumen fermentation and bacterial microbiota via 16S rRNA gene sequencing. Compared with the control, the 60% replacement group showed increased final body weight (+15.7%, p < 0.01), daily weight gain (+38.4%, p < 0.01), and dry matter intake (+8.6%, p < 0.05), and improved feed-to-gain ratio (F:G) (p < 0.01). Serum immunoglobulin A and G increased (p < 0.05), whereas tumor necrosis factor-α and interleukin-1β decreased (p < 0.05) in the 60% and 90% replacement groups. Serum MDA was significantly lower in the 90% CSBPS group than in the control at d 90 (p < 0.05), with no significant differences among groups at d 120. Rumen isobutyric and valeric acid concentrations were greater in the 60% replacement group than in the control (p < 0.05), accompanied by enrichment of fiber-degrading bacteria including the Lachnospiraceae NK3A20 group. Replacing 60% of whole-plant corn silage with cotton stalk and sugar beet pulp silage was associated with improved growth performance, enhanced immune function and antioxidant status, and optimized rumen fermentation in Suffolk ram lambs under the conditions of this study.

The use of agricultural by-products as feed is essential for sustainable animal husbandry. This study assessed the effects of substituting whole-plant corn silage with a mixed silage of cotton stalks and grape pomace on growth, serum biochemistry, and jejunal metabolomics in Suffolk rams. In this experiment, 135 rams (6-mo, 30.55 kg BW) were allocated to 0%, 50%, or 100% replacement (CG, EG50, EG100) and fed for 120 d after a 15-d adaptation. Compared with the CG, average daily gain improved by 27.3% and 17.5%, and feed conversion improved by 30.8% and 15.4% in EG50 and EG100 (p < 0.01). Compared with CG, the levels of BUN, TNF-α and IL-1β in serum of EG50 and EG100 were significantly decreased. The levels of IgG, IgM, IL-4, antioxidant enzymes and total antioxidant capacity were significantly increased (p < 0.05). Subsequently, the slaughter performance and jejunal content metabolome of CG and EG50 were further detected and analyzed. The results indicated that the live weight, eye area and muscle crude protein content of EG50 were extremely significantly higher than those of CG (p < 0.01). In jejunal contents, 31 differential metabolites (EG50 vs. CG) were enriched in ABC transporters, branched-chain amino acid biosynthesis, mineral absorption, purine and biotin metabolism, and glucagon signaling. In conclusion, substituting corn silage with the mixed silage promotes growth, improves antioxidant and immune status, reduces serum urea nitrogen, enhances muscle protein deposition (EG50), modulates intestinal nitrogen, purine, lipid, and carbohydrate metabolism (EG50), and supports sustainable meat sheep production.

In modern intensive mutton sheep farming, the high cost and limited supply of conventional feed resources necessitate the exploration of sustainable alternatives. Cotton stalks and sugar beet pulp, abundant agricultural by-products in China, have potential as ruminant feed after proper fermentation treatment, yet their systematic application in sheep production remains underinvestigated. This study evaluated the effects of replacing whole-plant corn microsilage with mixed fermented feed (cotton stalks and sugar beet pulp, 1:1 dry matter ratio) on Suffolk rams (n = 84, 4 months old). Animals were randomly assigned to four groups: control (CK, 0% replacement), MS30 (30% replacement), MS60 (60% replacement), and MS90 (90% replacement). After a 15-day adaptation, the 120-day feeding trial assessed growth performance, slaughter characteristics, meat quality, muscle metabolomics (LC-MS), and jejunal microbiota (16S rRNA sequencing). The MS60 group significantly outperformed the CK group in final body weight, carcass weight, and net weight gain (p < 0.01), slaughter rate (p < 0.05), and meat tenderness (p < 0.05). Fatty acid composition was optimized, with lower SFAs (p < 0.01) and higher MUFAs (p < 0.01). Metabolomic analysis revealed 206 differentially abundant metabolites, with significant enrichment in linoleic acid metabolism, unsaturated fatty acid biosynthesis, and primary bile acid synthesis pathways. The MS60 group exhibited significantly altered jejunal microbiota structure (p < 0.05), including increased Patescibacteria abundance (p < 0.05) and decreased Bifidobacterium (p < 0.001). Replacing 60% of whole-plant corn microsilage with cotton stalk–beet pulp mixed microsilage effectively improved production performance, meat quality, and fatty acid profiles in Suffolk rams, while modulating muscle metabolism and intestinal microbiota structure. These findings provide a practical strategy for sustainable sheep farming utilizing regional agricultural by-products.