Sustainable Use of Agro-Industrial By-Products as Feed in Finishing Pigs

In modern animal production systems, the use of alternative feed sources is essential for reducing production costs, protecting natural resources, and improving meat quality. This study evaluated the impact of a unique silage—one produced by agro-industrial by-products—on the growth, meat quality, and health parameters of finishing pigs. Eighteen pigs (120 days old, 59.47 ± 0.85 kg) were randomly assigned to three dietary treatments containing 0% (A), 5% (B), or 10% (C) silage. After 60 days, blood samples were collected for hematological and biochemical analyses; this was followed by slaughter for the collection of muscle tissues (triceps brachii, external abdominal oblique) and intestinal digesta (ileum, cecum). Final body weight did not differ among groups (124.54 ± 1.51 kg), and meat composition (fat, protein, collagen, and ash) and pH were unaffected (p > 0.05). ALT levels were significantly lower in group C than in A (p = 0.030). In the ileum, Enterobacteriaceae and Enterococci populations decreased, whereas Lactobacilli increased in B and C (p ≤ 0.05). Cecal Enterococci were reduced in both B and C (p ≤ 0.01), with a tendency for increased Lactobacilli in B. Group C showed higher total phenolic content (p ≤ 0.05) and an improved ω-6/ω-3 ratio (15.09 vs. 17.54 in A). The TBARS values did not differ among treatments. Campylobacter jejuni counts were lower in treatment C, and no Salmonella or Listeria monocytogenes were detected in any samples. The meat color of the triceps brachii was redder in treatments B and C (p = 0.001). Overall, the innovative silage increased phenolic content, supported improvements in gut microbiota, and maintained meat quality, indicating its potential as a sustainable feed ingredient.