Effects of dietary mealworm oil and chitosan supplementation on growth performance, ruminal fermentation, antioxidant status, meat quality and fatty acid profile in lambs

Chitosan (CH) is a natural bioactive polysaccharide with antioxidant and hypocholesterolemic properties, while mealworm oil (MO) is a sustainable lipid source rich in unsaturated fatty acids. This study evaluated the effects of dietary MO and CH supplementation on growth performance, ruminal fermentation, muscle fatty acid profile, antioxidant status, blood metabolites and meat quality in growing lambs. Thirty-two lambs were randomly assigned to four treatments (8/treatment) in a 2 × 2 factorial design with two levels of MO (0 and 3% dietary DM) and CH (0 and 0.2% dietary DM). Both MO and CH increased final body weight, average daily gain and gain-to-feed ratio, while reducing the feed conversion ratio (p < 0.05). Dry matter intake was unaffected, but metabolisable energy intake increased with MO (p < 0.001). The CH improved dry matter and organic matter digestibility and increased total volatile fatty acids (p ≤ 0.02), while both additives reduced the acetate-to-propionate ratio (p ≤ 0.007). In the Longissimus dorsi muscle, MO and CH decreased saturated fatty acids (SFA) and increased mono- and polyunsaturated fatty acids (PUFA), improving the PUFA/SFA ratio and lowering atherogenicity and thrombogenicity indices (p < 0.001). Dietary CH improved the serum lipid profile, whereas both additives enhanced antioxidant enzyme activities, reduced serum malondialdehyde and improved selected meat quality traits (p < 0.05). MO × CH interactions were not significant for almost all variables. Overall, dietary MO and CH supplementation improved growth performance, antioxidant status, muscle fatty acid composition and meat quality through independent main effects.