Nutraceutical and preservative potential of Acacia mearnsii and Acacia dealbata leaves for ruminant production and product quality enhancement

Seasonality and species are key aspects of the abiotic and biotic environment, respectively, that influence nutrient, phytochemical and antioxidant profiles of invasive alien plants leaf-meals. The current study investigated the effects of season on nutrient, amino acid, fatty acid, mineral, bioactive polyphenolic composition and antioxidant activity of Acacia mearnsii and A. dealbata leaf-meals. Overall, A. mearnsii leaf-meal harvested in the hot-dry-season had greater crude protein, ether extract, neutral detergent soluble fibre, 24 and 48 h in vitro neutral detergent fibre digestibility, macro-mineral contents, individual polyphenols, C18:1 n 9 and C18:2 n 6 compared to other leaf-meals. Regardless of the season, A. mearnsii leaf-meals had greater amino acid concentrations than A. dealbata leaf-meals. Hot-dry-season leaf-meals had a greater concentration of total flavonoids than the leaf-meals in the cool-wet-season irrespective of species. Antioxidant potency composite of the Acacia leaf-meals was in the order of A. dealbata × hot-dry-season > A. mearnsii × hot-dry-season > A. mearnsii × cool-wet-season > A. dealbata × cool-wet-season. The findings suggested that A. mearnsii leaf-meal harvested in the hot-dry-season has superior nutritional and polyphenolic profiles, which could support its use as a nutraceutical and preservative for the enhancement of ruminant production and product quality compared to other leaf meals.