Effects of Acacia mearnsii extract as a condensed-tannin source on animal performance, carcass yield and meat quality in goats

•The inclusion of tannins from Acacia mearnsii at levels up to 32 g/kg dry matter in the goat diet is recommended.•The dietary inclusion of Acacia mearnsii extract does not affect the physicochemical parameters of goat meat.•The dietary inclusion of condensed tannins from Acacia mearnsii increases the commercial cut weights of goat meat.•Dietary tannins improved total polyunsaturated fatty acid concentration and sensory acceptance of goat meat.•Tannins from Acacia mearnsii in the diet decreases C17:1 and C18:1 cis-9 and increases the C18:2 cis-9, cis-12. The objective of this study was to determine the optimum level of condensed tannins (CTs), delivered as Acacia mearnsii extract, for inclusion in the diet of goats for enhancing growth, commercial cuts, the physicochemical composition and fatty acid (FA) profile of the meat and meat sensory attributes. Thirty-two castrated crossbreed Boer goats with a mean age of four months and a mean body weight (BW) of 19.7 ± 2.05 kg were distributed in a completely randomized design. The diets varied in level of CTs [0, 16, 32 and 48 g/kg dry matter (DM)] from an Acacia mearnsii extract. Final BW; acid detergent fiber (ADF); shoulder, neck and rib weight; and loin yield increased quadratically (P ≤ 0.05) with the amount of CTs in the diet. Except for a trend of a quadratic reduction in luminosity color (P = 0.07) and a linear reduction in collagen deposition (P = 0.03) with increasing level of dietary CTs, the meat physicochemical parameters were unaffected by CTs inclusion. With increasing amount of CTs from Acacia mearnsii extract in the diet, the concentrations of C17:1 and C18:1 cis-9 in the longissimus lumborum of goats linearly decreased, whereas those of C18:0, C18:2 cis-9, cis-12 and C18:3 cis-9, cis-12, cis-15 (P ≤ 0.05) linearly increased. In addition, the values of total saturated FA (ΣSFA), polyunsaturated FA (ΣPUFA), ratio of ΣPUFA:ΣSFA and ΣPUFA:monounsaturated FA (ΣMUFA) increased (P ≤ 0.05) with increasing CTs level; in contrast, ΣMUFA and the ΣMUFA/ΣSFA ratio decreased. Other FA sums and ratios were not affected by the inclusion of CTs in the diet. The inclusion of dietary CTs tended to unfavorably reduce the FA index and enzymatic activity of Δ9-desaturase C16 (P ≤ 0.10). However, there was a linear decrease (P ≤ 0.05) in Δ9-desaturase C18 and elongase enzymatic activities and the hypocholesterolemic to hypercholesterolemic FA ratio (h:H) index with increasing level of dietary CTs, and the atherogenic