The objective of this study was to evaluate the effects of dietary supplementation of a polyherbal additive (PA) containing hydrolyzable tannins, flavonoids, and essential oils on productive performance, dietary energetics, carcass and meat characteristics, and blood metabolites of lambs in their finishing phase. Twenty-eight Pelibuey × Katahdin lambs (20.52 ± 0.88 kg body weight (BW)) were housed in individual pens and assigned to four treatments (n = 7) with different doses of PA: 0 (CON), 1 (PA1), 2 (PA2), and 3 (PA3) g of PA kg−1 of DM for 56 days. Compared to the CON, lambs in PA1 treatment had higher average daily gain (p = 0.03), higher dietary energy utilization (p = 0.01), greater backfat thickness (p = 0.02), greater Longissimus dorsi muscle area (p = 0.01), and better feed conversion ratio (p = 0.02). PA supplementation did not affect (p > 0.05) dry matter intake, carcass yield, biometric measures, and meat chemical composition. All hematological and most of the blood biochemical parameters were similar in lambs of all treatments (p > 0.05). However, compared to the CON, lambs assigned to the PA3 treatment had lower serum urea concentration (p = 0.05) and higher serum albumin concentration (p = 0.03). In conclusion, low doses of PA could be used as a growth promoter in finishing lambs without affecting dry matter intake, carcass yield, meat chemical composition, and health status of the lambs. However, more in vivo research is needed to better understand the impact of bioactive compounds from PA used on productivity, metabolism, and health status of finishing lambs.
Keywords: bioactive compounds; growth promoters; hematological profile; meat composition.