Narasin Supplementation Enhances Growth Performance in Grazing Cattle

Three experiments were conducted to evaluate the effects of narasin inclusion on the growth performance of grazing beef cattle under the same availability and quality forage conditions. All three experiments were arranged in a randomized complete block design according to the initial BW of each experiment. Exp 1: Two hundred Nellore calves were allocated in three treatments: 1) CONT: mineral supplement; 2) 1400N: inclusion of 1400 mg of narasin/kg of supplement; and 3) 2100N: inclusion of 2100 mg of narasin/kg of supplement. Narasin inclusion increased (P ≤ 0.01) ADG and final BW, with no effect (P ≥ 0.50) between doses of narasin supplementation. Exp 2: Two hundred and forty Nellore calves were allocated into two treatments: CONT and N1400. The inclusion of narasin increased (P ≤ 0.01) cattle ADG and final BW. Exp 3: One hundred and fifty Nellore yearlings were allocated in two treatments: 1) PROT: protein supplement, and 2) PROT250: inclusion of 250 mg of narasin/kg of supplement. The inclusion of narasin in the protein supplement increased (P ≤ 0.04) cattle ADG and final BW. In conclusion, the inclusion of narasin in mineral and protein supplements increased the growth performance of cattle on tropical pastures without changing supplement intake.