Effect of supplementing zilpaterol hydrochloride during different periods on energetics, growth performance, carcass traits and fatty acid profile in meat of finishing lambs

Abstract

To determine the effect of adding β2 agonist zilpaterol hydrochloride during different periods on growth performance, dietary energetic, carcass traits and fatty acid profile, forty male lambs Pelibuey × Katahdin (37.70 ± 0.83 kg) were blocked by body weight and randomly assigned to pens. Treatments consisted in: 1) control, no zilpaterol supplementation, 2) zilpaterol supplementation for 20 d (ZIL20), 3) zilpaterol supplementation for 30 d (ZIL30), and 4) zilpaterol supplementation for 40 d (ZIL40). Compared with control treatment, zilpaterol supplementation increased final live weight (FLW) (3.5 %; P = 0.0563), average daily gain (ADG, 14.8 %; P = 0.0598) and gain:feed ratio (10.3 %; P = 0.0324). As well as hot carcass weight (6.1 %; P = 0.0064), dress out percentage (2.6 %; P = 0.0139) and Longissimus dorsi muscle area (13.7 %; P = 0.0015). Compared to control group, zilpaterol increased (P = 0.0413) observed vs. expected dietary of NEm (net energy requirements for maintenance) and NEg (net energy requirements for growth) (5.7 and 8.1 %, respectively). Twenty days of zilpaterol treatment improved FLW (4.4 %, P = 0.0566) and tended to improve ADG (17.4 %, P = 0.0718) when compared to control group. Only intramuscular fat showed a positive linear effect (P = 0.0006) in stearic fatty acids proportion and negative linear effect (P = 0.0585) in araquidonic fatty acid proportion. We conclude that zilpaterol hydrochloride improved variables of growth performance, energy retention and carcass traits with noticeable effects from 20 d of zilpaterol supplementation.