Abstract
Simple SummaryZilpaterol hydrochloride (ZH) is a β-adrenergic agonist (βAA) to be feed to feedlot cattle at a rate of 8.3 mg/kg during the final 20 to 40 d of the finishing period followed by a minimum 3 d withdrawal period. This compound has the potential to increase animal performance, improve carcass weight and meat yield. Although significant information regarding the effects of duration of ZH supplementation and days on the feed of Bos taurus cattle has been provided, there is a lack of information relative to its effects on Bos indicus breeds such as Nellore cattle. The current study aimed to evaluate the effects of the duration of ZH supplementation and DOF on performance, carcass characteristics, and saleable meat yield of Nellore bulls. The HCW and total saleable meat yield linearly increased with the duration of ZH supplementation as well as when the length of the feedlot period increased. We recommend supplementing ZH for Nellore bulls at least for 20 days, independently of days on feed, to improve hot carcass weight, hindquarter, and saleable meat yields of Nellore bulls.This study evaluated the effects of the duration of ZH supplementation and days on feed (DOF) on performance, carcass characteristics, and saleable meat yield of Nellore young bulls. The fixed effects included the duration (0, 20, 30, or 40 d before slaughter plus a 3 d ZH withdrawal period—8.33 mg of ZH/kg of DM) and DOF (90 and 117 d). Feed efficiency (G:F) linearly increased when the duration of ZH supplementation increased (p < 0.01). Nellore bulls fed ZH had greater HCW (p < 0.01), dressing percentage (p < 0.01) and Longissimus muscle area (LMA) (p < 0.01), but less 12th-rib fat (p = 0.04) than the control group. The hot carcass weight (HCW) (p < 0.01), and dressing percentage increased linearly (p < 0.01) with the increase of duration of ZH supplementation. The HCW, ossification, and 12th-rib fat increased with DOF (p < 0.01). The ZH supplemented group had most of the individual cuts of hindquarters and total saleable meat increased compared with the control. Zilpaterol hydrochloride was effective in improving hot carcass weight, hindquarter, and saleable meat yields of Nellore bulls when fed for at least 20 d before slaughter, independently of days on feed.
Highlights
The length of the feedlot period in Brazil has been increased substantially, on average from 80 to 100 days on feed (DOF) [1,2] and some producers and feedlot technicians have mentioned that the DOF may continue increasing in the future motivated by better prices for finished cattle, aiming for ideal live weights or better premiums offered by meatpackers [3]
There was no interaction between the duration of Zilpaterol hydrochloride (ZH) supplementation and DOF for performance characteristics (Table 2)
There was no effect on the duration of ZH supplementation for the final BW, ADG, and DMI
Summary
The length of the feedlot period in Brazil has been increased substantially, on average from 80 to 100 days on feed (DOF) [1,2] and some producers and feedlot technicians have mentioned that the DOF may continue increasing in the future motivated by better prices for finished cattle, aiming for ideal live weights or better premiums offered by meatpackers [3]. Advancing DOF will promote a reduction in beef cattle performance fed high-grain-based diets due to the increase in energy required per unit of gain as cattle approach a mature BW [4]. The ZH supplementation in feedlots, during the last 20 to 40 DOF, can offset high feed costs and increase profitability in cattle finished in feedlots. The magnitude of enhancement, the efficiency of gain, modification of carcass characteristics, and meat quality of beef cattle are influenced by the duration of treatment with βAA [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
