Effect of ractopamine hydrochloride on environmental gas emissions, growth performance, and carcass characteristics in feedlot steers

Abstract

With a growing global population and increased environmental concerns around animal agriculture, it is essential to humanely maximize animal performance and reduce environmental emissions. The present study aims to determine the efficacy of feeding ractopamine hydrochloride (RAC), an orally active, β1–adrenergic agonist (β1AA), to feedlot steers in the last 42 d of finishing to reduce ammonia (NH3) emissions and improve animal performance. A randomized complete block design was used to allocate 112 Angus and crossbred Angus steers (Initial BW = 566.0 ± 10.4 kg) to 8 cattle pen enclosures. Pens (n = 4/treatment, 14 steers/pen, 56 steers/treatment) were randomly assigned to 1 of 2 treatments: 1) CON; finishing ration containing no RAC, 2) RAC; finishing ration containing 27.3 g/907 kg dry matter (DM) basis RAC. Steers were weighed on d -1 and 0 before treatment and d 14, 28, and 42 during treatment. Treatment rations were mixed and delivered daily by masked personnel. Measured emissions included NH3, nitrous oxide (N2O), methane (CH4), hydrogen sulfide (H2S), and carbon dioxide (CO2). The primary response variables assessed were emissions standardized by live weight (LW) and hot carcass weight (HCW). Steers were harvested on d 43 and carcass data was collected on d 43 and 44. Steers fed RAC reduced NH3 emissions by 17.21% from d 0 to 28 (P = 0.032) and tended to reduce NH3 from d 0 to 42 by 11.07% (P = 0.070) vs. CON. When standardized for LW, NH3 was reduced by 23.88% from d 0 to 14 (P = 0.018), 17.80% from d 0 to 28 (P = 0.006), and 12.50% for d 0 to 42 (P = 0.027) in steers fed RAC vs. CON. Steers fed RAC had 14.05% (P = 0.013) lower cumulative NH3 emissions when standardized by HCW vs. CON. Feeding RAC to Steers reduced H2S by 29.49% from d 0 to 14 (P = 0.009) and tended to reduce H2S over d 0 to 28 by 11.14% (P = 0.086) vs. CON. When H2S emissions were standardized for LW, RAC fed steers had a 28.81% reduction from d 0 to 14 (P = 0.008) vs. CON. From d 0 to 42 the RAC fed steers tended to have a 0.24 kg/d greater ADG (P = 0.066) and tended to eat 4.27% less (P = 0.069) on a DM basis vs. CON. The RAC fed steers had a 19.95% greater gain to feed ratio compared to CON (P = 0.012). Steers fed RAC had an average of 12.52 kg greater HCW (P = 0.006) and an increase of 1.93 percentage units in dressing percent (P = 0.004) vs. CON. Ractopamine is an effective medicated feed additive for reducing NH3 and improving end product performance through HCW yields.

Fortification of diets with omega-3 long-chain polyunsaturated fatty acids enhances feedlot performance, intramuscular fat content, fat melting point, and carcass characteristics of Tattykeel Australian White MARGRA lambs

“…Lamb consumers demand fresh, tasty, safe, and microbe-free meat with high eating quality and nutrient content, thus necessitating advanced nutrition and breeding strategies that integrate appropriate meat quality characteristics by sheep producers ( 4 ) to improve feedlot performance, dressing percentage, lean yield, and marbling score ( 5 , 6 ). To achieve accelerated lamb growth and early attainment of appropriate slaughter weights that meet market specifications, feedlotting remains a critical lamb finishing strategy for improving profitability ( 7 , 8 ).…”

Transfer of β‐agonists from animal feed into Tricholoma gambosum through manure

“…Steers fed with ractopamine hydrochloride were found to have significantly reduced Yunsheng Han and Tengfei Zhan contributed equally to the article. ammonia emissions (17.8% reduction from day 0 to 28), which may increase their nitrogen utilization rate [5]. Salbutamol has a repartitioning effect and increases both the proportion of lean carcass and the growth performance of animals [6,7].…”

“…Beta‐agonists, a class of synthetic sympathomimetic drugs, can increase animal growth by promoting protein synthesis and accelerating fat decomposition [3, 4]. Steers fed with ractopamine hydrochloride were found to have significantly reduced ammonia emissions (17.8% reduction from day 0 to 28), which may increase their nitrogen utilization rate [5]. Salbutamol has a repartitioning effect and increases both the proportion of lean carcass and the growth performance of animals [6, 7].…”