Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA.
J Anim Physiol Anim Nutr (Berl). 2011 Aug;95(4):409-16. doi: 10.1111/j.1439-0396.2010.01064.x. Epub 2010 Oct 29.
We studied effects of zilpaterol-HCl on steers consuming corn-based diets with nitrogen (N) supplementation provided by dried distillers grains with solubles (DDGS) or urea. Two sets of six steers (approximately 350 kg) were used in two replicates of similarly designed trials. Within each replicate, three steers were fed 60 mg/day of zilpaterol-HCl throughout the trial and three steers received no zilpaterol-HCl. Within zilpaterol treatment, three corn-based dietary N treatments were offered in Latin square designs: control (9.6% crude protein), urea (UREA; 12.4% crude protein) or DDGS (13.7% crude protein). Total feed intake was unexpectedly greater (p < 0.01) with zilpaterol feeding but was not affected by dietary N (p = 0.76). Nitrogen intake was greater (p < 0.01) when zilpaterol was fed and was greater (p < 0.05) for DDGS and UREA than for control. Despite greater N intake, zilpaterol did not affect urea entry rate (p = 0.80) or urea-N recycled to the gastrointestinal tract (GER; p = 0.94). As a percentage of N intake, urea entry rate (p = 0.19) tended to be less when zilpaterol was fed (91 vs. 123% of N intake), and GER was numerically (p = 0.34) less (72 vs. 92% of N intake). Microbial N flow was greater (p = 0.02) for zilpaterol than for control but did not differ (p = 0.78) among dietary N treatments. As a percentage of N intake, microbial N flow was unaffected by zilpaterol (p = 0.97), but was greater (p < 0.05) for control than DDGS or UREA. The lack of change in urea entry and GER in response to zilpaterol, despite greater N intake, as well as lower urea entry and GER when expressed as proportions of N intake provide some evidence that the amount of N available for urea production and recycling was reduced by zilpaterol.
我们研究了盐酸齐帕特罗对以玉米为基础的日粮的肉牛的影响，这些日粮通过添加干酒糟及其可溶物（DDGS）或尿素来提供氮（N）补充。在两个类似设计的试验中，使用了两组六头肉牛（约 350 公斤），每头肉牛每天接受 60 毫克盐酸齐帕特罗治疗，共接受 60 毫克盐酸齐帕特罗治疗。在每个重复试验中，三头肉牛接受了齐帕特罗-HCl 治疗，三头肉牛未接受齐帕特罗-HCl 治疗。在齐帕特罗处理中，采用拉丁方设计提供了三种以玉米为基础的日粮氮处理：对照（9.6%粗蛋白）、尿素（UREA；12.4%粗蛋白）或 DDGS（13.7%粗蛋白）。尽管齐帕特罗的摄入量较高（p < 0.01），但总采食量不受日粮 N 的影响（p = 0.76）。氮摄入量随着齐帕特罗的摄入而增加（p < 0.01），且 DDGS 和 UREA 的氮摄入量高于对照。尽管氮摄入量增加，但齐帕特罗并未影响尿素进入率（p = 0.80）或尿素-N 向胃肠道（GER）的再循环（p = 0.94）。作为氮摄入量的百分比，当齐帕特罗喂养时，尿素进入率（p = 0.19）有下降趋势（91%对氮摄入量的 123%），GER 也呈下降趋势（p = 0.34）（72%对氮摄入量的 92%）。与对照相比，齐帕特罗增加了微生物氮流量（p = 0.02），但日粮氮处理之间没有差异（p = 0.78）。作为氮摄入量的百分比，微生物氮流量不受齐帕特罗的影响（p = 0.97），但对照的微生物氮流量高于 DDGS 或 UREA。尽管氮摄入量增加，但齐帕特罗对尿素进入和 GER 没有产生影响，以及当用氮摄入量的比例表示时，尿素进入和 GER 较低，这表明齐帕特罗减少了用于尿素生产和再循环的氮的数量。
