Department of Animal and Food Sciences, Oklahoma State University, Stillwater, OK.
Livestock and Forestry Research Station, University of Arkansas, Batesville, AR.
J Anim Sci. 2020 Feb 1;98(2). doi: 10.1093/jas/skaa038.
Increased cotton production in the Southwestern United States has increased the availability of cotton byproducts for use in cattle diets. The objective of this experiment was to evaluate the inclusion of cotton byproducts in feedlot finishing diets on the performance, carcass traits, fecal characteristics, and plasma metabolites of steers. Crossbred beef steers (n = 64; BW = 318 ± 12.3 kg) were assigned to 1 of 2 experimental treatments in a randomized complete block design (8 pens per treatment; 4 steers per pen). Treatments included a control (CON) diet, which included prairie hay, Sweet Bran, rolled corn, and a corn steep and molasses-based liquid fat supplement, and a cotton byproduct (CTN) diet, which included cotton gin trash, whole cottonseed, rolled corn, and water. Both diets contained urea and dry supplement. Over the entire feeding period, DMI (P = 0.04) was greater for CTN steers than CON steers with no difference in the gain to feed ratio (P = 0.86) between treatments. The CTN steers tended to have heavier final BW (P = 0.09) and greater overall average daily gain (P = 0.08). The CTN steers had heavier hot carcass weight (P = 0.02) and greater fat thickness (P = 0.03) than CON steers, but marbling score and rib eye area were not different between treatments (P ≥ 0.64). Steers fed the CON diet tended to have a lower yield grade (P = 0.07), less kidney, pelvic and heart fat (P = 0.09), and decreased dressing percentage (P = 0.10) than CTN steers. Liver scores did not differ (P ≥ 0.17) between treatments. Fecal consistency scores were decreased for CTN steers on day 56 (P = 0.03) and fecal pH tended to be greater for the CTN steers on day 28 (P = 0.09) compared with CON steers, but neither differed during other periods (P ≥ 0.18). A treatment × day interaction (P = 0.04) was detected for plasma urea nitrogen (PUN) concentrations, where PUN concentrations differed between treatments only on days 28 and 56. On both days 28 and 56, CTN steers had lower PUN concentrations (P = 0.03, P = 0.002, respectively). No treatment × day interaction was detected for plasma glucose or lactate concentrations. A day effect was observed for both metabolites (P < 0.01). Results from this experiment suggest that cotton byproducts can be effectively used as a source of fiber, fat, and protein in feedlot rations without adverse effects on performance or carcass characteristics.
美国西南部棉花产量的增加增加了棉花副产品在牛饲料中的可用性。本试验的目的是评估在育肥日粮中添加棉副产品对肉牛的性能、胴体特性、粪便特性和血浆代谢物的影响。杂交肉牛（n = 64；BW = 318 ± 12.3 kg）按随机完全区组设计（每个处理 8 个围栏；每个围栏 4 头）分为 2 个试验处理之一。处理包括对照（CON）日粮，包括草原干草、甜麸、膨化玉米和玉米浸提和糖蜜基液体脂肪补充剂，以及棉副产品（CTN）日粮，包括轧棉废料、全棉籽、膨化玉米和水。两种日粮均含有尿素和干补充料。在整个饲养期内，CTN 组的干物质采食量（DMI）（P = 0.04）高于 CON 组，而处理间的增重与采食量比（P = 0.86）无差异。CTN 组的末重（P = 0.09）和平均日增重（P = 0.08）均较高。CTN 组的热胴体重（P = 0.02）和脂肪厚度（P = 0.03）均高于 CON 组，但大理石花纹评分和肋眼面积在处理间无差异（P≥0.64）。饲喂 CON 日粮的牛倾向于具有较低的产肉等级（P = 0.07）、更少的肾、骨盆和心脏脂肪（P = 0.09）和降低的出肉率（P = 0.10）比 CTN 牛。肝评分在处理间无差异（P≥0.17）。CTN 组在第 56 天的粪便稠度评分降低（P = 0.03），第 28 天的粪便 pH 值趋于更高（P = 0.09），但在其他时间无差异（P≥0.18）。血浆尿素氮（PUN）浓度存在处理×天数的交互作用（P = 0.04），仅在第 28 天和第 56 天处理间的 PUN 浓度不同。在第 28 天和第 56 天，CTN 组的 PUN 浓度较低（P = 0.03，P = 0.002）。血浆葡萄糖或乳酸浓度无处理×天数的交互作用。两种代谢物均有日效应（P < 0.01）。本试验结果表明，棉副产品可有效用作育肥日粮中的纤维、脂肪和蛋白质来源，对性能或胴体特性无不良影响。
