Terry Stephanie A, Yang Wenzhu, Beauchemin Karen A, Schwartzkopf-Genswein Karen S, Penner Gregory B, Wood Katharine M, McAllister Tim A
Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, Canada T1J 4B1.
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A8.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skae392.
This study evaluated the impact of grain processing method (dry- vs. steam-rolling) and diet uNDF concentration (low vs. high; 5.7% vs. 6.6% on DM basis by replacing silage with straw) in finishing diets on feed intake, feeding behavior, growth performance, ruminal pH, fermentation parameters, inflammatory stress responses, and carcass traits of 376 intact (initial body weight (BW) ± SD, 440 ± 33.6 kg), and 24 ruminally cannulated steers (initial BW ± SD, 474 ± 30.5 kg). Steers were housed in 32 pens with 4 pens of 30 steers, and 28 pens of 10 steers. Eight of the pens with 10 steers, and all of the pens with 30 steers were equipped with GrowSafe to record individual feed intake and feeding behavior. Three cannulated and 7 intact steers were housed in the smaller GrowSafe pens. Diets included (1) dry-rolled barley and barley silage; (2) dry-rolled barley and barley straw; (3) steam-rolled barley and barley silage; and (4) steam-rolled barley and barley straw, formulated to contain 89% barley-grain, 6% roughage and 5% vitamin and mineral supplement (DM basis). Interactions between the processing method and uNDF concentration were observed for maximum ruminal pH, and concentrations of blood glucose and lipopolysaccharide-binding proteins. Compared to dry-rolling, steam-rolling did not improve growth performance, ruminal pH, fermentation parameters, or liver abscess scores, but did increase longissimus muscle (LM) area (P = 0.01) and decrease the proportion of AAA carcasses (P = 0.01). Steam-rolled barley decreased (P = 0.04) glucose and increased (P = 0.01) blood concentrations of insulin and acute phase proteins. Increasing uNDF did not affect feed intake, growth, carcass traits, or liver abscess scores, but did increase (P = 0.01) bunk attendance, meal duration, and to a lesser extent meal intervals (P = 0.04) and eating rate (P = 0.01). Increased uNDF raised (P = 0.04) mean ruminal pH and reduced the duration of pH below 6.0, 5.8, and 5.2, and tended (P = 0.06) to increase the acetate to propionate ratio. The lack of growth response to dietary uNDF concentration could be due to the small differences in uNDF intake, or that uNDF concentration was sufficient to prevent digestive disturbances. Increasing dietary uNDF altered eating behavior and ruminal pH in a manner that could reduce the risk of clinical and subclinical ruminal acidosis.
本研究评估了育肥牛日粮中谷物加工方法（干碾压与蒸汽碾压）和日粮不可消化中性洗涤纤维（uNDF）浓度（低与高；以秸秆替代青贮饲料，干物质基础上分别为5.7%和6.6%）对376头未去势公牛（初始体重（BW）±标准差，440±33.6千克）和24头安装瘤胃瘘管的公牛（初始BW±标准差，474±30.5千克）的采食量、采食行为、生长性能、瘤胃pH值、发酵参数、炎症应激反应和胴体性状的影响。公牛被饲养在32个栏中，其中4个栏每个栏有30头公牛，28个栏每个栏有10头公牛。28个装有10头公牛的栏中的8个，以及所有装有30头公牛的栏都配备了GrowSafe系统以记录个体采食量和采食行为。3个安装瘤胃瘘管的公牛和7头未去势公牛被饲养在较小的GrowSafe栏中。日粮包括：（1）干碾压大麦和大麦青贮饲料；（2）干碾压大麦和大麦秸秆；（3）蒸汽碾压大麦和大麦青贮饲料；（4）蒸汽碾压大麦和大麦秸秆，配方中含有89%的大麦粒、6%的粗饲料以及5%的维生素和矿物质预混料（干物质基础）。观察到加工方法和uNDF浓度之间在瘤胃最大pH值、血糖浓度和脂多糖结合蛋白浓度方面存在交互作用。与干碾压相比，蒸汽碾压并未改善生长性能、瘤胃pH值、发酵参数或肝脓肿评分，但确实增加了背最长肌（LM）面积（P = 0.01）并降低了AAA级胴体的比例（P = 0.01）。蒸汽碾压大麦降低了血糖浓度（P = 0.04），并增加了血液中胰岛素和急性期蛋白的浓度（P = 0.01）。增加uNDF并未影响采食量、生长、胴体性状或肝脓肿评分，但确实增加了（P = 0.01）在饲槽边停留时间、采食持续时间，在较小程度上增加了采食间隔（P = 0.04）和采食速度（P = 0.01）。增加uNDF提高了（P = 0.04）瘤胃平均pH值，并缩短了pH值低于6.0、5.8和5.2的持续时间，且有增加乙酸与丙酸比例的趋势（P = 0.06）。对日粮uNDF浓度缺乏生长反应可能是由于uNDF摄入量差异较小，或者是uNDF浓度足以防止消化紊乱。增加日粮uNDF以一种可以降低临床和亚临床瘤胃酸中毒风险的方式改变了采食行为和瘤胃pH值。
