Beaty J L, Cochran R C, Lintzenich B A, Vanzant E S, Morrill J L, Brandt R T, Johnson D E
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506.
J Anim Sci. 1994 Sep;72(9):2475-86. doi: 10.2527/1994.7292475x.
Three experiments evaluated whether effects of altered frequency of supplementation on forage use and cow performance depended on supplement CP concentration and (or) grain type when fed to cattle eating low-quality forages. All experiments included supplementation frequency (daily = 7x; three times weekly = 3x) as one factor in a factorialized arrangement of treatments. In Exp. 1 and 2, the second factor was supplement CP concentration (10, 20, 30, and 40% CP), altered by changing the ratio of soybean meal to sorghum grain in supplements. Supplements were fed at 13.9 and 14.1 kg of DM/wk for Exp. 1 and 2, respectively. In Exp. 3, the second factor was supplement grain type (sorghum grain or corn) and supplements containing 21% CP were fed at 14.8 kg of DM/wk. In Exp. 1, eight ruminally fistulated steers (456 kg) consumed wheat straw ad libitum. Pregnant beef cows grazing dormant tallgrass prairie were used in Exp. 2 (475 kg; n = 128) and 3 (504 kg; n = 120). In Exp. 1, reducing supplementation frequency decreased (P < .01) straw intake but increased (P < or = .03) DM and NDF digestion. As CP concentration in supplements increased, straw DMI (P = .06) increased quadratically, whereas DM and NDF digestion increased linearly (P < .01). In Exp. 2, increasing CP concentration in supplements enhanced cows' ability to maintain BW and condition up to calving, with decreasing magnitude of difference between treatments at higher CP concentrations (P < .01). Increasing CP in supplements fed to the dams linearly (P = .05) increased calf weaning weight in Exp. 2. In Exp. 2 and 3, reducing supplementation frequency increased (P < or = .02) winter weight loss through calving. Grain type did not significantly affect most performance variables. In summary, response to supplementation frequency was not dependent on supplement CP concentration or grain type. Daily supplementation maximized forage intake and cow performance, although the magnitude of performance differences was not large.
三项试验评估了在给采食低质量牧草的牛投喂时，改变补饲频率对牧草利用和奶牛生产性能的影响是否取决于补饲的粗蛋白（CP）浓度和（或）谷物类型。所有试验都将补饲频率（每日 = 7次；每周三次 = 3次）作为析因试验设计处理中的一个因素。在试验1和试验2中，第二个因素是补饲CP浓度（10%、20%、30%和40% CP），通过改变补饲中豆粕与高粱谷物的比例来调整。试验1和试验2中，补饲量分别为每周13.9千克和14.1千克干物质（DM）。在试验3中，第二个因素是补饲谷物类型（高粱谷物或玉米），补饲含21% CP的饲料，每周投喂量为14.8千克DM。试验1中，8头装有瘤胃瘘管的阉牛（体重456千克）自由采食小麦秸秆。试验2（体重475千克；n = 128）和试验3（体重504千克；n = 120）使用了在休眠高草草原放牧的怀孕肉牛。在试验1中，降低补饲频率会使秸秆采食量减少（P < 0.01），但干物质和中性洗涤纤维（NDF）消化率提高（P ≤ 0.03）。随着补饲中CP浓度的增加，秸秆干物质采食量（P = 0.06）呈二次曲线增加，而干物质和NDF消化率呈线性增加（P < 0.01）。在试验2中，提高补饲中CP浓度可增强奶牛直至产犊时维持体重和体况的能力，在较高CP浓度下各处理间差异的幅度减小（P < 0.01）。在试验2中，给母牛补饲中增加CP可使犊牛断奶体重呈线性增加（P = 0.05）。在试验2和试验3中，降低补饲频率会增加（P ≤ 0.02）冬季到产犊时的体重损失。谷物类型对大多数生产性能变量没有显著影响。总之，对补饲频率的反应并不取决于补饲CP浓度或谷物类型。每日补饲可使牧草采食量和奶牛生产性能最大化，尽管生产性能差异的幅度不大。
