Hitz A C, Russell J R
Department of Animal Science, Iowa State University, Ames 50011, USA.
J Anim Sci. 1998 Feb;76(2):404-15. doi: 10.2527/1998.762404x.
We conducted a 3-yr study to measure herbage masses and chemical compositions of stockpiled perennial forages and corn crop residues and compare performance of cows grazing these forages or maintained in a drylot during winter. Midgestation, mature, medium-framed crossbred beef cows (mean BW, 506 kg; mean condition score, 5.3) 1) strip-grazed replicated fields containing stockpiled tall fescue-alfalfa, 2) strip-grazed stockpiled smooth bromegrass without (yr 1) and with (yr 2 and 3) red clover, 3) strip-grazed corn crop residues at 1.2 cows/ha, or 4) they were confined in a drylot for 129 to 141 d. All cows were offered grass-legume hay as large round bales to maintain a condition score of 5 on a 9-point scale. Mean initial amounts (P < .05) and daily changes (P < .01) of OM mass were greater in corn crop residues than in stockpiled perennial forages during the winter grazing seasons. Initial in vitro organic matter disappearance (IVOMD) and CP concentrations were greater (P < .05) and initial NDF, ADF, and ADIN concentrations in stockpiled forages were lower (P < .01) than those in corn crop residues. Mean changes in IVOMD, CP, NDF, and ADF concentrations during the grazing season were -.09, -.004, .10, and .11 percentage units OM/d, and they did not differ (P > .05) among forage species or grazed and nongrazed areas. Cows grazing stockpiled tall fescue-alfalfa had greater (P < .05) BW gains than those in other systems and greater (P < .05) body condition score increases than cows grazing corn crop residues. Because cows grazed stockpiled tall fescue-alfalfa, smooth bromegrass-red clover, and corn crop residues for 85, 83, and 57 d before beginning hay supplementation, cows grazing these forages required 1,069, 1,031, and 627 kg/cow less hay DM to maintain body condition than cows confined in a drylot.
我们进行了一项为期3年的研究，以测定多年生牧草和玉米作物秸秆的牧草量及化学成分，并比较冬季放牧这些牧草或圈养在干栏舍中的奶牛的生产性能。怀孕中期、成熟、中等体格的杂交肉牛（平均体重506千克；平均体况评分5.3）：1）条带放牧含有堆存高羊茅-苜蓿的重复地块；2）条带放牧堆存的无（第1年）和有（第2年和第3年）红三叶的草地早熟禾；3）以1.2头奶牛/公顷的密度条带放牧玉米作物秸秆；4）圈养在干栏舍中129至141天。所有奶牛均饲喂豆科干草制成的大捆圆草捆，以维持9分制下5分的体况评分。在冬季放牧季节，玉米作物秸秆中有机物质量的平均初始量（P<0.05）和每日变化量（P<0.01）均高于多年生牧草。与玉米作物秸秆相比，堆存牧草的初始体外有机物消失率（IVOMD）和粗蛋白（CP）浓度更高（P<0.05），而初始中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）和酸性洗涤不溶性氮（ADIN）浓度更低（P<0.01）。放牧季节IVOMD、CP、NDF和ADF浓度的平均变化分别为-0.09、-0.004、0.10和0.11个百分点/天，不同牧草品种或放牧与未放牧区域之间差异不显著（P>0.05）。放牧堆存高羊茅-苜蓿的奶牛体重增加幅度更大（P<0.05），体况评分增加幅度也大于放牧玉米作物秸秆的奶牛（P<0.05）。由于奶牛在开始补饲干草前，放牧堆存高羊茅-苜蓿、草地早熟禾-红三叶和玉米作物秸秆的天数分别为85天、83天和57天，因此与圈养在干栏舍中的奶牛相比，放牧这些牧草的奶牛维持体况所需的干草干物质少1069千克/头、1031千克/头和627千克/头。
