Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran.
J Dairy Sci. 2020 Apr;103(4):3191-3203. doi: 10.3168/jds.2019-17344. Epub 2020 Jan 31.
Steam-flaked corn (SFC) and ground corn (GC) of different particle sizes were evaluated for their effects on dry matter intake (DMI), milk yield and components, chewing activity, ration sorting, ruminal fermentation, and digestibility in lactating dairy cows. Eight multiparous Holstein cows in mid-lactation (46.6 ± 3.5 kg/d milk production and 101 ± 10 d in milk) were used in a double 4 × 4 Latin square design with 21-d periods. Cows were fed diets (dry matter basis) containing 36.2% forage (alfalfa hay and corn silage), 37.4% corn grain, and 26.4% other ingredients. The corn grain was ground (coarse: 1.08 mm; medium: 0.84 mm; and fine: 0.73 mm) or steam-flaked (SFC; density = 0.40 kg/L). The dry matter proportion retained on an 8-mm sieve was greater for the SFC diet than for the GC diets. There were no treatment effects on DMI, milk yield, fat-corrected milk, energy-corrected milk, fat or lactose yield, protein or lactose content, or milk urea nitrogen concentration. However, digestibility of dry matter and organic matter were greater for fine GC and SFC than the other diets. In addition, cows fed SFC had lower total-tract starch digestibility than cows fed GC diets. Cows fed SFC tended to have lower propionate proportion (22.8 vs. 27.1 mM) and total volatile fatty acid concentration (88.6 vs. 99.8 mM) in ruminal fluid than those fed GC diets. Acetate and butyrate concentration, acetate to propionate ratio, and ruminal concentration of ammonia-nitrogen were not affected by treatments. Ruminal pH (6.46 vs. 6.01) as well as milk fat content (2.75 vs. 2.59%) and efficiencies (fat-corrected milk/DMI and energy-corrected milk/DMI) were greater for SFC than GC, regardless of its particle size. Milk fat content tended to increase linearly with increasing particle size of GC. Eating activity (min/d) tended to be less for SFC compared with GC, but rumination activity (min/d) and total chewing activity (min/d) were not affected by processing or particle size. The results of study indicate that, compared with GC, steam flaking of corn with 400 g/L density increased milk fat content and efficiency of high-producing dairy cows without any negative effect on milk yield. For GC, milk fat content tended to linearly increase and starch digestibility decreased linearly with increasing particle size.
蒸汽压片玉米（SFC）和不同粒径的粉碎玉米（GC）对泌乳奶牛的干物质采食量（DMI）、产奶量和成分、咀嚼活动、日粮分类、瘤胃发酵和消化率的影响进行了评估。8 头处于泌乳中期（46.6±3.5kg/d 产奶量和 101±10d 泌乳期）的荷斯坦奶牛采用双 4×4 拉丁方设计，每个周期 21d。奶牛饲喂以（干物质基础）含 36.2%饲草（苜蓿干草和玉米青贮）、37.4%玉米谷物和 26.4%其他成分的日粮。玉米谷物经过粉碎（粗：1.08mm；中：0.84mm；细：0.73mm）或蒸汽压片（SFC；密度=0.40kg/L）。SFC 日粮的 8mm 筛上物的干物质比例大于 GC 日粮。DMI、产奶量、校正乳脂、校正乳能、脂肪或乳糖产量、蛋白质或乳糖含量或乳尿素氮浓度不受处理影响。然而，细 GC 和 SFC 的干物质和有机物消化率大于其他日粮。此外，饲喂 SFC 的奶牛总肠道淀粉消化率低于 GC 日粮。与 GC 日粮相比，饲喂 SFC 的奶牛瘤胃液丙酸比例（22.8 对 27.1mM）和总挥发性脂肪酸浓度（88.6 对 99.8mM）较低。乙酸和丁酸浓度、乙酸丙酸比以及瘤胃中氨氮浓度不受处理影响。瘤胃 pH（6.46 对 6.01）以及乳脂含量（2.75 对 2.59%）和效率（校正乳脂/DMI 和校正乳能/DMI）SFC 高于 GC，与颗粒大小无关。与 GC 相比，SFC 的产奶量和效率更高（脂肪校正奶/DMI 和能量校正奶/DMI），并且 SFC 的牛奶脂肪含量更高（2.75 对 2.59%）。与 GC 相比，SFC 的采食活动（min/d）较低，但反刍活动（min/d）和总咀嚼活动（min/d）不受加工或粒径的影响。研究结果表明，与 GC 相比，密度为 400g/L 的玉米蒸汽压片可提高高脂肪奶牛的乳脂含量和效率，而对产奶量无任何负面影响。对于 GC，随着粒径的增加，牛奶脂肪含量呈线性增加，淀粉消化率呈线性下降。
