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首页> 外文期刊>Livestock Science >Effect of strategies regarding concentrate supplementation and day-time grazing on N utilization at both field and dairy cow level
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Effect of strategies regarding concentrate supplementation and day-time grazing on N utilization at both field and dairy cow level

机译：田间和奶牛水平上补充浓缩物和日间放牧策略对氮利用的影响

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N utilization at cow and field level was examined over two grazing periods of 30 days with 64 Holstein dairy cows. At cow and field level the effect of sward type (diploid vs. tetraploid perennial ryegrass, both mixed with white clover) and compressed sward height (6 vs. 10 cm) was examined. At dairy cow level the effect of urea supplementation (0 vs. 145 g/day) and energy supplementation strategy (soy hulls(am)/barley(pm) vs. barley(am)/soy hulls(pm)) was also examined. Cows grazed grass/clover swards for 7.5 h/day and were restrictively fed in the barn (3.2 kg dry matter (DM) in maize silage, 3.6 kg ground barley, 3.6 kg soy hulls per day). In none of the two periods were yield of milk (Period 1: 30.9 kg, Period 2: 25.4 kg), fat, protein and lactose significantly affected by sward type, sward height, urea supplementation or energy supplementation strategy. Urea supplementation increased the urea concentration in milk. Also low sward height and feeding soy hulls(am)/barley(pm) increased the urea concentration, probably due to a higher protein content in the sward and a higher grass intake, respectively. N utilization at cow level was highest with high sward height and no urea supplementation. Feeding soy hulls(am)/barley(pm) increased milk yield numerically but was counterbalanced by an equivalent increase in estimated grass intake, and supplementation strategy seemed therefore not to affect N utilization. At field level the N surplus was higher on diploid than on tetraploid swards (50 and 21 kg N/ha) due to a higher clover content in the diploid swards, whereas the difference in N surplus between sward heights was minimal (32 and 38 kg N/ha). Estimated N removal from the pasture in the grazing periods (intake minus excretion) increased by 5.2 kg N/ha when feeding soy hulls(am)/barley(pm), whereas with no urea supplementation the net N removal increased by only 2.5 kg N/ha. It was concluded that N utilization in dairy cows can be improved by decreasing N intake from both herbage and supplementary concentrate without compromising milk yield, and that N balance at field level could be improved by strategic barn feeding.
机译：在64头荷斯坦奶牛的30天的两个放牧期内，对牛和田间的氮利用进行了检查。在母牛和田间水平上，研究了草地类型（二倍体对四倍体多年生黑麦草，均与白三叶草混合）和压缩草地高度（6对10 cm）的影响。在奶牛水平上，还检查了补充尿素（0对145克/天）和能量补充策略（大豆皮（上午）/大麦（下午）与大麦（上午）/大豆皮（下午））的影响。母牛每天放牧草/三叶草7.5小时，并在谷仓（玉米青贮饲料中的3.2千克干物质（DM），3.6千克地面大麦，3.6千克大豆皮/天）中进行限制性饲喂。在这两个时期中，没有一个时期的牛奶产量（时期1：30.9千克，时期2：25.4千克），脂肪，蛋白质和乳糖受到草地类型，草地高度，尿素补充或能量补充策略的显着影响。补充尿素会增加牛奶中的尿素浓度。此外，较低的草皮高度和饲喂大豆壳/大麦（pm）会增加尿素浓度，这可能分别是由于草皮中蛋白质含量较高和草摄入量较高。在高草高且不补充尿素的情况下，母牛水平的氮利用率最高。饲喂大豆壳（上午）/大麦（下午）在数值上增加了牛奶的产量，但被估计的草摄入量的相等增加所抵消，因此补充策略似乎不影响氮的利用。在田间水平，由于二倍体草中三叶草含量较高，二倍体上的氮过剩高于四倍体草（50和21 kg N / ha），而两茎高度之间的氮过剩差异最小（32和38 kg） N /公顷）。饲喂大豆壳（上午）/大麦（下午）时，放牧期间牧场（进水减去排泄物）的估计氮去除量增加了5.2 kg N / ha，而未添加尿素的净氮去除量仅增加了2.5 kg N /哈。结论是，可以通过减少牧草和补充精饲料中的氮摄入量而提高奶牛的氮利用率，而又不损害牛奶产量，并且通过战略性谷仓饲喂可以提高田间水平的氮平衡。

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