Forage quality of kikuyu (Pennisetum clandestinum): the effect of time of defoliation and nitrogen fertiliser application and in comparison with perennial ryegrass (Lolium perenne)
Forage quality of kikuyu (Pennisetum clandestinum): the effect of time of defoliation and nitrogen fertiliser application and in comparison with perennial ryegrass (Lolium perenne)
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基库尤草 (Pennisetum clandestinum) 的饲料品质：落叶时间和施氮肥的影响以及与多年生黑麦草 (Lolium perenne) 的比较
DOI：
10.1071/ar9961349
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发表时间：
1996
影响因子：
1.9
通讯作者：
R. Kellaway
中科院分区：
文献类型：
--
作者：
M. Reeves;W. Fulkerson;R. Kellaway
这项研究，在新南威尔士州的北部海岸进行，确定了最佳时间落叶基库尤（狼尾草clandestinum霍赫斯特前chiov。）牧草质量与每分蘖叶片数的关系。比较了管理良好的基库尤草和多年生黑麦草（Lolium perenne L.）牧场，以确定基库尤可能限制牛奶产量的营养。随着叶龄的增加，单个叶片的粗蛋白（CP）、P和K浓度下降; Ca和Mg增加;而Na水平保持不变。个别叶片的这些变化反映在质量的基库尤以上5厘米的残茬高度。每分蘖再生4.5片叶后，5cm留茬以上的有效绿色叶比例下降，而茎和死叶比例显著增加。这些变化反映在牧草的有机物消化率（OMD）和CP的大幅下降。0900和1500小时之间，水溶性碳水化合物（WSC）水平在基库尤以上的5厘米残茬高度增加的速度为5克/公斤干物质（DM）每小时，达到最高水平在下午。基库尤施肥量高的氮肥含有显着较高的硝酸盐水平比接受中等水平（3.12 v. 0。67 g/kg DM）。当粗蛋白质含量超过230 g/kg干物质时，硝酸盐含量呈线性增加。基库尤和黑麦草样品采摘，以模拟饲料消耗的奶牛挤奶，获得在中间的生长季节的每一个物种。基库尤的OMD低于黑麦草（733比842 g/kg DM），但含有较高水平的中性洗涤纤维（600比400 g/kg DM）。与黑麦草相比，基库尤的高CP水平和低WSC含量导致WSC：CP的比率低得多（分别为0.09 v.0.36）。基库尤含有50%的钙比黑麦草，其中大部分将被绑定到盐，从而无法放牧股票。基库尤的Na含量极低，与黑麦草相比（分别为0.15和3.67 g/kg DM）。就牧草质量和数量之间的折衷而言，最理想的基库尤再生长阶段似乎是4.5叶/分蘖。然而，即使在这个阶段，各种先天性营养缺乏似乎也会将产奶量限制在15-16 L牛奶/奶牛。
This study, conducted on the north coast of New South Wales, determined the optimal time to defoliate kikuyu (Pennisetum clandestinum Hochst ex chiov.) in terms of pasture quality in relation to the number of leaves per tiller. It also compared the quality of well-managed kikuyu grass and ryegrass (Lolium perenne L.) pasture to determine the nutrients in kikuyu likely to limit milk production. The crude protein (CP), P, and K concentrations of individual leaves declined; Ca and Mg increased; and Na levels remained constant with increasing age. These changes in individual leaves were reflected in the quality of kikuyu available above the 5-cm stubble height. The proportion of green leaf available above the 5-cm stubble height declined whilst the proportion of stem and dead material increased markedly after 4.5 leaves per tiller had regrown. These changes were reflected in a substantial decline in organic matter digestibility (OMD) and CP of herbage. Between 0900 and 1500 hours, water-soluble carbohydrate (WSC) levels in kikuyu above the 5-cm stubble height increased at a rate of 5 g/kg dry matter (DM) per hour, reaching maximum levels during the mid afternoon. Kikuyu fertilised at a high rate of N fertiliser contained significantly higher nitrate levels than that receiving moderate levels (3.12 v. 0. 67 g/kg DM, respectively). There was a linear increase in the levels of nitrate as the CP of forage exceeded 230 g/kg DM. Kikuyu and ryegrass samples plucked to simulate forage consumed by milking cows were obtained in the midst of the growing season for each species. Kikuyu had a lower OMD than ryegrass (733 v. 842 g/kg DM) but contained higher levels of neutral detergent fibre (600 v. 400 g/kg DM). High levels of CP and low content of WSC in kikuyu compared with ryegrass resulted in a much lower ratio WSC: CP (0.09 v. 0.36, respectively). Kikuyu contained 50% less Ca than ryegrass, much of which would be expected to be bound to oxalates and thus unavailable to grazing stock. The concentration of Na in kikuyu was extremely low compared with ryegrass (0.15 v. 3.67 g/kg DM, respectively). The most desirable stage of regrowth of kikuyu on which to graze lactating dairy cows, in terms of a compromise between forage quality and quantity, appears to be at 4.5 leaves/tiller. However, even at this stage, various innate nutrient deficiencies would appear to restrict milk production to 15-16 L milk/cow.day.