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牧草种子从发芽到最后成熟的整个生长发育过程中除了需要土壤、阳光、空气、水分、温度等生活条件以外,还需要多种营养元素,如碳、氢、氧、氮、磷、钾、钙、镁、硫、铁、锰、锌、铜、钼、硼、氯等。牧草需要的营养元素,不一定都要通过施肥来解决,比如碳、氢、氧可以从水中和空气中取得;某些微量元素牧草需要量极少,可以从土壤中取得,不需要通过施肥来补给;而氮、磷、钾牧草需要数量较多,其供应程度直接影响牧草的产量和品质,当土壤不能满足这些养分需要时,必须通过施肥来解决,所以称氮、磷、钾为牧草营养三要素。 相似文献
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营养快现是以海洋植物海藻作为主要原料,经科学加工制成的生物肥料。该产品由山东汇丰源农业科技发展有限公司生产,主要成分是从海藻中提取的有利于植物生长发育的天然活性物质和海藻,从海洋中吸收并富集在体内的矿物质营养元素,包括海藻多糖、酚类多聚化合物、甘露醇、甜菜碱、植物生长调节物质和氮、磷、钾及铜、铁、锌、硼、钼、碘等微量元素。 相似文献
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叶面喷施微肥对红豆草根系的影响陈宝书（甘肃农业大学）牧草正常生长发育，需要氮、磷、钾、钙、硫等大量元素，还需要多种微量营养元素。目前研究和使用得较多的微量元素有硼、钼、锰、锌、铁、铜等，它们在作物体中的含量仅占作物干重的千分之几至十万分之几，所起的生... 相似文献
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不同利用期对红三叶种群营养元素含量和积累速率的影响 总被引：4，自引：0，他引：4
本文研究不同利用期对四川巫溪县红地坝亚热带高海拔地区红三叶人工草地11种营养元素含量和积累速率的影响，结果如下：不同季节，即3～5月（Ⅰ）、6～7月（Ⅱ）和8～9月（Ⅲ），对红三叶营养元素含量和积累速率的影响如下：氮、磷、钙、镁．标的含量为Ⅰ＜Ⅱ＜大，钠为Ⅰ＞Ⅱ＞Ⅲ，钾、铜、钴为Ⅱ＞Ⅰ＞Ⅲ。锌的含量三者相近。营养元素最大积累速率出现的顺序为Ⅱ＞Ⅰ＞Ⅲ。红三叶在不同生育期对营养元素含量和积累速率的影响如下：随着生育期的后移，氮、磷、钾、铜、锌含量通常逐渐下降。在相同生育期的条件下，再生草与刈前比较，氮、磷、钾、铜、锌的含量较低，而钙含量较高。在生长初期营养元素的平均积累速率较低，但随着利用期的推迟而逐渐升高。在现蕾—开花期利用，大多数元素的平均积累速率最高。 相似文献
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氮、磷、钾、钙等元素是植物生长发育不可缺少的,虽然作物对这些元素需要的量相差很大,但是对作物生长发育起的作用同等重要,而且不可相互代替。过多地使用某种营养元素,不仅会对作物产生毒害,还会妨碍作物对其他营养元素的吸收,如磷过多会降低钙、锌、硼的有效性。土壤有效磷的测定,不仅可了解近期磷元素供应水平状况,而且是植物合理施肥的依据。因此,推广测土配方施肥,宣传植物所需营养元素的重要性及测定土壤中营养元素的含量非常必要。现就土壤有效磷的测定方法介绍如下。 相似文献
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影响海法白三叶生长的营养元素及磷钾施用效果 总被引：3，自引：0，他引：3
取云南省广南畜牧场原生红砂壤土,在温室采用盆栽手段对指示植物海法白三叶进行矿物营养元素筛分和磷、钾施量试验。结果表明:影响海法白三叶在红砂壤上生长的主要矿物元素是磷、钾,其次为钼。施用磷肥效果明显,并且施磷量与白三叶地上部分生物量间呈极显著的直线正相关YP=0.851+9.93X(r=0.94)。初步推断以施24kg/hm2磷、26～52kg/hm2钾为白三叶当年定植的有效施用量。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献