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为探讨中度放牧条件下放牧方式对家畜生产力的影响，开展了牦牛单牧（YG）、藏羊单牧（SG）、牦牛藏羊1∶6混牧（MG1∶6）、牦牛藏羊1∶4混牧（MG1∶4）和牦牛藏羊1∶2混牧（MG1∶2）5个控制性放牧试验，研究了牧草生长季不同生长时期对家畜日增重的影响以及不同放牧方式对牦牛和藏羊暖季增重、牧草营养和家畜采食量的影响。结果表明：1）在牧草返青期和生长期，牦牛和藏羊的日增重显著大于牧草枯黄期（P<0.05）;2）牦牛和藏羊日增重在不同的放牧方式下无显著差异（P>0.05），而牦牛暖季增重在YG下最高，在MG1∶2和MG1∶6相对较高，藏羊暖季增重在MG1∶2中最高，在SG和MG1∶4相对较高；3）不同放牧方式下牧草营养和单位面积家畜采食量无显著差异（P>0.05），单一家畜放牧单位面积增重SG最高，牦牛藏羊两种家畜混合放牧则MG1∶2单位面积增重最高。综上，牧草枯黄期牦牛和藏羊的补饲对于维持其生产性能具有重要的意义，且MG1∶2对于牦牛和藏羊生产是一种较优的组合生产方式。 相似文献
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不同放牧强度对草地和绵羊生产性能影响 总被引：4，自引：0，他引：4
本试验是1988年在湖南省南山牧场改良草地上用绵羊进行的3种放牧强度的放牧研究。结果表明:不同放牧强度对牧草产量、绵羊繁殖率和增重差异均不显著(P>0.05),但以每亩草地计算,不同放牧强度绵羊增重差异显著(P<0.01)。高放牧强度(每羊1.5亩草地)能促进人工栽培牧草分蘖,抑制野生杂草数量。 相似文献
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试验旨在探讨华北农牧交错带羊草、大赖草、扁穗冰草、无芒雀麦、野黑麦和梭罗草6种主要禾本科牧草不同生育期营养价值变化规律。利用常规化学成分分析、活体外消化技术和体外发酵产气技术测定6种禾本科牧草盛花期和结实期的主要营养成分、活体外消化率和瘤胃微生物体外发酵产气量。结果表明:除无芒雀麦外,结实期禾本科牧草粗蛋白(CP)和中性洗涤可溶物(NDS)含量相比开花期显著下降(P<0.05);中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量随生育期的延长而增加(P<0.05);6种牧草的干物质活体外消化率(DMD)、NDF活体外消化率(NDFD)、ADF活体外消化率(ADFD)随生育期延长呈下降趋势;除羊草外,5种牧草的2个生育期的24 h和48 h产气量差异显著(P<0.05),6种禾本科牧草2个生育期的理论最大产气量差异显著(P<0.05);随生育期延长,产气速度呈下降趋势,延滞期呈上升趋势。与开花期相比,禾本科牧草结实期的营养显著下降。 相似文献
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温性荒漠草原土壤酶与肥力的关系 总被引：1，自引：0，他引：1
为揭示放牧扰动下土壤养分供给水平的变化,对温性荒漠草原冬春季牧场不同放牧强度下土壤酶活性与肥力因子的关系进行了研究.结果表明:放牧区土壤呈弱碱性;随放牧强度的增加,土壤容重增大;除对照区外,各层土壤含水量、全氮、速效氮、有机质和速效磷均随放牧强度的增加而下降,且随土层深度的加深含量有递减趋势;除重牧区20～30cm土层外,各放牧区各土层土壤脲酶含量差异不显著;土壤碱性磷酸酶各放牧区极显著高于对照区(P＜0.01);过氧化氢酶除0～10cm土层随放牧强度的增加有增加趋势外,其他各层均表现LG＞ MG＞CK＞ HG的变化.相关分析表明,3种酶与土壤主要肥力因子间相关显著(P＜0.05)或极显著(P＜0.01),说明土壤酶可以用来表征土壤肥力状况;主成分分析同样得出土壤脲酶和过氧化氢酶活性与土壤肥力之间具有良好的相关性,可以用来指示草原退化与恢复状况. 相似文献
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垂穗披碱草Elymus nutans—星星草Puccinellia tenuiflora混播草地3个放牧季的牦牛放牧试验结果表明:相同放牧区每公顷草地牦牛总增重之间的差异不显著(P>0.05),同一放牧季各放牧区牦牛总增重之间的差异极显著(P<0.01),且各放牧季牦牛的个体增重与放牧强度均呈显著的线性回归关系;2003年单位面积草地牦牛增重随放牧强度的增加而增加,2004和2005年单位面积草地牦牛增重与放牧强度呈二次回归关系;通过二次回归方程计算得到:牧草生长季牦牛最佳放牧强度为7.23头/hm2。 相似文献
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为探讨不同放牧强度与生态系统稳定性的关系,在内蒙古短花针茅荒漠草原野外放牧试验基地(2004 年开始放牧)展开研究。试验采用完全随机区组设计,设置 4 个不同的放牧处理：对照 (CK)、轻度(LG)、中度(MG)、重度(HG)放牧,3 个区组(3 个重复)。2019 年对植物群落的物种数、盖度、密度、生物量进行观测,采用 Gordon 稳定性方法评估不同放牧强度对群落稳定性的影响。结果表明：随着放牧强度的增大,植物群落物种数、生物量和盖度显著降低(P＜0. 05),密度随放牧强度的增加呈先增加后降低的趋势,在中度放牧时最高。植物群落多样性指数与群落物种数、盖度、生物量呈显著相关性(P＜0. 05)。植物群落多样性随放牧强度增加而降低,中度放牧强度下群落稳定性最高。 相似文献
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认识放牧对草地植物群落结构和家畜生产性能的影响是修复放牧退化草地和制定可持续放牧体系的理论基础。本研究在内蒙古锡林郭勒典型草原开展了基于草地放牧留茬高度的适应性放牧实验,连续4年监测了无牧(NG)、轻牧(LG)、中牧(MG)和重牧(HG)条件下草地植物群落的变化和家畜生产性能,分析其对放牧强度的响应。结果表明：与NG相比,HG显著降低了优势种的相对生物量,提高了伴生种的相对生物量(P<0.05);LG和MG处理下主要提高了优势种的生产力,而在HG处理主要提高了伴生种的生产力;在所研究的典型草原采用适应性放牧方式下,中度放牧可获得最佳的草地植物生产和家畜生产性能。研究为制定合理的草原放牧制度、促进草地群落结构优化和草畜平衡发展提供了理论依据。 相似文献
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以青藏高原高山嵩草草甸优势植物高山嵩草（Kobresia pygmaea）和紫花针茅（Stipa purpurea）为对象,研究不同放牧强度对其营养成分变化的影响。结果表明,不同优势种对放牧响应不同,放牧有利于高山嵩草草甸优势植物钙和磷的吸收,高山嵩草重度放牧下钙与磷含量显著高于适度放牧与对照(零放牧)（P＜0.05）,且适度放牧与对照差异不显著（P＞0.05）。紫花针茅钙含量依次为重度放牧＞适度放牧＞对照,磷含量随着放牧强度的增加,出现先升高后下降的变化趋势;放牧家畜的啃食促进了植物的补偿性生长,放牧粗纤维含量显著低于对照（P＜0.05）;同时放牧增加了高山嵩草草甸优势植物粗脂肪和粗蛋白含量。放牧家畜对草地的影响,加速了牧草-土壤氮循环,促进了牧草对土壤氮的吸收,进而增加了牧草的粗蛋白含量,改善了牧草品质。 相似文献
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垂穗披碱草Elymus nutans-星星草Puccinellia tenuiflora混播草地3个放牧季的牦牛放牧试验结果表明:相同放牧区每公顷草地牦牛总增重之间的差异不显著(P>0.05),同一放牧季各放牧区牦牛总增重之间的差异极显著(P<0.01).且各放牧季牦牛的个体增重与放牧强度均呈显著的线性回归关系;2003年单位面积草地牦牛增重随放牧强度的增加而增加,2004和2005年单位面积草地牦牛增重与放牧强度呈二次回归关系;通过二次回归方程计算得到:牧草生长季牦牛最佳放牧强度为7.23头/hm2. 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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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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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
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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