不同放牧强度对当年混播草地的影响

研究了云南高降雨地区混播草地播种60 d后,不同放牧强度(0.5,1和1.5黄牛单位/公顷)对草地密度、盖度、高度、频度和生物量的影响。结果表明,放牧能明显抑制一年生禾本科杂草及播种多年生禾本科牧草的生长,但对白三叶和草地有害植物的生长都有促进作用。     

暖季放牧犊牦牛对高寒草甸地区人工草地的影响

为更好地了解青藏高原高寒草甸区暖季放牧条件下人工草地牧草的生长特点,为制定合理放牧制度提供依据,于2001~2003年开展了暖季放牧牦牛对多年生人工草地影响的试验。结果表明:放牧2年后轮牧人工草地播种牧草比例为95.27%,连续放牧人工草地为86.15%,无放牧人工草地为58.01%。轮牧人工草地牧草月风干重最高值3 198.8 kg/hm2,连续放牧人工草地为3 023.2 kg/hm2。放牧可以提高人工草地牧草生长率,轮牧人工草地的牧草生长率高于连续放牧人工草地。放牧还影响着第2年播种牧草的生长,轮牧能促进种子出苗数,播种牧草的鲜重,风干重和种子产量分别达到了5 088.88 kg/hm2,3 053.33 kg/hm2和480 kg/hm2,均高于连续放牧人工草地和无放牧草地,轮牧人工草地杂草鲜草产量最低,为193.33 kg/hm2。适宜的放牧是保持人工草地可持续利用的手段之一。     

不同播种时期对放牧草地牧草收获量和化学成分的影响

通过在Ｓａｓａ ｎｉｐｐｏｎｉｃａ Ｍａｋｉｎｏ占优势的天然草地晚秋强度放牧，秋、春播种的试验结果表明：春播区２年的牧草总收获量高于秋播区；秋、春播种区禾本科与豆科牧草比例基本相同，禾本科比例保持在７０％以上，主要禾本科鸭茅的比例在５０％以上；牧草的营养化学成分含量春播区稍主为秋播区，把Ｓａｓａ ｎｉｐｐｏｎｉｃａ Ｍａｋｉｎｏ占优势的天然草地改良成人工草地时，采用晚秋强度放牧，春季播种较好。     

滩羊不同放牧强度对盐池草地植被组成的影响

5种不同放牧强度,历时150 d的滩羊放牧试验结果如下:1)放牧强度与草地禾本科牧草现存量之间存在极显著负相关关系和极显著回归关系,禾本科牧草现存量随放牧强度变化趋势是先增后减。当放牧强度为0.45只/(hm2.d)时,禾本科牧草的现存量最大。2)随着放牧强度增大,禾本科牧草所占总产草量的比例减小。当放牧强度为0.45只/(hm2.d)时,禾本科牧草所占比例最大。3)随着放牧强度的增大,豆科牧草所占比例呈先减后增再减的变化趋势,即呈“V”字型。4)当放牧强度逐渐增大时,杂类草变化趋势呈“N”型变化。5)随着放牧强度的增大,禾本科牧草比例相对降低,而豆科牧草比例相对增加。草地植被组成改变。以宁夏盐池草地现状,放牧强度不能大于0.45只/(hm2.d)。     

春季放牧对高寒草地冬季地上现存量的影响

为研究春季放牧对高寒草地冬季植物存量的影响,2020年春季(3月～6月),在祁连县默勒镇老日根村开展了不同放牧利用率(A:0、B:25%～35%、C:45%～55%、D:65%～75%和E: 90%)控制试验。结果表明:随放牧利用率增大,禾本科代表物种紫羊茅、莎草科代表物种矮嵩草、阔叶类可食牧草代表物种矮火绒草和毒害草代表物种黄花棘豆株高均呈下降趋势,草地植被总盖度、禾本科和莎草科盖度、植被地上总生物量、优良牧草禾本科和莎草科生物量均呈降低趋势,毒害草生物量则呈先降低后升高再降低的变化趋势。春季休牧或轻度放牧可大幅度提高草地生产力,在春季对草地进行休牧或轻度放牧更有利于草地健康、可持续发展,认为春季休牧或轻度放牧是解决高寒牧区冷季缺草的重要途径。     

放牧对黑麦草＋白三叶混播草地植被构成的作用

通过4个放牧强度（轻牧、适牧、重牧和过牧,牧后草层高度分别为7.5、5.5、3.5和<2.0 cm）的轮牧试验,对黑麦草(Lolium perenne)、白三叶(Trifolium repens)混播草地土壤化学特性;黑麦草分蘖和白三叶匍匐茎、叶片数及其茎叶构成,牧草高度、生物量与植被构成进行系统研究。结果表明,土壤速效养分含量对放牧强度响应较大,稳定性较弱。随放牧强度的增加,黑麦草分蘖密度和叶片生物量显著增加,黑麦草分蘖质量和白三叶匍匐茎密度及牧草高度和生物量显著下降;黑麦草叶片数,白三叶叶片数、茎叶比和匍匐茎质量在放牧强度间无显著变化。放牧强度在降低黑麦草和白三叶生长特性整齐度的同时,增加其可塑性生长;黑麦草对放牧强度的响应比白三叶敏感,但白三叶的可塑性生长比黑麦草的高。鸭茅（Dactylis glomerata）和非播种植物种的生长特性在放牧强度内变异系数较大。综合分析认为,放牧对草地植被的作用体现于植物个体、种群和群落3个水平,播种的低组分禾草（鸭茅）和非播种禾草是混播草地植被构成变化的关键种。     

陡坡山地的牧草化和肉牛饲养技术(2)

<正> (三)适于倾斜地的草种 1.关于选择革种的一个试验结果免耕法建造的草地大多在倾斜地,一般供放牧利用。选择适合于倾斜地放牧用的草种必须从草地和家畜两个方面进行考虑,也就是要考虑到产草量及其季节分布、对蹄子踏伤的抗性、草地保护机能、家畜的适口性、家畜的生产性能等,而且也要考虑到向草地引进的草种是单一种还是数种混合(禾本科之间或禾本科与豆科)。     

保护播种对高寒区放牧型混播草地草产量和品质的影响

保护播种作为一种退化草地管理措施,对提高多年生人工草地覆盖度,解决建植当年产草量低及冬春季节饲草不足的矛盾具有重要意义。本试验采用4播种比例2草种作为保护播种,无保护播种为对照研究保护播种对放牧型混播草地草产量和品质影响。结果表明,燕麦（Avena sativa）和多花黑麦草（Lolium multiflorum）单播量的20%,30%,40%和50%对放牧型草地保护播种,前2年总干草产量较对照均有显著增加,播种多花黑麦草总干草产量较对照增加126%、161%、157%和144%,播种燕麦较对照增加223%、222%、254%和274%。保护播种后牧草粗蛋白含量也有所提高,20%、30%和40%多花黑麦草处理粗蛋白含量较对照分别增加11%、1%和7%。燕麦保护播种处理粗蛋白产量高于多花黑麦草,但燕麦对多年生牧草的生长影响大于多花黑麦草。综上,多花黑麦草单播量的30%为放牧型混播草地最佳保护草种及比例。     

放牧对青海湖北岸高寒草原植物群落特征的影响

基于青海湖北岸高寒草原连续3年放牧控制试验,研究了暖季和冷季放牧草地植物群落特征的变化。结果表明,暖季和冷季放牧草地群落地上生物量均随放牧强度的增加呈现下降趋势,禾本科地上生物量的变化趋势基本与群落地上生物量的一致;中度放牧对暖季放牧草地植被的影响程度高于冷季放牧草地;围栏封育区和冷季重度放牧草地的优势种均为紫花针茅(Stipapurpurea)和矮嵩草(Kobresia humilis),暖季放牧各放牧小区和冷季放牧草地轻度和中度放牧处理优势种均为紫花针茅和披针叶黄华(Thermopsis lanceolata);随放牧强度的增加,暖季放牧草地群落物种多样性指数和均匀度指数表现出先降低后增加的趋势,冷季放牧草地群落物种多样性指数和均匀度指数表现出增加的趋势,但是多样性指数在暖、冷季放牧草地均以重度放牧区最高。     

滩羊放牧强度对草地植被组成影响的研究

在试验区围成面积相等的5个放牧区和1个对照封育区(每区6.67hm2),每个放牧区隔成面积相等的3个小区(每小区2.22hm2)。5个放牧区放牧羊只数依次为3只、4只、5只、7只、10只。试验为期150d。试验结果如下:①放牧强度与草地禾本科牧草现存量之间存在极显著负相关关系和极显著回归关系,禾本科牧草现存量随放牧强度变化趋势是先增后减。当放牧强度为0.45只/hm2时,禾本科牧草的现存量最大。②随着放牧强度增大,禾本科牧草所占总产草量的比例减小。当放牧强度为0.45只/hm2时,禾本科牧草所占比例最大。③随着放牧强度的增大,豆科牧草所占比例呈现先减后增再减的变化趋势,即呈“V”字型。④当放牧强度逐渐增大时,杂类草变化趋势呈现“N”型变化。⑤随着放牧强度的增大,禾本科牧草比例相对降低,而豆科牧草比例相对增加,草地植被组成改变。以宁夏盐池草地现状,放牧强度不能大于0.45只/hm2。     

商会自治的基石——商会自治规范研究

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。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

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。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

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.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

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。     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …     

鸡败血支原体垂直传播模式及其阻断方法

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。     

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.