我国北方荒漠化土地面积及其不同成因的比例

我国北方荒漠化土地面积共达 3× 10 5ｋｍ2 以上。其中历史时期形成的荒漠化土地面积为 1.2× 10 5ｋｍ2 ,占荒漠化土地面积的 4 8.2 %。不当的人为活动是造成现代荒漠化土地的主要原因 ,其成因和所占比例为 :草原过度农垦 2 3 .3 % ,过度放牧 2 9.4 % ,过度采薪 3 2 .4 % ,水资源利用不当 8.6% ,工交建设引起 0 .8% ,自然风力条件下沙丘的前移入侵 5.5%。我国北方荒漠化土地面积及其不同成因的比例@蔡运龙     

飞播种草是加快黄土高原综合治理改善生态环境的有效措施

延安市属黄土高原丘陵沟壑区 ,地形地貌复杂 ,沟壑纵横 ,植被稀疏 ,水土流失严重 ,水土流失面积 2 .88× 1 0 4ｋｍ2 ,占总土地面积的 78.4% ,全市河流入黄泥沙达 2 .5 8× 1 0 8ｔ,占全省入黄泥沙总量的 30 %以上。为了加快草地改良步伐 ,1 979年以来 ,在农业部、省农业厅、财政、民航等部门的关心支持下 ,开展了飞机播种牧草试验 ,开辟了草地建设的新途径。先后在 5县飞播牧草近 4.0×1 0 4ｈｍ2 ,并取得了明显的经济效益和社会、生态效益。延安市土地面积大 ,许多宜草区地广人稀 ,交通不便 ,群众生活比较贫困 ,植被稀疏 ,水土流失严重。…     

发展家庭适度规模养殖是干旱地区农民解决温饱的重要途径

秦安县是甘肃省中部十八个干旱县之一，属陇中黄土高原西部梁峁沟壑区，人多地少，自然资源贫乏，群众生活比较困难。全县辖２２个乡镇，总人口５５２３万人，其中乡村人口５２７１万人，人口密度３４５人／ｋｍ２，总土地面积１６０１６ｋｍ２，耕地占总土地面积的...     

平凉地区生态环境保护与畜牧业可持续发展对策探讨

甘肃省平凉地区地处黄土高原 ,地形多为丘陵沟壑 ,属温和干旱大陆季风气候 ,适合多种牧草的生长 ,具有发展畜牧业得天独厚的自然资源。但是 ,由于距海遥远 ,气候干旱 ,植被较差 ,水土流失严重。由于历史原因和自然灾害频繁 ,生态环境日趋恶化 ,水土流失面积近 1万ｋｍ2 ,部分地方人为破坏严重。如平凉市南部山区以前丰富的天然草场由于多年来人为破坏及超载过牧而正以每年 2 %的速度退化 ,森林→次森林→灌木丛→山地草场→……现已到了荒漠化的边缘。而北部塬区植被覆盖率不足 1 8% ,连续几年的干旱更是引起人畜饮水困难。近年来 ,随着城镇…     

乐都县草地高原鼢鼠的危害与防治对策

青海省乐都县草地面积占土地总面积的 6 0 .31% ,长期以来 ,高原鼢鼠对全县草地、林地和山区农田危害较为严重 ,对生态和经济造成了一定的损失。特别是对近几年退耕地种植的苜蓿、沙棘等植物的破坏非常严重 ,对生态建设工程影响较大。为此 ,近几年我们大力开展了草地灭鼠工作 ,现将防治鼠害过程中的体会总结如下。1　高原鼢鼠对草原的破坏情况乐都县位于青海省东部 ,属湟水中下游地区。海拔 185 0～4 4 85m。草原类型有高寒草甸类和山地草甸类。据调查 ,全县高原鼢鼠危害草地和退耕还草地面积 5 .0 5万hm2 (危害退耕还草地 0 .30万hm2 )。其…     

鄂尔多斯市发展生态农牧业的现状与建议

内蒙古鄂尔多斯市位于内蒙古西南部,东侧是南北走向的吕梁山和芦芽山,西边则是贺兰山和西卓子山,北缘有东西走向并呈弯月型的阴山山脉,南靠东西走向的秦岭山脉北坡。地理坐标为北纬37°35'24″～40°51'40″,东经106°42'40″～111°27'20″。现设东胜区、达拉特旗、准格尔旗、伊金霍洛旗、杭锦旗、乌审旗、鄂托克旗、鄂托克前旗,其总面积8.7万多km2,而沙漠化土地面积就有4.3万km2,占全市总土地面积的48.8%,其中强度沙漠化面积2.77万km2,水土流失面积4.7万km2,其中堪称“世界水土流失之最”的砒砂岩裸露区约2万km2。其严重水蚀风蚀区总面积7…     

退耕还草保水土以草养畜发“洋财”

云阳县位于重庆市三峡库区腹心 ,东连奉节 ,西接万州天城、五桥 ,南与湖北利川相临 ,北与开县、巫溪接壤 ,浩瀚长江东西横贯全境 ,流程 6 8.1ｋｍ。该县也是国贫山区农业大县 ,全县 12 5万多人 ,农业人口占总人口的 91% ,幅员面积 36 49ｋｍ2 ,其中荒山草坡 14 .73万ｈｍ2 ,占幅员面积的 40 .2 % ,农业用地总面积 8.74万ｈｍ2 ,其中 2 5°以上的坡耕地 5 .0 2万ｈｍ2 ,占农业用地总面积的 5 7.0 4%。由于山大坡陡 ,加上过度开垦 ,生态环境很差。全县森林覆盖率只有 2 1% ,水土流失面积高达 2 5 14ｋｍ2 ,占幅员面积的 6 8.92 % ,每年土壤流…     

我市畜牧业发展的优势

陕西省榆林市位于陕西省最北部,地处陕甘宁蒙晋五省区接壤地带,东临黄河与山西相望,西连宁夏、甘肃,北邻内蒙,南接本省延安市。地域东西长385km,南北宽263km,总土地面积43578km2。黄河沿东界南下涉境270km,长城横贯东西700km。地貌大体以长城为界,北部为风沙草滩区,占总面积的42%;南部为黄土丘陵沟壑区,占58%。平均海拔1000至1500m。榆林地处毛乌素沙漠和黄土高原过渡地带,风蚀、沙化和水土流失严重,是黄河中上游水土流失最严重的地区之一,是国家“三北”防护林建设和重点流域治理区、全国生态环境建设和国家退耕还林还草重点地区。境内主要河流有无定河、秃尾河、窟野河、佳芦河,北部沙区有200多个内陆湖泊,属暖温带和温带半干旱大陆性季风气候,四季分明,日照时间长,年平均日照时数为2593～2914h。是养殖业发展的理想之地。     

我国北方沙漠化概况、沙区地貌与气候特征

1　沙漠及土地沙漠化概况我国北方 1 1省沙区共有沙漠 (包括风蚀沙地 )、戈壁及沙漠化土地 1 33.84万 km2 ,占沙区总面积 30 8.1 3万 km2 的 43.44%。其中沙漠 (沙丘、风蚀沙地 ) 5 9.2 5万 km2 ,占全国沙漠与沙漠化土地总面积的 44.2 7% ;戈壁 5 6.95万 km2 ,占沙漠及沙漠化土地面积的 42 .5 5 % ;已沙漠化土地1 7.64万 km2 ,占沙漠及沙漠化土地的 1 3.1 8%。根据朱震达先生等研究把我国东、中部沙地列入为历史时期由于人为利用植被不当而形成的沙漠化土地 ,笔者据此原则对有关省区沙漠面积作了调整。解放后由于人畜压力加大 ,对沙区植被利用过度 ,而沙区东、中部水热条件好 ,农牧业发展迅速 ,草地被广泛开垦为农田、牲畜的超载过牧与樵采植被作薪柴等越趋严重 ,故我国东、中部沙区成为全国土地沙漠化发展迅速地区 ,见表 1。表 1　我国沙区沙漠、戈壁及已沙漠化土地面积　省、区名称总面积面积(万 km2 )占总面积( % )沙漠面积(万 km2 )占总面积( % )戈壁面积(万 km2 )占总面积( % )已沙漠化土地面积(万 km2 )占...     

内蒙古草原蝗虫形成大暴发之势

据内蒙古自治区草原站报告 :由于去年暴发蝗灾面积达 6 93.3万ｋｍ2 ,防治面积 15 9.5 7万ｋｍ2 ,仅占灾害面积的 2 2 % ,造成残蝗基数大。 2 0 0 2年蝗虫再次大面积暴发 ,发生期将比往年有所提前。蝗灾面积预测　全区草原蝗灾面积将达6 94 .2万ｋｍ2 ,将涉及 11个盟 (市 ) 4 2个旗 (县、市、区 )。其中 :锡盟 393.2 7万ｋｍ2 、赤峰市 80万ｋｍ2 、兴安盟 75 .33万ｋｍ2 、通辽市 6 6 .6 7万ｋｍ2 、呼伦贝尔市 33.33万ｋｍ2 、乌盟 10万ｋｍ2 、包头市8.33万ｋｍ2 、巴盟 8万ｋｍ2 、呼市 7.9万ｋｍ2 、伊盟6 .6 7万ｋｍ2 、阿盟 4 .6 7万…     

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。     

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.     

Mechanism of Action of Probiotic Function of Lactobacilli

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.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis.