Cultivation and grazing altered evapotranspiration and dynamics in Inner Mongolia steppes

To examine the effects of cultivation and grazing on evapotranspiration (ET), continuous measurements of ET were conducted over almost two years, from December 2005 to September 2007, using the eddy-covariance technique in two paired ecosystems: a steppe and a cropland in Duolun and a fenced and a degraded steppe in Xilinhot, Inner Mongolia, China. The ET of the four ecosystems approached or exceeded precipitation in both years. During the growing season (May–September), cultivation reduced the ecosystem ET in Duolun by 15% in the wet year (2006) and 7% in the dry year (2007). Grazing reduced the ET of the steppe in Xilinhot by 13% during the growing season of 2006, while there was similar ET between the degraded and fenced steppes in 2007. The low soil moisture in the cropland and the degraded steppe compared with the steppe at each area was the reason for the decrease in ET of the steppe ecosystems. In addition, a shorter growing period during the growing season, due to the changes in type and phenology characteristics of the vegetation associated with cultivation, was suspected for the reduction in ET in Duolun. The low soil moisture, due to the low precipitation in the dry year, limited vegetation growth and decreased canopy surface conductance (g_c), resulting in reduced plant transpiration. In addition, cultivation and grazing increased the sensitivity of ET to soil moisture in the dry year, suggesting that future changes in precipitation would not only affect ET by changing soil moisture directly, but would also influence the relationship between ET and soil moisture.     

链霉菌3-10发酵液及提取物的稳定性研究

为合理利用链霉菌3-10的代谢产物,本研究采用不同极性的有机溶剂提取链霉菌3-10发酵液中的抗真菌物质并得到发酵液的提取物.在此基础上测定了温度、紫外线辐射、酸碱度和贮存条件对3-10抗真菌物质稳定性的影响.结果表明,乙酸乙酯为最佳提取溶剂,链霉菌3-10发酵液的乙酸乙酯提取物对灰霉病菌菌丝生长的抑制作用最强,提取后余...     

Plasma Progesterone Profile in Ovariectomized Beef Cows after Intra-vaginal Insertion of New, Once-used or Twice-used CIDR

Objective of this study was to show plasma progesterone concentrations in ovariectomized beef cows after treatment with new, once-used and twice-used controlled internal drug-releasing devices (CIDRs). Four ovariectomized beef cows were used for the experiment. Plasma concentrations of progesterone were quantified using a validated ELISA. The CIDR was inserted into vagina of cows by using a standard CIDR applicator and then removed 7 days after insertion. One week later, once-used CIDR was inserted and removed on day 7. Twice-used CIDR was, then inserted at an interval of 7 days. Mean plasma concentrations of progesterone 24 h after new CIDR insertion was 4.0 ± 0.1 ng/ml, which thereafter decreased gradually to 1.4 ± 0.1 ng/ml at day 7. In cows treated with once-used CIDR or twice-used CIDR, mean plasma progesterone concentrations at day 1 were 2.4 ± 0.2 or 1.8 ± 0.2 ng/ml and 1.0 ± 0 or 0.9 ± 0.1 ng/ml at day 7 respectively. The results suggest that once-used CIDR may be still effective to produce luteal phase progesterone concentrations in plasma in non-suckling beef cows.     

Kinetics of substrate oxidation and hydrogen peroxide production by Mycoplasma mycoides subsp. mycoides Large Colony (LC) type and Mycoplasma mycoides subsp. capri

Mycoplasma mycoides subsp. mycoides Large Colony (LC) type is a pathogen of goats causing contagious agalactia and respiratory disease, found on all continents where small ruminants are kept. It shares close genetic characteristics with M. mycoides subsp. capri. Substrate oxidation by 22 strains of M. mycoides subsp. mycoides LC from nine countries was compared with that of eight strains of M. mycoides subsp. capri from five countries. There was considerable similarity in the substrates used, but substrate saturation coefficients (K_s) varied for different substrates. Substrate utilization patterns and K_s values did not (1) significantly differentiate the LC strains from each other, (2) show any correlation with geographical origin, or (3) distinguish the LC strains from the capri strains. These results support previous studies justifying the reclassification of these subspecies as a single species.     

沼液对辣椒病害的防治效果及其产量的影响

为了探讨沼液对辣椒主要病害的控制效应及产量的影响,使用沼液与农家肥液进行了田间对比试验.结果表明:沼液灌根与清粪水灌根相比较,能使辣椒增产29.75%,极显著降低辣椒炭疽病、白斑病、黑斑病和青枯病的发生;沼液灌根+叶面喷施对辣椒炭疽病、白斑病、黑斑病的防效和增产效果优于沼液灌根处理,与清粪水灌根相比增产幅度达58.22...     

画眉草研究进展

画眉草Eragrostis pilosa是重要的牧草和草坪草,世界上许多国家都对画眉草进行了系统的研究,而国内对画眉草研究的报道较少。我国对画眉草的研究起步比较晚,主要集中在种子发育、抗性方面的研究,国外对画眉草的种子发育、利用方式、栽培方式、抗旱性、施氮量对画眉草产量的影响、画眉草叶片光合特性、遗传多样性等方面都进行了系统的研究。对国内外画眉草的研究和栽培种植的现状介绍,旨在为今后我国画眉草种质资源的进一步开发、利用提供科学合理的理论指导和借鉴依据,以供国内画眉草研究工作者学习和借鉴。     

浅谈《草原管理学》课程的发展历史与教学改革实践

介绍了畜牧业发达国家的《草原管理学》课程的起源与发展,对我国草业科学专业及《草原管理学》的发展历程进行了回顾,并对当前的发展现状进行了分析,提出课程改革应与时俱进的观点。高等教育的目的就是要培养符合国家及社会发展需要的复合型人才。结合沈阳农业大学草业科学系《草原管理学》课程的建设、改革与发展的实例,充分说明了通过与时俱进的课程内容和授课手段的教学研究与改革,对于培养适应时代发展需要的高素质草业人才具有重要的意义。     

奶牛全混合日粮添加过瘤胃脂肪饲养效果对比试验研究

[目的]为了研究日粮中添加过瘤胃脂肪能够有效降低奶牛产后负平衡效果.[方法]本试验选用围产期(产前3～4周)健康的奶牛48头,按照年龄、体重、胎次、体况评分、预产期相同或相近的原则,参考上胎产奶量或母亲产奶量等指标随机分为试验组和对照组,在试验组日粮中添加过瘤胃脂肪300 g/头·日,试验期145 d.[结果]表明:试验组日产奶量提高1.96 kg,产后初次配种间隔缩短8.86 d,差异极显著(P＜0.01);对奶牛体况的改善也有一定的作用,特别是对头胎牛的体况改善明显.[结论]在奶牛全混合日粮中添加过瘤胃脂肪可提高奶牛产奶量、繁殖性能,改善体况.     

Mycoplasma bovis and otitis in dairy calves in the United Kingdom

Signs of severe otitis media in 20% of dairy calves on one farm were associated with Mycoplasma bovis infection, based on isolation from the external ear canal and nares. Affected calves seroconverted to M. bovis and no other significant bacteria were isolated. Infection was considered likely to have originated from cows in the milking herd based on evidence of seroconversion and detection of infection in a milk sample. M. bovis infection should be considered when investigating otitis problems in calves.