东祁连山高寒草甸优势植物光响应特征

为研究高寒地区草地优势植物旺盛生长期光合特征,选取位于祁连山东段天祝藏族自治县抓喜秀龙乡的甘肃农业大学高山草原试验站围栏禁牧草地的矮嵩草(Kobresia humilis)、垂穗披碱草(Elymus nutans)、赖草(Leymus secalinus)、扁蓿豆(Melissitus rutenica)、黄花棘豆(Oxytropis ochrocephala)、二裂委陵菜(Potentilla bifurca)和麻花艽(Gentiana straminea)7种优势植物,利用GFS-3000便携式光合测定仪拟合了7-9月的光合-光响应曲线.结果显示:由于8月份的干旱,草地植物的光合能力受到严     

Practical capability of a DNA pool‐based genome‐wide association study using BovineSNP50 array in a cattle population

Genome‐wide association mapping for complex traits in cattle populations is a powerful, but expensive, selection tool. The DNA pooling technique can potentially reduce the cost of genome‐wide association studies. However, in DNA pooling design, the additional variance generated by pooling‐specific errors must be taken into account. Therefore, this study aimed to investigate factors such as: (i) the accuracy of allele frequency estimation; (ii) the magnitude of errors in pooling construction and in the array; and (iii) the effect of the number of replicate arrays on P‐values estimated by a genome‐wide association study. Results showed that the Illumina correction method is the most effective method to correct the allele frequency estimation; pooling errors, especially array variance, should be taken into account in DNA pooling design; and the risk of a type I error can be reduced by using at least two replicate arrays. These results indicate the practical capability and cost‐effectiveness of pool‐based genome‐wide association studies using the BovineSNP50 array in a cattle population.     

南方丘陵地区人工草地和旱作农田能量物质利用率

分析比较我国南方丘陵地区人工草地和旱作农田能量和养分物质的利用效率。结果表明:在建植第1年,人工草地的能量和氮的输出量大于旱作农田;牧草可有效提高光能利用率,对辅助能和氮、磷的利用效率也显著高于后者;二者经济效益相近;种草第2年的效益比第1年更好,其能量物质输出量、利用率和经济效益都显著高于旱作农田。     

Prevalence and significance of extracellular myelin‐like material in canine cerebrospinal fluid

Background: Myelin‐like material in canine cerebrospinal fluid (CSF) specimens has been attributed to demyelinating or myelomalacic conditions. In our experience, myelin‐like material is observed frequently, especially in lumbar samples, and in a variety of disease conditions. Objectives: The objective of this study was to determine if there are associations between the presence of myelin‐like material and CSF collection site, body weight, underlying disease, and patient outcome. Methods: Wright–Giemsa‐stained cytocentrifuged specimens of CSF from the cerebellomedullary cistern (n=51) and lumbar cistern (n=47) of 98 dogs with neurologic disease were evaluated retrospectively for the presence and amount of extracellular myelin‐like material. Results were compared based on collection site, body weight, type of neurologic disease, and outcome. Results: Myelin‐like material was observed in 20/98 (20%) samples and was more frequently observed in lumbar (17/47, 36%) than cerebellomedullary samples (3/51, 6%) (P=.0028). Samples from dogs <10 kg were more likely to contain myelin (14/36, 39%) compared with dogs ≥10 kg (5/60, 8%) (P=.0052). Larger amounts of myelin‐like material were observed in CSF from dogs with intervertebral disk disease compared with other diseases (P=.045). No association was found between myelin‐like material and outcome. Conclusion: The association of extracellular myelin‐like material in canine CSF samples with sampling site and body weight suggests it is more often an artifact of collection technique and anatomy rather than the result of neurologic disease. Myelin‐like material in CSF is not associated with a poorer prognosis.     

Effects of misty‐fan cooling and supplemental rbST on rumen function and milk production of crossbred Holstein cattle during early,mid and late lactation in a tropical environment

Two groups of five crossbred 87.5% Holstein cattle were housed in normal shade only (NS) as non‐cooled cows and in shaded housing with misty‐fan cooling (MF) as cooled cows. The cows were treated with recombinant bovine somatotropin (rbST) in early, mid and late lactation with three consecutive injections of rbST in every 14 days. Ambient temperatures and the temperature humidity index in the NS barn were significantly higher than those of the MF barn, whereas relative humidity in MF was higher than that of NS barn. The DMI of cooled cows were higher than those of non‐cooled cows, and cooled cows exhibited more response to rbST treatment. Exogenous rbST significantly increased milk yield throughout lactation. The rbST‐treated cows had higher total ruminal fermentation products as volatile fatty acid and ammonia nitrogen than the non‐rbST treated cows and associated changes were greater in cooled animals in all stages of lactation. Exogenous rbST increased the concentrations of milk urea nitrogen in both groups. These results suggest that the changes in ruminal fermentation with greater production of total VFA and NH₃N in response to rbST in crossbred cows whether under misty‐fan cooling or not, is in part through an increase in feed intake, thereby making more substrate available to the mammary gland for milk synthesis.     

CONTRAST‐ENHANCED MAGNETIC RESONANCE ANGIOGRAPHY FOR DIAGNOSIS OF PORTOSYSTEMIC SHUNTS IN 10 DOGS

Computed tomography angiography, sonography, scintigraphy, and portography can be used to evaluate the portal vasculature to evaluate for a portosystemic shunt (PSS). Time‐of‐flight magnetic resonance angiography (TOF‐MRA) and contrast‐enhanced MRA (CE‐MRA) are other potentially useful techniques. The aim of this study was to evaluate CE‐MRA in 10 dogs suspected of having a PSS. Noncontrast MR images of the abdomen were obtained using a Siemens Symphony MR‐scanner (1.5 T) and a T1‐weighted FLASH‐3D sequence with a very short scan time (about 20 s). After injection of contrast medium, the initial sequence was repeated five times. The sequence with the best contrast medium filling of the portal vasculature was selected subjectively, subtracted from the initial survey image series, and a maximum intensity projection (MIP) of the subtraction data, in multiple views, was created. The cross‐sectional and MIP images were evaluated for abnormal portosystemic vasculature. A single PSS was identified and confirmed at surgery in all dogs. A portocaval shunt was found in five dogs, a portophrenic shunt in three dogs, a portoazygos shunt in one, and a central divisional intrahepatic shunt in one other dog. Based on our results, CE‐MRA is a useful tool for imaging abdominal and portal vasculature and for the diagnosis of a PSS.     

EFFECTS OF ANESTHETIC PROTOCOL ON NORMAL CANINE BRAIN UPTAKE OF 18F‐FDG ASSESSED BY PET/CT

The purpose of this study was to assess the effects of four anesthetic protocols on normal canine brain uptake of 2‐deoxy‐2‐[¹⁸F]fluoro‐d ‐glucose (FDG) using positron emission tomography/computed tomography (PET/CT). Five clinically normal beagle dogs were anesthetized with (1) propofol/isoflurane, (2) medetomidine/pentobarbital, (3) xylazine/ketamine, and (4) medetomidine/tiletamine–zolazepam in a randomized cross‐over design. The standard uptake value (SUV) of FDG was obtained in the frontal, parietal, temporal and occipital lobes, cerebellum, brainstem and whole brain, and compared within and between anesthetic protocols using the Friedman test with significance set at P<0.05. Significant differences in SUVs were observed in various part of the brain associated with each anesthetic protocol. The SUV for the frontal and occipital lobes was significantly higher than in the brainstem in all dogs. Dogs receiving medetomidine/tiletamine–zolazepam also had significantly higher whole brain SUVs than the propofol/isoflurane group. We concluded that each anesthetic protocol exerted a different regional brain glucose uptake pattern. As a result, when comparing brain glucose uptake using PET/CT, one should consider the effects of anesthetic protocols on different regions of the glucose uptake in the dog's brain.     

Surveillance of Parapoxvirus Among Ruminants in Virginia and Connecticut

In 2008, two deer hunters in Virginia and Connecticut were infected with a unique strain of pseudocowpox virus, a parapoxvirus. To estimate the prevalence of this virus, and in an attempt to define the reservoir, Parapoxvirus surveillance was undertaken between November 2009 and January 2010. 125 samples from four ruminant species (cows, goat, sheep and white‐tailed deer) were collected in Virginia, and nine samples from white‐tailed deer were collected in Connecticut. We found no evidence that the parapoxvirus species that infected the deer hunters is circulating among domesticated ruminants or white‐tailed deer. However, parapoxvirus DNA of a different parapoxvirus species, bovine papular stomatitis virus (BPSV), was detected in 31 samples obtained from asymptomatic cattle in Virginia. Parapoxvirus DNA–positive cattle originated from the same counties indicating probable transmission among animals. Molecular analysis identified BPSV as the parapoxvirus affecting animals. Asymptomatic parapoxvirus infections in livestock, particularly young animals, may be common, and further investigation will inform our knowledge of virus transmission.     

违规放牧行为的博弈分析及对策研究

中国超过1/3的天然草地处于退化、沙化状态。退牧还草政策是应对草地退化的重要措施。退牧还草政策实施过程中常有违规放牧现象。本文采用博弈论方法,分析牧户和政府双方的策略集合,得出最优策略,并进行模拟计算。结果表明：提高违规放牧被检查到的概率,降低检查成本和增加罚款金额等措施,可促使牧户减少违规放牧行为。据此,我们提出减少或者杜绝违规放牧行为的措施主要包括：规划安置点将牧户由分散居住转为集中居住;违规放牧行为的检查工作由社会招聘监察人员和牧户监督员承担;划定管护责任区域,由常驻人员进行管护区域内的违规放牧检查工作;根据各地具体情况,设置合理罚款金额。本研究可为制定遏制违规放牧的对策提供依据,促进草原地区人口、资源和环境的协调发展。