Isolation of Pasteurella haemolytica and correlation with serum antibody response in clinically normal beef calves

Bacteria from the nasal cavity and trachea were cultured, and serum antibody titers determined for Pasteurella haemolytica serotype 1 in 164 beef calves obtained from a closed herd on range pasture. At the first sampling, P. haemolytica serotype 1 was cultured from 16.4% of the calves. Antibody titers were determined by a quantitative fluorimetric method and the mean titer was 9.5 +/- 5.8. Fifty-seven randomly selected calves were used to study the correlation of serum antibody response and positive culture of P. haemolytica under natural conditions. Clinical signs of respiratory disease were not observed in those calves. During the observation periods, there was a two-fold increase in the percentage of calves that were culture positive. There was no significant difference between mean serum antibody titers or frequency distribution of antibody titers from the two samplings. Comparisons between serum antibody titers, rise in titers, and P. haemolytica isolation failed to reveal any significant correlation. Of the 9 calves that had a decline in antibody titer to P. haemolytica, none was culture positive. Seroconversion to respiratory viruses did not correlate with P. haemolytica related variables.     

Nondestructive Estimation of Standing Crop and Fuel Moisture Content in Tallgrass Prairie

Accurate estimation of standing crop and herbaceous fuel moisture content (FMC) are important for grazing management and wildfire preparedness. Destructive sampling techniques have been used to accurately estimate standing crop and FMC, but those techniques are laborious and time consuming. Existing nondestructive methods for estimating standing crop in tallgrass prairie have limitations, and few studies have examined nondestructive estimation techniques for FMC in this environment. Therefore, our objective was to develop robust models for nondestructive estimation of standing crop and FMC in tallgrass prairie. We calibrated and validated stepwise multiple linear regression (SMLR) and artificial neural network (ANN) models for standing crop and FMC using data collected in tallgrass prairies near Stillwater, Oklahoma. Day of year (DOY), canopy height (CH), Normalized Difference Vegetation Index (NDVI), and percent reflectance in five wavelength bands were candidate input variables for the models. The study spanned two growing seasons and nine patches located within three pastures under patch burn management, and the resulting data set with > 3 000 observations was split randomly with 85% for model calibration and 15% withheld for validation. Standing crop ranged from 0 to 852 g m^? 2, and FMC ranged from 0% to 204%. With DOY, CH, and NDVI as predictors, the SMLR model for standing crop produced a root mean squared error (RMSE) of 119 g m^? 2 on the validation data, while the RMSE of the corresponding ANN model was 116 g m^? 2. With the same predictors, the SMLR model for FMC produced an RMSE of 26.7% compared with 23.8% for the corresponding ANN model. Thus, the ANN models provided better prediction accuracy but at the cost of added computational complexity. Given the large variability in the underlying datasets, the models developed here may prove useful for nondestructive estimation of standing crop and FMC in other similar grassland environments.     

Effect of cutting frequency on above‐ and belowground biomass production of Rumex alpinus,R. crispus,R. obtusifolius and the Rumex hybrid (R. patienta × R. tianschanicus) in the seeding year

Rumex species are important weeds in grasslands and on arable land. The Rumex hybrid (R. patienta × R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in the Czech Republic, but its ecological requirements and its potential to become a new weedy species have never been investigated. In 2010 and 2011, we performed a pot experiment to investigate the effect of none, one and two cuts per year on biomass production of Rumex OK‐2 and common broad‐leaved Rumex species (Rumex obtusifolius, R. crispus and R. alpinus). The higher cutting frequency can reduce the belowground biomass, but no effect on the aboveground biomass was detected. Flowering in the seeding year was recorded in only 50% of R. obtusifolius plants. Non‐flowering R. obtusifolius plants produced significantly more belowground biomass than flowering plants under no cutting or one cut treatments. The growth response of Rumex OK‐2 to different cutting treatments was very similar to R. crispus. These similarities indicate the weed potential of the hybrid to become a troublesome weedy species, similar to R. crispus.     

Dynamics of above‐ground and below‐ground biomass of Rumex crispus,Rumex obtusifolius and the new weedy species Rumex hybrid cv. OK‐2 (R. patientia x R. tianschanicus) in the seeding year

Docks can be serious weeds of arable land and permanent grasslands where they can persist through well‐established root systems. A Rumex hybrid (R. patientia x R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in Czechia and has now become a new weed species. As its ecological characteristics are unknown, there is a need for improved knowledge for developing control measures and strategies. In 2010 and 2011, we performed a tube pot experiment to investigate above‐ground and below‐ground biomass growth dynamics and below‐ground biomass allocation of Rumex OK‐2. We compared the hybrid with Rumex crispus and Rumex obtusifolius during the vegetation season in the seeding year. Above‐ground and below‐ground biomass of Rumex species tended to increase from July to September. In the seeding year, flowering was recorded only for one plant of Rumex OK‐2 and 27.5% of R. obtusifolius plants, whereas R. crispus did not flower. The proportion of below‐ground biomass of Rumex species in the upper 30 cm was about 70–80%. The growth dynamics and allocation of below‐ground biomass of Rumex OK‐2 were more like R. crispus than to R. obtusifolius. These similarities indicate the potential of Rumex OK‐2 to become a troublesome weedy species, comparable with R. crispus.     

基于改进OK模型的土壤有机质空间分布预测——以宜都市红花套镇为例

选择合适的土壤有机质（SOM）预测模型是提高区域化空间分布模拟精度的前提,也是监测土壤碳库动态变化和指导农田土壤肥力投入的基础。以湖北宜都红花套镇柑橘区为例,设置普通克里格（OK）插值的SOM结果作对照,分别建立SOM及其最显著相关辅助变量碱解氮间的建模协同克里格（COK₁）、全局协同克里格（COK₂）和两个融合辅助变量协同相关性的改进OK模型（CCOK₁、CCOK₂）,探讨纳入辅助变量、改变辅助信息插值数量以及结合辅助变量协同相关性对SOM含量预测的影响。结果表明：1）OK、CCOK₁和CCOK₂的块基比为25%~75%,表现出中等空间自相关性,而COK₁和COK₂的块基比小于25%,具有强烈的空间自相关,SOM的空间异质性受结构性因素影响的比重更大。2）SOM的预测含量范围为7.38~29.03 g·kg^-1,使用COK₁和COK₂模型插值获得的有机质空间分布较OK更为破碎,CCOK₁和CCOK₂的插值结果则呈连续片状分布,更符合研究区土地利用类型分布的实际情况。3）SOM的空间分布预测精度由高到低依次为CCOK₁ ≈ CCOK₂ > COK₂ > COK₁ ≈ OK,OK和COK₁两者精度指标相近,COK₂的拟合效果有一定改进,但CCOK₁和CCOK₂的相关系数（r）分别从0.10升高到0.70和0.69,均方根误差（RMSE）分别降低了15.40%和14.78%,预测精度最高。因此,本研究提出的融合辅助变量协同相关性的改进OK模型的估算效果最优且在最大程度上提高辅助信息的参与度,可为SOM预测提供参考。     

Pasteurella haemolytica: purification of saline-extractable proteins by isoelectrofocusing

A procedure was developed for separating antigens associated with a saline extract of Pasteurella haemolytica serotype 1. Seven antigens were identified by immunoelectrophoresis to be associated with the extract. The extract was subjected to preparative isoelectrofocusing in a pH range of 3-10. The majority of extracted proteins were found to have pI's of 4-6, whereas the carbohydrate antigen(s) were distributed over a pI range of 3.0-8.0. The fractions that were of interest were pooled and refocused in a narrower pH range to improve resolution of the protein antigens. Specific antigens from defined pH ranges were pooled to form 6 antigen groups. These antigen groups were examined further by immunoelectrophoresis, analytical isoelectrofocusing, and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The molecular weights of the proteins found in the capsular extracts ranged from 33 k to greater than 80 k. Injection of mice with capsular extract or antigen Groups 1-6 in Freund's incomplete adjuvant resulted in a serum antibody response to the various antigens as detected by an enzyme-linked immunosorbent assay. Significant protection (P less than 0.05) against challenge with virulent P. haemolytica was seen in mice injected with antigen Groups 2 and 4. Six calves were immunized with saline extract. These calves had greater resistance to experimental pneumonic pasteurellosis than did 6 non-vaccinated calves. A serum antibody response to the crude extract and to each antigen group was detected in vaccinated calves by an enzyme-linked immunosorbant assay.     

海伦市耕层土壤有机质含量空间预测方法研究

有机质含量是表征土壤肥力质量的重要属性,其空间分布模式对于施肥等耕作管理措施的推荐具有重要的指导意义。本文以我国黑土区黑龙江省海伦市为研究区域,在土壤采样点数量较有限的情况下,分别采用普通克里格、反距离权重、遥感反演和基于土壤学专业知识四种方法对耕层土壤有机质含量进行了空间预测。结果表明:四种方法表征的海伦耕地土壤有机质含量空间分布特征具有相似性,即由东北向西南方向递减。空间预测精度从高到低依次为反距离权重、普通克里格、基于土壤学专业知识和遥感反演法;而在有机质的局部变异细节表达方面,从高到低为遥感反演、基于土壤学专业知识、反距离权重和普通克里格法。四种方法中仅遥感反演法预测结果的极差范围较宽,普通克里格法则存在明显的平滑效应,而综合比较结果则表明,最合适的方法是基于土壤学专业知识的方法。     

土壤速效钾空间模拟的技术方法研究

采用GIS和地统计学中的普通克里格插值(Ordinary Kriging)和序贯高斯模拟方法(SGSV单次实现和SGSA平均实现)对河南省封丘县土壤速效钾的空间变异特征进行了分析研究。结果表明,Kringing插值具有明显的平滑效应;SGSV模拟与实测数据具有相似的空间自相关结构,既尊重了实测数据,又可以再现区域化变量的空间波动性;SGSA在一定程度上能够消除平滑效应的影响,同时还能兼顾实测数据的结构性特征。因此,SGSA模拟在土壤速效钾空间结构的研究中,能够达到更好的效果。     

南方丘陵耕地土壤有机质空间插值精度比较——以衢江区为例

以浙江省衢江区的耕地地力调查有机质数据为基础,比较分析普通克里格（OK）和反距离加权插值法（IDW）的有机质插值精度。研究结果表明,在同样的数据处理条件下,反距离加权插值优于普通克里格;在同一插值方法下,对按地形地貌分类、按耕地利用方式分类与整体不分类型3种情况比较,按耕地利用进行分类处理略优于按地形地貌分类处理,而按耕地利用分类和按地形地貌分类后插值精度均明显优于整体不分类型处理。     

气象要素空间插值方法的比较分析

气象要素是草原综合顺序分类中重要的指标,对生态系统中物种的组成、生长、演替更新及干物质的积累有很大的影响.年均温度、年降水量、年积温空间分布的一般规律是随海拔高度和纬度的增加而减少,但不同插值方法所计算出的空间插值之间,却有明显的不同.用ArcMap 8.3地理信息系统软件,对全国及周边地区2 114个气象台(站),1961-1990年30年的年均温度、年积温和年降水量,分别采用样条函数法(Spline)、反距离加权平方法(IDS)和普通克里金法(OK)进行空间插值分析.交叉验证结果表明:当选择合适的站点数目时,3种方法的精度都很高.在克里金法中,除高斯模型精度较低外,球状模型、环状模型、指数模型对同一气象因素插值,其相对平均误差也不大.3种插值方法的比较是,年均温度插值时,OK法优于Spline法,Spline法优于IDS法,相对平均误差分别为7.65%、7.9%和7.95%;年降水量插值时,OK法优于Spline法和IDS法,相对平均误差分别为8.31%、8.76%和8.76%;年积温插值时,OK法优于IDS法,IDS法优于Spline法,相对平均误差分别为5.82%、6.11%和6.13%.