非洲猪瘟自然弱毒株演变进程

自2018年非洲猪瘟(African swine fever,ASF)传入中国以来疫情得到了有效控制.但2021年以后,我国的ASF流行情况出现了新的变化,临床中出现了"自然变异株".这些毒株可能导致感染后临床症状不典型,容易与其他疫病混淆等问题.这与国外的流行演变规律一致,即当ASF在一个国家或地区流行较长时间后,其...     

高校音乐资料的管理趋向分析

针对当今信息时代信息传播和管理现状、音乐资料的特殊性以及信息化管理模式所具有的优越性三个方面进行分析,得出高校音乐资料的管理趋向是进行信息化管理模式。     

Use of real-time PCR to examine the relationship between disease severity in pea and <Emphasis Type="Italic">Aphanomyces euteiches</Emphasis> DNA content in roots

Aphanomyces euteiches causes severe root rot of peas. Resistance is limited in commercial pea cultivars. Real-time fluorescent PCR assay specific for A. euteiches was used to study the relationship between disease severity and pathogen DNA content in infected peas. Five pea genotypes ranging in levels of resistance were inoculated with five isolates of A. euteiches. Plants were visually rated for disease development and the amount of pathogen DNA in roots was determined using the PCR assay. The susceptible genotypes Genie, DSP and Bolero tended to have significantly more disease and more pathogen DNA than the resistant genotypes 90-2079 and PI 180693. PI 180693 consistently had less disease, while 90-2079 had the lowest amount of pathogen DNA. The Spearman correlation between pathogen DNA quantity and disease development was positive and significant (P < 0.05) for three isolates, but was not significant for two other isolates. This suggests that the real-time PCR assay may have limited application as a selection tool for resistance in pea to A. euteiches. Its utility as a selection tool would be dependent on the correlation between disease development and pathogen DNA content for a given pathogen isolate. The accuracy and specificity of the real-time PCR assay suggests considerable application for the assay in the study of mechanisms of disease resistance and the study of microbial population dynamics in plants.     

Comparison of calculated and experimentally determined SID of CP and AA in complex diets differing in AA contents for grower finisher pigs

In practice, the content of standardized ileal digestible AA in complex feeds for pigs is calculated on the basis of tabulated values for individual feedstuffs. It comes into question, however, whether this truly reflects an accurate content based upon the estimate made for the individual feedstuffs. The objective of this study was to compare standardized ileal digestibility (SID) of crude protein (CP) and selected AA in complex feeds for grower and finisher pigs either calculated or experimentally determined. Six diets with increasing AA levels were prepared for grower (BW from 30 to 70 kg) and finisher (BW from 70 to 120 kg) feed. Crystalline L‐lys, DL‐met and L‐thr were added to both diets, L‐trp and L‐val only to the grower feed. SID of both CP and AA was calculated from feed tables and experimentally determined in six adult minipigs (MINILEWE) with ileorectal anastomosis. With increasing AA levels, experimentally determined SID of supplemented AA increased (p < 0.05), but SID of CP (p ≥ 0.05) was not affected. In both grower and finisher feed, calculated and experimentally determined SID of CP, Met, Cys, Trp, Ile and Tyr differed by more than 2% units, but those of Lys and His only in the finisher feed. Yet this effect was not directly consistent. The margin of error following estimation of SID of AA via tabulated values for individual feedstuffs, however, seems to be acceptable for practical use.