优氯净对苏云金杆菌伴孢晶体消毒效果及机理的研究

苏云金杆菌(Bacillus thuringiensis,简称BT菌)的伴孢晶体被优氯净液处理后,在相差显微镜下观察,失去暗蓝色光泽,呈暗黑色,难溶于碱性缓冲液。虽能溶于昆虫的胃液,却失去致病性。用扫描电镜和SDS—聚丙烯酰胺凝胶电泳进一步研究,结果表明:优氯净能破坏伴孢晶体蛋白的一级和立体结构,使晶体蛋白失活,达到消毒的目的。消毒能力测定结果表明:1毫升0.03％有效氯优氯净液在3分钟内能消毒50微升BT菌液(3μg伴孢晶体/μl菌液)。消毒BT菌污染桑叶,用0.01％有效氯优氯净液浸泡3分钟即可。考虑到生产上的安全性,我们建议用0.05％有效氯优氯净消毒3—5分钟。     

Efficacy of oxolinic acid and other bactericides in suppression ofErwinia amylovora in pear orchards in Israel

The efficacy of oxolinic acid (at 200 and 300 μg a.i./l) and of several antibiotic compounds (streptomycin sulfate at 100 μg a.i./l, glycocide B at 700 μg a.i./l, kasugamycin at 80 μg a.i./l and gentamicin sulfate at 30 and 60 μg a.i./l) againstErwinia amylovora, the causal agent of fire blight in pears, was evaluated in 43 orchard experiments in 1997–2000 in Israel. In addition to the above orchard experiments, the efficacy of the bactericides was tested in live experiments with artificial inoculation. Natural fire blight symptoms were observed in 16 of the 43 experiments; in 13 of them, disease intensity and its distribution among the experimental plots provided a basis for data analysis, leading to reliable conclusions concerning the efficacy of the tested bactericides. Oxolinic acid at 300 μg a.i./l was highly effective againstE. amylovora and reduced disease severity significantly in all experiments, as compared with the untreated plots; however, a concentration of 200 μg a.i./l was not effective in some cases. Among the tested antibiotics, only gentamicin sulfate was as effective as oxolinic acid. Results of the artificial inoculation experiments corroborated those obtained in the naturally infected orchards. The pre-infection activity of oxolinic acid was determined on blossom clusters that were sprayed with the bactericide before inoculation. Control efficacy on blossom clusters sprayed 1–4 days before inoculation ranged from 68% to 80%, a level which did not differ significantly from that observed on blossom clusters sprayed on the day of inoculation (80% control). The postinfection activity of oxolinic acid was determined on blossom clusters that were sprayed with the compound after inoculation. Oxolinic acid was as effective when applied 1 or 2 days after inoculation as when it was applied on the day of inoculation; however, application of the bactericide 3 days after inoculation no longer resulted in significant disease suppression. Oxolinic acid has been used commercially in Israel since 1998 with appreciable success. Contribution No. 533-00 from the Agricultural Research Organization     

Estimation of genetic parameters for lactational milk yields using two-dimensional random regressions on parities and days in milk in Chinese Simmental cattle

A two‐dimensional random regression model with regressions on days in milk (DIM) and parity number was applied to lactational milk yields in Chinese Simmental cattle. Random regressions were fitted for additive genetic and permanent environmental effects using a two‐dimensional polynomial on DIM and parity number. A total of 4340 lactational milk yields from Chinese Simmental cattle which calved between 1980 and early 2000 were used in this study. Variance components were estimated using Bayesian methodology via Gibbs sampling. Variances of random regression coefficients associated with all terms of the polynomials were significant. A covariance function showed that heritabilities of lactational milk yields between 200 and 400 DIM over parities varied between 0.25 and 0.45. Heritabilities of 305‐day milk yields from 1st to 6–8th parities were 0.28, 0.30, 0.32 0.32, 0.32, and 0.31, respectively. Ratios of permanent environment variances to total variances at each DIM were greater than corresponding heritabilities. Generally, genetic correlations were higher between lactational milk yields with similar DIM and parity number.     

Influence of S. babylonica extract on feed intake, growth performance and diet in vitro gas production profile in young lambs

An experiment was completed to determine the effect of Salix babylonica (SB) extract supplementation to the diet of growing lambs. Eighteen Katahdin × Pelibuey male lambs (14?±?2 kg live body weight) were divided randomly in individual cages into three groups and fed three diets varying in SB: a control group was fed on total mixed ration (TMR) without SB (SB0), an SB25 group was fed on TMR plus SB extract at 25 mL/lamb/day, and an SB50 group was fed on TMR plus SB extract at 50 mL/lamb/day on dry matter intake (DMI), average daily gain (ADG), feed efficiency, and in vitro gas production (GP) in lambs fed on TMR. In vitro GP of the TMR fed to lambs was recorded at 2, 4, 6, 8, 10, 12, 24, 48, and 72 h of incubation with 0, 0.6, 1.2, and 1.8 mL extract per gram of DM. Addition of SB extract at low and high doses improved the DMI of lambs by 59.9 and 33.2 %, respectively. Relative to the control, low and high extract doses achieved greater lamb ADG during the experimental period. The asymptotic GP increased (P?<?0.05) with increasing dose of SB extract without affecting the rate of GP or the initial delay before GP begins. Linear increases for in vitro GP with advancing time with different SB extract doses were observed. It is suggested that the use of S. babylonica extract with the rate of 25 mL/lamb/day is beneficial to young lamb’s performance growth and thus can be safely used as a feed additive in diets without any negative effects on animal health.     

Chlamydiales in guinea-pigs and their zoonotic potential

The aim was to detect and characterize chlamydial infections in guinea-pigs (GP) with ocular disease, study their pathogenicity and zoonotic potential and to test for the presence of Acanthamoebae spp. in GP eyes and to investigate whether they could act as vectors for Chlamydia-like organisms. Overall 126 GP, of which 77 were symptomatic, were screened by clinical examination, cytology, gross pathology, histology, immunohistochemistry, polymerase chain reaction (PCR) and bacteriology. A new Chlamydiaceae-specific intergenic spacer rRNA gene PCR, designed to amplify this segment linking the 16S and 23S regions, was performed. DNA samples were also received from one owner including samples of his cat and rabbit. Guinea-pigs: 48 of 75 symptomatic, but only 11 of 48 asymptomatic GP were positive by PCR for Chlamydophila caviae guinea-pig inclusion conjunctivitis (GPIC) (P < 0.0001). Eighteen of 75 or 15/48, respectively, were positive for DNA from Chlamydia-like organisms. Acanthamoebae-DNA could be found in two GP, of which one was symptomatic. Owner, cat and rabbit: Samples of all three species were positive by PCR for C. caviae GPIC and the owner's one-day disposable contact lenses showed a positive PCR result for the Chlamydia-like organism Parachlamydia acanthamoebae. No Acanthamoebae-DNA could be detected. This study is the first to describe Chlamydia-like organisms in GP and to detect C. caviae GPIC in human, cat and rabbit. Therefore, C. caviae GPIC could pose a zoonotic potential. We believe that the finding of C. caviae GPIC in species other than GP is probably not unique.     

论蚕种场面临的困境与对策

目前蚕种场系统面临困境，本文就此进行了原因分析，并就茧量平衡，提高经营水平，综合开发，政策引导，科技改良等方提出了对策 。     

苹果渣作为饲料资源的开发与利用

本文主要介绍了苹果渣的营养价值,不同方法调制苹果渣饲料的特点和饲用方法以及苹果渣在畜禽生产上的应用效果。     

Effects of the synthetic selectin inhibitor TBC1269 on tissue damage during acute Mannheimia haemolytica-induced pneumonia in neonatal calves

OBJECTIVE: To determine effects of the selectin inhibitor TBC1269 on neutrophil-mediated pulmonary damage during acute Mannheimia haemolytica-induced pneumonia in newborn calves. ANIMALS: Eighteen 1- to 3-day-old colostrum-deprived calves. PROCEDURE: Mannheimia haemolytica or saline (0.9% NaCl) solution was inoculated in both cranial lung lobes of 12 and 6 calves, respectively. Calves were euthanatized 2 (saline, n = 3; M haemolytica, n = 4) or 6 hours (saline, n = 3; M haemolytica, n = 8) after inoculation. Four M haemolytica-inoculated calves euthanatized at 6 hours also received TBC1269 (25 mg/kg, IV) 30 minutes before and 2 hours after inoculation. Conjugated diene (CD) concentrations, inducible nitric oxide synthase (iNOS) expression, and apoptotic cell counts were determined in lung specimens collected during necropsy. RESULTS: Conjugated diene concentrations were significantly increased in all M haemolytica-inoculated groups, compared with saline-inoculated groups. Calves treated with TBC1269 had decreased concentrations of CD, compared with untreated calves, although the difference was not significant. Number of apoptotic neutrophils and macrophages increased significantly inTBC1269-treated calves, compared with untreated calves. Inducible nitric oxide synthase was expressed by epithelial cells and leukocytes. However, iNOS was less abundant in airway epithelial cells associated with inflammatory exudates. Degree of iNOS expression was similar between TBC1269-treated and untreated calves. CONCLUSIONS: Mannheimia haemolytica infection in neonatal calves resulted in pulmonary tissue damage and decreased epithelial cell iNOS expression. The selectin inhibitor TCB1269 altered, but did not completely inhibit, neutrophil-mediated pulmonary damage.