欧洲安全畜产品生产控制措施

自“疯牛病”和“二口恶英”事件在欧洲爆发后 ,全世界的消费者 ,开始对畜产品的安全忧心忡忡起来。为让消费者对畜产品重树信心 ,欧盟国家在遭受巨大经济损失之后 ,痛定思痛 ,总结了食品安全管理的经验教训 ,在畜产品质量安全性控制方面 ,开始实施“从农场到餐桌”的全过程质量控制模式。过程质量控制的基本原则 ,就是针对畜产品产出过程当中养殖、屠宰、加工、运输和贮存(上市 )的每个生产环节 ,均实行相应的质量保证体系 ,来确保其生产过程的安全性 ,从而最终满足消费者获得安全畜产品的需求。由于农场是畜产品产出的源头 ,对源头的控制 …     

Reproducible infection model for Clostridium perfringens in broiler chickens

Experiments were carried out to establish an infection and disease model for Clostridium perfringens in broiler chickens. Previous experiments had failed to induce disease and only a transient colonization with challenge strains had been obtained. In the present study, two series of experiments were conducted, each involving four groups of chickens with each group kept in separate isolators. A coccidial vaccine given at 10 times the prescribed dosage was used to promote the development of necrotic enteritis. In the first experiment, cultures of C. perfringens were mixed with the feed at day 9, 10, 11, and 12, and the coccidial vaccine was given at day 10, whereas in the second experiment, C. perfringens cultures were mixed with the feed at day 17, 18, 19, and 20, and the coccidial vaccine was given at day 18. Chickens were examined at day 9, 11, 12, and 15 (Experiment 1), and at day 17, 18, 20, and 24 (Experiment 2). There was no mortality in any of the groups; however, chickens in the groups receiving both coccidial vaccine and C. peifringens developed the subclinical form of necrotic enteritis, demonstrated by focal necroses in the small intestine, whereas chickens in control groups or groups receiving only coccidial vaccine or only C. perfringens cultures developed no necroses. The results underline the importance of predisposing factors in the development of necrotic enteritis.     

Recovery of Salmonella enterica from seropositive finishing pig herds

The aim of this study was to assess the probability of detecting Salmonella from pen faecal samples in seropositive classified finishing pig herds. The study involved 77 herds from Denmark (20), The Netherlands (20), Greece (17) and Germany (20). The serological herd status was determined by the blood-sampling of 50 finishing pigs. Bacteriological sampling was performed by 20 pen faecal samples per herd. Over-all, 47% of the blood samples had an OD% larger than 10 and 23% larger than 40. Salmonella was isolated from 135 (9.3%) pen faecal samples in 32 herds (42%). Twenty-eight of these herds (87.5%) had a within-herd seroprevalence larger than 50% at sample cut-off OD% > 10. In our study, there was an increasing probability of recovering Salmonella with increasing within-herd seroprevalence. However, this was only a moderate correlation. A correlation coefficient of 0.62 was found between the proportion of culture positive- and seropositive samples in a herd at cut-off OD%> 10 and of 0.58 at cut-off OD% > 40. Serology is a measure of historical exposure, which may or may not correlate closely to the microbiological burden at the time of sampling. Due to the low sensitivity of culture methods, apparent 'false-positive' serological results may well represent real infections not detected by bacteriological testing. For screening purposes, serological testing provides an indication of exposure to Salmonella, which forms the basis for targeted sampling, intervention and logistic slaughter procedures.     

Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds

Our objective was to find herd factors associated with pigs testing seropositive for Salmonella. Data were collected from 359 finishing-pig herds in Germany, Denmark, Greece, The Netherlands and Sweden, between 1996 and 1998. Pigs fed non-pelleted feed (dry or wet) had 2- and 2.5-times lower odds of seropositivity, compared to pigs fed pelleted feed. The protective effect of non-pelleted feed over pelleted feed may be ascribed to the structure and composition. Also, pigs that were given whey (to drink or as the liquid part of the diet) had 2.6-times lower odds to test seropositive than pigs not getting whey. Pigs produced in batches in herds with hygienic-lock facilities had >3-times lower odds for testing seropositive compared to pigs in herds where only one or neither factor was present. In herds where the caretaker(s) washed hands consistently before tending to the animals, pigs had 1.5-times lower odds of seropositivity than pigs in herds where the caretaker did not. Pigs which were able to have snout contact with pigs in neighbouring pens (because pen separations were either open or too low) had 1.7-times higher odds to test seropositive compared to pigs for which such contact was prevented. Pigs in herds recruiting from more than three supplier herds had three-times higher odds to test seropositive than pigs in herds which breed their own replacement stock or recruit from a maximum of three supplier herds.     

Evaluation of an antimicrobial resistance monitoring program for Campylobacter in poultry by simulation

An ideal national resistance monitoring program should deliver a precise estimate of the resistance situation for a given combination of bacteria and antimicrobial at a low cost. To achieve this, decisions need to be made on the number of samples to be collected at each of different possible sampling points. Existing methods of sample size calculation can not be used to solve this problem, because sampling decisions do not only depend on the prevalence of resistance and sensitivity and specificity of resistance testing, but also on the prevalence of the bacteria, and test characteristics of isolation of these bacteria. Our aim was to develop a stochastic simulation model that optimized a national resistance monitoring program, taking multi-stage sampling, imperfect sensitivity and specificity of diagnostic tests, and cost-effectiveness considerations into account. The process of resistance testing of Campylobacter spp. isolated from cloacal swab samples from poultry was modeled using a Markov Chain Monte Carlo model. Different sampling scenarios on the number of flocks to be tested, the number of birds from each flock, and the number of campylobacter colonies submitted to susceptibility testing were evaluated regarding the precision of the resulting prevalence estimate. Precision of the prevalence estimate was defined as the absolute difference between apparent and true prevalence of resistance. A partial budget approach was utilized to find the most cost-effective combination of samples to obtain a defined precision of the prevalence estimate. For a sampling scenario testing 100 flocks, five birds per flock, and one campylobacter colony per sample, the median error of the prevalence estimate was 2.5%, and 95% of the simulations resulted in an error of 7% or less. When the total number of samples was kept constant, maximizing the number of flocks tested, and only testing one bird per flock resulted in the most precise prevalence estimate. Submitting more than one campylobacter colony to resistance testing did not improve the prevalence estimate. Partial budget analysis indicated that the most cost-effective strategy was testing of two birds per flock, and submitting one colony per sample to resistance testing.     

Impacts of wetting-drying cycles on short-term carbon and nitrogen dynamics in Amynthas earthworm casts

Effects of earthworm casts on soil nutrient dynamics and their responses to changing moisture availability in subtropical ecosystems remain poorly understood. This study aimed to examine short-term carbon(C) and nitrogen(N) dynamics and their interactions with wetting-drying cycles in three different structural forms(i.e., granular, globular, and heap-like) of Amynthas earthworm casts. The rates of C and N mineralization in the earthworm casts were examined under two different wetting-drying cycles(i.e., 2-d and 4-d wetting intervals) using a rainfall simulation experiment. After three simulated rainfall events, subsamples of the earthworm casts were further incubated for 4 d for the determination of CO_2 and N_2O fluxes. The results of this study indicated that the impacts of wetting-drying cycles on the short-term C and N dynamics were highly variable among the three cast forms, but wetting-drying cycles significantly reduced the cumulative CO_2 and N_2O fluxes by 62%–83% and 57%–85%, respectively, when compared to the control without being subjected to any rainfall events. The C mineralization rates in different cast forms were affected by the amount of organic substrates and N content in casts, which were associated with the food preference and selection of earthworms. Meanwhile, the cumulative N_2O fluxes did not differ among the three cast forms. Repeated wetting and drying of casts not only enhanced aggregate stability by promoting bonds between the cast particles, but also inhibited microbial survival and growth during the prolonged drying period, which together hindered decomposition and denitrification. Our findings demonstrated that the interactions between the structural forms, aggregate dynamics, and C and N cycling in the earthworm casts were highly complex.     

调味剂应用技术研究

调味剂能改善饲料的适口性和风味,提高动物的采食量,降低饲料成本。目前,迫切需要进一步提高行业内人士对饲料调味剂的正确认识和研究。鉴于此,《新饲料》杂志社同上海BFI饲料科技有限公司合作2011年第4期"特别关注"栏目,并邀请行业内专家共同就调味剂加工工艺以及应用注意事项发表观点,以供广大饲料工作者参考。     

高锌和高铜对仔猪生长性能、免疫功能和抗氧化酶活性的影响

本试验选用杜洛克×约克夏×长白三元杂交仔猪8窝（72头）,随机分为3个处理,每个处理3个重复,每个重复8头。处理1饲喂基础口粮＋Cu250mg·kg-1＋Zn100mg·kg-1,处理2饲喂基础日粮＋Zn1500mg·kg-1＋Cu16mg·kg-1,处理3饲喂基础口粮＋Zn3000mg．kg-1＋Cu16mg．kg-1。试验期21d。试验结果表明：处理3生长性能表现最好,处理1次之,处理2最差。其中处理1与2及处理2与3间增重差异显著,处理3与处理1增空差异不显著,但处理3比处理1增重提高29．2％。从饲料报酬上看,高锌处理2和3均高于处理1。高锌处理2和处理3仔猪腹泻率比处理1分别降低15．3％和9．0％。对血液白细胞的数量和分类及IgG的检测结果表明,高钢和高锌都能使仔猪免疫功能得到加强,高锌比高铜更能促进仔猪的体液免疫反应。对血液中抗氧化酶（SOD,CAT和GSH-PX）活性的测定结果表明,高锌处理组仔猪的抗氧化能力大于高铜处理1组的仔猪,这可能表明,高锌使机体抗应激能力增强的幅度大于高铜。     

黑龙江省猪完整繁育体系猪群结构优化的研究

本文以黑龙江省猪品种资源构成、养猪生产具体条件及过去杂交试验等为基础，拟定了二元、回交和三元杂交方案．在系统分析的基础上，运用线性规划模型优化了不同杂交方案下不同品种组合的猪完整繁育体系内猪群结构．得出，不同杂交方案下猪完整繁育体系各阶层母猪群的最优数量结构呈金字塔形．     

A longitudinal study of Salmonella enterica infections in high-and low-seroprevalence finishing swine herds in The Netherlands

The purpose of this investigation was to study the incidence and course of Salmonella infections in finishing pig herds in order to asses the stability of a given Salmonella herd status. Five low- and 7 high-seroprevalence herds were followed for seven sampling rounds. Each round, blood and faecal samples were tested in an indirect ELISA and by bacteriological culturing, respectively. In high-seroprevalence herds a positive Salmonella status was an indication of a long-term problem and the status was relatively stable over time. The herds experiencing clinical salmonellosis were not necessarily the herds with the highest seroprevalence. It is possible to deliver sero-negative finishers to the slaughterhouse, even though these pigs were seropositive as growers. In three out of five low-prevalence herds, major infection incidents occurred, indicating that changes in the Salmonella status should be anticipated. Low-prevalence herds can remain negative over a longer period of time as a result feeding a complete liquid feed containing fermented by-products.