Impaired immunoproteasome assembly and immune responses in PA28-/- mice

In vitro PA28 binds and activates proteasomes. It is shown here that mice with a disrupted PA28b gene lack PA28a and PA28b polypeptides, demonstrating that PA28 functions as a hetero-oligomer in vivo. Processing of antigenic epitopes derived from exogenous or endogenous antigens is altered in PA28-/- mice. Cytotoxic T lymphocyte responses are impaired, and assembly of immunoproteasomes is greatly inhibited in mice lacking PA28. These results show that PA28 is necessary for immunoproteasome assembly and is required for efficient antigen processing, thus demonstrating the importance of PA28-mediated proteasome function in immune responses.     

Risk for interspecies transmission of zoonotic pathogens during poultry processing and pork production in Peru: A qualitative study

Interspecies transmission of pathogens is an unfrequent but naturally occurring event and human activities may favour opportunities not previously reported. Reassortment of zoonotic pathogens like influenza A virus can result from these activities. Recently, swine and birds have played a central role as “mixing vessels” for epidemic and pandemic events related to strains like H1N1 and H5N1. Unsafe practices in poultry markets and swine farms can lead to interspecies transmission, favouring the emergence of novel strains. Thus, understanding practices that lead to interspecies interactions is crucial. This qualitative study aimed to evaluate poultry processing practices in formal and informal markets and the use of leftovers by swine farmers in three Peruvian cities: Lima (capital), Tumbes (coastal) and Tarapoto (jungle). We conducted 80 direct observations at formal and informal markets and interviewed 15 swine farmers. Processors slaughter and pluck chickens and vendors and/or processors eviscerate chickens. Food safety and hygiene practices were suboptimal or absent, although some heterogeneity was observed between cities and chicken vendors versus processors. Both vendors (76%) and processors (100%) sold the chicken viscera leftovers to swine farmers, representing the main source of chicken viscera for swine farms (53%). Swine farmers fed the chicken viscera to their swine. Chicken viscera cooking times varied widely and were insufficient in some cases. Non‐abattoired poultry leads to the sale of poultry leftovers to small‐scale swine farms, resulting in indirect but frequent interspecies contacts that can lead to interspecies transmission of bacterial pathogens or the reassortment of influenza A viruses. These interactions are exacerbated by suboptimal safety and hygiene conditions. People involved in these activities constitute an at‐risk population who could play a central role in preventing the transmission of pathogens between species. Educational interventions on hygiene and food safety practices will be important for reducing the risk of interspecies influenza transmission.     

Feeding of yeast (Candida spp.) improves in vitro ruminal fermentation of fibrous substrates

In vitro gas production technique (IVGPT) was used with the objective of determining the inclusion effect of live cells of two strains of Candida yeast on in vitro ruminal fermentation of two fibrous substrates. In order to achieve this, two experiments were performed: A) using oat straw (Avena sativa) as substrate; B) using alfalfa hay (Medicabo sativa) as substrate, comparing the effect of two different strains of Candida genre, both isolated from the rumen, on the mentioned substrates. Levica 25 (Candida tropicalis) yeast belongs to the culture collection of the Institute of Animal Science, Cuba, and Levazoot 15 (Candida norvegensis) yeast is part of the collection of the Faculty of Zootechnology and Ecology of the Autonomous University of Chihuahua, Mexico. Both strains demonstrated their potential in activating the ruminal fermentation. They stimulated (P<0.0001) the ruminal fermentation of the substrates under study. However, the Levazoot strain stimulated the dry matter (DM) fermentation of alfalfa in 21.43%, more than Levica 25. It is concluded that there is an influence of yeast strain and diet on the rumen environment and, therefore, it is important to select the appropriate strain in every production condition.     

Comparison of hydroponic and aeroponic cultivation systems for the production of potato minitubers

Summary Two different cultivation systems, aeroponics and hydroponics in greenhouse beds, were compared for the production of potato minitubers. Plants in the aeroponic system showed increased vegetative growth, delayed tuber formation and an extended vegetative cycle of about seven months after transplanting. Therefore in 1999, two production cycles were obtained with the hydroponic system, but only one with the aeroponic system. However, compared with total production in hydroponics, the tuber yield per plant in the aeroponic system was almost 70% higher and tuber number more than 2.5 fold higher. Average tuber weight was reduced by 33% in the aeroponic system. Advantages and possible problems with the aeroponic system for minituber production are discussed.     

Public health and policy

Antimicrobial agent usage data are essential for focusing efforts to reduce misuse and overuse of antimicrobial agents in food producing animals because these practices may select for resistance in bacteria of animals. Transfer of resistant bacteria from animals to humans can lead to human infection caused by resistant pathogens. Resistant infections can lead to treatment failures, resulting in prolonged or more severe illness. Multiple World Health Organization (WHO) reports have concluded that both antimicrobial resistance and antimicrobial usage should be monitored on the national level. The system for collecting antimicrobial usage data should be clear and transparent to facilitate trend analysis and comparison within and among countries. Therapeutic, prophylactic and growth promotion use should be recorded, along with route of administration and animal species and/or production class treated. The usage data should be compared to resistance data, and the comparison should be made available in a timely manner. In the United States, surveillance of antimicrobial resistance in foodborne bacteria is performed by the National Antimicrobial Resistance Monitoring System (NARMS) for enteric bacteria, however, the United States still lacks a mechanism for collecting antimicrobial usage data. Combined with antimicrobial resistance information from NARMS, antimicrobial usage data will help to direct education efforts and policy decisions, minimizing the risk that people will develop antimicrobial resistant infections as a result of eating food of animal origin. Ultimately mitigation strategies guided by usage data will be more effective in maintaining antimicrobial drugs for appropriate veterinary use and in protecting human health.     

Habitat factors related to wild rabbit conservation in an agricultural landscape

Populations of European wild rabbit (Oryctolagus cuniculus) have been decreasing since the 1950s. Changes in agricultural practices have been suggested as reasons for their decline in Mediterranean landscapes. We evaluated the environmental variables affecting rabbit distribution in a semiarid agricultural landscape of Northeastern Spain. Sampling was performed in 147 sites randomly distributed across Zaragoza province. At each site, data were recorded in five 100 m segments along a 1 km transect, following ecotones between crops and natural-vegetation areas. A rabbit abundance index was estimated from latrine count, pellet density and number of plots with pellets. In addition to environmental variables that have been shown to be related to rabbit abundance in other habitats, as climate, soil hardness and topography of the site, we measured landscape components related to agricultural use, such as structure of natural vegetation in remaining areas non-devoted to agricultural use and distances to different types of crops and to ecotone between crop and natural vegetation. Our results showed that rabbit abundance was positively correlated to yearly mean temperature, February and May mean rainfall, and negatively correlated to September and November mean rainfall, hardness of soil, and site topography. In relation to agricultural use, rabbit abundance was positively correlated to the scrub structure of natural-vegetation areas and negatively correlated to distance to edge between cultivated unirrigated cereal crops (wheat or barley) and yearly resting cereal crops. Rabbit abundance increased only when the edge between alternate cereal crops was less than 50 m from the ecotone between crops and natural vegetation.This revised version was published online in May 2005 with corrections to the Cover Date.     

Evaluation of 5 serologic assays to detect Rhodococcus equi pneumonia in foals

OBJECTIVE: To determine the sensitivity and specificity of 5 serologic assays used to diagnose Rhodococcus equi pneumonia in foals and to determine whether any of the assays could be used to identify affected foals prior to the onset of clinical signs or to differentiate between affected and unaffected foals when clinical signs first become apparent. DESIGN: Nested case-control study. ANIMALS: 26 foals. PROCEDURE: Serum samples were obtained from all foals at 2, 4, and 6 or 7 weeks of age. Additional samples were obtained from affected foals at the time of diagnosis of R equi pneumonia and from age-matched unaffected foals. Samples were tested with 3 ELISA, an agar gel immunodiffusion assay, and a synergistic hemolysis inhibition assay. RESULTS: Sensitivity and specificity data indicated that none of the assays could be used to reliably differentiate affected from unaffected foals at any testing period. Proportions of foals that had an increase in test values between paired samples collected at 4 and 6 or 7 weeks of age were not significantly different between affected and unaffected foals. For all assays, result values increased significantly over time; however, the rate of increase was not significantly different between affected and unaffected foals. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that serologic assays, whether performed on single or paired samples, cannot be used to reliably establish, confirm, or exclude a diagnosis of R equi pneumonia in foals.     

Supplementation with bypass fat in silvopastoral systems diminishes the ratio of milk saturated/unsaturated fatty acids

This study was conducted to evaluate if supplementing bypass fat to cows under silvopastoral systems, increases the concentration of unsaturated fatty acids in milk, thus improving the saturated/unsaturated ratio without a negative effect on total milk yield in fat or protein. Two concentrations of two different sources of bypass fat were evaluated for 40 days, each in a group of 24 multiparous Lucerna (Colombian breed) cows. A cross-over design of 8 Latin squares 3 × 3.was used The variables submitted to analysis were body condition, daily milk production and milk composition. Body condition, milk yield and milk quality were not different but there was a significant decrease in the amount of saturated fatty acid in both experiments while the unsaturated fat increased significantly in experiment 1 and remained stable in experiment 2. Results, such as these have as far as we know, not been reported previously and they provide an approach for the improvement of milk as a “functional food”.