以食品安全为饲料目标

动物饲料是食物链的开端,与食品安全有着千丝万缕的联系。霉菌毒素和细菌病原体是动物源性食品安全的主要威胁。饲料是通过营养调控方式生产安全动物源性食品的一个绝佳途径。多年来,建明欧洲公司提出了一个全方位的食品安全计划,其主要包括两个部分:通过改善饲料卫生条件避免有毒物质的影响,进行营养调控以确保食品安全。为了确保以食品安全为饲料目标就需要完整并系统地考虑这两个方面。良好的饲料卫生非常重要,不但可以减少动物接触各种毒物的风险,而且是法规要求。可以使用一种创新的干燥清洁方法——固体消毒,来保持设备和车辆的清洁。良好的饲料原料储存方法可以避免霉菌的生长和霉菌毒素的产生。在饲料生产中可以采用最佳安全模型来控制病原,这个模型考虑了诸如温度、湿度、时间、压力和强力抗菌产品(如沙门净)的用量等多种因素。这个模型涵盖了最有效和最经济的热处理和化学处理方法。饲料卫生本身并不能解决食品安全的所有问题,但却是动物源性食品安全的一个必要前提。通过饲料营养调控减少霉菌毒素和弯曲杆菌的威胁也是饲料安全的一个重要方面。研制和评估霉菌毒素结合剂的技术一直在发展(例如欧洲建明公司研制的吸附-脱附模型),但仍需要全面了解胃肠道微生物的定殖机理。有机酸在过去只是被用作饲料防腐剂或者酸化剂,而现在有机酸在调控肠道微生物菌群平衡方面起着越来越重要的作用,但使用酸化剂的目的并不相同。这是建明欧洲公司在全方位营养计划下的一个活跃的研究领域。以食品安全作为饲料目标的观点已被动物生产行业普遍接受。欧洲建明的全方位营养计划,已为生产安全的动物饲料和改善食品安全提出了一个概念性的模型,并将为全球食品安全做出重要贡献。     

Sucrolytic activities in cherry tomato fruits in relation to temperature and solar radiation

A study has been made concerning the influence of two environmental factors (temperature and solar radiation) on sugar content and sucrolytic activity in cherry tomato fruits during the crop cycle. For this, Solanum lycopersicum cv. Naomi plants were grown in an experimental greenhouse. Three fruit samples were taken over the entire production period: the first sampling at the beginning of harvest [85 days after transplanting (dat)], the second at mid-harvest (160 dat), and the third at the end of harvest (229 dat). The values for temperature and solar radiation peaked in the third sampling, coinciding with an increase in lipid peroxidation, without lowering yield with respect to previous samplings. Regarding the sugar content in the cherry tomatoes, our results showed that the increase in temperature and solar radiation diminished the sucrose content at 229 dat and raised the hexoses (glucose and fructose) as well as starch content, produced primarily by the enzyme sucrose synthase. On the contrary, the rest of the enzymes responsible for sucrose degradation, acid and neutral invertases, showed no notable changes in their activity at the end of the crop cycle. In short, our results suggest that the increase in sucrolytic activity, induced mainly by sucrose synthase under these conditions, contributes to the mechanisms of antioxidant defense by supplying precursors (glucose and fructose) of antioxidant compounds in order to restrict the massive accumulation of ROS and thereby avoid the appearance of cell necrosis and reduce yield losses.     

Growth characteristics of some native tree species used in silvopastoral systems in the humid lowlands of Costa Rica

Research for developing silvopastoral systems includes tree species selection and management, and interactions of trees with pastures. In the Caribbean humid lowlands of Costa Rica, total height, diameters at breast height (DBH), survival, basal area and bole volume were compared among three plantations with four species each, in pure stands as well as in the mixture of the four species. In Plantation 1, at 86 months old the pure plantations of Jacaranda copaia and Vochysia guatemalensis, and the mixed plantations (Jacaranda copaia + Vochysia guatemalensis + Calophyllum brasiliense + Stryphnodendron microstachyum) had the largest DBH. Vochysia guatemalensis is one of the most preferred species in the region for reforestation of degraded pastures, while Jacaranda copaia is not preferred because it has low local economic value. In Plantation 2, at 81 months, the greatest DBH was found in Virola koschnyi, Terminalia amazonia and the mixed plantations (Virola koschnyi + Terminalia amazonia + Dipteryx panamensis + Pseudosamanea guachapele). Dipteryx panamensis has good economic value and has a relatively open canopy that produces moderate shade. Virola koschnyi and Terminalia amazonia have denser canopies, are preferred by farmers, and they could be planted in low density in silvopastoral systems. In Plantation 3, at 70 months, the greatest DBH was found in Vochysia ferruginea, Hieronyma alchorneoides and the mixed plantation (Vochysia ferruginea + Hieronyma alchorneoides + Genipa americana + Balizia elegans). Most of these species are currently used in silvopastoral systems in the region. Mixed plantations may combine beneficial effects of the different species' characteristics, with the additional advantage of product diversification. This revised version was published online in June 2006 with corrections to the Cover Date.     

Differential photosynthetic and survival responses to soil drought in two evergreen Nothofagus species

We asked if differences in distribution between Nothofagus nitida and N. dombeyi were associated with differences in drought tolerance. Survival, gas exchange and chlorophyll fluorescence were measured on seedlings subjected to a gradual drought. At a predawn leaf water potential (Ψ_m) of ?2.7 MPa, survival of N. nitida was 50%, compared to 100% in N. dombeyi. Under well-watered conditions, the two species displayed similar stomatal conductance (g _w ) and transpiration (E), but net photosynthesis (A) and instantaneous water-use efficiency (WUE _i ) were slightly higher in N. nitida. A, E and g _w declined in N. nitida along the gradual drought but increased in N. dombeyi at a Ψ_m between ?1.5 and ?2.5 MPa, and declined then drastically at a Ψ_m below < ?2.5 MPa. As N. dombeyi was able to maintain A at higher levels despite declining g _w , this species displayed significantly increased WUE _i at Ψ_m below ?2.5 MPa. Photochemical efficiency of PSII in the light (ΔF/Fmr) and photochemical quenching (qP) were always lower in N. nitida and along with the photochemical efficiency in the dark (Fv/Fm) they declined in both species. Non-photochemical quenching (NPQ) increased slowly in N. dombeyi along with the gradual drought, whilst it decreased in N. nitida. These results show that differences in drought tolerance are in agreement with sorting of Nothofagus species along moisture gradients in south-central Chile.     

In vitro plantlet regeneration from Australian Red Cedar (Toona ciliata,Meliaceae)

In vitro regeneration of complete plants from nodal single-bud segments of 2-year-old Australian Cedar (Toona ciliata) trees were obtained under defined nutritional and environmental conditions. Explants were dissected from plants obtained by germination of seeds and growth in pots in a greenhouse. The best medium for shoot regeneration was that of Murashige and Skoog at 1/4 strength with 3% sucrose (1/4 MS), supplemented with 0.1 mg/l IBA and 0.5 mg/l BAP. Rooting of regenerated shoots was observed in MS medium with 0.1 mg/l IBA. Using mature tree material was more difficult. Forced flushing was used to induce shoot development on branches of a 10-year-old tree. Nodal segments of these epicormic shoots formed shoots in vitro on 1/4 MS + 0.01 mg/l IBA + 5 mg/l BAP, but rooting was never observed.     

Safety and accuracy of blind vs. ultrasound-guided dorsal retrobulbar nerve blocks in horses—A cadaveric study

Objective

There is limited knowledge regarding the safety and accuracy of ultrasound-guided retrobulbar nerve blocks in horses. The aim of this study was to compare these parameters between blind and ultrasound-guided injection techniques for the dorsal retrobulbar nerve block in horses.

Methods

Equine cadaver heads were used to inject the retrobulbar space with contrast medium (CM). Injections were performed either blindly based on anatomic landmarks (blind group, n = 44) or under ultrasonographic guidance (US-group, n = 44), equally divided between an experienced and unexperienced operator. Needle position and distribution of CM were assessed with computed tomography imaging and evaluated by a board-certified veterinary diagnostic imager blinded to the technique. Safety and accuracy of both techniques were compared.

Results

Ocular penetration was observed in two cases (n = 2/44) in the blind group but not in the US group (n = 0/44). No intrathecal, intraneural, or intravascular injections were seen in either group. Safety was significantly improved in the US group (p = .026). There was no statistically significant difference between the groups regarding the accuracy of the injection. Excellent accuracy was achieved more often with the ultrasound-guided technique (n = 11/22) than with the blind technique (n = 7/22) when performed by the unexperienced operator, but this difference was not statistically significant.

Conclusion

To prevent globe-threatening complications and improve the safety of the injection, we recommend using the ultrasound-guided injection technique for the dorsal retrobulbar nerve block.     

Effects of etamsylate on equine platelets: in vitro and in vivo studies

The aim of this study was to investigate whether etamsylate produces equine platelet activation. In vitro and in vivo studies were designed in which seven and eight adult healthy horses were included, respectively. In the in vitro study, citrated blood was incubated with different concentrations of etamsylate, and P-selectin expression and annexin V binding were determined by flow cytometry. In the in vivo study, blood was collected before and 1 and 2h after IV administration of etamsylate, and P-selectin expression was evaluated. In the in vitro study, a significant increase in P-selectin expression, leukocyte-platelet aggregate formation and annexin V binding were observed. In the in vivo study, a marked increase in P-selectin expression and heterotypic aggregate formation was seen in two and five horses, respectively, although no significant differences were detected when analyzing results from all the animals together. The results of the in vitro study indicate that etamsylate produces a pre-activation state in equine platelets, but this fact could be confirmed by the in vivo study.     

Ecological approaches in veterinary epidemiology: mapping the risk of bat-borne rabies using vegetation indices and night-time light satellite imagery

Rabies remains a disease of significant public health concern. In the Americas, bats are an important source of rabies for pets, livestock, and humans. For effective rabies control and prevention, identifying potential areas for disease occurrence is critical to guide future research, inform public health policies, and design interventions. To anticipate zoonotic infectious diseases distribution at coarse scale, veterinary epidemiology needs to advance via exploring current geographic ecology tools and data using a biological approach. We analyzed bat-borne rabies reports in Chile from 2002 to 2012 to establish associations between rabies occurrence and environmental factors to generate an ecological niche model (ENM). The main rabies reservoir in Chile is the bat species Tadarida brasiliensis; we mapped 726 occurrences of rabies virus variant AgV4 in this bat species and integrated them with contemporary Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The correct prediction of areas with rabies in bats and the reliable anticipation of human rabies in our study illustrate the usefulness of ENM for mapping rabies and other zoonotic pathogens. Additionally, we highlight critical issues with selection of environmental variables, methods for model validation, and consideration of sampling bias. Indeed, models with weak or incorrect validation approaches should be interpreted with caution. In conclusion, ecological niche modeling applications for mapping disease risk at coarse geographic scales have a promising future, especially with refinement and enrichment of models with additional information, such as night-time light data, which increased substantially the model’s ability to anticipate human rabies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0235-7) contains supplementary material, which is available to authorized users.