Evaluation of the impacts of climate change on disease vectors through ecological niche modelling.

Vector-borne diseases are exceptionally sensitive to climate change. Predicting vector occurrence in specific regions is a challenge that disease control programs must meet in order to plan and execute control interventions and climate change adaptation measures. Recently, an increasing number of scientific articles have applied ecological niche modelling (ENM) to study medically important insects and ticks. With a myriad of available methods, it is challenging to interpret their results. Here we review the future projections of disease vectors produced by ENM, and assess their trends and limitations. Tropical regions are currently occupied by many vector species; but future projections indicate poleward expansions of suitable climates for their occurrence and, therefore, entomological surveillance must be continuously done in areas projected to become suitable. The most commonly applied methods were the maximum entropy algorithm, generalized linear models, the genetic algorithm for rule set prediction, and discriminant analysis. Lack of consideration of the full-known current distribution of the target species on models with future projections has led to questionable predictions. We conclude that there is no ideal 'gold standard' method to model vector distributions; researchers are encouraged to test different methods for the same data. Such practice is becoming common in the field of ENM, but still lags behind in studies of disease vectors.

Bioimpedance as a Non-Invasive Method to Evaluate Eggs and Poultry

The need to comply with animal welfare has motivated the research for non-invasive methods that allow the evaluation of poultry and eggs to be painless while providing accurate measurements. In this scenario, bioelectrical impedance was tested as a minimally invasive tool for sexing day-old chicks of two different chicken strains and for evaluating the quality of eggs submitted to different days of storage relative to their hatchability. The resistance and phase angle measured allowed the differentiation between chicken strains, but not between sexes. Eggs stored for seven days showed higher resistance and lower phase angle those stored for only one day. Although the bioimpedance method seems to be a promising method to evaluate egg and chick quality, the results of the present study suggest that further studies are needed to validate its utilization, particularly in terms of electrode type and positioning, as well as for the determination of which electrodes and equipment are best suited for different evaluation purposes. (AU)

Bioimpedance as a Non-Invasive Method to Evaluate Eggs and Poultry

The need to comply with animal welfare has motivated the research for non-invasive methods that allow the evaluation of poultry and eggs to be painless while providing accurate measurements. In this scenario, bioelectrical impedance was tested as a minimally invasive tool for sexing day-old chicks of two different chicken strains and for evaluating the quality of eggs submitted to different days of storage relative to their hatchability. The resistance and phase angle measured allowed the differentiation between chicken strains, but not between sexes. Eggs stored for seven days showed higher resistance and lower phase angle those stored for only one day. Although the bioimpedance method seems to be a promising method to evaluate egg and chick quality, the results of the present study suggest that further studies are needed to validate its utilization, particularly in terms of electrode type and positioning, as well as for the determination of which electrodes and equipment are best suited for different evaluation purposes.

Meta-analytical study of productive and nutritional interactions of mycotoxins in growing pigs.

A meta-analysis was carried out in order to study the association of mycotoxins with performance and organ weights in growing pigs. A total of 85 articles published between 1968 and 2010 were used, totaling 1012 treatments and 13 196 animals. The meta-analysis followed three sequential analyses: graphical, correlation and variance-covariance. The presence of mycotoxins in diets was seen to reduce the feed intake by 18% and the weight gain in 21% compared with the control group. Deoxynivalenol and aflatoxins were the mycotoxins with the greatest impact on the feed intake and growth of pigs, reducing by 26% and 16% in the feed intake and by 26% and 22% in the weight gain. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination in equations for estimating the effect of mycotoxins on weight gain. The mycotoxin effect on growth proved to be greater in younger animals. In addition, the residual analysis showed that the greater part of the variation in weight gain was explained by the variation in feed intake (87%). The protein and methionine levels in diets could influence the feed intake and the weight gain in challenged animals. The weight gain in challenged pigs showed a positive correlation with the methionine level in diets (0.68). The mycotoxin effect on growth was greater in males compared with the effect on females. The reduction in weight gain was of 15% in the female group and 19% in the male group. Mycotoxin presence in pig diets has interfered in the relative weight of the liver, the kidneys and the heart. Mycotoxins have an influence on performance and organ weight in pigs. However, the magnitude of the effects varies with the type and concentration of mycotoxin, sex and the animal age, as well as nutritional factors.