Solubility of Tin in Aqueous Media: Implications for Regulatory Ecotoxicity Testing?

Effects caused in ecotoxicity tests by physical factors due to precipitated particles cannot be used for classification in Europe under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). For tin (Sn), results from ecotoxicity tests have been observed to be difficult to interpret in regard to exposures of dissolved Sn. Experiments were undertaken with Sn(IV) chloride at 2-2000 µg L-1 in aquatic test media of differing pHs and hardness. A predictive Sn precipitation model was derived using these data and speciation modelling. Previous ecotoxicity tests assessed with the model indicated that organisms were exposed to Sn precipitates. It was therefore not possible to establish the dissolved Sn doses in the tests, invalidating the results for use in risk assessment. Developing an understanding of the speciation and precipitation behaviour of trace elements should be considered a priority before conducting ecotoxicity testing.

The Value of 'Cow Signs' in the Assessment of the Quality of Nutrition on Dairy Farms.

The aim of this review is to provide dairy farm advisors, consultants, nutritionists, practitioners, and their dairy farmer clients with an additional toolkit that can be used in the assessment of the quality of their dairy cattle nutrition. Cow signs are behavioral, physiological, and management parameters that can be observed and measured. They are detected by examining and observing the cattle. Other physiological parameters such as fecal scoring, rumen fill, and body condition scoring are also included in 'cow signs'. The assessment should be both qualitative and quantitative; for example, is the cattle individual lame and what is the severity of lameness. The 'diagnosis' of a problem should be based on establishing a farm profile of 'cow signs' and other relevant information. Information gathered through assessment of cow signs should be used as an advisory tool to assist and improve decision making. Cow signs can be used as part of an investigation and or farm audit.

Assessment of the effects of supplementation with vitamin E on health and production of feedlot cattle using meta-analysis.

Delivery of supplemental antioxidant vitamins to cattle placed in feedlots might be expected to improve health and performance outcomes by reducing the effects of oxidative stress to which these cattle are presumably exposed. Meta-analytic procedures were used in this study to assess published experiments on the effects of vitamin E supplementation in feedlot cattle. The health outcome of morbidity, and the production outcomes of average daily gain (ADG) and gain to feed ratio (G:F), were analysed. The currently available data do not support the use of supplemental vitamin E administered as an injection (morbidity risk ratio=1.17; P=0.17). The authors conclude that supplemental dietary vitamin E should be fed within the [NRC, 1996. National Research Council. Nutrient Requirements of Beef Cattle, 7th ed. Natl. Acad. Press, Washington, DC] recommended range.