Repeated measurements of motor activity in rats in long-term toxicity studies.

INTRODUCTION: In the light of 3R (replace, reduce, refine) principles in animal experimentation and increased focus on delayed effects of treatment on central nervous system, the incorporation of behavioural tests into standard toxicology studies as a complement or substitution of a stand-alone safety pharmacology study appears very attractive, but poses some challenges. In the present study, we evaluated the results of an open field test (standard part of the behavioural test batte- ries) incorporated into the 3-month regulatory toxicology study. METHODS: The study was performed in two rat strains most commonly used in toxicology studies (Wistar and Sprague Dawley (SprD)). Open field test was performed according to the standard protocol for stand-alone behavioural test (modified Irwin test) before the start of treat- ment (Day-7, "naïve" animals), on Day 2, inWeek 6 and inWeek 13 of treatment with saline. RESULTS AND DISCUSSION: There was no overall difference between strains, and only minor differences were detected at the individual time points. With regard to time effect, the average values for most of the parameters were comparable throughout the study but individual variability in the performance in the arena was increased at repeated measurements compared to the start. In conclusion, performance in the open field arena did not differ principally between Wistar and SprD rats of both genders. However, individual variability in the behaviour in the open field arena increased with time. This has clear implications for deciding the appropriate group size for this type of study and has to be taken into account in the design of a toxicology study with integrated safety pharmacology endpoints.

The estimated accuracy of the EU reference dissection method for pig carcass classification.

This experiment was designed to describe the accuracy of the EU-reference dissection method, and to describe the types of factors influencing the accuracy and assess their size. The experiment was conducted in four different European countries at two abattoirs within each country. A total of 128 carcasses was selected according to carcass weight, fat class and sex, and 8 butchers from different countries dissected the carcasses. Due to the experimental design of the experiment a variation in pig type was found between countries. The accuracy was expressed by the repeatability and reproducibility standard deviation, which were found to be 0.87 and 1.10, respectively, and by the reliability, found to be 0.87. This indicates a high accuracy, although a significant effect was found on the estimation of lean meat percentage (LMP) of butcher, and also that jointing of the carcass was of overall importance to the accuracy of the EU-reference dissection method.