Abstract
In this issue several articles are published with relevance to diets and animal experimentation.1–6 One needs to realize that feeding laboratory animals has become important and questions arise on the content of chow pellets, the consistency or variations in food pellet formulae according to specific diets, or research objectives. It has long been known that diets may affect health and longevity, or influence a variety of diseases,7,8 including many types of cancer, cardiovascular diseases, obesity, behavioral or age-related changes and cognition. Therefore, studies that investigate differences in diets and behavior may only help to improve animal welfare. The review of Dr Jensen and colleagues 1 addressed the effect of fasting of mice to facilitate optimization procedures and maximize scientific outcome, but at the same time minimize discomfort of mice and ensure high-quality animal welfare. The report of Dr Korou and colleagues 2 investigated the question of whether the age of experimental animals plays a role when a high-fat diet is applied to younger or to older animals. Interestingly, younger animals showed a slower weight gain. Therefore, the starting age needs to be considered as a confounding factor with diets. Dr Laaksonen and colleagues 3 presented a study design of an aspen wood board with grooves filled with fitting food pellets as the only food source, while the animals in the control group had the same boards but without pellets and were fed in the regular fashion. The dashboard feeding with integrated food pellets reduced body weight and fatty tissue moderately but significantly in males, as animals which grind out food pellets have to seek food more actively. The original article of Dr Chaudhry and colleagues 4 used a well known toxin, streptozotocin, that is selective in studying the induction of diabetes in pancreatic ß-cells. This compound was found to be equally effective whether mice were fed or fasted prior to its administration. Dr Carpenter and colleagues 5 optimized fat mass gain in a murine obesity model by testing different formulae and ratios of fat macronutrients. The optimal composition allowed a substantial weight gain over the same period and the use of fewer animals. This is a good example of refinement and reduction. The short report of Dr Pritchett-Corning and colleagues 6 looked at the phenomenon of some laboratory mice gnawing food pellets without ingesting them; and producing more waste material than others, also called orts. By increasing enrichment the production of orts was reduced significantly. However, this result should not be surprising since mice are of the order of rodentia, characterized by a single pair of continuously growing incisors in each of the upper and lower jaws that must be kept short by gnawing. Yet, the authors concluded that a simple need to gnaw cannot on its own explain food grinding, and that a nutritional motivation may also be involved.
Given the importance of food for the survival of any species, it seems also appropriate in Laboratory Animals to reflect on standard food pellet composition. One wonders whether different food pellet formulae may have an influence on experiments and reproducibility of experimental results. How far should one go to indicate the composition of food chows or consider whether storage conditions and date of exemption may affect results? Is it really necessary to mention all details? It seems more important to mention critical points that will allow others to repeat the experiments. Another point is the publication of data on fasting and food restriction. When it comes to publishing, it seems essential to mention cases where interruption criteria were applied to avoid excessive weight loss and premature death. With excessive weight gain one should also fix an upper limit. The feeding of animals is not just a routine thing: it is a very important aspect of animal experimentation and noting it is essential for the reproduction of data and for good animal welfare.