Optimizing the experimental design using the house mouse (Mus musculus L.) as a model for determining grain feeding preferences

Authors: FUERST, E - Washington State University; Morris, Craig; DASGUPTA, N - Washington State University; MCLEAN, D - Washington State University

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2013
Publication Date: 10/14/2013
Publication URL: http://handle.nal.usda.gov/10113/58811
Citation: Fuerst, E.P., Morris, C.F., Dasgupta, N., Mclean, D.J. 2013. Optimizing the experimental design using the house mouse (Mus musculus L.) as a model for determining grain feeding preferences. Journal of Food Science. 78:S1614-S1620.

Interpretive Summary: The house mouse (Mus musculus L.) is one of the most widely used and effective model systems for mammalian biology research. In our previous study, we found that individually housed laboratory mice demonstrated dramatic differences in consumption preferences when provided with binary mixtures of wheat (Triticum aestivum L.) varieties. Most apparent was a preference for varieties that were softer in texture, a genetic trait conditioned by the Puroindoline genes. Within a texture class, i.e., 'hard' wheat or 'soft' wheat, there was evidence for a preference for 'white' wheat (wheat that lacks pigmentation in the bran) over 'red' wheat (wheat with reddish brown pigments in the bran). 'White' wheat is actually a light creamy to ivory color and lacks the reddish-brown pigments found in the bran of 'red' wheats. Because this apparent preference might relate to flavor and/or aroma compounds, we plan to conduct a more detailed study of inter-varietal preferences. This manuscript focuses on the issue of obtaining reasonable statistical inferences about consumption preference from a mixture of wheat varieties while minimizing the labor and number of animals required. We used a ‘standard procedure’ which included a cohort of 15 C57BL/6 female mice of similar age which were provided a grain mixture. Daily consumption of each mouse was monitored over four 24-hr periods. Our longer term goal is to use mice as a model for identifying quantitative trait loci associated with feeding preferences in wheat varieties using bi-parental or association genetic mapping. Since such a study would require large numbers of varieties to be tested simultaneously, it is vital to gain insight into how to conduct these experiments as efficiently as possible.

Technical Abstract: Technical Abstract: BACKGROUND: There is little research evaluating flavor preferences among wheat varieties. We previously demonstrated that mice exert very strong preferences when given binary mixtures of wheat varieties. We plan to utilize mice to identify varieties and genes associated with preferred flavor, eventually relating this back to human preferences. Here we explore the effects of experimental design including the number of days (from one to four) and number of mice (from two to fifteen) in order to identify designs that provide significant statistical inferences while minimizing requirements for labor and animals. The experimental design utilized daily repeated measures on replicate mice. RESULTS: When mice expressed a significant preference between two wheat varieties, increasing the number of days (for a given number of mice) increased the significance level (decreased P-values) for their preference, as expected, but with diminishing benefit as more days were added. However, increasing the number of mice (for a given number of days) provided a more dramatic log-linear decrease in P-values and thus increased statistical power. CONCLUSION: When evaluating mouse feeding preferences in binary mixtures of grain, experimental efficiency was improved more by reducing the number of days than by reducing the number of mice, thus shortening the experiment duration and reducing the overall requirement for labor and animals. This conclusion would apply to other animal preference studies utilizing similar experimental designs.