A study of the responses of four strains of mice to three different environments: a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University

Abstract

Over the last few years a great deal of information has been obtained on the different mechanisms whereby small mammals maintain thermal balance in cold environments. The physiological adjustments that take place to acclimation (exposure to a constant temperature in the laboratory) and acclimatization to cold have recently been reviewed at the International Symposium on Cold Acclimation Fed. Proc. 22 No. 3 1964. These studies have been confined mainly to the white rat and the Norway rat exposed in the laboratory and outdoors to cold temperatures. Few attempts have been made to investigate genetic differences in the possible adjustments that take place on exposure to cold within any one species of mammal. The amount of data concerning the mechanisms whereby small mammals adjust to high temperatures is small. Again, no attempts have been made using small mammals to investigate genetic differences in the response to high temperatures within any one species. The present study was designed to investigate the possibility of differences in response of four strains of mice to high and low temperatures. The factors studied were:- 1. Body Temperatures. 2. Body weight and tail length and the relationships between these two factors. 3. Tail weight. 4. Hair weight. 5. Pelt weight. 6. Total body fat. 7. Abdominal fat. 8 Food intake. Differences in the adjustments to temperature treatments in the four strains were considered likely to show as differences in some or all of these more easily measured factors. If such differences were found to occur between the four strains this should then provide a basis for more detailed studies of their genetic and physiological basis.