Effect of Aggregation of Laboratory Mice (Mus Musculus) on Food Intake at Different Temperatures

Several authors have studied the effects of aggregati on upon various physiological processes. Most of the previous work has l)een done on invertel)rates avid p)oikilotherluic vertebrates. Only limited stu(lies have l)een made on warml)looded animals, p)articularly on small rodents. The experiments of Vetulani (1931) have demonstrate(l that the postweaning growth of laboratory mice, as indicated by weight increase, is influenced b)v the number of animals in the cage. He found that the weight gain of male mice, kept 2 to 4 per cage, was 17.98 percent higher than the gain of mice kept 1 animal per cage; the weight increase of animals kept 9 to 12 per cage was 8.14 l)ercent more than that of those kept 1 to a cage. These studies were repeated by Retzlaff 1939), who confirmed the findings of Vettulani au(l came to the conclusion that environmental teml)erature is the main factor causing the dlifference in Nveight gain in various population samples. Trhe failure of females to show the same growth response as males, which was observed by both authors, was assigned to pectuliarities in female 1)pvxsiolo-y. (erstell ( 1939) in several experiments has demonstrated that huddling, which tends to conserve body heat, is an important factor in the survival of the bobwhite quail (Colinus virginianus virginiai lits) at low aml)ient temperatures. Sealander (1952) has studied the effect of huddling on the survival of Peromnyscus kept at a low temnperattlre without food and water. He found that the survival time of mice exposed to a mean temnperatutre of -230C was prolonged in groups with 2 to 4 animals per cage, as compared with indivi(lually caged animals. The study of King and Connon (1955) on the effect of social relationships upon mortality in young C57L/ 10 mice has shown that the stirvival of two-week-old animals weighing 7 grams or less (lel)ends significantly on proper thermal con(litions which may he supl)lie(l by other indivi(luals as they huddle together. The relationship between crowding and food consuml)tion has been studied by only a few investicators. It has been demonstrated by Adolph (1931), that crowded tadpoles consumed less food per animal than isolated individuals. Also the growth rate of the crowded animals was decreased. Kalabtuchov (1933, cited by Allee, 1934) has found that individually kept honey-bees eat more T rhis work w-as supported in part by an Institutional Grant from the American Cancer Society, Intc.