FEEDING PATTERNS OF S-CRASSICAUDATA (MARSUPIALIA, DASYURIDAE) - ROLE OF GENDER, PHOTOPERIOD, AND FAT STORES

Little is known about feeding regulation in marsupials. Sminthopsis cr assicaudata is a small nocturnal marsupial, whose tail contains simila r to 25% total body fat. We have characterized the effect of gender, p hotoperiod, food deprivation, and tail removal (lipectomy) on food int ake in S. crassicaudata. Males and females maintained in captivity on long-day (LD, 16:8-h light-dark cycle) and short-day (SD, 9:15-h light -dark cycle) light regimens were studied. Feeding patterns under LD an d SD photoperiods were initially measured under conditions of ad libit um food supply and then in groups of animals exposed to 24- and 36-h p eriods of food deprivation. Feeding occurred predominantly in the dark . Females maintained on SD photoperiods for 5 wk ate less (P < 0.005) than females on LD or males on either SD or LD, but this reduction in food intake was not associated with a decrease either in body weight o r tail width. After both 24- and 36-h fasts, total food intake in the subsequent 24 h increased (P < 0.001) up to 100% in all groups, with n o gender or photoperiod effect. SD females, however, ate less (P < 0.0 5) than LD females in the first 6 h after refeeding. Tail width decrea sed (P < 0.05) in all groups of animals after the 36-h fast but only i n LD animals after the 24-h fast (P < 0.05). Body weight decreased sim ilarly in all groups of animals after fasting. The effect of tail remo val was studied in LD males. The procedure, which was well tolerated, resulted in an initial decrease in body weight (P < 0.005), which reco vered within 3 wk. On day 45 in the animals whose tails were removed, body fat was similar to 30% greater than body fat of controls (P < 0.0 2). No significant increase in food intake occurred after tail removal . These data demonstrate in Sminthopsis crassicaudata 1) a photoperiod and gender-dependent effect on food intake, 2) the ability to regulat e the amount and distribution of total body fat, and 3) a dissociation between the regulation of food intake and changes in body fat stores, which suggest alterations in energy expenditure.