Study On The Reproduction And Daily Topor Of The Stri Ped Hamster(Cricetulus Barabensis) In Laboratory

Daily torpor of small mammals is one of the most favorable adaptive strategies to adapt to adverse environment and reduce the energy consumption.In order to explore daily torpor of small mammals under laboratory conditions,the wild Cricetulus barabensis(from Changtu,Liaoning)were propogated under the laboratory conditions to get laboratory population.We observed the Striped Hamster(3 months old)under the conditions of 16L:8D,20±2?,and then randomly divided them into two groups with different acclimated conditions(16L:8D,20±2?or 8L:16D,10±2?)for 30 weeks.Surface body temperature was measured everyday,body weight,food intake and fecal weight were measured every 6 days.The energy intake was calculated indirectly according to the amount of food intake and the weight of feces.Daily torpor was monitored all the time.Core body temperature,activity,metabolic rate and respiratory quotient of the daily torpor ones were determined,daily torpor induction by fasting-refeeding were repeated for the Striped Hamster without daily torpor.The main results and conclusions are as follows:1.The Striped Hamster can breed in all seasons(except February),however,the reproduction rate was significantly higher in 4-9 months than in other months(>25%).The body weight and relative food intake of subadult male animals were significantly higher than females.2.The stirped hamster is a typical nocturnal animal from the physiological characteristics of body temperature,activity and metabolic rate.This species should be a good model to study Circadian rhythm.3.The torpor phase was less than 24 h under the environment temperratue of 10?.The minimum core body temperature was below 30?(18.3±0.42?),the lowest metabolic rate is lower than basal metabolic rate(0.74±0.15 m LO2g-1h-1).It is a typical daily torpor.4.Female animal with lower body weight entered daily torpor at low temperature,short photoperiod and the less energy from food for heat production in the small individals under lower environment temperatue.5.This may be related to the more heat loss and the energy from food was not enough for need.Food intake of daily torpor group was significantly lower than the non-torpor group under the condition of short light and cold.This means daily torpor is a kind of survival straitegy for energy saving.6.Body weight of the hamsters reduced during the fasting phase without daily torpor(including some one died),but return to the original level after refeeding.This means fasting can not induce Striped Hamster enter into daily torpor.