Effects Of Tannin On Food Selectivity Of Brandt's Vole(Lasiopodomys Brandtii)

Foraging is a basic behavior of animals,which affects survival and reproduction of animals.Under natural conditions,food selection of rodents is affected by many factors,such as food nutrient content,secondary metabolites and so on.Tannin,one of the most common secondary metabolites in plants,is one of the identification of bitter substances in food,and can combine with bitter taste receptor of taste buds of rodents and can cause the mice to produce bitter perception,and as a result rodents will refuse to take this food.In addition,tannin can combine with proteins to complexes,and affect digestion and absorption of proteins.High concentrations of tannin can damage liver,kidney and other organs.At present,studies on the effects of tannin on animals are mainly concentrated on diet,digestion,physiology and metabolism.In order to further study the effect of tannin on rodents,we use Brandt's vole(Lasiopodomys brandtii)as experimental animals to study the effects of tannin on food selection,digestive function,activity ability,organs and steroid hormone.The main results are as follows:(1)The feeding amount of the low tannin content(3%,5%)was higher than that of without tannin group and high tannin content(7%,10%)group.In addition,the weight increment of the experimental animals with tannin food was significantly higher than that of the control group.(2)The food with 10% tannin content has lethal effect on Brandt's vole,and other groups have no lethal effect.The lowest unit weight intake of voles fed with tannin content is 10% group.The digestibility of dry matter of 0%,3%,and 5% groups are higher than that of 7% and 10% groups.As the weight gain rate of Brandt's voles,3%,5%,and 7% groups are respectively higher than those of 0% and 10% groups.Compared with 10% group,the food with 3% and 5% tannin content have better effect on the survival of Brandt's vole.(3)The main organ weight(liver,kidney,spleen,stomach,small intestine,testis,ovary)of the Brandt's vole were gradually decreased with the increase of tannin content(0%,3%,5%,7%,10%).The results showed that tannin might have a certain effect on the growth and development of Brandt's vole.(4)The movement of Brandt's vole was more active in low tannin content than high tannin content,including rest period,mean speed,slow movement and fast movement.(5)The content of estradiol,testosterone and corticosterone in Brandt's vole decreased with the increase of tannin content(0%,3%,5%,7%,10%).Results from the perspective of hormones,tannin may have a certain effect on the growth and development of Brandt's vole in a certain range.The results implied that 1)Brandt's vole showed obvious selection on food containing tannin;2)the high tannin content led to the decrease in bodymass,but the low tannin did not;3)tannin increased the activity ability of rodents to a certain extent;4)tannin decreased the organs weight of Brandt's vole;5)tannin reduced steroid hormone of Brandt's vole.In conclusion,the high tannin content has obvious effect on food selection,activity ability,organs and steroid hormone of Brandt's vole,however,the low tannin content shows no significant effectiveness.This result may be from the evolution of rodents to the tannin-contained-food in their habitat.Therefore,these results will be meaningful to explain the evolution of food habit and adaption in Brandt's vole.