Effects Of Diet Diversity And Composition On Physiological Indices And Gut Microbiota Community Of Brandt's Vole(Lasiopodomys Brandtii)

How the animal and plant interacts with each other is the core question for modern animal ecology,and the global climate change and human activities play a key role in affecting this process by altering the diversity of plant community.Herbivorous rodents would feed on a number of many plant species to get enough nutrients for their basic metabolism,body growth,development,nesting and reproduction.Balanced nutrition can promote the growth and reproduction of rodents,and improve the competitiveness of rodents.In contrast,the nutritional deficiency due to the lack of food diversity would lead to the decline in immunity of rodents and cause some diseases for them.Diet diversity(DD)is one of the important factors that may affect animal adaptability.Different food composition would affect the digestibility for voles also shape the composition and functioning of the gut microbiota,eventually may regulate the leptin content and immune response.Brandt's vole(Lasiopodomys brandtii)is the dominant species in the steppe grassland of Inner-Mongolia.Its population outbreak would cause huge damage to the grassland and lead to a decline in functional services of grassland ecosystem.Our previous study showed that long-term livestock grazing alters the diet composition for Brandt's voles and result in changes in gut microbiota composition and co-occurrence network.As climate change and human disturbance occur widely,the diversity of plant community in the habitat of wildlife has been changed a lot.However,we still know little about the effect of the richness of food items on vole's gut microbiota and related functioning on individual's fitness.In this study,we select out 5 plant species(i.e.Leymus chinensis,Stipa krylovii,Medicago sativa,Allium mongolicum and Convcolvulaceae sepium)based on the preference index by Brandt's vole,and made some artificial food according by the combinations of these five plant species.We fed this artificial food to voles for 40 days.We aim to test how the diets with different food items affect the survival rate,body growth,gut microbiota,leptin content and Ig A content of Brandt's vole.We found that(1)As the richness of food items increased,the survival rate of Brandt's vole was significantly increased(p < 0.05).Compared with voles fed with diet only containing one plant species,voles fed with diet containing 2,3 and 4 plant species increased their survival rates by 15.6%,18% and 12.2% respectively.Each specific plant species contributed differently to the survival rate of Brandt's vole(p < 0.01).With the increase in the proportion of Stipa krylovii and Convcolvulaceae sepium in the dietary,the survival rate of Brandt's vole was significantly decreased(p < 0.05).(2)As the richness of food items increased,the body growth rate of Brandt's vole was significantly decreased at 1-5 weeks(p < 0.05).Each specific plant species contributed differently to the body growth rate of Brandt's vole(p < 0.01).With the increase in the proportion of Leymus chinensis in the dietary,the body growth rate of Brandt's vole was significantly increased at 1-5 weeks(p < 0.01).With the increase in the proportion of Stipa krylovii in the dietary,the body growth rate of Brandt's vole was significantly decreased at 1-3 and 1-5 weeks(p < 0.05).With the increase in the proportion of Convcolvulaceae sepium in the dietary,the body growth rate of Brandt's vole was significantly decreased at 1-3 weeks(p < 0.01).(3)As the richness of food items increased,we found an increasing trend in Ig A contents of voles fed with diets with different food items,although there was no significant difference.Compared with voles fed with diet containing one plant species,voles fed with diet containing 2,3 and 4 plant species increased their Ig A contents by 4.4%,3.6% and 6.1% respectively.(4)As the richness of food items increased,we found an increasing trend in LEP contents of voles fed with diets with different food items,although there was no significant difference.Compared with voles fed with diet containing one plant species,voles fed with diet containing 2,3 and 4 plant species increased their Ig A contents by 1%,1.649%,and 7.64% respectively.There is no significant effect of the involvement of each specific plant species in different diets.(5)We found no difference in alpha diversity of gut microbiota between voles fed with different diets.However,the composition of gut microbiota has been changed accordingly.The relative abundance of Clostridia,Lachnospiraceae,Firmicutes and Clostridiales can be used as biomarkers to distinguish voles fed with different diets form other group of voles.The relative abundance of Metabolism,Genetic-lnformation-Processing,Cellular-Processes,Human-Diseases and Organismal-Systems can be used as functional-differences to distinguish voles fed with different diets form other group of voles.In summary,different richness of food items could affect the survival rate and the composition and function of gut microbiota.Some specific plant species contributed differently to the survival rate and growth rate of Brandt's vole.No differences in Ig A and LEP content was found between voles fed with different diets containing diversified food items.