Developmental And Succession Of Gut Microbes In Saxaul Sparrow Chicks

The intestinal microbiota have now been shown to largely affect host health through various functional roles in terms of nutrition,immunity,and other physiological systems.Studying the intestinal microbiota of birds can better elucidate the diversity of microbes and their role and importance in bird physiology.Current research on the gut microbiome of birds has rarely described in detail the construction of the gut microbiota during the nesting period.In this study 16 SrRNA sequencing was used to analyze the succession of intestinal microbiota during chick development and whether the intestinal microbiota of two nest chicks changed in different seasons and changes of intestinal microbiota between adults and chicks.The main research results are as follows:1.The dominant bacterial phyla(relative abundance > 1%)in the intestinal tract of saxaul sparrow chicks were Firmicutes,Actinobacteria,Proteobacteria,Cyanobacteria and Bacteroidota.During the growth and development of chicks,the relative abundance of Firmicutes in the two nests was generally in a downward trend,the relative abundance of Proteobacteria and Actinobacteria showed an increasing trend,and the relative abundance of Cyanobacteria in the first best,and the overall growth trend in the second nest is in a downward trend.The relative abundance of Actinobacteria generally showed a downward trend in the first nest,and an overall increasing trend in the second nest.With the increase of the chicks’ age,the Chao1 index,which measures the number of species,was in an obvious decreasing trend in the first nest,and had a slow increasing trend in the second nest.The Simpson index related to species dominance did not change significantly in the first nest,but showed a slight increasing trend in the second nest.2.Comparison of gut microbial diversity among saxaul sparrow chicks between days of age found that the abundance,diversity,and microbial composition of the gut flora of the first nest chicks significantly changed at 9 days of age.The abundance of15 phyla,including Firmicutes,Actinobacteria,Planctomycetota,Myxococcota,Acidobacteriota,Gemmatimonadota,Chloroflexi,Latescibacterota,Methylomirabilota,NB1-j,Desulfobacterota,Synergistota,Entotheonellaeota,RCP2-54,Bdellovibrionota,had a clear boundary between the 1-8 day-old group and the9-14-day-old group,which is consistent with the fact that the food delivered by the adult birds to the chicks is mainly from related to the shift from animal foods to plant foods.3.In the wild,it was observed that the adult saxaul sparrows did not swallow feces.Further analysis of the relative abundance of probiotics in the intestinal flora of chicks show that the relative abundance of probiotics did not change significantly at different ages,and no significant decrease was found with increasing age,which verified the hypothesis that the behavior of adult birds swallowing chick feces may be related to probiotics.4.The number of operational taxonomic units(OTU)and the diversity index of Chao1 in the gut of the second nest were significantly higher than those of the first nest.There was no significant difference in the abundance of 5 dominant phyla(relative abundance > 1%)between the two nests,and there were significant differences in the relative abundance of 38 phyla among other phyla.Among the dominant bacterial genera,there were significant differences in the relative abundance of Candidatus＿Arthromitus,Escherichia-Shigella,and Ligilactobacillus,and there were significant differences in the relative abundance of 551 genera among other genera.This suggests that changes in environment and food abundance between different nests during the same breeding period caused significant differences in gut microbial composition between the two nests.5.The proportion of OTUs shared by intestinal microorganisms of adult birds and chicks at different ages gradually increased with age.The analysis of 4 indexs to measure the alpha diversity of intestinal flora found that compared with young chicks,the alpha diversity index of intestinal flora of 13-day-old and 14-day-old chicks that were closer to the flying state was more similar adult birds.In the results of the similarity of intestinal flora composition between adult birds and chicks at different ages,it was found that there were significant differences in the intestinal flora composition between chicks at 1-2 days and 7-8 days of age with adults.9-10 days old,11-12 days old,13-14 days old three groups of chicks and adult birds intestinal flora composition is different,but not significant.This suggests that as chicks age,many of the rare or short-lived environmental microbes in the gut flora will disappear due to competition or the gradual improvement of the chick’s immune system,the alpha diversity of gut microbiota in chicks was then more similar to that in adults.This study clarifies the succession of gut microbes during the development of chicks of herbivorous passerine birds,further explores the relationship between bird feces swallowing behavior and intestinal probiotics,and revealing the important role of food and environmental factors in the process of gut microbes construction in chicks.