Transcriptome analysis of fasting caecotrophy on hepatic lipid metabolism in New Zealand rabbits

Abstract

Background: Rabbit produce two kinds of feces: hard and soft feces, and they have a preference for consuming the latter. Although this habit of rabbits has been reported for many years, little is known on whether this behavior will impact growth performance and metabolism. The RNA-Seq technology is an effective means of analyzing transcript groups to clarify molecular mechanisms. The aim of the present study was to investigate the effects of fasting caecotrophy on growth performance and lipid metabolism in rabbits. Results:Our results indicated that, compared with the control group, the final body weight, weight gain, liver weight, specific growth rate and feed conversion ratio were all decreased in the experimental group (P<0.05). Oil red staining of the liver tissue indicated that fasting caecotrophy resulted in decrease of lipid droplet accumulation. RNA sequencing (RNA-seq) analysis revealed a total of 301.2 million raw reads approximately 45.06 Gb of high-quality clean data. The data were mapped to the rabbit genome (http://www.ensembl.org/Oryctolagus_cuniculus). After a five step filtering process, 14964 genes were identified, including 444 differentially expressed genes (P<0.05, foldchange≥1). Especially for remarkable changes of genes related to lipid metabolism, RT-PCR further validated the remarkable decrease of these genes in fasting caecotrophy group, including CYP7A1, PPARG, ABCA1, ABCB1, ABCG1, GPAM, SREBP, etc. KEGG annotation of the differentially expressed genes indicated that the main pathways affected were retinol metabolism, pentose and glucuronide interactions, starch and sucrose metabolism, fatty acid degradation, steroid hormone biosynthesis. Conclusion:In conclusion, the present study revealed that banning caecotrophy reduced growth rate and altered lipid metabolism, our results laid instructive basis for rabbit feeding and production. These data also provides a reference for studying the effects of soft feces on other small herbivores. Introduction 2 Many small herbivores have a natural instinct of caecotrophy[1]. Because of the 3 small body shape and their digestive tract volume is limited, the average residence 4 time of food in the digestive tract is relatively short [2, 3]. In order to meet their 5 nutrition needs, small herbivores need to obtain adequate high-quality food[4]. Small 6 herbivores mainly rely on low-quality, high-fiber plant stems and leaves as food 7 sources, with cellulose from symbiotic microorganisms in the hind-gut aiding in 8 digestion[5, 6]. Because microbial fermentation takes longer time than the average 9 residence time of food in the digestive tract, increasing digestibility by ingesting 10 incompletely-digested nutrients is an important nutritional strategy for small 11 herbivores [7-9]. 12 There are two types of feces excreted by rabbits: hard feces (nutrient-poor) and 13 soft feces (consist of protein, vitamins, and inorganic salts) [10-12]. Soft feces also 14 contain a large number of microorganisms, which are important for microbial 15 fermentation in he...

Influence of cecotrophy on fat metabolism mediated by caecal microorganisms in New Zealand white rabbits

“…In this study, the genes of riboflavin metabolism were significantly more enriched in the intestinal microbes of NZW rabbits in the soft faeces fasting group than in those of the control group. The TC content was lower in the soft faeces fasting group than in the control group; the results are consistent (Wang et al, ).…”

“…ascorbate and aldarate metabolism, riboflavin metabolism and bile secretion exhibited significant differences ( p < .05) between the soft faeces fasting group and the control group and can participate in the metabolic processes of NZW rabbits. In our previous study, riboflavin metabolism genes enriched in the intestinal microbes of NZW rabbits were significantly higher in the soft faeces fasting group than in the control group (Wang et al, ). A high level of riboflavin can reduce the concentration of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (HMGR) in the liver (Cogburn et al, ).…”

“…In our previous study, riboflavin metabolism genes enriched in the intestinal microbes of NZW rabbits were significantly higher F I G U R E 4 STAMP difference analysis diagram for the KEGG Function. The left graph shows the abundance ratios for different functions between the two groups of samples; the middle graph shows within the 95% confidence interval the difference in functional abundance; and the right group is the p value, with p < .05 indicating a significant difference [Colour figure can be viewed at wileyonlinelibrary.com] in the soft faeces fasting group than in the control group (Wang et al, 2019). A high level of riboflavin can reduce the concentration of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) in the liver (Cogburn et al, 2018).…”

“…Preventing cecotrophy and concomitant reduced growth and altered lipid metabolism provided the instructive basis for rabbit feeding and production in our previous study (Wang et al, ). Briefly, a total of thirty‐six 28‐day‐old New Zealand white rabbits (NZW rabbits) were divided into two groups (the soft faeces fasting group and the control group) and fed to 90 days.…”

“…Preventing cecotrophy and concomitant reduced growth and altered lipid metabolism provided the instructive basis for rabbit feeding and production in our previous study (Wang et al, 2019).…”