Background Rearing systems can affect livestock production directly, but whether they have effects on intestinal growth states and ceca microorganisms in ducks is largely unclear. The current study used Nonghua ducks to estimate the effects of rearing systems on the intestines by evaluating differences in intestinal growth indices and cecal microorganisms between ducks in the floor-rearing system (FRS) and net-rearing system (NRS). Results The values of relative weight (RW), relative length (RL) and RW/RL of the duodenum, jejunum, ileum and ceca in the FRS were significantly higher than those in the NRS during weeks 4, 8 and 13 (p < 0.05). A total of 157 genera were identified from ducks under the two systems, and the dominant microorganisms in both treatments were Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria at the phylum level. The distribution of microorganisms in the ceca of the two treatments showed significant separation during the three time periods, and the value of the Simpson index in the FRS was significantly higher than that in the NRS at 13 weeks (p < 0.05). Five differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 4, seven differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 8, and four differential microorganisms and two differential metabolic pathways were found in the ceca at week 13. Conclusions The rearing system influences duck intestinal development and microorganisms. The FRS group had higher intestinal RL, RW and RW/RL and obviously separated ceca microorganisms compared to those of the NRS group. The differential metabolic pathways of cecal microorganisms decreased with increasing age, and the abundance of translation pathways was higher in the NRS group at week 13, while cofactor and vitamin metabolism were more abundant in the FRS group.

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Background There are great differences in physiological and biological functions between animals of different genders. However, whether there would be a consensus in duck intestinal development and microorganisms is still unknown. Methods Male and female ducks were weighed at 2, 5 and 10 weeks, respectively, then the duodenum, jejunum, ileum and cecum were sampled and measured, and the content were analyzed by 16S RNA. Results The results showed that male duck hold shorter intestinal length with higher density and jejunum VH/CD, and the similarity, evenness and diversity of the total intestinal microorganism of male duck were higher, with 99.66% OTUs shared by both gender, while Rikenellae , Prevotella and Nocardia were only in male duck. Proeobacteria hold higher abundance than Bacteroidetes in female intestine, while the value of Firmicutes/Bacteroides was lower than male duck. Whats more, the different functional pathway of microorganisms was only showed in jejunum, among which the metabolic and disease pathways of male ducks were higher, while gene pathways was lower. Conclusions The intestines of male ducks have higher development, nutrient absorption, fat deposition and metabolic capacity while their disease resistance was relatively weak, providing a basic reference for intestinal development and microorganism symbiosis of duck in different genders.

Background Rearing systems can affect livestock production directly, but the effects of floor-reared systems (FRSs) and net-reared systems (NRSs) on the intestinal growth states and microbial diversity in the cecum of ducks are largely unclear. Methods The ducklings in this study were randomly divided into FRS and NRS groups, weighed at 4, 8 and 13 weeks, respectively, then the duodenum, jejunum, ileum and cecum were sampled and measured, and the content of cecum were analyzed by 16S RNA. Results The values of relative weight (RW), relative length (RL) and RW/ RL of four intestinal segments in FRS were significantly higher than that in the NRS during week 4, 8 and 13 (p < 0.05). A total of 157 genus were identified from ducks under the two systems,the dominant microorganisms in both groups were Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria at phyla level. The distribution of microorganisms in cecum of two groups showed significant separation in three time periods, and the value of Simpson index in FRS was significantly higher than NRS at 13 weeks (p < 0.05).Five differential microorganisms and 25 differential metabolic pathways were found in the cecum at week 4, 7 differential microorganisms and 25 differential metabolic pathways were found in the cecum at week 8, and 4 differential microorganisms and 2 differential metabolic pathways were found in the cecum at week 13. Conclusions There were differences in intestinal growth and microorganism between FRS and NRS ducks.