Effects of purple sweet potato polysaccharide on performance, egg quality characteristics, jejunal morphology, and gut microbiota of Hy-Line Brown laying hens

Abstract

This study was conducted to investigate the effects of dietary purple sweet potato polysaccharide (PSPP) supplementation on production performance, egg quality characteristics, jejunal morphology, and gut microbiota modulation of Hy-line Brown laying hens. A total of 288 23-wk-old Hy-line Brown laying hens were randomly divided into 1 of the 4 dietary treatment groups, with 6 replicates and 12 laying hens per replicate. The 4 groups were fed basal diet supplemented with varying concentrations of PSPP (0, 1, 2, or 4 g/kg) for 6 wks. At the end of the feeding trials, eggs were collected for egg quality analysis, jejunal samples were collected for morphology assessment, and cecal content was analyzed by 16S rRNA high-throughput sequencing to determine intestinal microbiota. Experimental treatments did not differ regarding laying performance and egg quality. However, polynomial contrast analysis showed that there was a linear decrease (P = 0.042) in yolk color. The jejunal morphology did not differ among the treatment groups. The alpha and beta diversity were not different between the treatment groups. The cecal microbiota was dominated by Bacteroidota and Firmicutes at the phylum level and Bacteroides at the genus level. The relative abundance of Firmicutes was increased (P = 0.012) and Bacteroidota was decreased (P = 0.009) in the cecal content of PSPP2. Firmicutes to Bacteroidota ratio increased (P = 0.005) in the PSPP2 group. Polynomial contrast analysis showed that PSPP had a quadratic effect on Firmicutes to Bacteroidota ratio (P = 0.004) and on the relative abundance of Firmicutes (P = 0.006) and Bacteroidota (P = 0.006). At the genus level, increasing PSPP level showed a pattern of linear increase (P = 0.046) in [Ruminococcus]_torques_group and linear decrease (P = 0.015) in the Rikenellaceae_RC9_gut_group. It can be concluded that PSPP altered the gut microbiota, but did not influence jejunal morphology or laying performance and egg quality of laying hens. Further research is recommended to fully understand the potential and determine the optimal level of PSPP in laying hens.