Table 1.
Chemical composition levels of basal diets (air-dried basis) %.
Table 2.
Effects of ammonia on growth performance of rabbits.
Table 3.
Effects of ammonia on lipid metabolism indexes in rabbit’s serum.
Fig 1.
The concentrations of acetate, butyrate and propionate in cecal digesta.
* p < 0.05 and ** p < 0.01 indicates significant and high significant differences, respectively. CG, control group (0 ppm; LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm).
Fig 2.
Analysis of cecal morphology between CG, LAC and HAC groups.
a: cecal shape in CG (×400); b: cecal shape in LAC group (×400); c: cecal shape in HAC group (×400); d: count of mucosal and serosal thickness. The vacuolar degeneration of mucosal epithelium is represented by a green arrow (↑), lymphocytes by an orange arrow (↑), and plasma cells by a red arrow (↑). *, ** indicate significant (p < 0.05) and highly significant (p < 0.01) differences, respectively. CG, control group (0 ppm); LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm) groups.
Table 4.
Alpha diversity analysis of the cecal microbiota of rabbits.
Fig 3.
Beta diversity analysis of microbial communities using principal component analysis (PCA) based on un-weighted UniFrac distances.
CG, control group (0 ppm); LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm).
Fig 4.
The relative burden of bacterial phyla (a) and genera (b) in the cecal microbiota of rabbits in different groups. CG, control group (0 ppm); LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm).
Table 5.
Differentially abundant phyla in the cecum of rabbits of three treatments.
Fig 5.
Predicted microbial function comparison.
(a) Comparison of cecal microbial function between 10 ppm and (b) 30 ppm ammonia (n = 6) and control (n = 6) groups. Statistical analyses were conducted by two-sided Welch’s t-test and Benjamini–Hochberg FDR correction between two groups, and the p-value of different functions lower than 0.05 was shown.
Fig 6.
Prediction of potentially pathogenic bacteria.
CG, control group (0 ppm); LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm).
Table 6.
Differentially abundant genera in the cecum of rabbits of three treatments.
Fig 7.
Spearman’s rank correlation analysis (SRCA) between significantly modified microbiota, serum lipid metabolism indexes and SCFA concentrations of rabbits.
* indicates p < 0.05 and ** indicates p < 0.01. Red and blue colors represent positive and negative correlations, respectively. CG, control group (0 ppm); LAC, low ammonia concentration (10 ppm); HAC, high ammonia concentration (30 ppm); TC, total cholesterol; TG, triglyceride; HDL, high density lipoprotein; LDL, low density lipoprotein; glucose, Glu; apoA1, apolipoprotein A1; apoB, apolipoprotein B; ins, insulin.