Low Crude Protein Diet Affects the Intestinal Microbiome and Metabolome Differently in Barrows and Gilts

Abstract

Low protein diets are commonly used in the growing-finishing pig stage of swine production; however, the effects of low dietary protein on the intestinal microbiota and their metabolites, and their association with pig sex, remain unclear. The present study aimed to assess the impact of a low crude protein (CP) diet on the gut microbiome and metabolome, and to reveal any relationship with sex. Barrows and gilts (both n = 24; initial body = 68.33 ± 0.881 kg) were allocated into two treatments according to sex. The four groups comprised two pairs of gilts and barrows fed with a high protein diet (CP 17% at stage I; CP 13% at stage II) and a low protein diet (CP 15% at stage I; CP 11% at stage II), respectively, for 51 d. Eight pigs in each group were slaughtered and their colon contents were collected. Intestinal microbiota and their metabolites were assessed using 16S rRNA sequencing and tandem mass spectrometry, respectively. The low protein diet increased intestinal microbiota species and richness indices (P < 0.05) in both sexes compared with the high protein diet. The sample Shannon index was different (P < 0.01) between barrows and gilts. At the genus level, unidentified Clostridiales (P < 0.05), Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were affected by dietary protein levels. The relative abundance of unidentified Prevotellaceae was different (P < 0.01) between barrows and gilts. The influence of dietary protein levels on Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were associated with sex. Metabolomic profiling indicated that dietary protein levels mainly affected intestinal metabolites in gilts rather than barrows. A total of 434 differentially abundant metabolites were identified in gilts fed the two protein diets. Correlation analysis identified that six differentially abundant microbiota communities were closely associated with twelve metabolites that were enriched for amino acids, inflammation, immune, and disease-related metabolic pathways. These results suggested that decreasing dietary protein contents changed the intestinal microbiota in growing-finishing pigs, which selectively affected the intestinal metabolite profiles in gilts.

Multispecies probiotic supplementation in diet with reduced crude protein levels altered the composition and function of gut microbiome and restored microbiome-derived metabolites in growing pigs

“…Our results strongly suggest that low CP diet could reduce beneficial gut microbiome metabolites, but the addition of probiotics could restore metabolite production by the gut commensals in low CP diet. Moreover, we observed that reduction in dietary CP level also influenced the function of the gut microbiome, which is consistent with the results of previous studies (Liu et al, 2021;Tao et al, 2021). Pathways related to amino acid metabolism were enriched in the LP-P and NP-P groups compared with the NP or LP groups.…”

Low Protein Diet Improves Meat Quality and Modulates the Composition of Gut Microbiota in Finishing Pigs

“…By these results, we also found that the LP diet induced a significant decrease of Lactobacillus abundance in the ileal digesta of finishing pigs compared to the HP diet in the present study. Similarly, a recent study also showed that the LP diet increased intestinal microbiota species and richness indices in both barrows and gilts, and the relative abundances of unidentified Clostridiales, Neisseria , unidentified Prevotellaceae , and Gracilibacteria at genus level were significantly affected by dietary CP levels ( 50 ). Consistently, we found that the LP diet significantly affected the diversity index of microbiota in the ileal digesta of finishing pigs.…”

Crude protein content in diets associated with intestinal microbiome and metabolome alteration in Huanjiang mini-pigs during different growth stages

“…In addition to the intestinal tract, metabolites can also be affected by sex, and a lower CP content in the diet has a greater impact on sow metabolism ( Tao et al, 2021 ). However, no differential metabolic pathways were detected in the jejunum and ileum of pigs when the pigs were feeding a diet containing 20% CP compared to the pigs fed a diet containing 22% CP in the present study, possibly because of their small differences in protein content.…”