A blend of medium-chain fatty acids, butyrate, organic acids, and a phenolic compound accelerates microbial maturation in newly weaned piglets

Abstract

Inclusion of additive blends is a common dietary strategy to manage post-weaning diarrhea and performance in piglets. However, there is limited mechanistic data on how these additives improve outcomes during this period. To evaluate the effects of Presan FX (MCOA) on the intestinal microbiota and metabolome, diets with or without 0.2% MCOA were compared. Pigs fed MCOA showed improved whole-body metabolism 7 days post-weaning, with decreased (P < 0.05) creatine, creatinine and β-hydroxybutyrate. Alterations in bile-associated metabolites and cholic acid were also observed at the same time-point (P < 0.05), suggesting MCOA increased bile acid production and secretion. Increased cholic acid was accompanied by increased tryptophan metabolites including indole-3-propionic acid (IPA) in systemic circulation (P = 0.004). An accompanying tendency toward increased Lactobacillus sp. in the small intestine was observed (P = 0.05). Many lactobacilli have bile acid tolerance mechanisms and contribute to production of IPA, suggesting increased bile acid production resulted in increased abundance of lactobacilli capable of tryptophan fermentation. Tryptophan metabolism is associated with the mature pig microbiota and many tryptophan metabolites such as IPA are considered beneficial to gut barrier function. In conclusion, MCOA may help maintain tissue metabolism and aid in microbiota re-assembly through bile acid production and secretion.

Fig 1. Comparison of growth performance.

a. Average daily gain (ADG) and b. average daily feed intake (ADFI) for pigs fed a control diet (CON) or a control diet supplemented with blend of medium chain fatty acids and organic acids on top (MCOA) for the first thirteen days post-weaning. ADG was significantly different (P = 0.04) while ADFI was not significantly different (P = 0.19) between groups (n = 19 for CON and 22 for MCOA) for the thirteen-day period.

Fig 2. Summary of overall effects of MCOA on weaned pig metabolome.

PCAs of metabolites on D3, 7, and 14 in jugular plasma; Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14). Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14).

Fig 3. Whole-body metabolic indicators of tissue deposition.

Differences between pre-weaning, MCOA, and control groups shown on D7 and 14 include a. Creatine; b. Creatinine; c. Acetylcarnitine; d. L-carnitine; e. ß-Hydroxybutyrate; f. Homocysteine. Metabolomics was performed using LC-MS/MS with a SWATH method for peak identification and analyzed in Metaboanalyst 5.0. Compounds shown in Fig 3B, 3D and 3F were not captured in intestinal LC-MS/MS. Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14). Pre-weaning samples are denoted as PW. Groups with statistically different means (P < 0.05) are denoted by different letters.

Fig 4. Bile acid changes observed on D7 and 14 post-weaning in response to feeding a control diet or a diet containing MCOA.

a. Cholic acid; b. Choline; c. Taurine. Metabolomics was performed using LC-MS/MS with a SWATH method for peak identification and analyzed in Metaboanalyst 5.0. Taurine was not detected intestinal metabolome. Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14). Pre-weaning samples are denoted as PW. Groups with statistically different means (P < 0.05) are denoted by different letters.

Fig 5. Tryptophan and metabolite alterations in response to a control diet or a diet containing MCOA.

a Tryptophan; b. Indole-3-carboxylic acid; c. N-Acetyltryptophan; d. Indole-3-carboxyaldehyde; e. 3-Indolepropionic acid. Metabolomics analysis was performed using LC-MS/MS and a SWATH peak identification method. Statistical analysis was performed in Metaboanalyst 5.0. Compounds shown in 6b, d and e were not identified in intestinal metabolomics. Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14). Pre-weaning samples are denoted as PW. Groups with statistically different means (P < 0.05) are denoted by different letters.

Fig 6. Summary of overall effects of MCOA on weaned pig microbiota and metabolic pathways.

a. Weighted Unifrac distance of colon microbiota on D7 and 14; b. Alpha diversity measures of colon microbiota on D7 and 14; c. Metabolic pathways enriched in the jugular plasma of MCOA pigs on D7 post-weaning; d. Lactobacillus relative abundance D7 in the small intestine. Group names indicate treatment (CON vs. MCOA) and day of sampling (7 or 14). Differences are denoted as * P < 0.10, ** P < 0.05 and *** P < 0.01.

Fig 7. Microbe-metabolite relationships.

a. Network analysis of core SI intestinal microbiota and metabolites at D7 with a significant correlation (P < 0.05) threshold r² of 0.6; b. Microbe-metabolite network analysis results for all significant correlations (P < 0.05) with core small intestine microbial taxa on D7; c. Correlation between Lactobacillus relative abundance and cholic acid in all pigs from the study (P = 0.08, rho = 0.21).