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Background: The effects of dietary garcinol on diarrhea and intestinal barrier function associated with its modulation of gut microbiota in weaned piglets were investigated. Method: One hundred forty four weaned piglets (Duroc × Yorkshire × Landrace) from 16 pens (9 piglets per pen) were randomly divided into four treatment groups: controls (CON) or those supplemented with 200 mg/kg (LOW), 400 mg/kg (MID), or 600 mg/kg (HIGH) diet garcinol. After 14-day trial, three piglets per pen were chosen to collect plasma, intestinal tissue and colonic digesta samples. Results: We demonstrated for the first time that garcinol promoted growth performance, as increased average daily feed intake (ADFI) and decreased feed/gain ratio (F/G); and reduced diarrhea incidence (P < 0.05); and strengthened antioxidant capacity, as an increased antioxidative index (P < 0.05). Additionally, garcinol ameliorated intestinal barrier dysfunction, as an increased villus height to crypt depth ratio, increased zonula occludens protein 1 (ZO-1), occludin and claudin-1 expression in the jejunum and ileum (P < 0.05), and decreased intestinal permeability (P < 0.05); and reduced inflammation, as decreased cytokine interleukin (IL)-6, IL-10, IL-1β and tumor necrosis factor-α (TNF-α) levels in the mucosa of the jejunum and ileum, and NF-κB p65 translocation (P < 0.05). Moreover, garcinol inhibited the growth of most harmful bacteria in the gut, especially Escherichia coli, and increased the growth of the beneficial bacteria Lactobacillus. Conclusion: This work provides a fundamental basis for the future development of garcinol-functional food use for improving diarrhea and intestinal barrier function in weaned piglets and for understanding the biological effects of garcinol and its potential as a functional feed additive.

Hepatic metabolic syndrome is associated with inflammation, as inflammation stimulates the reprogramming of nutrient metabolism and hepatic mitochondria-generated acetyl-CoA, but how acetyl-CoA affects the reprogramming of nutrient metabolism, especially glucose and fatty acids, in the condition of inflammation is still unclear. Here, we used an acute inflammation model in which pigs were injected with lipopolysaccharide (LPS) and found that hepatic glycolysis and fatty acid oxidation are both promoted. Acetyl-proteome profiling of LPS-infected pigs liver showed that inflammatory stress exacerbates the acetylation of mitochondrial proteins. Both mitochondrial glutamate oxaloacetate transaminase 2 (GOT2) and malate dehydrogenase 2 (MDH2) were acetylated, and the malate-aspartate shuttle (MAS) activity was stimulated to maintain glycolysis. With the use of C-carbon tracing in vitro, acetyl-CoA was found to be mainly supplied by lipid-derived fatty acid oxidation rather than glucose-derived pyruvate oxidative decarboxylation, while glucose was mainly used for lactate production in response to inflammatory stress. The results of the mitochondrial experiment showed that acetyl-CoA directly increases MDH2 and, in turn, the GOT2 acetylation level affects MAS activity. Treatment with palmitate in primary hepatocytes from LPS-injected pigs increased the hepatic production of acetyl-CoA, pyruvate, and lactate; MAS activity; and hepatic MDH2 and GOT2 hyperacetylation, while the deficiency of long-chain acetyl-CoA dehydrogenase resulted in the stabilization of these parameters. These observations suggest that acetyl-CoA produced by fatty acid oxidation promotes MAS activity and glycolysis via nonenzymatic acetylation during the inflammatory stress response.

Exposure to gaseous ammonia, even at low levels, can be harmful to pigs and human health. However, less is known about the effects of sustained exposure to gaseous ammonia on nasal microbiota colonization in growing pigs. A total of 120 Duroc×Landrace×Yorkshire pigs were housed in 24 separate chambers and continuously exposed to gaseous ammonia at 0,5, 10, 15, 20, and 25 ppm (four groups per exposure level) for 4 weeks. Then, we used high-throughput sequencing to perform 16S rRNA gene analysis in nasal swabs samples from 72 pigs ( n = 12). The results of the nasal microbiota analysis showed that an increase in ammonia concentration, especially at 20 and 25 ppm, decreased the alpha diversity and relative abundance of nasal microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria , and Chloroflexi were the most abundant phyla. In addition, the relative abundances of 24 microbial genera significantly changed as the ammonia level increased. Four microbial genera ( Pseudomonas, Lactobacillus, Prevotella , and Bacteroides ) were significantly decreased at 25 ppm, while only two genera ( Moraxella and Streptococcus ) were increased at 25 ppm. PICRUSt analyses showed that the relative abundances of the nasal microbiota involved in cell motility, signal transduction, the nervous system, environmental adaptation, and energy and carbohydrate metabolism were significantly decreased, while genes involved in the immune system, endocrine system, circulatory system, immune system diseases and metabolism of vitamins, lipid, and amino acids were increased with increased ammonia levels. The results of in vivo tests showed that an increase in ammonia levels, especially an ammonia level of 25 ppm, caused respiratory tract injury and increase the number of Moraxella and Streptococcus species, while simultaneously decreasing respiratory immunity and growth performance, consistent with the increased presence of harmful bacteria identified by nasal microbiota analysis. Herein, this study also indicted that the threshold concentration of ammonia in pig farming is 20 ppm.