The production of short chain fatty acid and colonic development in weaning piglets

Dietary nutrition, intestinal microbiota dysbiosis and post-weaning diarrhea in piglets

Weaning is a critical transitional point in the life cycle of piglets. Early weaning can lead to post-weaning syndrome, destroy the intestinal barrier function and microbiota homeostasis, cause diarrhea and threaten the health of piglets. The nutritional components of milk and solid foods consumed by newborn animals can affect the diversity and structure of their intestinal microbiota, and regulate post-weaning diarrhea in piglets. Therefore, this paper reviews the effects and mechanisms of different nutrients, including protein, dietary fiber, dietary fatty acids and dietary electrolyte balance, on diarrhea and health of piglets by regulating intestinal function. Protein is an essential nutrient for the growth of piglets; however, excessive intake will cause many harmful effects, such as allergic reactions, intestinal barrier dysfunction and pathogenic growth, eventually aggravating piglet diarrhea. Dietary fiber is a nutrient that alleviates post-weaning diarrhea in piglets, which is related to its promotion of intestinal epithelial integrity, microbial homeostasis and the production of short-chain fatty acids. In addition, dietary fatty acids and dietary electrolyte balance can also facilitate the growth, function and health of piglets by regulating intestinal epithelial function, immune system and microbiota. Thus, a targeted control of dietary components to promote the establishment of a healthy bacterial community is a significant method for preventing nutritional diarrhea in weaned piglets.

Short-chain fatty acids modulate the IPEC-J2 cell response to pathogenic E. coli LPS-activated PBMC

Intestinal disorders can affect pigs of any age, especially when animals are young and more susceptible to infections and environmental stressors. For instance, pathogenic E. coli can alter intestinal functions, thus leading to altered nutrient adsorption by interacting with local cells through lipopolysaccharide (LPS). Among several compounds studied to counteract the negative effects on the intestine, short-chain fatty acids (SCFA) were demonstrated to exert beneficial effects on gut epithelial cells and resident immune cells. In this study, acetate and propionate were tested for their beneficial effects in a co-culture model of IPEC-J2 and porcine PBMC pre-stimulated with LPS from E. coli 0111:B4 aimed at mimicking the interaction between intestinal cells and immune cells in an inflammatory/activated status. IPEC-J2 viability was partially reduced when co-cultured with activated PBMC and nitric oxide concentration increased. IPEC-J2 up-regulated innate and inflammatory markers, namely BD-1, TLR-4, IL-8, TNF-α, NF-κB, and TGF-β. Acetate and propionate positively modulated the inflammatory condition by sustaining cell viability, reducing the oxidative stress, and down-regulating the expression of inflammatory mediators. TNF-α expression and secretion showed an opposite effect in IPEC-J2 depending on the extent of LPS stimulation of PBMC and TGF-β modulation. Therefore, SCFA proved to mediate a differential effect depending on the degree and duration of inflammation. The expression of the tight junction proteins (TJp) claudin-4 and zonula occludens-1 was up-regulated by LPS while SCFA influenced TJp with a different kinetics depending on PBMC stimulation. The co-culture model of IPEC-J2 and LPS-activated PBMC proved to be feasible to address the modulation of markers related to anti-bacterial immunity and inflammation, and intestinal epithelial barrier integrity, which are involved in the in vivo responsiveness and plasticity to infections.

Microbe-derived Antioxidants Enhance Lipid Synthesis by Regulating the Hepatic AMPKα-SREBP1c Pathway in Weanling Piglets

BACKGROUND

Weaning usually causes low feed intake and weight loss in piglets, which mobilizes lipid to energize. The microbe-derived antioxidants (MAs) exhibit great potential in antioxidation, anti-inflammation, and metabolic regulation.

OBJECTIVES

We aimed to investigate the changes of lipid metabolism postweaning and effects of MA on growth performance and hepatic lipid metabolism in weanling piglets.

METHODS

In the first experiment, piglets weaned at 21 d of age were slaughtered on weaning day (d0), 4 (d4), and 14 (d14) postweaning (6 piglets per day). In the second experiment, piglets were divided into 2 groups, receiving MA (MA) and saline gavage (CON), respectively. All piglets were weaned at 21 d of age and 6 piglets from each group were slaughtered at 25 d of age.

RESULTS

In experiment 1, the serum triglyceride, total cholesterol (TC), and LDL cholesterol on d4 and d14 declined significantly compared with d0 (P < 0.05). The serum leptin on d0 was higher than that on d4 and d14 (P < 0.05). The serum ghrelin kept increasing from d0 to d14 (P < 0.05). The hepatic hormone-sensitive lipase and adipose triglyceride lipase first increased from d0 to d4 and then decreased from d4 to d14 (P < 0.05). In experiment 2, the average daily gain and average daily feed intake from 21 to 25 d of age increased in the MA group compared with the CON group (P < 0.05). The serum TC, hepatic TC, and glucose of MA group showed a significant increase than that of the CON group (P < 0.05). The expression of SCD1, ACAT2, and PPARγ were upregulated in the MA group (P < 0.05). Contrary to the decreased expression of phosphorylation of adenosine 5'-monophosphate-activated protein kinase alfa subunit (Thr172), the nuclear sterol regulatory element-binding protein 1c, fatty acid synthase, and peroxisome proliferator-activated receptor gamma of MA group increased than that of CON group (P < 0.05).

CONCLUSIONS

Weaning promoted hepatic lipolysis and MA could enhance lipid synthesis by regulating adenosine 5'-monophosphate-activated protein kinase alfa subunit-sterol regulatory element-binding protein 1c pathway, thus improving growth performance of weanling piglets.

Early feeding leads to molecular maturation of the gut mucosal immune system in suckling piglets

Introduction

Diet-microbiota-host interactions are increasingly studied to comprehend their implications in host metabolism and overall health. Keeping in mind the importance of early life programming in shaping intestinal mucosal development, the pre-weaning period can be utilised to understand these interactions in suckling piglets. The objective of this study was to investigate the consequences of early life feeding on the time-resolved mucosal transcriptional program as well as mucosal morphology.

Methods

A customised fibrous feed was provided to piglets (early-fed or EF group; 7 litters) from five days of age until weaning (29 days of age) in addition to sow's milk, whereas control piglets (CON; 6 litters) suckled mother's milk only. Rectal swabs, intestinal content, and mucosal tissues (jejunum, colon) were obtained pre- and post-weaning for microbiota analysis (16S amplicon sequencing) and host transcriptome analysis (RNA sequencing).

Results

Early feeding accelerated both microbiota colonisation as well as host transcriptome, towards a more "mature state", with a more pronounced response in colon compared to jejunum. Early feeding elicited the largest impact on the colon transcriptome just before weaning (compared to post-weaning time-points), exemplified by the modulation of genes involved in cholesterol and energy metabolism and immune response. The transcriptional impact of early feeding persisted during the first days post-weaning and was highlighted by a stronger mucosal response to the weaning stress, via pronounced activation of barrier repair reactions, which is a combination of immune activation, epithelial migration and "wound-repair" like processes, compared to the CON piglets.

Discussion

Our study demonstrates the potential of early life nutrition in neonatal piglets as a means to support their intestinal development during the suckling period, and to improve adaptation during the weaning transition.

Early weaning leads to the remodeling of lipid profile in piglet jejunal crypt cells during post-weaning days

Reportedly, proteins involved in lipid metabolism change significantly in the jejunal crypt cells of early-weaned piglets, but the exact lipid profile change remains uncertain. In the present study, 32 piglets weaned at 21 d of age were randomly divided into 4 groups with 8 replicates. The jejunal crypt cells of a group of piglets on the post-weaning day (PWD) 1, 3, 7, and 14 were isolated per time point. Crypt cell lipid profiles were analyzed using ultra-high-performance liquid chromatography coupled with hybrid quadrupole time-of-flight mass spectrometry. This study showed that piglets suffered the greatest weaning stress on PWD 3 in terms of the lowest relative weight of the small intestine, the highest relative weight of the spleen, and the highest levels of malondialdehyde, cholesterol, and low-density lipoprotein cholesterol. The lipid profile of jejunal crypt cells including carnitine, sulfatide, sphingomyelin, hexosylceramide, and ceramide greatly changed after weaning, especially between PWD 3 and 14 (P < 0.05). The differential lipid species between these 2 d were mainly involved in the glycerophospholipid metabolism pathway. In addition, potential lipid biomarkers for weaning stress in crypt cells such as phosphatidylcholine (PC) (9:0/26:1), PC (17:0/18:2), carnitine (24:0), carnitine (22:0), sphingomyelin (d14:1/22:0), PC (P-18:0/18:4), phosphatidylethanolamine (P-16:0/20:4), phosphatidylinositol (15:1/24:4), and dihexosylceramide (d14:1/26:1) were identified. The changes in lipid profile might be related to the inflammation caused by early weaning. These findings might provide new therapeutical targets for intestinal dysfunctions caused by weaning stress.

Exploring a Possible Link between the Fecal Microbiota and the Production Performance of Pigs

The backfat thickness of pigs not only affects the physical properties and taste of meat, but it also closely relates to the reproduction performance of sows. Accumulating evidence indicates that, apart from genetic factors, gut microbiota can also modulate the fat deposition and muscle growth. However, the differential microbiota in pigs with different backfat thickness, and whether microbiota affects backfat thickness, remains elusive. Firstly, 16S ribosomal RNA (16S rRNA) gene sequencing was performed on 62 fecal samples from pigs with different backfat thicknesses, and the compositions of microbiota among different groups with different backfat thicknesses were different. The abundance of Lactobacillus. reuteri (L. reuteri) and Prevotella sp RS2 was significantly higher in pigs with low-backfat thickness than that in pigs with middle and high-backfat thickness; meanwhile, the abundance of Desulfovibrio piger was significantly lower (p < 0.05) in pigs with low-backfat thickness. Furthermore, the functional profiling of microbial communities suggested that the abundance of isoquinoline alkaloid biosynthesis and styrene degradation were significantly lower (p < 0.05) in the low-backfat thickness group than that in middle and high-backfat thickness groups. Finally, L. reuteri fed to Meishan piglets was capable of improving the production performance and had the potential to reduce backfat thickness. This study provides new evidence that microbiota can regulate the phenotype of the host, and dietary supplementation with L. reuteri can improve the production performance of piglets.

Clostridium butyricum improves the intestinal health of goats by regulating the intestinal microbial community

Clostridium butyricum, as a probiotic with a variety of active products, has been widely used to improve the intestinal health of humans and animals. Previous studies had demonstrated that Clostridium butyricum exhibited potential protective and positive effects in human disease research and animal production by producing a variety of beneficial substances, such as intestinal inflammation, the intestinal epithelial barrier, metabolic diseases, and regulation of the gut microbiota. Therefore, we hypothesized that dietary Clostridium butyricum supplementation could improve gut health in fattening goats by modulating gut microbiota. However, it is unclear whether Clostridium butyricum can reach the intestine through the rumen, so 15 healthy Albas goats were selected and randomly divided into 3 treatments with 5 replicates in each group. The groups were divided as follows: control group (CON: basal diet), rumen-protected Clostridium butyricum group (RPCB: basal diet plus 1.0 × 10⁹ CFU/kg Clostridium butyricum coated with hydrogenated fat), and Clostridium butyricum group (CB: basal diet plus 1.0 × 10⁹ CFU/kg Clostridium butyricum). The experiment was slaughtered after a 70-day growth test, and the jejunal mucosa and intestinal contents of the goats were collected to determine tight junction proteins related genes expression and 16S rDNA microbial sequencing analysis to evaluate the intestine health. The results showed that dietary supplementation with Clostridium butyricum significantly increased the expression of the Claudin-4 gene of the jejunal mucosa (P < 0.05) and had a trend toward a significant increase in the Occludin gene (0.05 < P < 0.10). However, Clostridium butyricum had no significant effect on the expression of intestinal inflammatory factors (P > 0.10). In addition, the relative fractionation of Clostridium and Clostridiaceae_unclassified in the gut microbiota at the genus level decreased significantly compared with controls (P < 0.05). The results of the analysis of the level of Clostridium species showed that Clostridium butyricum only existed in the treatment group. And the correlation results showed that Occludin and Claudin-4 genes were positively correlated with Sharppea and Clostridium butyricum, and negatively correlated with Clostridium (P < 0.05). Supplementing Clostridium butyricum in the diet did not significantly affect the intestinal immune function of goats, while regulation of the intestinal microbiota was associated with improving the intestinal epithelial barrier.

Effects of Protein Restriction and Succedent Realimentation on Jejunal Function and Bacterial Composition of Different Colonic Niches in Weaned Piglets

Recent studies have proved that protein succedent realimentation could rescue the loss of growth performance in weaning piglets caused by a prior protein restriction. However, how the protein restriction and succedent realimentation influence the jejunal function and bacterial composition of different colonic niches microbiota in weaning piglets needs a further investigation. After protein succedent realimentation, we found that the treatment group (TRE) piglets had a higher IGF-1 content and IGF-1R gene expression level in jejunal mucosa than the control group (CON) piglets. The ZO-1 gene expression level was up-regulated in the jejunal mucosa of TRE piglets during protein restriction and succedent realimentation, while the jejunal permeability of TRE piglets was only decreased after protein succedent realimentation. In addition, we found that protein restriction and succedent realimentation increased the gene expression of Pept-1 and the fecal apparent digestibility of crude protein in TRE piglets, but decreased the fecal nitrogen content. After 16S rRNA MiSeq sequencing of bacteria in different colonic niches (mucosa and digesta), TRE piglets had a higher relative abundance of beneficial bacteria and a lower relative abundance of potential pathogens than CON piglets in different colonic niches after protein restriction and succedent realimentation. Our data showed that protein restriction and succedent realimentation decreased the concentrations of branch chain fatty acids and ammonia-N in the colon of TRE piglets. In addition, protein succedent realimentation increased the concentration of total short chain fatty acids in the colon of TRE piglets. All these findings demonstrated that the strategy of protein restriction and succedent realimentation is an effective way to improve intestinal health of weaning piglets, and provided new insights into the nutrition management of piglets during the weaning period.

Effects of Phytic Acid-Degrading Bacteria on Mineral Element Content in Mice

Trace minerals are extremely important for balanced nutrition, growth, and development in animals and humans. Phytic acid chelation promotes the use of probiotics in nutrition. The phytic acid-degrading strain Lactococcus lactis psm16 was obtained from swine milk by enrichment culture and direct plate methods. In this study, we evaluated the effect of the strain psm16 on mineral element content in a mouse model. Mice were divided into four groups: basal diet, 1% phytic acid, 1% phytic acid + psm16, 1% phytic acid + 500 U/kg commercial phytase. Concentrations of acetic acid, propionic acid, butyric acid, and total short-chain fatty acids were significantly increased in the strain psm16 group compared to the phytic acid group. The concentrations of copper (p = 0.021) and zinc (p = 0.017) in liver, calcium (p = 0.000), manganese (p = 0.000), and zinc (p = 0.000) in plasma and manganese (p = 0.010) and zinc (p = 0.022) in kidney were significantly increased in psm16 group, while copper (p = 0.007) and magnesium (p = 0.001) were significantly reduced. In conclusion, the addition of phytic acid-degrading bacteria psm16 into a diet including phytic acid can affect the content of trace elements in the liver, kidney, and plasma of mice, counteracting the harmful effects of phytic acid.

Differential effects of early-life and post-weaning galactooligosaccharides intervention on colonic bacterial composition and function in weaning piglets

Recently, we have proved that the early-life galactooligosaccharides (GOS) intervention could improve the colonic function by altering the bacterial composition in the suckling piglets. However, whether the early-life GOS (ELG) intervention could have a long influence of the colonic microbiota, and the ELG and post-weaning GOS (PWG) combined intervention would have an interaction effect on maintaining colonic health in weaning piglets remain to be explored. Thus in this study, we illustrated the differential effect of ELG and PWG intervention on colonic microbiota and colonic function of weaning piglets. Our results showed that both the ELG and PWG intervention decreased the diarrhea frequency of weaning piglets, while the PWG intervention increased colonic indexes. After 16S rRNA MiSeq sequencing of gut bacteria belonged to colonic niches (mucosa and digesta), the PWG increased the α-diversity of colonic mucosal bacteria was revealed. In addition, we found both the ELG and PWG intervention enriched the abundance of short chain fatty acids (SCFAs) producer in different colonic niches and increased total SCFAs concentrations in colonic digesta. These changes selectively modulated the mRNA expression of pattern recognition receptors and barrier proteins in the colonic mucosa. Of note, the combined effect of ELG and PWG effectively enhanced colonic SCFAs producer enrichment and up-regulated the butyrate concentration. Meanwhile, the gene expression of MyD88-NFκB signaling and the pro-inflammatory cytokines contents were markedly reduced under the combined effect of ELG and PWG. Importance Reducing the disorders of gut ecosystem is an effective way to relieve weaning stresses of piglets and save economic losses in the modern swine industry. To this end, prebiotics were often added in diet during the weaning transition. In present study, we demonstrated that the ELG and PWG intervention had shown different effects on the bacterial composition of different colonic niches and colonic function in the weaning piglets. Especially under the combined effect of ELG and PWG intervention, the gene expression of MyD88-NFκB signaling and the contents of pro-inflammation cytokines decreased with the increasing concentration of butyrate, which is one of the important microbial metabolites in the colon of weaning piglets. These findings further provided new insights into nutritional interventions to alleviate intestinal ecosystem dysbiosis and gut dysfunction in the piglets during the weaning transition.

Herbal Extract Mixture Modulates Intestinal Antioxidative Capacity and Microbiota in Weaning Piglets

Recently, herbal extracts have been applied in multiple aspects, such as medicine and animal feed. Different compositions of herbal extract mixture (HEM) have various components and diverse functions. This study aimed to evaluate the effects of HEM (Lonicera japonica, Astragalus membranaceus, Eucommia folium, and Codonopsis pilosula) on intestinal antioxidant capacity and colonic microbiota in weaned pigs. A total of 18 piglets [Duroc × (Landrace × Yorkshire)] with the initial body weight of 5.99 ± 0.13 kg (weaned at 21 days) were randomly divided into two groups (n = 9): the control group (CON, basal diet) and the HEM treatment group (HEM, 1,000 mg/kg HEM + basal diet). The experiment period lasted for 14 days. Our results showed that dietary supplementation with HEM modulated the antioxidant capacity through decreasing the activity of superoxide dismutase (SOD) in the ileum and glutathione peroxidase (GSH-PX) in the serum, and decreasing the mRNA expression of Kelch like-ECH-associated protein 1 (Keap1) in the jejunum and the protein level of Keap1 in the ileum. Moreover, the HEM group modified the composition of colonic microbiota with affecting relative abundances of the Firmicutes and Bacteroidetes at the phylum level. Taken together, supplementation of HEM can regulate the antioxidant capacity and modify the composition of colonic bacteria in weaning piglets. This study provides new insights into the combination effects of herbal extracts on weaning piglets.

Dietary niacin affects intestinal morphology and functions via modulating cell proliferation in weaned piglets

Niacin deficiency leads to inflammation of mucous membranes and diarrhoea. There are few reports on the effects of niacin on the intestinal health of weaned piglets. The present study was conducted to analyse the effects of niacin in weaned piglets along with its underlying mechanism. A total of 48 25-day-old weaned piglets (24 females and 24 males) were randomly allotted into four groups, each treatment were supplemented with 22.5, 30, 45, and 75 mg kg^-1 niacin for a period of 14 days, with 12 piglets per diet and 1 piglet per pen. Six piglets (3 males and 3 females) were randomly selected from each treatment group and euthanised for intestinal tissue sampling on days 7 and 14 after the weaning day (day 0), respectively. Dietary niacin did not affect the growth performance of weaned piglets but quadratically affected (P < 0.05) the diarrhoea rate from days 7 to 14. The duodenal villus height and width and crypt depth in the 30 mg kg^-1 niacin group were greater than those in the 45 mg kg^-1 niacin group on day 7, and the jejunal crypt depth, ileal crypt depth, villus height and villus width decreased (linear, P < 0.05) with the increase in dietary niacin. However, the dietary supplementation with niacin increased (linear, P < 0.001) the jejunal villus height, crypt depth and villus width on day 14. Dietary niacin increased (linear, P < 0.05) the alkaline phosphatase activity in the jejunal mucosa of weaned piglets on day 7 but decreased (linear, P < 0.05) its activity on day 14. The number of Ki67 positive cells per crypt was decreased (linear, P < 0.05) with the dietary niacin on day 7 but increased (linear, P < 0.05) with dietary niacin contents on day 14. Moreover, dietary niacin altered (P < 0.05) SLC5A1, SLC15A1, SLC6A19, TJP-1, occludin and claudin-1 mRNA expression in the small intestine. These results indicate that dietary niacin has different effects on intestinal morphology and functions in the first and second weeks postweaning and that the dietary supplementation with niacin may, by modulating intestinal cell proliferation, affect the intestinal health.

Effects of rhamnolipids on growth performance and intestinal health parameters in Linnan yellow broilers

This study determined the effects of dietary supplementation of rhamnolipids (RLS) on the growth performance, gut morphology, immune function, intestinal volatile fatty acid, and microflora community in Linnan yellow broilers. A total of 480 1-day-old broiler chicks were randomly assigned to groups for supplementation with one of the following for 56 d: no supplement (control), 30 mg/kg bacitracin (ANT), 500 mg/kg RLS, or 1,000 mg/kg RLS (RLS2). The RLS2 diet was found to improve the final BW and ADG on day 56. The RLS diet reduced jejunal crypt depth, increased jejunal villus length, and increased serum IgA, IgM, IgY, IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels. The RLS broilers had higher cecum concentrations of acetic acid, propionic acid, butyrate, isobutyric acid, valerate, and isovalerate. High-throughput sequencing indicated that RLS affected microbial quantity and diversity in the cecum. Bacterial richness was higher in the RLS broilers than the ANT broilers. The RLS broilers had higher relative abundances of Megasphaera hypermegale and Lachnospiraceae bacterium 19gly4 on day 28 and Clostridium spiroforme and Alistipes obesi on day 56. These results suggest that RLS supplementation improves growth performance, benefits the intestinal villus morphology, regulates host immune function, and raises intestinal volatile fatty acid content and the relative abundance of the gut microbiota in broiler chickens.

Changes in cecal morphology, cell proliferation, antioxidant enzyme, volatile fatty acids, lipopolysaccharide, and cytokines in piglets during the postweaning period

Weaning stresses often induce markedly structural and functional changes in the small intestine. However, little data are available on the changes of the morphology, function, and health in the cecum of piglets post-weaning. This study was conducted to measure the effects of weaning on the cecum in piglets. Forty piglets were weaned at 21 d and samples were collected at different time points (days 0, 1, 3, 7, and 14) post-weaning. The crypt depth, crypt width, and total epithelial cell numbers increased on days 7 and 14, compared with days 0, 1, and 3 (P < 0.001). The value of Ki67/total epithelial cells was highest on day 0 compared with all other days (P < 0.05). Besides, a higher concentration of malondialdehyde was observed on day 3 (P < 0.001). The activity of CuZn-superoxide dismutase (P < 0.05) enhanced from day 0 to 1 and the activity of catalase increased from day 1 to 3 (P < 0.001). In addition, days 3, 7, and 14 had greater acetic, propanoic, and butyric acid contents than on day 1 (P < 0.001). The pH and monocarboxylate transporter 1 (MCT1) expression increased from day 0 to 1 and from day 3 to 7 and decreased between days 1 and 3 (P < 0.001). The mRNA expression of solute carrier family 9 member A3 (SLC9A3) decreased on day 1 compared to all other postweaning days (P < 0.05). The abundance of toll-like receptor 4 (TLR4) and interferon-γ (IFN-γ) mRNA expression increased (P < 0.05) during the first 24 h after weaning. The concentration of lipopolysaccharide increased from day 3 to 7, then decreased on day 14 (P < 0.05). The mRNA expression of tumor necrosis factor-α (TNF-α) enhanced from day 7 to 14 (P < 0.05). The abundance of phosphorylated mammalian target of rapamycin protein was lower on day 14 than day 0 (P < 0.05). Taken together, these results show that weaning in piglets influences intestinal morphology, function, and health in the cecum.