The kinetics of glutathione in the gastrointestinal tract of weaned piglets supplemented with different doses of dietary reduced glutathione.

This study aimed to investigate the kinetics of dietary GSH in the gastrointestinal tract and the effect of GSH on the intestinal redox status of weaned piglets. Forty-eight piglets with an average age of 26 days and an average body weight of 7.7 kg were used in this study. The piglets were divided into three treatment groups including the control group with a basal diet (CON) and two GSH groups with a basal diet supplemented with 0.1% GSH (LGSH) and 1.0% GSH (HGSH), respectively. The basal diet did not contain any GSH. The experiment lasted for 14 days, with eight animals sampled from each group on d5 and 14. The parts of 0-5%, 5-75%, and 75-100% of the length of the small intestine were assigned to SI1, SI2, and SI3. The results showed that GSH almost completely disappeared from the digesta at SI2. However, no difference in the GSH level in mucosa, liver, and blood erythrocytes was found. The level of cysteine (CYS) in SI1 digesta was significantly higher in HGSH than CON and LGSH on d14, and similar findings were observed for cystine (CYSS) in SI3 digesta on d5. The CYSS level in HGSH was also significantly higher than LGSH in the stomach on d14, while no CYS or CYSS was detected in the stomach for control animals, indicating the breakdown of GSH to CYS already occurred in the stomach. Irrespective of the dietary treatment, the CYS level on d14 and the CYSS level on d5 and 14 were increased when moving more distally into the gastrointestinal tract. Furthermore, the mucosal CYS level was significantly increased at SI1 in the LGSH and HGSH group compared with CON on d5. Glutathione disulfide (GSSG) was recovered in the diets and digesta from the LGSH and HGSH group, which could demonstrate the auto-oxidation of GSH. It is, therefore, concluded that GSH supplementation could not increase the small intestinal mucosal GSH level of weaned piglets, and this could potentially relate to the kinetics of GSH in the digestive tract, where GSH seemed to be prone to the breakdown to CYS and CYSS and the auto-oxidation to GSSG.

Araceae root and citrus fibers tend to decrease Escherichia coli adhesion and myeloperoxidase levels in weaned piglets.

Introduction: Weaning is a stressful experience in the piglet's life, and it often coincides with impaired gut health. Post-weaning diarrhea in piglets is frequently caused by enterotoxigenic Escherichia coli (E. coli). The first step of an E. coli infection is the adhesion to host-specific receptors present on enterocytes, leading to pro-inflammatory immune responses. The aim of this study was to examine if specific fiber fractions in the piglet diet can prevent E. coli adhesion and subsequent immune responses. Methods: The trial included 200 piglets (Danbred × Piétrain): 10 piglets/pen × 10 pens/dietary treatment × 2 dietary treatments. From weaning until 14 days (d14) post-weaning, piglets were fed a control diet or test diet with 2 kg/ton of a mixture of specific fiber fractions derived from Araceae root and citrus. Afterwards, 1 piglet per pen was euthanized, a section was taken at 75% of small intestinal length and E. coli colonization on the mucosal epithelium was quantified by scraping and conventional plating. From the same small intestinal section, histo-morphological indices were assessed, and mucosal scrapings were analyzed for gene expression of pro- and anti-inflammatory cytokines, and NF-kB. Analyses of specific intestinal bacteria and SCFA were performed on samples of intestinal content (small intestine, caecum, colon). Fecal samples were taken to measure myeloperoxidase (MPO), calprotectin and PAP/RAG3A as biomarkers for intestinal inflammation. Results and discussion: Piglets fed the fiber mixture tended to have decreased E. coli colonization to the mucosal epithelium (5.65 vs. 4.84 log10 CFU/g; P = 0.07), less E. coli in the caecum (8.91 vs. 7.72 log10 CFU/g; P = 0.03) and more Lachnospiraceae in the colon (11.3 vs. 11.6 log10 CFU/g; P = 0.03). Additionally, the fiber mixture tended to increase cecal butyric acid (10.4 vs. 19.1 mmol/kg; P = 0.07). No significant effect on histo-morphological indices and on gene expression of pro- and anti-inflammatory cytokines and NF-kB was observed. The fecal MPO concentration tended to decrease (20.2 vs. 10.4 ng/g; P = 0.07), indicating less intestinal inflammation. In conclusion, this study showed that specific fiber fractions from Araceae root and citrus in piglet weaner diets may decrease the risk of pathogen overgrowth by reducing E. coli adhesion and intestinal inflammation.

Gluconic acid improves performance of newly weaned piglets associated with alterations in gut microbiome and fermentation.

BACKGROUND: Weaning is a critical phase in the pigs' life and gut health might be compromised. Gluconic acid was shown to be poorly absorbed but readily fermented to butyrate in the gut which in turn can improve gut function. Hence, a total of 144 weaning pigs were fed the experimental diets for 42 days. Three treatments were replicated in 8 pens with 6 piglets each: control; low dietary dose of gluconic acid, 9 g/kg; and high dietary dose of gluconic acid, 18 g/kg. After 21 days, one piglet from each pen was sampled for blood haematology and biochemistry, fore- and hindgut digesta characteristics and microbiota, and distal small intestinal histo-morphological indices and gene expression. RESULTS: Feeding gluconic acid enhanced performance in period d 0-14 post-weaning, in particular feed intake was increased (P = 0.028), though the high dose did not show benefits over the low dose. Regarding d 0-42, feed intake was elevated (P = 0.026). At d 21, piglets fed 18 g/kg gluconic acid showed a trend for lower number of total white blood cells (P = 0.060), caused by particularly lower numbers of lymphocytes as compared to control (P = 0.028). Highly reduced plasma urea was found for groups fed gluconic acid, it amounted to 2.6 and 2.6 mmol/L for the 9 and 18 g/kg level, respectively, as compared to 3.8 mmol/L in control (P = 0.003). Feeding gluconic acid promoted the relative abundance of lactic-acid-producing and acid-utilizing bacteria. In distal small intestine, Lactobacillus amylovorus increased substantially from 11.3 to 82.6% for control and gluconic acid 18 g/kg, respectively (P < 0.05). In mid-colon, the butyrate producers Faecalibacterium prausnitzii (P > 0.05) and Megasphaera elsdenii (P < 0.05) showed highest abundance in gluconic acid 18 g/kg. Consequently, in caecum and mid-colon, increased relative molar percentage of butyrate were found, e.g., 10.0, 12.9 et 14.7% in caecum for gluconic acid at 0, 9, and 18 g/kg, respectively (P = 0.046). Elevated mRNA anti-inflammatory cytokine and survival signalling levels in distal small intestinal mucosa were found by feeding gluconic acid which might be mediated by butyrate. CONCLUSIONS: Gluconic acid may have potential to alleviate the postweaning growth-check in pigs by altering microbiota composition and fermentation in the gut.

Effect of supplemental methyl sulfonyl methane on performance, carcass and meat quality and oxidative status in chronic cyclic heat-stressed finishing broilers.

Methyl sulfonyl methane (MSM) is available as a dietary supplement for human and has been associated with multiple health benefits such as reduction of oxidative stress. Heat stress (HS) is an environmental stressor challenging poultry production and known to inflict oxidative stress. We hypothesized that dietary MSM could attenuate HS-induced detrimental effects in broilers mediated by enhancement of antioxidant defenses. Hence, seven hundred ninety-two 1-day-old male Ross 308 broilers were allocated to 3 dietary treatments composed of corn-soybean meal diets with 0 (Ctrl), 1, or 2 g/kg MSM, with 12 replicates (22 birds each) per treatment for 39 d and subjected to a chronic cyclic HS model (temperature of 34°C and 52-58% relative humidity for 6 h daily) from d 24 to 39. MSM at 1 and 2 g/kg linearly increased daily gain and decreased feed-to-gain ratio compared with Ctrl in the grower phase (d 10-21, both P < 0.05). In the finisher phase (d 21-39) none of the performance and carcass indices were affected by treatment (P > 0.05). Nonetheless, data suggest reduced mortality by feeding MSM during HS. Also, during HS the diets with graded levels of MSM resulted in reduced rectal temperatures (P < 0.05) along with linearly decreased panting frequency on d 24 (P < 0.05). MSM supplemented birds showed a trend for linearly decreased thiobarbituric acid reactive substances of breast meat upon simulated retail display (P = 0.078). In addition, MSM administration linearly decreased lipid oxidation in plasma (d 25 and 39, P < 0.05) and breast muscle at d 23 (P < 0.05), concomitantly with linearly increased glutathione levels in erythrocytes (d 23 and 39, P < 0.05; d 25, P < 0.1) and breast muscle (d 23, P < 0.05; d 39, P < 0.1). In conclusion, MSM increased growth performance of broilers during grower phase, and exhibited positive effects on heat tolerance mediated by improved antioxidant capacity in broilers resulting in lower mortality in finisher phase.

The Effect of Drenching (Very) Low Birth Weight Piglets with a Dense, Concentrated Milk Replacer at Farms with Differing Farrowing Management.

Introducing hyperprolific sows has led to proportionally more (very) low birth weight ((V)LBW) piglets, accompanied by higher mortality. To improve the survival of (V)LBW piglets, drenching a dense milk replacer (DMR) could be applied. A first experiment evaluated the effect of drenching DMR (1 or 3 doses within 24 h after birth) to LBW ((mean litter birth weight - 1*SD) and weighing between 1 kg and 750 g) and VLBW piglets ((mean litter birth weight - 1.5*SD) and weighing less than 750 g). On days 1, 2, 3, 9, and two days post-weaning, body weight, growth, skin lesions, and mortality were monitored. No effect of DMR was observed on any of the parameters. In a second experiment, LBW piglets were supplemented with DMR (similarly to experiment 1) at two farms differing in the level of perinatal care. The same parameters were evaluated, and again none were affected by drenching DMR. Overall survival of the LBW piglets was significantly higher at the farm with high perinatal care. It can be concluded that good perinatal management is more effective in enhancing the survival of LBW piglets than drenching.

Cinnamaldehyde Induces Release of Cholecystokinin and Glucagon-Like Peptide 1 by Interacting with Transient Receptor Potential Ankyrin 1 in a Porcine Ex-Vivo Intestinal Segment Model.

Cinnamaldehyde and capsaicin have been reported to exert effects on the gastric function, mediated by the interaction with transient receptor potential ankyrin channel 1 (TRPA1) and transient receptor potential vanilloid channel 1 (TRPV1), respectively. This study examined whether these compounds could trigger the release of cholecystokinin (CCK) and/or glucagon-like peptide 1 (GLP-1) in the pig's gut in a porcine ex-vivo intestinal segment model. Furthermore, it was verified whether this response was mediated by TRPA1 or TRPV1 by using the channel's antagonist. These gut peptides play a key role in the "intestinal brake", a feedback mechanism that influences the function of proximal parts of the gut. Structural analogues of cinnamaldehyde were screened as well, to explore structure-dependent activation. Results showed a significant effect of capsaicin on GLP-1 release in the proximal small intestine, TRPV1 independent. TRPA1 showed to be strongly activated by cinnamaldehyde, both in proximal and distal small intestine, evidenced by the release of CCK and GLP-1, respectively. Out of all structural derivates, cinnamaldehyde showed the highest affinity for TRPA1, which elucidates the importance of the α,ß-unsaturated aldehyde moiety. In conclusion, cinnamaldehyde as a TRPA1 agonist, is a promising candidate to modulate gastric function, by activating intestinal brake mechanisms.

Handling Associated with Drenching Does Not Impact Survival and General Health of Low Birth Weight Piglets.

The increase in litter sizes in recent years has resulted in more low birth weight (LBW) piglets, accompanied by a higher mortality. A potential intervention to overcome this is drenching bioactive substances. However, if the act of drenching provokes additional stress in LBW piglets, it might counteract the supplement's effect and be detrimental for the piglet's survival. To study the effect of the drenching act, piglets from 67 sows were weighed within 4 h after birth. The mean litter birth weight (MLBW) and standard deviation (SD) were calculated. LBW piglets (n = 76) were defined as weighing between (MLBW-1*SD) and (MLBW-2.5*SD). They were randomly allocated to two treatments: "sham" (conducting the act of drenching by inserting an empty 2.5 mL syringe in the mouth during 20 s, once a day, d1 till d7; n = 37) or "no treatment" (no handling; n = 39). On day 1, 3, 9, 24 and 38, piglets were weighed and scored for skin lesions. Blood samples were collected on day 9 and 38 and analyzed to determine glucose, non-esterified fatty acids (NEFA), urea, immunoglobulin G (IgG), insulin-like growth factor 1 (IGF-1) and a standard blood panel test. There was no difference between sham drenched and untreated piglets regarding any of the parameters. In conclusion, this study showed that drenching does not impose a significant risk to LBW piglets and can be applied safely during the first 7 days after birth.

Drenching Bovine Colostrum, Quercetin or Fructo-Oligosaccharides Has No Effect on Health or Survival of Low Birth Weight Piglets.

The introduction of hyperprolific sows has resulted in more low birth weight (LBW) piglets, accompanied by higher mortality. A possible strategy to enhance the resilience and survival of LBW piglets is oral supplementation (drenching) of bioactive substances. This study evaluated the supplementation of bovine colostrum, short-chain fructo-oligosaccharides (scFOS) or quercetin that were dissolved separately in a milk replacer. The study was divided into two sub-experiments. First, the milk replacer was compared with a sham drenched group. Secondly, each dissolved compound was compared with the milk replacer. The LBW piglets, defined as weighing between (mean litter birth weight -1*SD) and (mean litter birth weight -2.5*SD), were randomly allocated to the different treatments and drenched once a day for seven days. On day 1, 3, 9, 24 and 38, piglets were weighed and scored for skin lesions. Blood samples were collected on day 9 and 38 and analyzed to determine glucose, non-esterified fatty acids, urea, immunoglobulin G, insulin-like growth factor 1, and a standard blood panel test. There was no difference between sham drenched piglets and piglets that were drenched with milk replacer regarding any of the parameters. No effect was observed between the milk replacer group and any of the bioactive compounds either, except a higher mortality within the scFOS group. In conclusion, this study showed that drenching the evaluated bioactive compounds, in the used dosages, did not improve LBW piglets' resilience or survival and more research is required to determine the effect of scFOS on small piglets.

Expression of Transient Receptor Potential Ankyrin 1 and Transient Receptor Potential Vanilloid 1 in the Gut of the Peri-Weaning Pig Is Strongly Dependent on Age and Intestinal Site.

Transient receptor potential (TRP) channels contribute to sensory transduction in the body, agonized by a variety of stimuli, such as phytochemicals, and they are predominantly distributed in afferent neurons. Evidence indicates their expression in non-neuronal cells, demonstrating their ability to modulate gastrointestinal function. Targeting TRP channels could potentially be used to regulate gastrointestinal secretion and motility, yet their expression in the pig is unknown. This study investigated TRPA1 and TRPV1 expression in different gut locations of piglets of varying age. Colocalization with enteroendocrine cells was established by immunohistochemistry. Both channels were expressed in the gut mucosa. TRPV1 mRNA abundance increased gradually in the stomach and small intestine with age, most notably in the distal small intestine. In contrast, TRPA1 exhibited sustained expression across ages and locations, with the exception of higher expression in the pylorus at weaning. Immunohistochemistry confirmed the endocrine nature of both channels, showing the highest frequency of colocalization in enteroendocrine cells for TRPA1. Specific co-localization on GLP-1 immunoreactive cells indicated their possible role in GLP-1 release and the concomitant intestinal feedback mechanism. Our results indicate that TRPA1 and TRPV1 could play a role in gut enteroendocrine activity. Moreover, age and location in the gut significantly affected gene expression.

Antibiotic affects the gut microbiota composition and expression of genes related to lipid metabolism and myofiber types in skeletal muscle of piglets.

BACKGROUND: Early-life antibiotic administration is known to affect gut microbiota and host adiposity, but the effects of antibiotic exposure on skeletal muscle properties remain unknown. The present study evaluated the changes in skeletal muscle properties including myofiber characteristics and composition, as well as intramuscular fat (IMF) content in skeletal muscle of piglets when exposed to a tylosin-containing diet. RESULTS: A total of 18 piglets (28 days of age) were randomly allocated into two groups: control basal diet (Control) and Control + 100 mg tylosin phosphate/kg of feed (Antibiotic). The trial lasted for 39 days. High-throughput amplicon sequencing revealed that no significant difference in initial gut microbiota composition was existed between Control and Antibiotic groups. Antibiotic administration increased body weight and growth rate and decreased feed to gain ratio of pigs (P < 0.05). The carcass lean and fat volumes of pigs were increased by the tylosin administration (P < 0.05). Antibiotic treatment increased myofiber density and the expression of genes related to type I and type IIb myofibers in longissimus muscle (P < 0.05). The IMF content in longissimus muscle was increased by antibiotic exposure (P < 0.05). Antibiotic administration increased expression of genes related to fatty acid uptake and de novo synthesis, and decreased expression of genes related to triglyceride hydrolysis (P < 0.05). Tylosin administration affected taxonomic distribution and beta diversity of the caecal and colonic microbiota of piglets. CONCLUSION: These results confirm that the growth performance, myofiber composition and muscle lipid metabolism are affected by antibiotic administration, which may be associated with an altered gut microbiota, suggesting that the gut microbiota could be served as a potential target for modulating skeletal muscle properties of host.

Short-chain fructo-oligosaccharides supplementation to suckling piglets: Assessment of pre- and post-weaning performance and gut health.

Farmers face difficulties in redeeming their investment in larger litter sizes since this comes with larger litter heterogenicity, lower litter resilience and risk of higher mortality. Dietary oligosaccharides, given to the sow, proved beneficial for the offspring's performance. However, giving oligosaccharides to the suckling piglet is poorly explored. Therefore, this field trial studied the effect of dietary short-chain fructo-oligosaccharides (scFOS; 1g/day; drenched) supplementation to low (LBW, lower quartile), normal (NBW, two intermediate quartiles) and high (HBW, upper quartile) birth weight piglets from birth until 7 or 21 days of age. Performance parameters, gut microbiome and short-chain fatty acids profile of feces and digesta were assessed at birth (d 0), d 7, weaning (d 21.5) and 2 weeks post-weaning (d 36.5). Additional parameters reflecting gut health (intestinal integrity and morphology, mucosal immune system) were analysed at d 36.5. Most parameters changed with age or differed with the piglet's birth weight. Drenching with scFOS increased body weight by 1 kg in NBW suckling piglets and reduced the post-weaning mortality rate by a 100%. No clear difference in the IgG level, the microbiota composition and fermentative activity between the treatment groups was observed. Additionnally, intestinal integrity, determined by measuring intestinal permeability and regenerative capacity, was similar between the treatment groups. Also, intestinal architecture (villus lenght, crypt depth) was not affected by scFOS supplementation. The density of intra-epithelial lymphocytes and the expression profiles (real-time qPCR) for immune system-related genes (IL-10, IL-1ß, IL-6, TNFα and IFNγ) were used to assess mucosal immunity. Only IFNγ expression, was upregulated in piglets that received scFOS for 7 days. The improved body weight and the reduced post-weaning mortality seen in piglets supplemented with scFOS support the view that scFOS positively impact piglet's health and resilience. However, the modes of action for these effects are not yet fully elucidated and its potential to improve other performance parameters needs further investigation.

Weaning affects the glycosidase activity towards phenolic glycosides in the gut of piglets.

Phenolic compounds in pig diets, originating either from feed ingredients or additives, may occur as glycosides, that is conjugated to sugar moieties. Upon ingestion, their bioavailability and functionality depend on hydrolysis of the glycosidic bond by endogenous or microbial glycosidases. Hence, it is essential to map the glycosidase activities towards phenolic glycosides present along gut. Therefore, the activity of three key glycosidases, that is α-glucosidase (αGLU), ß-glucosidase (ßGLU) and ß-galactosidase (ßGAL), was quantified in small intestinal mucosa and digesta of piglets at different gastrointestinal sites (stomach, three parts of small intestine, caecum and colon) and at different ages around weaning (10 days before and 0, 2, 5, 14 and 28 days after weaning). Activity assays were performed with p-nitrophenyl glycosides at neutral pH. The αGLU activities in mucosa and digesta were low (overall means 1.4 and 60 U respectively) as compared to ßGLU (15.2 and 199 U) and ßGAL (23.4 and 298 U; p < .001). Moreover, αGLU activity in mucosa was unaffected by age. Conversely, ßGLU and ßGAL activities dropped significantly after weaning. Minimal levels, ranging between 18% and 54% of the pre-weaning values, were reached at 5 days post-weaning. Similarly, in small intestinal digesta, reductions from 60% up to 90% were observed for the three enzyme activities on day five post-weaning as compared to pre-weaning levels. In caecal contents, activities were lowest at 14 days post-weaning, while in stomach and colon no clear weaning-induced effects were observed. Our data suggest that weaning affects the glycosidase activity in mucosa (mainly endogenous origin) and digesta (primarily bacterial origin) with the most pronounced effects occurring 5 days post-weaning. Moreover, differences in activities exist between different glycosidases and between gut locations. These insights can facilitate the prediction of the fate of existing and newly synthetized glycosides after oral ingestion in piglets.

Changes of the glutathione redox system during the weaning transition in piglets, in relation to small intestinal morphology and barrier function.

BACKGROUND: Weaning is known to result in barrier dysfunction and villus atrophy in the immediate post-weaning phase, and the magnitude of these responses is hypothesized to correlate with changes in the glutathione (GSH) redox system. Therefore, these parameters were simultaneously measured throughout the weaning phase, in piglets differing in birth weight category and weaning age, as these pre-weaning factors are important determinants for the weaning transition. Low birth weight (LBW) and normal birth weight (NBW) littermates were assigned to one of three weaning treatments; i.e. weaning at 3 weeks of age (3w), weaning at 4 weeks of age (4w) and removal from the sow at 3 d of age and fed a milk replacer until weaning at 3 weeks of age (3d3w). For each of these treatments, six LBW and six NBW piglets were euthanized at 0, 2, 5, 12 or 28 d post-weaning piglets, adding up 180 piglets. RESULTS: Weaning increased the glutathione peroxidase activity on d 5 post-weaning in plasma, and duodenal and jejunal mucosa. Small intestinal glutathione-S-transferase activity gradually increased until d 12 post-weaning, and this was combined with a progressive rise of mucosal GSH up till d 12 post-weaning. Oxidation of the GSH redox status (GSH/GSSG Eh) was only observed in the small intestinal mucosa of 3d3w weaned piglets at d 5 post-weaning. These piglets also demonstrated increased fluorescein isothiocyanate dextran (FD4) and horseradish peroxidase fluxes in the duodenum and distal jejunum during the experiment, and specifically demonstrated increased FD4 fluxes at d 2 to d 5 post-weaning. On the other hand, profound villus atrophy was observed during the weaning transition for all weaning treatments. Finally, LBW and NBW piglets did not demonstrate notable differences in GSH redox status, small intestinal barrier function and histo-morphology throughout the experiment. CONCLUSION: Although moderate changes in the GSH redox system were observed upon weaning, the GSH redox status remained at a steady state level in 3w and 4w weaned piglets and was therefore not associated with weaning induced villus atrophy. Conversely, 3d3w weaned piglets demonstrated GSH redox imbalance in the small intestinal mucosa, and this co-occurred with a temporal malfunction of their intestinal barrier function.

Fate of Thymol and Its Monoglucosides in the Gastrointestinal Tract of Piglets.

The monoterpene thymol has been proposed as a valuable alternative to in-feed antibiotics in animal production. However, the effectiveness of the antimicrobial is comprised by its fast absorption in the upper gastrointestinal tract. In this work, two glucoconjugates, thymol α-d-glucopyranoside (TαG) and thymol ß-d-glucopyranoside (TßG), were compared with free thymol for their potential to deliver higher concentrations of the active compound to the distal small intestine of supplemented piglets. Additionally, an analytical method was developed and validated for the simultaneous quantification of thymol and its glucoconjugates in different matrices. In stomach contents of pigs fed with 3333 µmol kg-1 thymol, TαG, or TßG, total thymol concentrations amounted to 3048, 2357, and 1820 µmol kg-1 dry matter, respectively. In glucoconjugate-fed pigs, over 30% of this concentration was present in the unconjugated form, suggesting partial hydrolysis in the stomach. No quantifiable levels of thymol or glucoconjugates were detected in the small intestine or cecum for any treatment, indicating that conjugation with one glucose unit did not sufficiently protect thymol from early absorption.

Effects of Thymol and Thymol α-D-Glucopyranoside on Intestinal Function and Microbiota of Weaned Pigs.

The present study evaluated gluco-conjugation as a measure to delay thymol absorption and enhance its antimicrobial activity in the gut of weaned piglets. The three dietary treatments consisted of a basal diet without additives (TCON), supplemented with thymol at 3.7 mmol/kg dry matter (TTHY), or with an equimolar amount of thymol α-D-glucopyranoside (TTαG). Each dietary treatment was replicated in 6 pens with 2 piglets per pen (n = 12 for analytical parameters) and was supplemented for 14 days. The total (free plus gluco-conjugated) thymol concentrations in the stomach contents were 14% lower in TTαG as compared to TTHY piglets. Neither of the additives could be detected further down the gut. E.coli counts in the proximal small intestine were significantly lower in TTHY than in TTαG pigs (3.35 vs. 4.29 log10 CFU/g); however, other bacterial counts and their metabolites were unaffected by treatment. A metagenomic bacterial analysis revealed a great relative abundance of Lactobacillus spp. in the distal small intestine (range 88.4%-99.9%), irrespective of treatment. The intestinal barrier function was improved by TTHY, but not TTαG, compared to TCON. In conclusion, gluco-conjugation did not result in higher thymol concentrations in the gut, but conversely, it seemed to diminish the biological effects of thymol in vivo.

The Effect of Dietary Quercetin on the Glutathione Redox System and Small Intestinal Functionality of Weaned Piglets.

Quercetin has been shown to alleviate mucosal damage and modulate the glutathione (GSH) redox system in the colon of rodents. In the current study, we assessed whether quercetin was able to mitigate small intestinal dysfunction in weaned pigs. Here, 224 weaned piglets were fed a diet containing quercetin at either 0, 100, 300, or 900 mg/kg diet until d14 post-weaning, followed by a common basal diet until d42. Eight animals per treatment were sampled at d5 and d14 post-weaning. In these animals, the small intestinal histomorphology, barrier function, and protein abundance of occludin, caspase-3, and proliferating cell nuclear antigen were assessed. None of these parameters were affected, and neither did quercetin improve performance up to d42 post-weaning. The GSH redox system was evaluated in blood, small intestinal mucosa, and liver. Quercetin did not affect the glutathione peroxidase, glutathione reductase, and glutamate-cysteine ligase activity in these tissues. In contrast, the hepatic glutathione transferase (GST) activity was significantly increased by quercetin supplementation at d5 post-weaning of 100, 300, and 900 mg/kg. Importantly, d5 was characterized by a more oxidized GSH redox status. To conclude, dietary quercetin had little effect on the small intestine, but did upregulate hepatic GST in the occurrence of redox disturbance.

Effects of N-Acetyl-Cysteine Supplementation through Drinking Water on the Glutathione Redox Status during the Weaning Transition of Piglets.

This study investigated the effect of N-acetyl-cysteine (NAC) supplementation through drinking water on animal performance and the glutathione (GSH) redox system in weaned piglets, particularly in relation to the immediate post-weaning feed intake. To this end, 168 piglets were weaned and either fed ad libitum or fasted the first two days, and either or not administered 200 mg/L NAC via the drinking water until d14 post-weaning. Next to animal performance until day 42 (d42), the GSH redox system was measured in erythrocytes, small intestinal mucosa, liver, lung, and kidney tissue at d0, d2, and d14 post-weaning. Animal performance and GSH levels were not affected by NAC, nor by fasting. Irrespective of treatment, a significant drop in GSH at d2 post-weaning was found as compared to d0, in particular in liver (-69%), distal jejunal mucosa (-72%), and lung tissue (-80%). Post-weaning changes of the GSH redox status were strongly tissue-dependent. To conclude, this research indicates that GSH redox homeostasis was largely affected in multiple organs during the weaning transition. NAC supplementation did not increase GSH levels in any tissue, not even in fasted animals, questioning the fact if cysteine is the first or only limiting factor determining the rate of GSH synthesis in the early post-weaning phase.

Effect of zinc oxide sources and dosages on gut microbiota and integrity of weaned piglets.

Zinc oxide (ZnO) supplied at pharmacological dosage in diets of weaned piglets improves growth performance. However, it causes environmental contamination and induces bacterial antibiotic resistance, yet this practice is debated. The effects on gut microbiota and integrity in weaned piglets of conventional ZnO at nutritional and pharmacological dosage (110 and 2,400 mg/kg Zn, respectively) were compared to an alternative ZnO source at 110 and 220 mg/kg Zn. Each of the four treatments was applied to four pens (two piglets/pen; weaning age, 20 days) for 15 days, and piglets were sampled on day 15 to determine indices of gut integrity. Feeding conventional ZnO at 2,400 mg/kg Zn reduced coliforms and Escherichia coli in distal small intestine as compared to conventional ZnO at 110 mg/kg (-1.7 and -1.4 log10 cfu/g, respectively), whereas the alternative ZnO reduced only coliforms, irrespective of dosage (-1.6 to -1.7 log10 cfu/g). Transepithelial electrical resistance of distal small intestinal mucosa was higher for pigs fed the alternative ZnO source as compared with groups fed 110 mg/kg Zn of conventional ZnO, in line with a trend for higher gene expression of claudin-1 and zona occludens-1. Interestingly, the alternative ZnO source at 110 and 220 mg/kg Zn increased intestinal alkaline phosphatase gene transcript as compared to conventional ZnO at 110 mg/kg Zn, whereas the alternative ZnO source at 110 mg/kg Zn exhibited higher Zn concentrations in mucosa (2,520 µg/g) as compared to conventional ZnO at 110 mg/kg Zn (1,211 µg/g). However, assessing alkaline phosphatase activity, no significant effects were found. In conclusion, the alternative ZnO reduced digesta Enterobacteriaceae numbers and improved gut integrity, albeit similar or better, depending on the dosage, to the effects of pharmacological dosage of conventional ZnO.

Mycotoxin binder improves growth rate in piglets associated with reduction of toll-like receptor-4 and increase of tight junction protein gene expression in gut mucosa.

BACKGROUND: Deoxynivalenol (DON) is a mycotoxin produced by Fusarium species in the field, commonly found in cereal grains, which negatively affects performances and health of animals. Mycotoxin binders are supposed to reduce the toxicity of mycotoxins. METHOD: The effect of a mycotoxin binder (containing acid-activated bentonite, clinoptilolite, yeast cell walls and organic acids) on growth performance and gut health was studied. Hundred and twenty weaning piglets were allocated to 4 treatments, with 5 pens of 6 piglets each, arranged in a 2 × 2 factorial design: control diet; control diet with 1 kg/t binder; control diet with DON; and control diet with DON and 1 kg/t binder. From d0-14, the diet of DON-challenged groups was artificially contaminated with a mixture of DON (2.6 mg/kg), 3-acetyl-deoxynivalenol (0.1 mg/kg) and 15-acetyl-deoxynivalenol (0.3 mg/kg), after which the total contamination level was reduced to 1 mg/kg, until d37. On d14, one pig from each pen was euthanized and distal small intestinal mucosa samples were collected for the assessment of intestinal permeability, and gene expression of tight junction proteins, toll-like receptor 4, inflammatory cytokines and intestinal alkaline phosphatase. RESULTS: After 37 d, there were no differences in growth performance between control and DON-challenged groups (P > 0.05). Nevertheless, groups that received diets with binder had a significantly higher average daily gain (ADG) and average daily feed intake (ADFI) for the first 14 d as well as for the whole period, compared to groups without binder (P ≤ 0.05). Groups with binder in the diet also exhibited lower expression of toll-like receptor 4 in distal small intestinal mucosa at d14, compared to groups without binder (P ≤ 0.05). Interestingly, comparing the two DON treatments, piglets fed DON and binder had significantly higher ADFI and ADG compared to those with only DON for the first 14-d (P ≤ 0.05). Addition of binder to DON contaminated diets, also down-regulated the gene expression of toll-like receptor 4 (P ≤ 0.05) and increased mRNA level zona occludens 1 (P ≤ 0.10) as compared to DON. CONCLUSIONS: The present data provide evidence that the binder improves growth rate in piglets associated with reduction of toll-like receptor-4 and increase of tight junction protein gene expression. However, the current study does not allow to assess whether the effects of the binder are mediated by alterations in the toxicokinetics of the mycotoxin.

Artificial rearing influences the morphology, permeability and redox state of the gastrointestinal tract of low and normal birth weight piglets.

BACKGROUND: In this study the physiological implications of artificial rearing were investigated. Low (LBW) and normal birth weight (NBW) piglets were compared as they might react differently to stressors caused by artificial rearing. In total, 42 pairs of LBW and NBW piglets from 16 litters suckled the sow until d19 of age or were artificially reared starting at d3 until d19 of age. Blood and tissue samples that were collected after euthanasia at 0, 3, 5, 8 and 19 d of age. Histology, ELISA, and Ussing chamber analysis were used to study proximal and distal small intestine histo-morphology, proliferation, apoptosis, tight junction protein expression, and permeability. Furthermore, small intestine, liver and systemic redox parameters (GSH, GSSG, GSH-Px and MDA) were investigated using HPLC. RESULTS: LBW and NBW artificially reared piglets weighed respectively 40 and 33% more than LBW and NBW sow-reared piglets at d19 (P < 0.01). Transferring piglets to a nursery at d3 resulted in villus atrophy, increased intestinal FD-4 and HRP permeability and elevated GSSG/GSH ratio in the distal small intestine at d5 (P < 0.05). GSH concentrations in the proximal small intestine remained stable, while they decreased in the liver (P < 0.05). From d5 until d19, villus width and crypt depth increased, whereas PCNA, caspase-3, occludin and claudin-3 protein expressions were reduced. GSH, GSSG and permeability recovered in artificially reared piglets (P < 0.05). CONCLUSION: The results suggest that artificial rearing altered the morphology, permeability and redox state without compromising piglet performance. The observed effects were not depending on birth weight.