Selenium and vitamin E together improve intestinal epithelial barrier function and alleviate oxidative stress in heat-stressed pigs.

What is the central question of this study? Oxidative stress may play a role in compromising intestinal epithelial barrier integrity in pigs subjected to heat stress, but it is unknown whether an increase of dietary antioxidants (selenium and vitamin E) could alleviate gut leakiness in heat-stressed pigs. What is the main finding and its importance? Levels of dietary selenium (1.0 p.p.m.) and vitamin E (200 IU kg(-1) ) greater than those usually recommended for pigs reduced intestinal leakiness caused by heat stress. This finding suggests that oxidative stress plays a role in compromising intestinal epithelial barrier integrity in heat-stressed pigs and also provides a nutritional strategy for mitigating these effects. Heat stress compromises the intestinal epithelial barrier integrity of mammals through mechanisms that may include oxidative stress. Our objective was to test whether dietary supplementation with antioxidants, selenium (Se) and vitamin E (VE), protects intestinal epithelial barrier integrity in heat-stressed pigs. Female growing pigs (n = 48) were randomly assigned to four diets containing from 0.2 p.p.m. Se and 17 IU kg(-1) VE (control, National Research Council recommended) to 1.0 p.p.m. Se and 200 IU kg(-1) VE for 14 days. Six pigs from each dietary treatment were then exposed to either thermoneutral (20°C) or heat-stress conditions (35°C 09.00-17.00 h and 28°C overnight) for 2 days. Transepithelial electrical resistance and fluorescein isothiocyanate-dextran (4 kDa; FD4) permeability were measured in isolated jejunum and ileum using Ussing chambers. Rectal temperature, respiratory rate and intestinal HSP70 mRNA abundance increased (all P < 0.001), and respiratory alkalosis occurred, suggesting that pigs were heat stressed. Heat stress also increased FD4 permeability and decreased transepithelial electrical resistance (both P < 0.01). These changes were associated with changes indicative of oxidative stress, a decreased glutathione peroxidase (GPX) activity and an increased glutathione disulfide (GSSG)-to-glutathione (GSH) ratio (both P < 0.05). With increasing dosage of Se and VE, GPX-2 mRNA (P = 0.003) and GPX activity (P = 0.049) increased linearly, the GSSG:GSH ratio decreased linearly (P = 0.037), and the impacts of heat stress on intestinal barrier function were reduced (P < 0.05 for both transepithelial electrical resistance and FD4 permeability). In conclusion, in pigs an increase of dietary Se and VE mitigated the impacts of heat stress on intestinal barrier integrity, associated with a reduction in oxidative stress.

A comparative analysis of gastrointestinal tract barrier function and immune markers in gilt vs. sow progeny at birth and weaning.

Progeny born to primiparous sows (gilt progeny; GP) have lower birth, weaning and slaughter weights than sow progeny (SP). GP also have reduced gastrointestinal tract (GIT) development, as evidenced by lower organ weights. Therefore, the aim of this experiment was to quantify changes in GIT barrier function that occur in birth and weaning, representing two major challenges to the young piglet. The effects of parity (GP vs. SP) in GIT barrier integrity function were quantified at four timepoints: birth (~0 h), 24 h after birth (24 h), 1-d preweaning (PrW), and 1-d postweaning (PoW) in commercially reared piglets. Due to inherent differences between newborn and weanling pigs, the results were analyzed in two cohorts, birth (0 vs. 24 h, n = 31) and weaning (PrW vs. PoW, n = 40). Samples of the stomach, jejunum, ileum, and colon were excised after euthanasia and barrier integrity was quantified by measuring transepithelial resistance (TER), macromolecular permeability, the abundance of inflammatory proteins (IL-8, IL-1ß, and TNF-α) and tight junction proteins (claudin-2 and -3). Papp was characterized using a dual tracer approach comprising 4 KDa fluorescein isothiocyanate (FD4) and 150 kDa tetramethyl rhodamine isothiocyanate (T150)-labeled dextrans. Characteristic effects of the initiation of feeding and weaning were observed on the GIT with the initiation of feeding, such as increasing TER and reducing Papp at 24 h, consistent with mucosal growth (P = 0.058) This was accompanied by increased cytokine abundance as evidenced by elevations in TNF-α and IL-1ß. However, GP had increased IL-8 abundance (P = 0.011 and 0.063 for jejunum and ileum respectively) at birth than 24 h overall. In the weaning cohort, jejunal and ileal permeability to FD4 was higher in GP (P = 0.05 and 0.022, respectively) while only higher ileal T150 was observed in GP (P = 0.032). Ileal claudin-2 abundance tended to be higher in SP overall (P = 0.063), but GP ileal claudin-2 expression was upregulated weaning while no change was observed in SP (P = 0.043). Finally, other than a higher jejunal TNF-α abundance observed in SP (P = 0.016), no other effect of parity was observed on inflammatory markers in the weaning cohort. The results from this study indicate that the GIT of GP have poorer adaptation to early life events, with the response to weaning, being more challenging which is likely to contribute to poorer postweaning growth.

The progeny of primiparous sows (gilt progeny; GP) have poorer lifetime growth performance in comparison to progeny from multiparous sows (sow progeny; SP). Previous research suggests that there is an underlying biological basis for reduced growth performance which is attributed to differences in gastrointestinal tract (GIT) barrier development during early life. This study aimed to clarify the timeframes of when these differences are in effect by investigating GIT development during two major events of a piglet's life: birth and weaning. To do this, GIT tissue was collected from GP and SP at four time points; birth, 24 h after birth, 1-d preweaning, and 1-d postweaning and assessed for functional development. The main findings from this study indicate there are early signs of variation in GIT development within the first 24 h of life between GP and SP, and that these differences increase through the preweaning period, with GP entering weaning with poorer GIT development and function. Possible explanations for the reduced GI development may be reduced maternal nutrition during the suckling period.

Evaluation of Sugarcane-Derived Polyphenols on the Pre-Weaning and Post-Weaning Growth of Gilt Progeny.

Gilt progeny (GP) exhibit poorer growth compared with sow progeny (SP), particularly in the pre-weaning and post-weaning period. Late gestation/lactation sow diets and weaner diets were supplemented with 0.5% Polygain (POL), a sugarcane extract rich in polyphenols, to collectively improve GP growth in these periods. Gilts (n = 60) and sows (n = 68, parities 2 and 3) were fed a control or POL diet. Weaned GP (n = 79) and SP (n = 92) born to these dams were also fed either a CON or POL diet. Gilts litters weighed less than sow litters at birth and 21 days (p < 0.001 for both) and were not improved by POL (p = 0.80 and 0.54, respectively). GP were lighter than SP at day 7 and day 14 post-weaning (p < 0.001 for both) and were not improved by the POL diet at these timepoints (p = 0.61 and 0.97, respectively). Plasma interleukin-1ß (IL-1ß) was increased at weaning despite POL supplementation (p = 0.022) and GP had reduced IL-1ß overall (p = 0.021). Overall, POL was unable to improve growth in GP and the attenuated immune response seen in GP could be contributing to their poor growth performance.

The Effect of Heat Stress on Respiratory Alkalosis and Insulin Sensitivity in Cinnamon Supplemented Pigs.

With increases in the frequency, intensity and duration of heat waves forecast plus expansion of tropical agriculture, heat stress (HS) is both a current and an emerging problem. As cinnamon has been shown to increase insulin sensitivity, which is part of the adaptive response to HS, the aim of this experiment was to determine if cinnamon could improve insulin sensitivity and ameliorate HS in grower pigs. In a 2 × 2 factorial design, 36 female Large White × Landrace pigs were fed control (0%) vs. cinnamon (1.5%) diets and housed for 7 day under thermoneutral (20 °C, TN) vs. HS conditions (8 h 35 °C/16 h 28 °C, 35% relative humidity). At the completion of the challenge, insulin sensitivity was assessed by an intravenous glucose tolerance test (IVGTT). Heat stress increased parameters such as respiration rate and rectal temperature. Furthermore, biochemical changes in blood and urine indicated the pigs were experiencing respiratory alkalosis. Minimal modelling of parameters of insulin sensitivity showed that HS pigs had a lower insulin response to the IVGTT and improved insulin sensitivity. Cinnamon had additive effects with heat stress, reflected in lowering the insulin area under curve (AUC) and elevated insulin sensitivity compared to TN. However, this apparent improvement in insulin sensitivity did not ameliorate any of the other physiological symptoms of HS.

Dietary Inclusion of 1,3-Butanediol Increases Dam Circulating Ketones and Increases Progeny Birth Weight.

1,3-Butanediol (BD) is a ketogenic substance that can improve piglet growth and survival and potentially increase performance in gilt progeny when provided as a dietary supplement during late gestation. Gilts (n = 77; parity 1) and sows (n = 74; parities 2 and 3) were fed either a standard commercial gestation diet or a diet supplemented with 4% BD from day 90 of gestation until farrowing. Dams fed with diets supplemented with BD had higher plasma beta-hydroxybutyrate (p = 0.01) and lower non-esterified fatty acid concentrations (p < 0.001). The percentage of progeny that were light-for-age (<1.1 kg) at birth was decreased by BD (18.2 vs. 13.5%, p < 0.006), particularly in gilts (24.0 vs. 18.3%, p < 0.034). Individual birth weights and litter weights birth weights tended to be increased by the BD diet (p = 0.085 and 0.078; respectively) although these effects were not maintained to weaning. Pre-weaning mortality was greater in gilt than in sow progeny and was not altered by dietary BD. Feeding BD in late gestation can improve birth weight, but further work is needed to see if these effects are carried through subsequent stages of growth, particularly in gilt progeny.

A comparison of the anatomical and gastrointestinal functional development between gilt and sow progeny around birth and weaning1.

Gilt progeny (GP) often have restricted growth performance and health status in comparison to sow progeny (SP) from birth, with the underlying mechanisms responsible for this yet to be fully understood. The present study aimed to compare differences in growth and development between GP and SP in the first 24 h after birth and in the periweaning period. Two cohorts of pigs including 36 GP and 37 SP were euthanized at 1 of 4 time points: a birth cohort (at birth before suckling, 0 h; and 24 h after birth, 24 h; n = 33) and a weaning cohort (at approximately 29 d of age; "pre-weaning," PrW; and 24 h after weaning; "post-weaning," PoW; n = 40). Pigs were individually weighed at 0 h, 24 h, PrW, and PoW up until the point of euthanasia, at which time the weights of selected tissues and organs were recorded and analyzed relative to BW. The length of the small intestine (SI), femur, and body were also measured, and a serum sample was collected and analyzed for IgG concentration. Samples of jejunal and ileal mucosa were collected and analyzed for total protein and specific activity of lactase. Euthanized GP were lighter (P < 0.01) than SP at all time points. At all time points, the ratios of quadriceps weight to femur length, BW to body length, spleen to BW (all P < 0.05), and SI weight to length (P < 0.10) were lower in GP than in SP. There was no difference (P ≥ 0.05) in stomach or heart to BW ratios between GP and SP in either cohort. The brain to liver weight ratio was greater (P = 0.044) in GP than in SP in the birth cohort, and the brain to BW ratio was greater (P < 0.01) in GP in both the birth and weaning cohorts. The liver to BW ratio was similar (P = 0.35) at birth but greater (P = 0.014) in GP around weaning. Total mucosal protein content in the jejunum and ileum was lower (P = 0.007) in GP at 24 h compared with SP, and specific activity of lactase was greater (P = 0.022) in GP in the birth cohort, whereas there were no differences in the weaning cohort (P ≥ 0.10). Gilt progeny had lower (P < 0.001) serum IgG concentration compared with SP at 24 h, but there was no difference (P ≥ 0.10) in the weaning cohort. Collectively, these findings suggest that the early development of GP may be delayed compared with SP and that a number of the anatomical differences between GP and SP that exist after birth are also present at weaning.

Primiparous and Multiparous Sows Have Largely Similar Colostrum and Milk Composition Profiles Throughout Lactation.

It is important to understand the biological factors influencing the poorer lifetime performance of gilt progeny in comparison to sow progeny and determine whether this may be partially due to differences in lactation performance between primiparous and multiparous sows. It was hypothesized that primiparous sows would have lower levels of immunoglobulin G (IgG) in colostrum and milk compared to multiparous sows, and lower levels of other energetic components. Differences in colostrum and milk composition between ten primiparous and ten multiparous sows (parities 3 and 4) from a commercial herd were examined throughout lactation (day 0, 1, 2, 3, 7, 14, and 21). Overall, there were no (p ≥ 0.05) parity differences in total IgG, fat, protein, lactose, and net energy (NE) concentrations. Primiparous sows had higher lactose levels at day 2 (parity by timepoint interaction; p = 0.036) and lower NE at day 3 (p = 0.091), and multiparous sows had higher lactose levels at days 14 and 21. Results suggest that shortcomings of gilt progeny are unlikely due to insufficient nutrient levels in colostrum and milk, and more likely to reduced colostrum and milk intake and their capacity to digest and absorb each component.

Feeding Conjugated Linoleic Acid without a Combination of Medium-Chain Fatty Acids during Late Gestation and Lactation Improves Pre-Weaning Survival Rates of Gilt and Sow Progeny.

Feeding conjugated linoleic acid (CLA) or medium-chain fatty acids (MCFA) to dams has been shown to improve progeny growth and survival, and hence may be particularly advantageous to gilt progeny. Primiparous (n = 129) and multiparous sows (n = 123; parities 3 and 4) were fed one of four diets from day 107 of gestation (107.3 ± 0.1 days) until weaning (day 27.2 ± 0.1 of lactation): (i) control diet; (ii) 0.5% CLA diet; (iii) 0.1% MCFA diet; and (iv) equal parts of (ii) and (iii). Progeny performance data were collected and, from a subset of sows (n = 78) and their piglets (n = 144), a colostrum (day 0), milk (day 21), and piglet serum sample (day 3) were analyzed for immunoglobulin G and several selected metabolites. Liveborn pre-weaning mortality tended to be lowest (p = 0.051) in piglets from sows fed 0.5% CLA. However, sows fed the CLA diet had more (p = 0.005) stillbirths than those on the other diets. There were few effects of diet or the dam parity x diet interaction (p ≥ 0.05) on other parameters. Overall, feeding CLA or MCFA did not improve the performance of primiparous sows, multiparous sows, or their progeny.

Potential of in vivo real-time gastric gas profiling: a pilot evaluation of heat-stress and modulating dietary cinnamon effect in an animal model.

Gastroenterologists are still unable to differentiate between some of the most ordinary disorders of the gut and consequently patients are misdiagnosed. We have developed a swallowable gas sensor capsule for addressing this. The gases of the gut are the by-product of the fermentation processes during digestion, affected by the gut state and can consequently provide the needed information regarding the health of the gut. Here we present the first study on gas sensor capsules for revealing the effect of a medical supplement in an animal (pig) model. We characterise the real-time alterations of gastric-gas in response to environmental heat-stress and dietary cinnamon and use the gas profiles for understanding the bio-physiological changes. Under no heat-stress, feeding increases gastric CO2 concentration, while dietary cinnamon reduces it due to decrease in gastric acid and pepsin secretion. Alternatively, heat-stress leads to hyperventilation in pigs, which reduces CO2 concentration and with the cinnamon treatment, CO2 diminishes even more, resulting in health improvement outcomes. Overall, a good repeatability in gas profiles is also observed. The model demonstrates the strong potential of real-time gas profiler in providing new physiological information that will impact understanding of therapeutics, presenting a highly reliable device for monitoring/diagnostics of gastrointestinal disorders.