Effects of resistant starch on behaviour, satiety-related hormones and metabolites in growing pigs

Sugary and salty former food products in pig diets affect energy and nutrient digestibility, feeding behaviour but not the growth performance and carcass composition

Former foodstuff products (FFPs) are promising alternative ingredients for reducing the waste of natural resources and the environmental impact of food production. This study investigates the effects of salty and sugary FFPs on growth performance, apparent total tract digestibility (ATTD), and growing-finishing pigs' empty body and carcass composition. Thirty-six Swiss Large White male castrated pigs were assigned to three growing (G) and finishing (F) diets: (1) standard diet (ST), 0% FFPs; (2) 30% conventional ingredients replaced by sugary FFPs (SU); and (3) 30% conventional ingredients replaced by salty FFPs (SA). Faecal samples from 24 selected pigs were collected to assess the ATTD of gross energy, crude fibres, and CP. The BW was measured weekly, while feed intake was determined daily. Average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR), and ATTD were calculated for both the growing and finishing periods. Pigs' body composition was determined at ≥20 and ≥98 kg using dual-energy X-ray absorptiometry. In the growing but not finishing period, the FCR was lower (P < 0.05) in ST compared to SA and SU pigs. Considering the entire growing and finishing period, neither the inclusion level nor the type of FFPs influenced (P > 0.05) ADG, ADFI, FCR, or BW at slaughter. In both the growing and finishing periods, the gross energy ATTD was higher (P < 0.05) in the SA than in the ST group, with intermediate values in the SU group. In the growing period, the CP ATTD was higher (P < 0.05) in the SA than in the SU and ST groups. In the finishing period, the crude fibre ATTD was lower (P < 0.05) in the SA and SU than in the ST group. Throughout the overall period, the average daily fat intake was higher (P < 0.05) in pigs fed an SU diet, even though both categories of FFPs had no (P > 0.05) effects on the parameters related to the pigs' body composition (e.g., average daily fat weight gain). Finally, the carcasses of the SU group had the thickest belly fat, even though the total fat content was similar among the groups. This study confirms that including FFPs has no detrimental effects on growth performance or live body/carcass composition in growing and finishing pigs.

The Effect of Prebiotic Supplements on the Gastrointestinal Microbiota and Associated Health Parameters in Pigs

Establishing a balanced and diverse microbiota in the GIT of pigs is crucial for optimizing health and performance throughout the production cycle. The post-weaning period is a critical phase, as it is often associated with dysbiosis, intestinal dysfunction and poor performance. Traditionally, intestinal dysfunctions associated with weaning have been alleviated using antibiotics and/or antimicrobials. However, increasing concerns regarding the prevalence of antimicrobial-resistant bacteria has prompted an industry-wide drive towards identifying natural sustainable dietary alternatives. Modulating the microbiota through dietary intervention can improve animal health by increasing the production of health-promoting metabolites associated with the improved microbiota, while limiting the establishment and proliferation of pathogenic bacteria. Prebiotics are a class of bioactive compounds that resist digestion by gastrointestinal enzymes, but which can still be utilized by beneficial microbes within the GIT. Prebiotics are a substrate for these beneficial microbes and therefore enhance their proliferation and abundance, leading to the increased production of health-promoting metabolites and suppression of pathogenic proliferation in the GIT. There are a vast range of prebiotics, including carbohydrates such as non-digestible oligosaccharides, beta-glucans, resistant starch, and inulin. Furthermore, the definition of a prebiotic has recently expanded to include novel prebiotics such as peptides and amino acids. A novel class of -biotics, referred to as "stimbiotics", was recently suggested. This bioactive group has microbiota-modulating capabilities and promotes increases in short-chain fatty acid (SCFA) production in a disproportionally greater manner than if they were merely substrates for bacterial fermentation. The aim of this review is to characterize the different prebiotics, detail the current understating of stimbiotics, and outline how supplementation to pigs at different stages of development and production can potentially modulate the GIT microbiota and subsequently improve the health and performance of animals.

Effects of different starch structures on energy metabolism in pigs

BACKGROUND

Starch is a major component of carbohydrates and a major energy source for monogastric animals. Starch is composed of amylose and amylopectin and has different physiological functions due to its different structure. It has been shown that the energy supply efficiency of amylose is lower than that of amylopectin. However, there are few studies on the effect of starch structure on the available energy of pigs. The purpose of this study was to measure the effect of different structures of starch in the diet on the net energy (NE) of pigs using a comparative slaughter method and to establish a prediction equation to estimate the NE of starch with different structures. Fifty-six barrows (initial BW 10.18 ± 0.11 kg) were used, and they were housed and fed individually. Pigs were divided into 7 treatments, with 8 replicates for each treatment and 1 pig for each replicate. One of the treatments was randomly selected as the initial slaughter group (ISG). Pigs in the remaining treatments were assigned to 6 diets, fed with basic diet and semi-pure diets with amylose/amylopectin ratio (AR) of 3.09, 1.47, 0.25, 0.15 and 0.12, respectively. The experiment lasted for 28 d.

RESULTS

Results showed that compared with the high amylose (AM) groups (AR 3.09 and 1.47), the high amylopectin (AP) group (AR 0.15) significantly increased the final BW, average daily weight gain and average daily feed intake of pigs (P < 0.05), but the F:G of the AM group was lower (P < 0.01). In addition, AR 0.15 and 0.12 groups have higher (P < 0.01) nutrient digestibility of dry matter, crude protein, gross energy and crude ash. Meanwhile, compared with other groups, AR 0.15 group has a higher (P < 0.05) NE intake and energy retention (RE). The regressive equation for predicting with starch structures was established as RE = 1,235.243 - 48.298AM/AP (R2 = 0.657, P = 0.05).

CONCLUSIONS

In conclusion, NE intake and RE of pigs augmented with the increase of dietary amylopectin content, indicating that diets high in amylopectin were more conducive to promoting the growth of pigs in the late conservation period.

Effects of substituting wheat by rye in diets for young fattening pigs on nutrient digestibility, performance, products of intestinal fermentation, and fecal characteristics

Climate change and increasing demands to reduce the environmental impact of feed production are major challenges for animal nutritionists. Compared to wheat, which is commonly used in high levels in European piglet diets, rye is more efficient in using limited resources, most importantly, water and phosphorus. As a result, its cultivation has a relatively low carbon footprint. The high amounts of non-starch polysaccharides of rye might lead to an increased intestinal fermentation with potential beneficial effects on gut health. However, the high levels of non-starch polysaccharides in rye, which have a major impact on the physico-chemical conditions of the digesta, might affect digestibility and performance especially in young animals. It was therefore of interest to compare the effects of isoenergetic diets with increasing levels of rye as a replacement for wheat fed to young fattening pigs (bodyweight: 16-40 kg). The control diet contained 69% of wheat, while in the other three experimental diets, the amount of wheat was gradually replaced (by a third in each case) with rye. Thus, the experimental diets contained 23, 46, and 69% of rye. A total of 40 young pigs were housed individually in four dietary treatment groups. During a 4 week trial, effects on performance, digestibility, products of intestinal fermentation, and fecal characteristics were evaluated. There were no negative effects on feed intake and gains, even though the feed conversion ratio increased with the highest dietary rye level (69%). Digestibility rates of organic matter and crude protein did not differ significantly. Without affecting the characteristics of the feces, numerically higher amounts of intestinal fermentation products and higher colonic digesta mass were observed.

Resistant starch: Implications of dietary inclusion on gut health and growth in pigs: a review

Starch from cereal grains, pulse grains, and tubers is a major energy substrate in swine rations constituting up to 55% of the diet. In pigs, starch digestion is initiated by salivary and then pancreatic α-amylase, and has as final step the digestion of disaccharides by the brush-border enzymes in the small intestine that produce monosaccharides (glucose) for absorption. Resistant starch (RS) is the proportion of starch that escapes the enzymatic digestion and absorption in the small intestine. The undigested starch reaches the distal small intestine and hindgut for microbial fermentation, which produces short-chain fatty acids (SCFA) for absorption. SCFA in turn, influence microbial ecology and gut health of pigs. These fermentative metabolites exert their benefits on gut health through promoting growth and proliferation of enterocytes, maintenance of intestinal integrity and thus immunity, and modulation of the microbial community in part by suppressing the growth of pathogenic bacteria while selectively enhancing beneficial microbes. Thus, RS has the potential to confer prebiotic effects and may contribute to the improvement of intestinal health in pigs during the post-weaning period. Despite these benefits to the well-being of pigs, RS has a contradictory effect due to lower energetic efficiency of fermented vs. digested starch absorption products. The varying amount and type of RS interact differently with the digestion process along the gastrointestinal tract affecting its energy efficiency and host physiological responses including feed intake, energy metabolism, and feed efficiency. Results of research indicate that the use of RS as prebiotic may improve gut health and thereby, reduce the incidence of post-weaning diarrhea (PWD) and associated mortality. This review summarizes our current knowledge on the effects of RS on microbial ecology, gut health and growth performance in pigs.

Beneficial effects of a plant-fish oil, slow carbohydrate diet on cardio-metabolic health exceed the correcting effects of metformin-pioglitazone in diabetic pigs fed a fast-food diet

Background

Lifestyle influences endocrine, metabolic and cardiovascular homeostasis. This study investigated the impact of diet and oral anti-diabetic medication on cardio-metabolic health in human-sized diabetic pigs.

Methods

After a growing pre-phase from ~30 to ~69 kg during which domestic pigs were fed either a low fat, low sucrose diet (group A) or a fast food-type diet elevated in lard (15%) and sucrose (40%) (group B), the pigs were subdivided in 5 groups (n = 7–8 pigs per group). Group 1, normal pigs from group A on a low fat, low sugar (L) pig diet and group 2, normal pigs from group B on a high lard (25%), sucrose-fructose (40%), cholesterol (1%) fast food-type (F) diet. Diabetes (D) was induced in group B pigs by streptozotocin and group 3 received the F diet (DF), group 4 received the F diet with Anti-diabetic medication metformin (2 g.day^-1)-pioglitazone (40 mg.day^-1) (DFA) and group 5 switched to a Plant-Fish oil (25%), Slowly digestible starch (40%) diet (DPFS). The F and PFS diets were identical for fat, carbohydrate and protein content but only differed in fat and carbohydrate composition. The 5 pig groups were followed up for 7 weeks until reaching ~120 kg.

Results

In normal pigs, the F diet predisposed to several abnormalities related to metabolic syndrome. Diabetes amplified the inflammatory and cardiometabolic abnormalities of the F diet, but both oral FA medication and the PFS diet partially corrected these abnormalities (mean±SEM) as follows: Fasting plasma TNF-ɑ (pg.ml^-1) and NEFA (mmol.l^-1) concentrations were high (p<0.02) in DF (193±55 and 0.79±0.16), intermediate in DFA (136±40 and 0.57±012) and low in DPFS pigs (107±31 and 0.48±0.19). Meal intolerance (response over fasting) for glucose and triglycerides (area under the curve, mmol.h^-1) and for lactate (3-h postprandial, mmol.l^-1) was high (p<0.03) in DF (489±131, 8.6±4.8 and 2.2±0.6), intermediate in DFA (276±145, 1.4±1.1 and 1.6±0.4) and low in DPFS (184±62, 0.7±1.8 and 0.1±0.1). Insulin-mediated glucose disposal (mg.kg^-1.min^-1) showed a numerical trend (p = NS): low in DF (6.9±2.2), intermediate in DFA (8.2±1.3) and high in DPFS pigs (10.4±2.7). Liver weight (g.kg^-1 body weight) and liver triglyceride concentration (g.kg^-1 liver) were high (p<0.001) in DF (23.8±2.0 and 69±14), intermediate in DFA (21.1±2.0 and 49±15) and low in DPFS pigs (16.4±0.7 and 13±2.0). Aorta fatty streaks were high (p<0.01) in DF (16.4±5.7%), intermediate in DFA (7.4±4.5%) and low in DPFS pigs (0.05±0.02%).

Conclusion

This translational study using pigs with induced type 2 diabetes provides evidence that a change in nutritional life style from fast food to a plant-fish oil, slowly digestible starch diet can be more effective than sole anti-diabetic medication.

Cooked Black Turtle Beans Ameliorate Insulin Resistance and Restore Gut Microbiota in C57BL/6J Mice on High-Fat Diets

Colored common beans are associated with health promoting and chronic disease prevention effects. Male C57BL/6J mice were fed high-fat (HF) diets supplemented with cooked black turtle beans (HFB) to prevent obesity related insulin resistance. Mice on both HF and HFB were obese compared to mice fed a low-fat (LF) diet. Plasma low density lipoprotein (LDL) and triglyceride concentrations of mice fed HFB diet were 28% and 36.6% lower than those on HF diet. Homeostatic model assessment of insulin resistance (HOMA-IR) index of mice fed HFB diet was 87% lower than that of mice fed HF diet. Diabetes related biomarkers, gastric inhibitory polypeptide (GIP), leptin, glucagon, and inflammatory cytokines interleukin 4 (IL-4) and IL-5, 10 and 12, IFN-g and TNF-α were significantly affected by HFB diet. Pparα, Cyp7a1 and Fasn were down-regulated by HFB diet while LDL-R, Srebp-2, Adipoq and Slc2a4 were up-regulated by HFB diet. The ratio of Firmicutes/Bacteroidetes (F/B) was also decreased 64.1% by HFB diet compared to HF diet. The results indicated that cooked black turtle bean consumption could ameliorate insulin resistance and lower plasma LDL in mice fed HF diet through glucose signaling pathway and JNK/c-Jun pathway. Meanwhile, cooked black turtle bean consumption restored the gut microbiome.

Obesity Development and Signs of Metabolic Abnormalities in Young Göttingen Minipigs Consuming Energy Dense Diets Varying in Carbohydrate Quality

Consumption of fructose has been associated with a higher risk of developing obesity and metabolic syndrome (MetS). The aim of this study was to examine the long-term effects of fructose compared to starch from high-amylose maize starch (HiMaize) at ad libitum feeding in a juvenile Göttingen Minipig model with 20% of the diet provided as fructose as a high-risk diet (HR, n = 15) and 20% as HiMaize as a lower-risk control diet (LR, n = 15). The intake of metabolizable energy was on average similar (p = 0.11) among diets despite increased levels of the satiety hormone PYY measured in plasma (p = 0.0005) of the LR pigs. However, after over 20 weeks of ad libitum feeding, no difference between diets was observed in daily weight gain (p = 0.103), and a difference in BW was observed only at the end of the experiment. The ad libitum feeding promoted an obese phenotype over time in both groups with increased plasma levels of glucose (p = 0.005), fructosamine (p < 0.001), insulin (p = 0.03), and HOMA-IR (p = 0.02), whereas the clinical markers of dyslipidemia were unaffected. When compared to the LR diet, fructose did not accelerate the progression of MetS associated parameters and largely failed to change markers that indicate a stimulated de novo lipogenesis.

Effects of Rice with Different Amounts of Resistant Starch on Mice Fed a High-Fat Diet: Attenuation of Adipose Weight Gain

Increasing the amount of resistant starch (RS) in the diet may confer protective effects against chronic diseases. Rice, a good dietary source of carbohydrates, also contains RS. However, it remains unclear if RS at the amount consumed in cooked rice has a health benefit. To address the question, we examined the effects of cooked rice containing different levels of RS in a diet-induced obesity rodent model. Rice containing RS as low as 1.07% attenuated adipose weight and adipocyte size gain, induced by a moderately high-fat (HF) diet, which correlated with lower leptin levels in plasma and adipose tissue. Rice with 8.61% RS increased fecal short-chain fatty acid levels, modulated HF-diet-induced adipose triacylglycerol metabolism and inflammation-related gene expression, and increased fecal triglyceride excretion. Hence, including rice with RS level at ≥1.07% may attenuate risks associated with the consumption of a moderately HF diet.

Effect of semolina pudding prepared from starch branching enzyme IIa and b mutant wheat on glycaemic response in vitro and in vivo: a randomised controlled pilot study

Refined starchy foods are usually rapidly digested, leading to poor glycaemic control, but not all starchy foods are the same. Complex carbohydrates like resistant starch (RS) have been shown to reduce the metabolic risk factors for chronic diseases such as hyperglycaemia and overweight. The aim of the project was to develop a semolina-based food made from a starch branching enzyme II (sbeIIa/b-AB) durum wheat mutant with a high RS content and to measure its glycaemic index using a double-blind randomised pilot study. We report here the amylose, RS and non-starch polysaccharide concentration of raw sbeIIa/b-AB and wild-type control (WT) semolina. We measured RS after cooking to identify a model food for in vivo testing. Retrograded sbeIIa/b-AB semolina showed a higher RS concentration than the WT control (RS = 4.87 ± 0.6 g per 100 g, 0.77 ± 0.34 g per 100 g starch DWB, respectively), so pudding was selected as the test food. Ten healthy participants consumed ∼50 g of total starch from WT and sbeIIa/b-AB pudding and a standard glucose drink. Capillary blood glucose concentrations were measured in the fasting and postprandial state (2 h): incremental area-under-the-curve (iAUC) and GI were calculated. We found no evidence of difference in GI between sbeIIa/b-AB pudding and the WT control, but the starch digestibility was significantly lower in sbeIIa/b-AB pudding compared to the WT control in vitro (C90 = 33.29% and 47.38%, respectively). Based on these results, novel sbeIIa/b-AB wheat foods will be used in future in vivo studies to test the effect of different RS concentrations and different food matrices on glycaemia.

Toxicity of canola-derived glucosinolates in pigs fed resistant starch-based diets

A study was conducted to determine effects of reducing hindgut pH through dietary inclusion of high-amylose cornstarch (HA-starch) on growth performance, organ weights relative to live body weight (BW), blood thyroid hormone levels, and glucosinolate degradation products of nursery pigs fed cold-pressed canola cake (CPCC). A total of 240 pigs (initial BW: 7.1 kg), which had been weaned at 21 d of age, were housed in 40 pens (6 pigs per pen) and fed 4 diets (10 pens per diet) in a randomized complete block design for 28 d. Four diets were a basal diet with CPCC at 0 or 40%, and with HA-starch at 0 or 40% in a 2 × 2 factorial arrangement. The diets were fed in two phases: Phase 1 from day 0 to 14 and Phase 2 from day 14 to 28 and were formulated to have the same net energy, standardized ileal digestible AA, Ca, and standardized total tract digestible P contents. Dietary inclusion of CPCC and HA-starch was achieved by a partial or complete replacement of corn, soybean meal, and soy protein. At the end of the study, one pig from each pen was euthanized to determine organ weights, blood parameters, hindgut pH, and glucosinolate degradation products. Dietary CPCC reduced (P < 0.05) overall average daily gain (ADG) by 15%; increased (P < 0.05) relative weights of liver and thyroid gland by 27% and 64%, respectively; and reduced (P < 0.05) serum tetraiodothyronine (T4) level from 30.3 to 17.8 ng/mL. Heart, kidney, and gastrointestinal tract weights; serum triiodothyronine level; and hindgut pH of pigs were unaffected by dietary CPCC. Dietary HA-starch reduced (P < 0.05) overall ADG, relative weight of thyroid gland, cecal, and colonic pH; but increased (P < 0.05) relative weight of colon; tended to increase (P = 0.062) serum T4 level. Dietary CPCC and HA-starch interacted (P = 0.024) on relative weight of thyroid gland such that dietary CPCC increased (P < 0.05) weight of thyroid gland for HA-starch-free diet (120 vs. 197 mg/kg of BW) but not for HA-starch-containing diet (104 vs. 130 mg/kg of BW). Dietary CPCC and HA-starch interacted (P = 0.001) on cecal isothiocyanate content such that dietary CPCC increased (P < 0.05) level of isothiocyanates for HA-starch-containing diet but not for HA-starch-free diet. In conclusion, dietary CPCC reduced growth performance, increased liver, size and interfered with thyroid gland functions of pigs. However, the negative effects of dietary CPCC on thyroid gland functions of nursery pigs were alleviated by dietary HA-starch.

Sustained effects of resistant starch on the expression of genes related to carbohydrate digestion/absorption in the small intestine

Resistant starch (RS) consumption has beneficial effects on health, such as reduced postprandial blood glucose levels. In this study, we evaluated the effect of a 14-day diet containing RS on α-glucosidase activity and the expression of genes related to carbohydrate digestion/absorption in rats. We examined whether the effects of RS persist when the rats were shifted to a control diet. The results suggest that RS consumption reduces α-glucosidase activity and Mgam, Si and Sglt1 mRNA levels in the proximal jejunum. In addition, RS consumption appeared to influence the serum GIP level, up to 2 days after the animals were shifted to a control diet. To our knowledge, this is the first report that RS has a sustained effect on gut hormone expression and the expression of genes related to carbohydrate digestion/absorption in the proximal jejunum.

What Is the Impact of Diet on Nutritional Diarrhea Associated with Gut Microbiota in Weaning Piglets: A System Review

Piglets experience severe growth challenges and diarrhea after weaning due to nutritional, social, psychological, environmental, and physiological changes. Among these changes, the nutritional factor plays a key role in postweaning health. Dietary protein, fibre, starch, and electrolyte levels are highly associated with postweaning nutrition diarrhea (PWND). In this review, we mainly discuss the high protein, fibre, resistant starch, and electrolyte imbalance in diets that induce PWND, with a focus on potential mechanisms in weaned piglets.

Effect of rate and extent of starch digestion on broiler chicken performance

Dietary starch with lower rate and extent of digestion improves broiler feed efficiency, but previous results might have been confounded by non-starch components of the grains. Therefore, the objective of this research was to study the effects of starch digestion on broilers using semi-purified starch. Semi-purified wheat (WS, rapidly digested) and pea (PS, slowly digested) starch were combined to create 6 WS:PS ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100) in starter, grower and finisher diets. Each treatment was fed to Ross 308 male (2,124) and female (2,376) broilers housed in 72 L floor pens from 0 to 31 d of age to measure performance and meat yield relative to live weight. On day 33, the effects of diet on 8 h feed withdrawal was assessed in 20 males per treatment. Data were analyzed with ANOVA and linear and quadratic regression analyses using SAS 9.4. Significance was accepted at P ≤ 0.050. Body weight gain declined linearly with increasing PS. Male feed intake decreased with increasing PS, but PS did not affect female feed intake. Mortality corrected gain:feed ratio was quadratically influenced by diet (estimated maximum at 25% PS). Breast meat increased linearly with PS, while fat pad and breast and thigh skin decreased linearly. Quadratic responses were found for thigh meat and whole drum (estimated maximum values at 56 and 54% PS, respectively). Males grew faster, ate more, and had higher mortality than females. They also had heavier pectoralis major, thigh bone, and whole drum, while females had heavier pectoralis minor and more breast and thigh skin. After feed withdrawal, digesta content decreased linearly with time in all sections, except for the crop and duodenum, which declined quadratically. Ileal digesta pH increased linearly with time, while crop and caecal pH decreased for 2 h before steadily increasing. Diet did not affect digestive tract emptying or digesta pH. In conclusion, dietary PS maximized feed efficiency at 25% PS and linearly improved breast meat yield, but did not affect digesta clearance after feed withdrawal.

Transglycosylated starch accelerated intestinal transit and enhanced bacterial fermentation in the large intestine using a pig model

Resistant starch can alter the intestinal nutrient availability and bulk of digesta, thereby modulating the substrate available for microbial metabolic activity along the gastrointestinal tract. This study elucidated the effect of transglycosylated starch (TGS) on the retention of digesta in the upper digestive tract, ileal flow and hindgut disappearance of nutrients, and subsequent bacterial profiles in pigs. Fourteen ileal-cannulated growing pigs were fed either the TGS or control (CON) diet in a complete crossover design. Each period consisted of a 10-d adaptation to the diets, followed by 3-d collection of faeces and ileal digesta. Consumption of TGS decreased the retention of digesta in the stomach and small intestine, and increased ileal DM, starch, Ca and P flow, leading to enhanced starch fermentation in the hindgut compared with CON-fed pigs. TGS increased ileal and faecal total SCFA, especially ileal and faecal acetate and faecal butyrate. Gastric retention time positively correlated to Klebsiella, which benefitted together with Selenomonas, Lactobacillus, Mitsuokella and Coriobacteriaceae from TGS feeding and ileal starch flow. Similar relationships existed in faeces with Coriobacteriaceae, Veillonellaceae and Megasphaera benefitting most, either directly or indirectly via cross-feeding, from TGS residuals in faeces. TGS, in turn, depressed genera within Ruminococcaceae, Clostridiales and Christensenellaceae compared with the CON diet. The present results demonstrated distinct ileal and faecal bacterial community and metabolite profiles in CON- and TGS-fed pigs, which were modulated by the type of starch, intestinal substrate flow and retention of digesta in the upper digestive tract.

Impact of Diet-Modulated Butyrate Production on Intestinal Barrier Function and Inflammation

A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat, and sugar, and low in dietary fibre is a key environmental factor responsible for this development, which may cause local and systemic inflammation. A low intake of dietary fibre is a limiting factor for maintaining a viable and diverse microbiota and production of short-chain fatty acids in the gut. A suppressed production of butyrate is crucial, as this short-chain fatty acid (SCFA) can play a key role not only in colonic health and function but also at the systemic level. At both sites, the mode of action is through mediation of signalling pathways involving nuclear NF-κB and inhibition of histone deacetylase. The intake and composition of dietary fibre modulate production of butyrate in the large intestine. While butyrate production is easily adjustable it is more variable how it influences gut barrier function and inflammatory markers in the gut and periphery. The effect of butyrate seems generally to be more consistent and positive on inflammatory markers related to the gut than on inflammatory markers in the peripheral tissue. This discrepancy may be explained by differences in butyrate concentrations in the gut compared with the much lower concentration at more remote sites.

Male grower pigs fed cereal soluble dietary fibres display biphasic glucose response and delayed glycaemic response after an oral glucose tolerance test

Acute and sustained soluble dietary fibre (SDF) consumption are both associated with improved glucose tolerance in humans and animal models (e.g. porcine). However, the effects on glucose tolerance in grower pigs, adapted to diets with a combination of SDF have not been studied previously. In this experiment, cereal SDF wheat arabinoxylan (AX) and oat β-glucan (BG) were fed individually and in combination to determine the effect on glucose tolerance in jugular vein catheterized grower pigs. Five groups of Large White male grower pigs were fed highly digestible diets containing either 10% AX, 10% BG, 5% AX with 5% BG, a model cereal whole wheat flour (WWF), or a control wheat starch diet (WS) with no SDF. Blood was collected via jugular vein catheters over 240 minutes following a feed challenge and an oral glucose tolerance test (OGTT) on two separate days. Postprandial blood samples were used to determine plasma glucose, insulin, non-esterified fatty acids (NEFA), glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine tyrosine (PYY), ghrelin, glucagon and cortisol concentrations. No dietary effects on glycaemic response were observed following the feed challenge or the OGTT as determined by the area under the curve (AUC). A biphasic glucose and insulin response was detected for all pigs following the OGTT. The current study showed male grower pigs have tight glycaemic control and glucose tolerance regardless of diet. In addition, pigs fed the combined SDF had a reduced GIP response and delayed insulin peak following the feed challenge. Incretin (GLP-1 and GIP) secretion appeared asynchronous reflecting their different enteroendocrine cell locations and response to nutrient absorption.

Postprandial PYY increase by resistant starch supplementation is independent of net portal appearance of short-chain fatty acids in pigs

Increased dietary fiber (DF) fermentation and short-chain fatty acid (SCFA) production may stimulate peptide tyrosine-tyrosine (PYY) secretion. In this study, the effects of hindgut SCFA production on postprandial PYY plasma levels were assessed using different experimental diets in a porto-arterial catheterized pig model. The pigs were fed experimental diets varying in source and levels of DF for one week in 3×3 Latin square designs. The DF sources were whole-wheat grain, wheat aleurone, rye aleurone-rich flour, rye flakes, and resistant starch. Postprandial blood samples were collected from the catheters and analyzed for PYY levels and net portal appearance (NPA) of PYY was correlated to NPA of SCFA. No significant effects of diets on NPA of PYY were observed (P > 0.05), however, resistant starch supplementation increased postprandial NPA of PYY levels by 37 to 54% compared with rye-based and Western-style control diets (P = 0.19). This increase was caused by higher mesenteric artery and portal vein PYY plasma levels (P < 0.001) and was independent of SCFA absorption (P > 0.05). The PYY levels were higher in response to the second daily meal compared with the first daily meal (P < 0.001), but similar among diets (P > 0.10). In conclusion, the increased postprandial PYY responses in pigs fed with different levels and sources of DF are not caused by an increased SCFA absorption and suggest that other mechanisms such as neural reflexes and possibly an increased flow of digesta in the small intestine may be involved. The content of DF and SCFA production did not affect PYY levels.

Transglycosylated Starch Improves Insulin Response and Alters Lipid and Amino Acid Metabolome in a Growing Pig Model

Due to the functional properties and physiological effects often associated with chemically modified starches, significant interest lies in their development for incorporation in processed foods. This study investigated the effect of transglycosylated cornstarch (TGS) on blood glucose, insulin, and serum metabolome in the pre- and postprandial phase in growing pigs. Eight jugular vein-catheterized barrows were fed two diets containing 72% purified starch (waxy cornstarch (CON) or TGS). A meal tolerance test (MTT) was performed with serial blood sampling for glucose, insulin, lipids, and metabolome profiling. TGS-fed pigs had reduced postprandial insulin (p < 0.05) and glucose (p < 0.10) peaks compared to CON-fed pigs. The MTT showed increased (p < 0.05) serum urea with TGS-fed pigs compared to CON, indicative of increased protein catabolism. Metabolome profiling showed reduced (p < 0.05) amino acids such as alanine and glutamine with TGS, suggesting increased gluconeogenesis compared to CON, probably due to a reduction in available glucose. Of all metabolites affected by dietary treatment, alkyl-acyl-phosphatidylcholines and sphingomyelins were generally increased (p < 0.05) preprandially, whereas diacyl-phosphatidylcholines and lysophosphatidylcholines were decreased (p < 0.05) postprandially in TGS-fed pigs compared to CON. In conclusion, TGS led to changes in postprandial insulin and glucose metabolism, which may have caused the alterations in serum amino acid and phospholipid metabolome profiles.

Gut microbial metabolism defines host metabolism: an emerging perspective in obesity and allergic inflammation

The presence of >100 trillion microorganisms (collectively called gut microbiota) in our large intestine is essential for the maintenance of health. The gut microbiota starts to develop before birth and matures within first three years of life. The Western diet and lifestyle have been implicated in causing an imbalance of gut microbial communities and their metabolites that consequence in disease states, such as obesity and asthma. With more than 13% of the world population currently living with obesity and one out of 10 children diagnosed with asthma, we explore here the recent developments in the biosynthesis and mode of action of the key metabolites in relation to these two chronic inflammatory conditions.

Enzymatically Modified Starch Favorably Modulated Intestinal Transit Time and Hindgut Fermentation in Growing Pigs

Aside from being used as stabilizing agents in many processed foods, chemically modified starches may act as functional dietary ingredients. Therefore, development of chemically modified starches that are less digestible in the upper intestinal segments and promote fermentation in the hindgut receives considerable attention. This study aimed to investigate the impact of an enzymatically modified starch (EMS) on nutrient flow, passage rate, and bacterial activity at ileal and post-ileal level. Eight ileal-cannulated growing pigs were fed 2 diets containing 72% purified starch (EMS or waxy cornstarch as control) in a cross-over design for 10 d, followed by a 4-d collection of feces and 2-d collection of ileal digesta. On d 17, solid and liquid phase markers were added to the diet to determine ileal digesta flow for 8 h after feeding. Reduced small intestinal digestion after the consumption of the EMS diet was indicated by a 10%-increase in ileal flow and fecal excretion of dry matter and energy compared to the control diet (P<0.05). Moreover, EMS feeding reduced ileal transit time of both liquid and solid fractions compared to the control diet (P<0.05). The greater substrate flow to the large intestine with the EMS diet increased the concentrations of total and individual short-chain fatty acids (SCFA) in feces (P<0.05). Total bacterial 16S rRNA gene abundance was not affected by diet, whereas the relative abundance of the Lactobacillus group decreased (P<0.01) by 50% and of Enterobacteriaceae tended (P<0.1) to increase by 20% in ileal digesta with the EMS diet compared to the control diet. In conclusion, EMS appears to resemble a slowly digestible starch by reducing intestinal transit and increasing SCFA in the distal large intestine.

Substantial replacement of lactose with fat in a high-lactose milk replacer diet increases liver fat accumulation but does not affect insulin sensitivity in veal calves

In veal calves, the major portion of digestible energy intake originates from milk replacer (MR), with lactose and fat contributing approximately 45 and 35%, respectively. In veal calves older than 4 mo, prolonged high intakes of MR may lead to problems with glucose homeostasis and insulin sensitivity, ultimately resulting in sustained insulin resistance, hepatic steatosis, and impaired animal performance. The contribution of each of the dietary energy sources (lactose and fat) to deteriorated glucose homeostasis and insulin resistance is currently unknown. Therefore, an experiment was designed to compare the effects of a high-lactose and a high-fat MR on glucose homeostasis and insulin sensitivity in veal calves. Sixteen male Holstein-Friesian calves (120±2.8kg of BW) were assigned to either a high-lactose (HL) or a high-fat (HF) MR for 13 consecutive weeks. After at least 7 wk of adaptation, whole-body insulin sensitivity and insulin secretion were assessed by euglycemic-hyperinsulinemic and hyperglycemic clamps, respectively. Postprandial blood samples were collected to assess glucose, insulin, and triglyceride responses to feeding, and 24-h urine was collected to quantify urinary glucose excretion. At the end of the trial, liver and muscle biopsies were taken to assess triglyceride contents in these tissues. Long-term exposure of calves to HF or HL MR did not affect whole-body insulin sensitivity (averaging 4.2±0.5×10^-2 [(mg/kg∙min)/(μU/mL)]) and insulin secretion. Responses to feeding were greater for plasma glucose and tended to be greater for plasma insulin in HL calves than in HF calves. Urinary glucose excretion was substantially higher in HL calves (75±13g/d) than in HF calves (21±6g/d). Muscle triglyceride content was not affected by treatment and averaged 4.5±0.6g/kg, but liver triglyceride content was higher in HF calves (16.4±0.9g/kg) than in HL calves (11.2±0.7g/kg), indicating increased hepatic fat accumulation. We conclude that increasing the contribution of fat to the digestible energy intake from the MR from 20 to 50%, at the expense of lactose does not affect whole-body insulin sensitivity and insulin secretion in calves. However, a high-lactose MR increases postprandial glucose and insulin responses, whereas a high-fat MR increases fat accumulation in liver but not muscle.

Dietary Resistant Starch Supplementation Increases High-Density Lipoprotein Particle Number in Pigs Fed a Western Diet

Resistant starch (RS) has been well characterized for its glycemic control properties; however, there is little consensus regarding the influence of RS on blood lipid concentrations and lipoprotein distribution and size. Therefore, this study aimed to characterize the effect of daily RS supplementation in a controlled capsule delivery on biomarkers of cardiovascular (blood lipids, lipoproteins) and diabetes (glucose, insulin) risk in a pig model. Twelve 8-week-old male Yorkshire pigs were placed on a synthetic Western diet and randomly divided into two groups (n = 6/group) for 30 days: (1) a placebo group supplemented with capsules containing unmodified pre-gelatinized potato starch (0 g/RS/day); and (2) an RS group supplemented with capsules containing resistant potato starch (10 g/RS/day). Serum lipids including total-cholesterol (C), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides did not differ (p > 0.05) between the RS and placebo groups. Although the total numbers of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) particles were similar (p > 0.05) between the two groups, total high-density lipoprotein (HDL) particles were higher (+28%, p < 0.05) in the RS group compared with placebo, resulting from an increase (p < 0.05) in the small HDL subclass particles (+32%). Compared with the placebo group, RS supplementation lowered (p < 0.05) fasting serum glucose (-20%) and improved (p < 0.05) insulin resistance as estimated by Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) without a change in insulin. Additionally, total serum glucagon-like-peptide 1 (GLP-1) was higher (+141%, p < 0.05) following RS supplementation compared with placebo. This data suggests that in addition to the more well-characterized effect of RS intake in lowering blood glucose and improving insulin sensitivity, the consumption of RS may be beneficial in lipid management strategies by enhancing total HDL particle number.

Positive effects of resistant starch supplementation on bowel function in healthy adults: a systematic review and meta-analysis of randomized controlled trials

Animal experimental studies have found that resistant starch can significantly improve bowel function, but the outcomes are mixed while conducting human studies. Thus, we conducted a systematic review and meta-analysis of randomized controlled trials to evaluate the relationship between resistant starch supplementation and large intestinal function. Three electronic databases (PubMed, Embase, Scopus) were searched to identify eligible studies. The standardized mean difference (SMD) or weighted mean difference (WMD) was calculated using a fixed-effects model or a random-effects model. The pooled findings revealed that resistant starch significantly increased fecal wet weight (WMD 35.51 g/d, 95% CI 1.21, 69.82) and butyrate concentration (SMD 0.61, 95% CI 0.32, 0.89). Also, it significantly reduced fecal PH (WMD -0.19, 95% CI -0.35, -0.03), but the increment of defecation frequency were not statistically significant (WMD 0.04stools/g, 95% CI -0.08, 0.16). To conclude, our study found that resistant starch elicited a beneficial effect on the function of large bowel in healthy adults.[Formula: see text].

Critical review evaluating the pig as a model for human nutritional physiology

The present review examines the pig as a model for physiological studies in human subjects related to nutrient sensing, appetite regulation, gut barrier function, intestinal microbiota and nutritional neuroscience. The nutrient-sensing mechanisms regarding acids (sour), carbohydrates (sweet), glutamic acid (umami) and fatty acids are conserved between humans and pigs. In contrast, pigs show limited perception of high-intensity sweeteners and NaCl and sense a wider array of amino acids than humans. Differences on bitter taste may reflect the adaptation to ecosystems. In relation to appetite regulation, plasma concentrations of cholecystokinin and glucagon-like peptide-1 are similar in pigs and humans, while peptide YY in pigs is ten to twenty times higher and ghrelin two to five times lower than in humans. Pigs are an excellent model for human studies for vagal nerve function related to the hormonal regulation of food intake. Similarly, the study of gut barrier functions reveals conserved defence mechanisms between the two species particularly in functional permeability. However, human data are scant for some of the defence systems and nutritional programming. The pig model has been valuable for studying the changes in human microbiota following nutritional interventions. In particular, the use of human flora-associated pigs is a useful model for infants, but the long-term stability of the implanted human microbiota in pigs remains to be investigated. The similarity of the pig and human brain anatomy and development is paradigmatic. Brain explorations and therapies described in pig, when compared with available human data, highlight their value in nutritional neuroscience, particularly regarding functional neuroimaging techniques.

Glycemic Index of a Novel High-Fiber White Rice Variety Developed in India--A Randomized Control Trial Study

BACKGROUND

White rice, a common Indian staple, has a high glycemic response and is associated with high risk of type 2 diabetes. The aim of this study was to compare the Glycemic Index (GI) of a newly developed high-fiber white rice (HFWR) with that of commercial white rice (WR).

MATERIALS AND METHODS

HFWR was developed using biochemical screening approaches and classical plant breeding techniques. The GI of HFWR was determined using a validated protocol in 30 healthy participants in the year 2013 and repeated in a subsample of 15 participants in the year 2014; the results were compared with the value for WR. The incremental area under the curve was calculated geometrically by applying the trapezoid rule for both reference food (glucose) and the test foods (HFWR and WR). Proximate principles along with dietary fiber, resistant starch, and amylose content were analyzed using standardized methods.

RESULTS

The dietary fiber content of HFWR was fivefold higher (8.0 ± 0.1 vs. 1.58 ± 0.17 g%), resistant starch content was 6.5-fold higher (3.9 ± 0.2 vs. 0.6 ± 0.03 g%) (P < 0.001), and amylose content was significantly higher (32.8 ± 1.1 vs. 26.0 ± 0.2 g%) (P < 0.001), compared with WR. HFWR was found to be of medium GI (61.3 ± 2.8), whereas WR was of high GI (79.2 ± 4.8). Overall, HFWR had 23% lower GI compared with WR (P = 0.002).

CONCLUSIONS

The new HFWR variety can be considered as a potentially healthier alternative to commercial WR in rice-eating populations, on account of its lower GI and high fiber content.

Effects of Resistant Starch and Arabinoxylan on Parameters Related to Large Intestinal and Metabolic Health in Pigs Fed Fat-Rich Diets

This study compared the effects of a resistant starch (RS)-rich, arabinoxylan (AX)-rich, or low-DF Western-style control diet (all high-fat) on large intestinal gene expression, adiposity, and glycemic response parameters in pigs. Animals were slaughtered after 3 weeks of treatment. Plasma butyrate concentration was higher following the high-DF diets, whereas plasma glucose, insulin, and insulin resistance increased after 3 weeks irrespective of diet. The mRNA abundance in the large intestine of genes involved in nutrient transport, immune response, and intestinal permeability was affected by segment (cecum, proximal, mid or distal colon) and some genes also by diet. In contrast, there was no diet-induced effect on adipose mRNA abundance or adipocyte size. Overall, a high level of RS or AX did not demonstrate strong beneficial effects on large intestinal gene expression as indicators of colonic health or glycemic response parameters when included in a high-fat diet for pigs as a model of healthy humans.

High Amylose Starch with Low In Vitro Digestibility Stimulates Hindgut Fermentation and Has a Bifidogenic Effect in Weaned Pigs

BACKGROUND

Dietary amylose resists enzymatic digestion, thereby providing a substrate for microbial fermentation that stimulates proliferation of beneficial microbiota and production of short-chain fatty acids (SCFAs) in the large intestine of pigs and humans. However, the effect of increasing dietary amylose in pigs immediately postweaning on growth, nutrient digestibility and flow, and intestinal microbial and SCFA profiles has not been studied and can be used as a model for newly weaned human infants.

OBJECTIVE

We studied the effects of increasing dietary amylose on growth, nutrient digestibility, and intestinal microbial and metabolite profiles in weaned pigs.

METHODS

Weaned pigs (n = 32) were randomly allocated to 1 of 4 diets containing 67% starch with 0%, 20%, 28%, or 63% amylose for 21 d. Subsequently, pigs were killed to collect feces and digesta for measuring starch digestion and microbial and metabolite profiles.

RESULTS

Feeding weaned pigs 63% compared with 0%, 20%, and 28% amylose decreased (P < 0.05) feed intake by 5% and growth by ≥ 12%. Ileal digestibility of dry matter decreased (P < 0.05) by 10% and starch by 9%, thereby increasing (P < 0.05) hindgut fermentation, cecal and colonic total SCFAs, and colonic Bacteroides, and lowering (P < 0.01) ileal, cecal, and colonic pH in pigs consuming 63% compared with 0%, 20%, and 28% amylose. Cecal and colonic Bifidobacteria spp. increased by 14-30% (P < 0.05) and Clostridium clusters IV and XIVa were decreased (P < 0.01) in pigs consuming 63% compared with 0%, 20%, and 28% amylose.

CONCLUSION

Increasing dietary amylose in pigs immediately postweaning stimulated hindgut fermentation and Bifidobacteria spp., thereby manipulating the gut environment, but also reduced intake and growth. An optimum dietary amylose concentration should be determined, which would maintain desired growth rate and gut environment in weaned pigs.

Considerations on pig models for appetite, metabolic syndrome and obese type 2 diabetes: From food intake to metabolic disease

(Mini)pigs have proven to be a valuable animal model in nutritional, metabolic and cardiovascular research and in some other biomedical research areas (toxicology, neurobiology). The large resemblance of (neuro)anatomy, the gastro-intestinal tract, body size, body composition, and the omnivorous food choice and appetite of the pig are additional reasons to select this large animal species for (preclinical) nutritional and pharmacological studies. Both humans and pigs are prone to the development of obesity and related cardiovascular diseases such as hypertension and atherosclerosis. Bad cholesterol (LDL) is high and good cholesterol (HDL) is low in pigs, like in humans. Disease-relevant pig models fill the gap between rodent models and primate species including humans. Diet-induced obese pigs show a phenotype related to the metabolic syndrome including high amounts of visceral fat, fatty organs, insulin resistance and high blood pressure. However, overt hyperglycaemia does not develop within 6 months after initiation of high sugar-fat feeding. Therefore, to accelerate the induction of obese type 2 diabetes, obese pigs can be titrated with streptozotocin, a chemical agent which selectively damages the insulin-producing pancreatic beta-cells. However, insulin is required to maintain obesity. With proper titration of streptozotocin, insulin secretion can be restrained at such a level that hyperglycaemia will be induced but lipolysis is still inhibited due to the fact that inhibition of lipolysis is more sensitive to insulin compared to stimulation of glucose uptake. This strategy may lead to a stable hyperglycaemic, non-ketotic obese pig model which remains anabolic with time without the necessity of exogenous insulin treatment.

Dietary fibre and crude protein: impact on gastrointestinal microbial fermentation characteristics and host response

The role of the gastrointestinal tract microbiota in animal health and nutrition has become the subject of intensive research. Carbohydrates and crude protein are major components of swine diets and numerous studies have been performed looking at the effect of inclusion of dietary fibre with possible functional properties. In recent years, our understanding of the diversity and functionality of the gastrointestinal tract microbiota has increased further enabling the possibility for their targeted modulation. However, favouring potential beneficial bacteria, inhibiting possible pathogens or promotion of the formation of desired metabolites, is complex and underlies many factors and uncertainties. Approaches targeting this complex ecosystem (and discussed in this review) include the utilisation of fermentable carbohydrates such as resistant starch, cereal 1–3/1–4 β-glucans, arabinoxylans, inulin or other sources from legumes and industrial by-products. In addition, strategies regarding protein level and the protein : carbohydrate ratio are discussed briefly. Results are both promising and sometimes rather disillusioning considering the dietary concentrations needed to show biologically relevant effects. Deriving recommendations for an optimal inclusion rate of dietary fibre for weaning, growing pigs and sows and maximum levels for dietary crude protein may be one of the main challenges in the near future in the swine industry.

Tail biting in pigs: blood serotonin and fearfulness as pieces of the puzzle?

Tail biting in pigs is a widespread problem in intensive pig farming. The tendency to develop this damaging behaviour has been suggested to relate to serotonergic functioning and personality characteristics of pigs. We investigated whether tail biting in pigs can be associated with blood serotonin and with their behavioural and physiological responses to novelty. Pigs (n = 480) were born in conventional farrowing pens and after weaning at four weeks of age they were either housed barren (B) or in straw-enriched (E) pens. Individual pigs were exposed to a back test and novel environment test before weaning, and after weaning to a novel object (i.e. bucket) test in an unfamiliar arena. A Principal Component Analysis on behaviours during the tests and salivary cortisol (novel object test only) revealed five factors for both housing systems, labeled ‘Early life exploration’, ‘Near bucket’, ‘Cortisol’, ‘Vocalizations & standing alert’, and ‘Back test activity’. Blood samples were taken at 8, 9 and 22 weeks of age to determine blood platelet serotonin. In different phases of life, pigs were classified as tail biter/non-tail biter based on tail biting behaviour, and as victim/non-victim based on tail wounds. A combination of both classifications resulted in four pig types: biters, victims, biter/victims, and neutrals. Generally, only in phases of life during which pigs were classified as tail biters, they seemed to have lower blood platelet serotonin storage and higher blood platelet uptake velocities. Victims also seemed to have lower blood serotonin storage. Additionally, in B housing, tail biters seemed to consistently have lower scores of the factor ‘Near bucket’, possibly indicating a higher fearfulness in tail biters. Further research is needed to elucidate the nature of the relationship between peripheral 5-HT, fearfulness and tail biting, and to develop successful strategies and interventions to prevent and reduce tail biting.

Effects of alginate and resistant starch on feeding patterns, behaviour and performance in ad libitum-fed growing pigs

This study assessed the long-term effects of feeding diets containing either a gelling fibre (alginate (ALG)), or a fermentable fibre (resistant starch (RS)), or both, on feeding patterns, behaviour and growth performance of growing pigs fed ad libitum for 12 weeks. The experiment was set up as a 2×2 factorial arrangement: inclusion of ALG (yes or no) and inclusion of RS (yes or no) in the control diet, resulting in four dietary treatments, that is, ALG-RS- (control), ALG+RS-, ALG-RS+, and ALG+RS+. Both ALG and RS were exchanged for pregelatinized potato starch. A total of 240 pigs in 40 pens were used. From all visits to an electronic feeding station, feed intake and detailed feeding patterns were calculated. Apparent total tract digestibility of energy, dry matter (DM), and CP was determined in week 6. Pigs' postures and behaviours were scored from live observations in weeks 7 and 12. Dietary treatments did not affect final BW and average daily gain (ADG). ALG reduced energy and DM digestibility (P<0.01). Moreover, ALG increased average daily DM intake, and reduced backfat thickness and carcass gain : digestible energy (DE) intake (P<0.05). RS increased feed intake per meal, meal duration (P<0.05) and inter-meal intervals (P=0.05), and reduced the number of meals per day (P<0.01), but did not affect daily DM intake. Moreover, RS reduced energy, DM and CP digestibility (P<0.01). Average daily DE intake was reduced (P<0.05), and gain : DE intake tended to be increased (P=0.07), whereas carcass gain : DE intake was not affected by RS. In week 12, ALG+RS- increased standing and walking, aggressive, feeder-directed, and drinking behaviours compared with ALG+RS+ (ALG×RS interaction, P<0.05), with ALG-RS- and ALG-RS+ in between. No other ALG×RS interactions were found. In conclusion, pigs fed ALG compensated for the reduced dietary DE content by increasing their feed intake, achieving similar DE intake and ADG as control pigs. Backfat thickness and carcass efficiency were reduced in pigs fed ALG, which also showed increased physical activity. Pigs fed RS changed feeding patterns, but did not increase their feed intake. Despite a lower DE intake, pigs fed RS achieved similar ADG as control pigs by increasing efficiency in DE use. This indicates that the energy utilization of RS in pigs with ad libitum access to feed is close to that of enzymatically digestible starch.

Satiety and energy intake after single and repeated exposure to gel-forming dietary fiber: post-ingestive effects

BACKGROUND

Viscous or gel-forming dietary fibers can increase satiety by a more firm texture and increased eating time. Effects of viscous or gel-forming fibers on satiety by post-ingestive mechanisms such as gastric emptying, hormonal signals, nutrient absorption or fermentation are unclear. Moreover, it is unclear whether the effects persist after repeated exposure.

OBJECTIVE

To investigate satiety and energy intake after single and repeated exposure to gelled fiber by post-ingestive mechanisms.

DESIGN

In a two-arm crossover design, 32 subjects (24 female subjects, 21±2 y, BMI 21.8±1.9 kg m(-2)) consumed test foods once daily for 15 consecutive days, with 2 weeks of washout. Test foods were isocaloric (0.5 MJ, 200 g) with either 10 g gel-forming pectin or 3 g gelatin and 2 g starch, matched for texture and eating time. Hourly satiety ratings, ad libitum energy intake and body weight were measured on days 1 (single exposure) and 15 (repeated exposure). In addition, hourly breath hydrogen, fasting glucose, insulin, leptin and short-chain fatty acids were measured.

RESULTS

Subjects rated hunger, desire to eat and prospective intake about 2% lower (P<0.015) and fullness higher (+1.4%; P=0.041) when they received pectin compared with control. This difference was similar after single and repeated exposure (P>0.64). After receiving pectin, energy intake was lower (-5.6%, P=0.012) and breath hydrogen was elevated (+12.6%, P=0.008) after single exposure, but not after repeated exposure. Fasting glucose concentrations were higher both after single and repeated exposure to pectin (+2.1%, P=0.019). Body weight and concentrations of insulin, leptin and short-chain fatty acids did not change during the study.

CONCLUSIONS

Gelled pectin can increase satiety and reduce energy intake by post-ingestive mechanisms. Although the effects were small, the effects on satiety were consistent over time, whereas the effects on energy intake reduction were not.