The ileal and total tract digestibility fibre and nutrients in pigs fed high-fibre cereal-based diets provided without and with a carbohydrase complex.

The effect of carbohydrase can be variable according to the complexity of cereal grains and co-products. Studies on the effect of carbohydrase on cereal diets varying in complexity are scarce. This study was conducted to investigate the apparent ileal (AID) and total tract digestibility (ATTD) of energy, fibre and nutrients in pigs fed diets based on cereal grains and co-products without and with supplementation with a carbohydrase complex in the form of xylanase, arabinofuranosidase and ß-glucanase. The experiment was carried out as an 8 × 4 Youden Square design (eight diets and four periods by two blocks) using 16 growing pigs (33.3 ± 0.8 kg) surgically fitted with a T-cannula in the terminal ileum. The pigs were fed eight experimental diets based on either - maize, wheat, rye, or a wheat and rye mix that were provided with or without enzyme supplementation. The AID and ATTD of DM, organic matter, energy, CP, fat, starch, and soluble and insoluble non-starch polysaccharides (NSPs) were studied using titanium dioxide as an indigestible marker. There was a cereal type effect (P < 0.05) of the AID of most of the nutrients investigated but ash and NSP and some of its constituents but with no interactions between cereal types and carbohydrase supplementation (P > 0.05). The ATTD of nutrients in the large intestine was mainly influenced by the fibre composition and was significantly lower (P < 0.001) for NSP, protein and energy for the Maize than the other diets. Supplementation of the cereal diets with the carbohydrase complex partially degrades arabinoxylan (AX) and ß-glucan giving rise to a generally higher AID of high-molecular weight arabinoxylan (P = 0.044), starch (P = 0.042), a tendency (P < 0.10) of higher AID of non-cellulosic polysaccharide glucose residue (ß-glucan) and soluble arabinoxylan (AX) whereas none of the other components were affected (P > 0.05). Collectively, the results indicate that the carbohydrase complex degrades AX in the stomach and small intestine, leading to a higher AID but with no influence on the ATTD of fibres, nutrients, and energy.

Digestibility of fractionated green biomass as protein source for monogastric animals.

Globally, there is an increased demand for sustainable protein sources for animal feed. Grass and forage legumes have the yield potential to become such alternatives, but the protein needs to be separated from the fibres. Red clover, white clover, lucerne and perennial ryegrass were fractionated into a green juice and a fibrous pulp in a screw-press and protein was subsequently precipitated. The nitrogen (N) and amino acid composition of the produced fractions was analysed and the digestibility of dry matter (DM) and N was evaluated using a rat digestibility trial. The aim was to determine the effect of fractionation on composition and digestibility in order to evaluate the four plants as potential protein sources for monogastrics. Protein concentrates with CP concentrations of 240 to 388 g/kg DM and fibrous pulps with CP concentrations of 111 to 216 g/kg DM were produced. The sum of all analysed amino acids was highest in the protein concentrates corresponding to a low concentration of non-protein nitrogen ranging from 4.9% to 10.4%. Only small variations were seen in the amino acid compositions of the different plants and fractions. The concentration of the essential lysine and methionine in the protein concentrate ranged from 6.27 to 6.67 g/16 g N and 1.54 to 2.09 g/16 g N for lysine and methionine, respectively. For all plants species, total tract digestibility of DM and standardised N digestibility was significantly higher in the protein concentrates (60.8% to 76.5% and 75.4% to 85.0% for DM and N, respectively) compared to pulp (21.2% to 43.4% and 52.1% to 72.5% for DM and N, respectively). Digestibility of lucerne protein concentrate (76.5% and 85.0% for DM and N, respectively) was higher than of the unprocessed plant (39.6% and 74.9% for DM and N, respectively), whereas for red and white clover no difference was found. The amino acids methionine and cysteine were limiting for pigs and broilers in all fractions regardless of plant origin, and low scores were also found for lysine. The study demonstrated great potential of using green plants as a protein source for monogastrics because of high protein content, balanced amino acid composition and high digestibility of DM and N. The effects of processing and protein precipitation were pronounced in lucerne where significantly improved digestibility was observed in the protein concentrate. The results from the study provide valuable and enhanced knowledge to the production of alternative and sustainable protein sources for monogastric feed.

Effect of xylanases on ileal viscosity, intestinal fiber modification, and apparent ileal fiber and nutrient digestibility of rye and wheat in growing pigs.

Two experiments were performed to study the effect of xylanase on ileal extract viscosity, in vivo fiber solubilization and degradation, and apparent ileal digestibility (AID) of fiber constituents, OM, CP, starch, and crude fat in rye and wheat in ileal-cannulated pigs. In Exp. 1, coarse rye without (NX) or with addition of xylanase from Aspergillus niger (AN), (BS), or (TR) was fed to 8 ileal-cannulated barrows (initial BW 30.9 ± 0.3 kg) for 1 wk each according to a double 4 × 4 Latin square design. In Exp. 2, fine rye, fine wheat, and coarse wheat with or without a combination of xylanase from and were fed to 6 ileal-cannulated barrows (initial BW 33.6 ± 0.5 kg) for 1 wk according to a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of enzyme and cereal matrix. Chromic oxide (0.2%) was used as an inert marker. Ileal effluent was collected for 8 h on d 5 and 7 and pooled for analysis. In Exp. 1, TR reduced intestinal viscosity of pigs fed rye from 9.3 mPa·s in the control diet (NX) to 6.0 mPa·s ( < 0.001), whereas AN and BS had no effect. None of the enzymes changed the concentration of total arabinoxylan, high-molecular-weight arabinoxylan (HMW-AX), or arabinoxylan oligosaccharides (AXOS) in the liquid phase of digesta. In Exp. 2, the enzyme combination reduced intestinal viscosity for all 3 cereal matrices ( < 0.05), but the viscosity was much higher with fine rye (7.6 mPa·s) than with fine and coarse wheat (<1.7 mPa·s). Simultaneously, the total concentration of arabinoxylan in the liquid phase of digesta increased by 82.4% in fine wheat ( < 0.002) and by 45.9% in coarse wheat ( < 0.006), and AXOS increased 16-fold with enzyme addition. Similar effects of enzyme were not seen with rye. The concentration of xylooligosaccharides in the liquid phase of digesta increased with enzyme addition, but for xylose, it was only significant for wheat, for which it increased 3.9-fold ( < 0.001). None of the xylanases affected AID of arabinoxylan of rye in Exp. 1. In Exp. 2, the enzyme combination increased AID of arabinoxylan by 91% to 107% ( < 0.001) across cereal matrices. Enzyme addition did not affect AID of nutrients in any of the experiments except for a higher starch and crude fat digestibility of fine wheat with enzyme addition ( < 0.012) in Exp. 2. Collectively, the results suggest that xylanase is more efficient in degrading arabinoxylan from wheat than from rye.

Xylanase increased the ileal digestibility of nonstarch polysaccharides and concentration of low molecular weight nondigestible carbohydrates in pigs fed high levels of wheat distillers dried grains with solubles.

The objective was to study the effect of a commercially available xylanase (CAX), an experimental xylanase (EX), and EX in combination with protease (EXP) on the degradation of nondigestible carbohydrates (NDC) and apparent ileal digestibility (AID) of nutrients in wheat distillers dried grains with solubles (wDDGS). The control and 3 enzyme diets contained 96% wDDGS supplemented with vitamins, minerals, L-lysine, and chromic oxide as a digestibility marker in addition to enzyme premix. Eight ileal cannulated pigs were fed 4 experimental diets containing 96% wDDGS-a control diet or 1 of 3 diets with CAX, EX, or EXP-in a double 4 × 4 Latin square design. The experimental period lasted 7 d; adaptation lasted 4 d, and the ileal digesta were collected for 8 h on d 5 and 7, when spot samples of feces were also collected. Digesta samples were analyzed for NDC, total and soluble nonstarch polysaccharides (NSP), low molecular weight (LMW) NDC, OM, CP, fat, starch, and marker. Compared with the control diet, addition of CAX, EX, and EXP increased the AID of arabinoxylan by 32 (P < 0.001), 28 (P = 0.001), and 24% (P = 0.004), respectively. In addition, EXP increased the AID of noncellulosic polysaccharide glucose by 21% compared with the control (P = 0.005). Compared with the control, addition of EX, EXP, and CAX decreased the concentration of soluble arabinoxylan in ileal digesta by 40 (P < 0.0001), 40 (P < 0.0001), and 21% (P = 0.022), respectively. Furthermore, addition of CAX, EXP, and EX increased the concentration of LMW arabinoxylan in ileal digesta by 40 (P = 0.0001), 36 (P = 0.0006), and 24% (P = 0.023), respectively, compared with the control. Addition of EX and EXP decreased the concentration of soluble NSP of ileal digesta by 25 (P = 0.001) and 26% (P < 0.001), respectively, compared with the control diet. Addition of CAX (P < 0.0001) and EXP (P = 0.013) increased the arabinose-to-xylose ratio in the insoluble arabinoxylan fraction in ileal digesta compared with the control diet, and CAX increased the uronic acid-to-xylose ratio of the ileal insoluble NSP fraction (P < 0.0001) compared with the control diet. Enzyme addition did not affect AID of OM, CP, starch, and fat (P > 0.3). In conclusion, addition of xylanases to wDDGS diets increased the ileal digestibility of NSP and generated LMW NDC components in the small intestine of pigs but did not affect ileal digestibility of nutrients in the current study.

Carbohydrate composition and in vitro digestibility of dry matter and nonstarch polysaccharides in corn, sorghum, and wheat and coproducts from these grains.

The objectives of this work were to determine carbohydrate composition and in vitro digestibility of DM and nonstarch polysaccharides (NSP) in corn, wheat, and sorghum and coproducts from these grains. In the initial part of this work, the carbohydrate composition of 12 feed ingredients was determined. The 12 ingredients included 3 grains (corn, sorghum, and wheat), 3 coproducts from the dry grind industry (corn distillers dried grains with solubles [DDGS] and 2 sources of sorghum DDGS), 4 coproducts from the wet milling industry (corn gluten meal, corn gluten feed, corn germ meal, and corn bran), and 2 coproducts from the flour milling industry (wheat middlings and wheat bran). Results indicated that grains contained more starch and less NSP compared with grain coproducts. The concentration of soluble NSP was low in all ingredients. Cellulose, arabinoxylans, and other hemicelluloses made up approximately 22, 49, and 29% (DM basis), respectively, of the NSP in corn and corn coproducts and approximately 25, 43, and 32% (DM basis), respectively, of the NSP in sorghum and sorghum DDGS. Cellulose, arabinoxylans, and other hemicelluloses made up approximately 16, 64, and 20% (DM basis), respectively, of the NSP in wheat and wheat coproducts. The concentration of lignin in grains was between 0.8 and 1.8% (DM basis), whereas coproducts contained between 2.2 and 11.5% lignin (DM basis). The in vitro ileal digestibility of NSP was close to zero or negative for all feed ingredients, indicating that pepsin and pancreas enzymes have no effect on in vitro degradation of NSP. A strong negative correlation ( = 0.97) between in vitro ileal digestibility of DM and the concentration of NSP in feed ingredients was observed. In vitro total tract digestibility of NSP ranged from 6.5% in corn bran to 57.3% in corn gluten meal. In conclusion, grains and grain coproducts contain mostly insoluble NSP and arabinoxylans make up the majority of the total NSP fraction. The in vitro digestibility of NSP depends on the amount and type of NSP and degree of lignification in the feed ingredient. The NSP composition of grains and grain coproducts plays an important role in determining the extent of fermentation of NSP; therefore, NSP composition influences the energy value of grains and grain coproducts.

Postprandial effects of test meals including concentrated arabinoxylan and whole grain rye in subjects with the metabolic syndrome: a randomised study.

BACKGROUND/OBJECTIVES: Prospective studies have shown an inverse relationship between whole grain consumption and the risk of type 2 diabetes, where short chain fatty acids (SCFA) may be involved. Our objective was to determine the effect of isolated arabinoxylan alone or in combination with whole grain rye kernels on postprandial glucose, insulin, free fatty acids (FFA), gut hormones, SCFA and appetite in subjects with the metabolic syndrome (MetS). SUBJECTS/METHODS: Fifteen subjects with MetS participated in this acute, randomised, cross-over study. The test meals each providing 50 g of digestible carbohydrate were as follows: semolina porridge added concentrated arabinoxylan (AX), rye kernels (RK) or concentrated arabinoxylan combined with rye kernels (AXRK) and semolina porridge as control (SE). A standard lunch was served 4 h after the test meals. Blood samples were drawn during a 6-h period, and appetite scores and breath hydrogen were assessed every 30 min. RESULTS: The AXRK meal reduced the acute glucose (P=0.005) and insulin responses (P<0.001) and the feeling of hunger (P=0.005; 0-360 min) compared with the control meal. The AX and AXRK meals increased butyrate and acetate concentrations after 6 h. No significant differences were found for the second meal responses of glucose, insulin, FFA, glucagon-like peptide-1 or ghrelin. CONCLUSIONS: Our results indicate a stimulatory effect of arabinoxylan on butyrate and acetate production, however, with no detectable effect on the second meal glucose response. It remains to be tested in a long-term study if a beneficial effect on the glucose response of the isolated arabinoxylan will be related to the SCFA production.

Effects of concentrated arabinoxylan and ß-glucan compared with refined wheat and whole grain rye on glucose and appetite in subjects with the metabolic syndrome: a randomized study.

BACKGROUND/OBJECTIVES: Several studies emphasise that arabinoxylan and ß-glucan have more beneficial effects on glucose metabolism than low-dietary fibre (DF) meals. Less attention has been paid to the effects of concentrated DF compared with whole grain. We compared the effects of DF and whole grain on glucose, hormone responses and appetite in subjects with the metabolic syndrome (MetS). SUBJECTS/METHODS: Fifteen subjects with MetS participated in this acute, randomised, cross-over intervention study. The test breads provided 50 g of digestible carbohydrate: wheat bread with concentrated arabinoxylan (AX) or ß-glucan (BG), rye bread with kernels (RK) and wheat bread (WB) as control. Blood samples were drawn for 270 min to determine glucose, insulin, glucagon-like peptide-1, glucose-dependent insulinotropic peptide (GIP) and ghrelin. Appetite score was addressed every 30 min. Ad libitum energy intake (EI) was measured 270 min after test meals. RESULTS: Compared with WB, BG and RK induced lower initial glycaemic responses (P<0.001), whereas AX only reduced the glucose peak value (P<0.001). RK reduced insulin (P<0.001) and GIP responses (P<0.001) compared with the other breads. BG lowered insulin responses more than AX (P<0.001). AX, BG and RK increased satiety feeling (P<0.001) more than WB, but did not differ significantly in terms of subsequent EI (P=0.089). CONCLUSION: BG and RK had beneficial impact on the glucose response, whereas AX had only effect on the postprandial glucose peak. The impact of the AX bread was influenced by higher protein content. Whether the metabolic effects of the breads are still present to mixed meals remains to be tested.

Influence of forage inclusion in the diet on ileal and total tract digestibility.

The present investigation aimed to study the ileal and total tract digestibility of 3 forages (clover-grass, clover-grass silage, and field pea (Pisum sativum)-barley (Hordeum vulgare) silage) supplemented to a basal diet. A total of 24 pigs, adapted to eating forages by supplementing a basal feed with clover-grass silage from weaning, were fitted with a T-cannula at the terminal ileum at approximate 30 kg BW. For each of the 3 types of forage, 2 balance trials with a 4 wk interval were carried out. Two pigs in each test were fed the basal diet and 6 others were fed the basal diet plus forage throughout the whole experiment. The intake of forages was low and quite variable and on average accounted for only 10 to 12% of the DMI. Ileal digestibility of protein estimated by collection from the T-cannula was higher (P = 0.031) than the digestibility estimated by the slaughter technique indicating some separation of the digesta collected from the T-cannula. The forages had, as expected, a lower total tract DM and energy digestibility than the basal diet (P < 0.05). The fresh clover-grass had a higher energy digestibility than the 2 silages (60 vs. 48%; P < 0.05). Inclusion of 10% of GE in the diet as forage reduced (P < 0.05) the energy digestibility of the ration by 2.2% for clover-grass, 3.4% for clover-grass silage, and 5.0% for pea-barley silage. In organic slaughter pig production, the overall energy supply from these forages is limited, but they may play an important role in satiety and rooting behavior.

Evaluation of two external markers for measurement of ileal and total tract digestibility of pigs fed human-type diets.

External markers for determination of nutrient digestibility have often been evaluated in conventional dry feeds but less often in conventional feeds such as human-type diets used in animal model studies. In the present study, 5 ileal-cannulated pigs were fed 5 types of soft bread-based diets supplemented with Cr(2)O(3) and AIA as digestibility markers for 1 wk in a Latin square design. Ileal contents were collected twice for 5 h and a fecal grab sample was obtained once per week. Ileal and total tract digestibility of OM and nonstarch polysaccharides (NSP) based on the 2 markers were compared by linear regression. Across dietary treatments and site of collection, high correlation existed between digestibility values obtained with Cr(2)O(3) and AIA, resulting in a R(2) > 0.77 (P < 0.001) and a linear relation close to unity. For ileal samples, the correlation was poor, particularly for NSP, which had R(2) = 0.09 (P = 0.14) whereas OM had an R(2) = 0.52 (P <0.001). On the other hand, fecal grab samples led to R(2) > 0.92 (P < 0.001) for both OM and NSP. However, AIA gave higher values than Cr(2)O(3), particularly in samples with lower digestibility. The discrepancy is presumably caused by analytical difficulties due to a high fecal ash contents or interference with other components in the human-type diets.

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties.

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.