Two high-amylose maize starches with different amounts of resistant starch vary in their effects on fermentation, tissue and digesta mass accretion, and bacterial populations in the large bowel of pigs

Four groups of young pigs (n 6) were fed a diet containing 50% maize starch as either a highly digestible waxy starch (control; 0% amylose) or one of three resistant starch (RS) diets, namely a high-amylose maize starch (HAMS; 85% amylose), this starch subjected to hydrothermal treatment (HTHAMS; 85% amylose), or a blend of HAMS and HTHAMS included in equal amounts, for 21 d. Food intake and live weight at the end of the study were similar among the four groups. Ileal starch digestibility was lower in pigs fed the three RS diets but was greater for HAMS(88%) than for HTHAMS (70%; P<0.05). Faecal output and large bowel digesta mass, and concentrations and pools of individual and total SCFA were higher (by about two- to threefold; all P<0.05) and digesta pH lower (by about 1 unit, all P<0.001) in pigs fed either HAMS or HTHAMS compared to the controls. These differences in biomarkers were seen along the length of the large bowel. Colon length was 0.5-0.9 m longer (19-35%) in pigs fed the high-RS diets relative to those fed the highly digestible starch diet (P<0.05). Faecal and proximal colonic lactobacilli and bifidobacteria numbers were higher (by 1 and 3 log units; P< 0.05) in pigs fed the HAMS or HTHAMS diets. Although both high-amylose starches promoted fermentation throughout the large bowel, the data suggest that the effects of HTHAMS may be more pronounced in the distal region compared to those of HAMS.     

D-tagatose has low small intestinal digestibility but high large intestinal fermentability in pigs

The digestibility of D-tagatose, its effect on the digestibility of macronutrients and the metabolic response of the microbiota of the gastrointestinal tract to the ingestion of this carbohydrate were studied in pigs. Eight pigs were fed a low fiber diet comprising 15% sucrose (control group). Another eight pigs were fed a similar diet except that 100 g sucrose per kg diet was replaced by D-tagatose (test group). After 18 d, the pigs were killed and the gastrointestinal contents removed for analysis. The digestibility of D-tagatose was 25.8 +/- 5.6% in the distal third of the small intestine. The small intestinal digestibilities of dry matter (86.9 +/- 1.3 vs. 92.9 +/- 0.9%), gross energy (74.4 +/- 1.6 vs. 80.7 +/- 1.8%) and sucrose (90.4 +/- 2.5 vs. 98.0 +/- 0.5%) were lower (P < 0. 05) in the pigs fed D-tagatose. Digestibilities of starch, protein and fat did not differ between groups. D-Tagatose, sucrose and starch were fully digested in the large intestine. The fecal digestibilities of energy, dry matter and fat did not differ between the two groups, whereas D-tagatose reduced the fecal digestibility of protein (91.1 +/- 0.6 vs. 93.5 +/- 0.7%, P < 0.05). D-Tagatose served as a substrate for the microbiota in the cecum and proximal colon as indicated by a reduced pH, and a greater ATP concentration, adenylate energy charge (AEC) ratio and concentration of short-chain fatty acids. In particular, the increase in the concentrations of propionate, butyrate and valerate suggests possible health benefits of this monosaccharide.     

Resistant starch supplementation influences blood lipid concentrations and glucose control in overweight subjects

Resistant starch (RS) includes the sum of starch and degradation products of starch that resist small intestinal digestion and enter the colon. This study was planned to examine the effect of resistant starch on hypolipidemic actions, blood glucose, insulin levels and humoral immune responses in healthy overweight subjects. Healthy overweight subjects (over 120% of their ideal body weights) were fed either 24 g/d of resistant corn starch (RS) or regular corn starch (CS) for 21 d with their regular meals. Although this double-blind feeding regiment resulted in no significant changes in their weights or other physical parameters for the relatively acute period of intakes, there were significant lowering effects of serum total cholesterol (p < 0.05) and serum LDL-cholesterol (p < 0.05) in subjects supplemented RS. Compared with the control starch group, the RS supplementation also reduced the mean fasting serum glucose concentrations (p < 0.05). Resistant starch supplement resulted in the increase in serum immunoglobulin G (IgG) concentrations. Serum insulin and complement 3 (C3) were unaffected. Tested resistant starch supplementation was reported to be palatable with minimal bowel discomfort. These results suggest that RS supplementation improves the blood lipid profile and controls the blood glucose levels in healthy overweight subjects without bowel discomfort. Therefore, RS has a potential to be used as one of the promising food ingredients for reducing risk factors involved in the development of atherosclerosis and type 2 diabetes in overweight individuals. However, in order to prove RS as a novel therapeutic agent of cardiovascular diseases and diabetes, controlled trials with larger sample sizes and longer duration are warranted.     

不同消化速率的淀粉对断奶仔猪脂肪代谢相关血清生化指标的影响

目的研究仔猪采食不同消化速率的淀粉(玉米淀粉、糯米淀粉和抗性淀粉)后血液脂肪代谢相关指标的变化。方法18头21d龄断奶的三元杂交仔猪,按体重随机分为3组,分别代表玉米淀粉组、糯米淀粉组和抗性淀粉组。所有试猪经外科手术安装颈静脉插管,术后恢复3d后开始正式试验。每4h饲喂一次,日喂6次。试验D7通过颈静脉插管采集血样,测定餐后不同时间点血清甘油三酯(TG)、胆固醇(TC)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)浓度和脂肪酶(LPS)活性。结果各采食周期内糯米淀粉组试猪餐后血清TG、TC和HDL-C浓度以及LPS活性及其变化幅度均显著高于玉米淀粉组和抗性淀粉组(P0.05),玉米淀粉组试猪餐后血清LDL-C浓度高于糯米淀粉组和抗性淀粉组。结论不同消化速率的淀粉能引起仔猪餐后不同时间点血糖浓度的变化从而影响机体脂类代谢,尤其是影响与幼龄动物智力发育至关重要的TC代谢。     

Quantifying resistant starch using novel, in vivo methodology and the energetic utilization of fermented starch in pigs

To quantify the energy value of fermentable starch, 10 groups of 14 pigs were assigned to one of two dietary treatments comprising diets containing 45% of either pregelatinized (P) or retrograded (R) corn starch. In both diets, a contrast in natural 13C enrichment between the starch and nonstarch components of the diet was created to partition between enzymatic digestion and fermentation of the corn starch. Energy and protein retention were measured using indirect calorimetry after adapting the pigs to the diets for 3 wk. Fecal 13C enrichment was higher in the R-fed pigs (P < 0.001) and 43% of the R resisted enzymatic digestion. Energy retained as protein was unaffected and energy retained as fat was 29% lower than in P-fed pigs (P < 0.01). Prior to the morning meal, end products of fermentation substantially contributed to substrate oxidation in the R-fed pigs. During the 3-4 h following both meals, heat production was higher (P < 0.05) in P-fed pigs, but this was not preferentially fueled by glucose from corn starch. Digestible energy intake, metabolizable energy intake, and energy retention were reduced (P < 0.05) in R-fed pigs compared with P-fed pigs by 92, 54, and 33 kJ/(kg?·?? · d), respectively. Therefore, the energy values of fermented resistant starch were 53, 73, and 83% of the digestible, metabolizable, and net energy values of enzymatically degradable starch, respectively. Creating a contrast in natural 13C enrichment between starch and nonstarch dietary components provides a promising, noninvasive, in vivo method for estimating the proportion of dietary starch fermented in the gastrointestinal tract.     

Feeding different types of cooked white rice to piglets after weaning influences starch digestion, digesta and fermentation characteristics and the faecal shedding of beta-haemolytic Escherichia coli

Forty-eight, 21-d-old pigs were used to examine the effects of different types of cooked white rice on starch digestion, digesta and fermentation characteristics, shedding of beta-haemolytic Escherichia coli and performance after weaning. Pigs received one of three rice-based diets: (i) medium-grain Amaroo (AM), (ii) long-grain Doongara (DOON), and (iii) waxy (WAXY). The remainder of the diet consisted predominantly of animal proteins. A fourth diet contained mainly wheat, barley and lupins (WBL). On days 1, 3, 7 and 9 after weaning, a faecal swab was taken for assessment of beta-haemolytic E. coli and faecal consistency. Apparent digestibility of starch measured in the ileum 14 d after weaning was highest (P = 0.004) in AM and WAXY and lowest, but the same (P>0.05), in DOON and WBL. Starch digestibility in the rectum was highest in all rice diets (P < 0.001). Digesta viscosity was highest in pigs fed WBL in both the ileum (P < 0.001) and caecum (P = 0.027). Pigs fed rice generally had lighter (P < 0.05) gastrointestinal organs than pigs fed WBL. Performance of pigs was similar for all treatments; however, pigs fed rice-based diets had a higher (P < 0.001) carcass percentage than pigs fed WBL. Pigs fed WBL produced more acid (P < 0.05) but had lower molar proportions of acetate (P < 0.05), isobutyrate (P < 0.01) and isovalerate (P < 0.001) and a higher molar proportion of butyrate (P < 0.01) in the large intestine than pigs fed rice. Shedding of E. coli was low; however, pigs fed AM and WBL shed less E. coli than pigs fed other diets.     

Consumption of raw potato starch increases colon length and fecal excretion of purine bases in growing pigs

Male growing pigs were fed a diet containing 250 g/kg of native corn starch (CS; 26% amylose, 74% amylopectin) or 250 g/kg of raw potato starch (RPS), as examples of digestible starch and resistant starch (Type II), respectively. Whole-tract digestibilities of organic matter, crude protein and starch were greater in pigs fed CS than in those fed RPS through at least d 23 of the study. However, the values progressively increased in the RPS-fed pigs up to d 38, at which time the groups did not differ in organic matter and starch digestibility. The digestive tract and colonic digesta were heavier and colon length longer in pigs fed the RPS diet. Digestibility of starch in the ileum on d 38 was significantly lower in RPS-fed pigs, but rose from ileum to rectum; most starch was extensively fermented in the cecum and proximal colon. Purine base (PB) and short-chain fatty acid (SCFA) concentrations in feces initially increased and then decreased beginning on d 4 for PB and on d 21 for SCFA. PB concentration in feces was greater in pigs fed RPS than in those fed CS. In the large bowel digesta, PB and SCFA concentrations increased from the ileum to the cecum and proximal colon and then fell in the distal colon. Pigs fed the RPS diet had a higher PB concentration in the middle colonic digesta and a greater SCFA concentration in the proximal colonic digesta than the CS-fed group. Adaptation of growing pigs to supplementary RPS required 5 wk, as reflected by whole-tract digestibility and PB and SCFA fecal excretion data.     

Starch with high amylose content and low in vitro digestibility increases intestinal nutrient flow and microbial fermentation and selectively promotes bifidobacteria in pigs

Diets containing different starch types can affect enzymatic digestion of starch and thereby starch availability for microbial fermentation in the gut. However, the role of starch chemistry in nutrient digestion and flow and microbial profile has been poorly explained. Eight ileal-cannulated pigs (29.4 ± 0.9 kg body weight) were fed 4 diets containing 70% purified starch (amylose content, <5, 20, 28, and 63%; reflected by in vitro maximal digestion rate; 1.06, 0.73, 0.38, and 0.22%/min, respectively) in a replicated 4 × 4 Latin square. Ileal and fecal starch output, postileal crude protein yield, fecal total SCFA and total butyrate content, and gene copies of Bifidobacterium spp. in feces were higher (P < 0.05) when pigs consumed the slowly digestible starch diet than the remaining 3 starch diets. The in vitro starch digestion rate had a negative, nonlinear relationship with ileal starch flow (R(2) = 0.98; P < 0.001). Ileal starch flow was positively related to Bifidobacterium spp. (R(2) = 0.27; P < 0.01), Lactobacillus group (R(2) = 0.22; P < 0.01), and total butyrate content (R(2) = 0.46; P < 0.01) but was not related to Enterobacteriaceae (R(2) < 0.00; P = 0.92). In conclusion, starch with high amylose content and low in vitro digestibility increased postileal nutrient flow and microbial fermentation and selectively promoted Bifidobacterium spp. in the distal gut.     

A novel high-amylose barley cultivar (Hordeum vulgare var. Himalaya 292) lowers plasma cholesterol and alters indices of large-bowel fermentation in pigs

Hordeum vulgare var. Himalaya 292 is a new barley cultivar with altered starch synthesis and less total starch but more amylose, resistant starch (RS) and total and soluble NSP including beta-glucan. To determine its nutritional potential, young pigs were fed diets containing stabilised wholegrain flours from either Himalaya 292, Namoi (a commercial barley), wheat bran or oat bran at equivalent dietary NSP concentrations for 21 d. Serum total cholesterol was significantly lowered by the Himalaya 292 diet relative to wheat bran, indicating that Himalaya 292 retained its hypocholesterolaemic potential. In all groups SCFA concentrations were highest in the proximal colon and decreased towards the rectum. Digesta pH was lowest in the proximal colon and highest in the distal colon. Large-bowel and faecal pH were significantly lower in the pigs fed the barley and oat diets, indicating greater bacterial fermentation. Caecal and proximal colonic pH was lowest and SCFA pools highest in the pigs fed Himalaya 292. Total and individual SCFA were lowest in the mid- and distal colon of the pigs fed Himalaya 292 or oat bran. These data suggest the presence of more RS in Himalaya 292 and suggest that its fermentation was rapid relative to transit. Differences in faecal and large-bowel anaerobic, aerobic, coliform and lactic acid bacteria were relatively small, indicating a lack of a specific prebiotic action. These data support the potential of this novel barley cultivar to improve health through plasma cholesterol reduction and increased large-bowel SCFA production.     

Long-term intake of resistant starch improves colonic mucosal integrity and reduces gut apoptosis and blood immune cells

OBJECTIVE: The potential effect of a long-term intake of resistant starch on colonic fermentation and on gut morphologic and immunologic indices of interest in bowel conditions in humans was studied in pigs. METHODS: Sixteen growing pigs were meal fed for 14 wk on a diet containing a large amount of raw potato starch (RPS; resistant starch) or corn starch (CS; digestible starch). Effects were assessed in the colon from the physicochemical properties of digesta and in the intestinal morphology, including lymphocytic infiltration, apoptosis, and proliferation activities. Hematologic and blood leukocyte cell subsets analysis were performed. RESULTS: After 97 d, the digestive content from RPS pigs was heavier than for CS pigs, producing a hypertrophy of tunica muscularis (P < 0.05). The proportion of butyrate was two-fold higher in proximal colon digesta in RPS pigs (P < 0.05). RPS-fed pigs had reduced apoptosis in the crypts, lamina propria and lymphoid nodules in the colon, and ileal Peyer's patches (P < 0.05). Fermentation of RPS reduced indices associated with damage to epithelial cells, such as crypt cell proliferation and magnesium excretion, whereas mucin sulfuration was increased, which promotes epithelial protection. The numbers of intraepithelial T cells and of blood leukocytes, neutrophils, and lymphocytes, mainly T-helper lymphocytes, were reduced in RPS pigs (P < 0.05). CONCLUSION: Long-term intake of RPS induces pronounced changes in the colonic environment, reduces damage to colonocytes, and improves mucosal integrity, reducing colonic and systemic immune reactivity, for which health benefits in inflammatory conditions are likely to be associated.     

富碳水化合物食品血糖生成指数的体外回归模型

目的通过探讨富碳水化合物(CHO)食品营养组成及体外消化特性与体内血糖指数的关系,尝试建立体外回归模型。方法选择30种富CHO食品分析蛋白质、脂肪及CHO组成;在AOAC抗性淀粉测定的实验条件下,修改建立体外消化实验方法,测定淀粉在20min、120min、240min和16h的消化量以及不能消化的抗性淀粉含量;并采用国际标准方法完成食物血糖生成指数(GI)评估;通过逐步回归方法探讨各成分组成与GI关系。结果30种食品GI值分布为26～113,GI值高低与20min和120min内消化的淀粉量(S20、S120)呈明显正相关(P<0.05),而与抗性淀粉(RS)呈明显负相关(P<0.01)。将S120与葡萄糖含量相加定义为易利用糖(EAG),建立GI体外测试的回归方程为GI=39.65+1.008EAG-1.072RS。结论食品碳水化合物组成和体外消化实验有助于解释富碳水化合物食物体内血糖应答反应及预测GI值。     

抗性淀粉对大鼠锌营养状况的影响

目的 :　研究抗性淀粉 ( RS)对大鼠锌营养状况的影响。方法 :　 ( 1 )正常大鼠锌代谢 :3组 Wistar大鼠分别用基础饲料 (对照组 )、含有 1 3%或 2 6% RS的饲料喂养 1 8d,收集尿样、粪样 ,及血样 ,测定锌含量 ,计算锌表观吸收率。 ( 2 )高糖 ( 5 0 % )饮食大鼠锌营养状况 :3组 Wistar大鼠分别用基础饲料、高糖淀粉饲料 ( S- DS)及高糖抗性淀粉饲料 ( S- RS,含 1 4% RS)喂养 1 2 w。收集尿样 ,血样、肝脏、胰脏、肾脏等样品 ,测定锌含量。结果 :　 ( 1 )正常大鼠锌表观吸收率分别为 :对照组 5 6.5 9% ,1 3% RS组 5 0 .1 1 %及 2 6% RS组 5 4 .40 %。 ( 2 )高糖饲料使 S- DS组大鼠餐后血糖和糖化血红蛋白升高 ,空腹胰岛素水平降低 ;血锌和胰脏锌显著低于对照组 ( P<0 .0 5 )。 S- RS组血糖状态正常 ,尿锌排出低于 S- DS组 ,红细胞锌高于 S- DS组 ,且肾锌增高 ( P<0 .0 5 )。结论 :　 RS不影响正常大鼠锌表观吸收率 ,却可通过调节血糖维持高糖饮食大鼠锌营养状况。     

Differential effects of dietary whey, casein and soya on colonic DNA damage and large bowel SCFA in rats fed diets low and high in resistant starch

Feeding higher levels of dietary animal protein (as casein or red meat) increases colonic DNA damage and thins the colonic mucus barrier in rats. Feeding resistant starch (RS) reverses these changes and increases large bowel SCFA. The present study examined whether high dietary dairy (casein or whey) or plant (soya) proteins had similar adverse effects and whether dietary RS was protective. Adult male rats were fed diets containing 15 or 25 % casein, whey or soya protein with or without 48 % high amylose starch (as a source of RS) for 4 weeks. DNA damage was measured in isolated colonocytes using the comet assay. Higher dietary casein and soya (but not whey) increased colonocyte DNA damage. DNA damage was highest with soya when fed at 15 or 25 % protein without RS. Dietary RS attenuated protein-induced colonocyte DNA damage in all groups but it remained significantly higher in rats fed 25 % soya compared with those fed 15 % protein. Dietary protein level did not affect colonic mucus thickness overall but the barrier was thinner in rats fed high dietary casein. This effect was reversed by feeding RS. Caecal total SCFA and butyrate pools were higher in rats fed RS compared with digestible starch. Caecal and faecal SCFA were unrelated to genetic damage but correlated with mucus thickness. The present data confirm that higher dietary protein affected colonocyte DNA and colonic mucus thickness adversely but that proteins differ in their effects on these indices of colon health. The data show also that these changes were reversed by RS.     

Increasing digesta viscosity using carboxymethylcellulose in weaned piglets stimulates ileal goblet cell numbers and maturation

Intestinal mucin, a family of glycoproteins secreted by goblet cells, is the main constituent of the mucus protecting the gastrointestinal tract. For optimal mucosal protection, both the quantitative and qualitative characteristics of mucin are essential. To evaluate how viscosity influences ileal apparent digestibility and mucin biology, a highly viscous nonfermentable soluble polysaccharide, carboxymethylcellulose (CMC), was fed to weaned piglets for 15 d. The ileal crude mucin concentration was determined by ethanol precipitation, and changes in goblet cell subtypes were analyzed by the histochemistry of ileal and colonic tissues. As expected, CMC increased the viscosity of ileal digesta and the moisture of feces (P < 0.001). The crude mucin concentration and output at the ileum were higher (P < 0.05) in pigs fed CMC than those fed the control diet. Increasing intestinal content viscosity in pigs fed CMC had no significant effects on the ileal apparent digestibility of dry matter, organic matter, nitrogen, and minerals. The number of total ileal goblet cells per villus also was higher (+30%, P < 0.05) in pigs fed the CMC diet compared with controls. This increase was essentially accounted for by increased numbers of acidic and acidic sulfated mucin-containing cells (+30%, P < 0.05). Trends (P = 0.06) toward decreased numbers of neutral and acidic mucin-containing cells in ileal crypts were also noted. In conclusion, increasing intestinal content viscosity in weaned piglets fed CMC increased the ileal mucin output and numbers and maturation of goblet cells in ileal villi without effects on the apparent digestibility of the diet.     

Large bowel fermentation of maize or sorghum-acorn diets fed as a different source of carbohydrates to Landrace and Iberian pigs

Twenty-four finishing pigs (twelve Iberian and twelve Landrace) were used in a growing and slaughtering experiment. Animals were fed two diets differing in their ingredients, maize (diet C) or sorghum-acorn (diet A). At an average weight of 107.0 kg pigs were slaughtered and hindgut digesta sampled to study the effect of breed and diet on large bowel fermentation. Flows of digesta to the hindgut compartment were estimated based on an indigestible flow marker (Cr2O3) and were higher in Iberian than in Landrace pigs (P<0.001), and higher in animals fed diet A than diet C (P=0.07). The higher flows in Iberian pigs were mainly associated with a higher voluntary feed intake (3.50 v. 2.70 kg/d, P<0.01) and lower ileal digestibility of NSP (-12.8 v. 47.8, P<0.01). Differences between diets were mainly associated with a lower ileal digestibility of starch from diet A (89.2 v. 96.9 %, P=0.06), although no differences in the resistant starch content were observed in vitro. Fermentation of different carbohydrates through the large bowel showed that NSP-glucose had lower digestibility in Iberian than in Landrace pigs (62.5 v. 94.2 %, P<0.001), but no differences were observed in starch, or other NSP-fibre fractions (arabinose, xylose and galactose). The type and amount of carbohydrates reaching the large bowel were related to the diet but also to breed, and promoted differences in the fermentative activity associated with different volatile fatty acid patterns and changes in microbial enzymic activity.     

Starch with high amylose and low in vitro digestibility increases short-chain fatty acid absorption, reduces peak insulin secretion, and modulates incretin secretion in pigs

Diets containing different starch types affect peripheral glucose and insulin responses. However, the role of starch chemistry in kinetics of nutrient absorption and insulin and incretin secretion is poorly understood. Four portal vein-catheterized pigs (35.0 ± 0.2 kg body weight) consumed 4 diets containing 70% purified starch [0-63.2% amylose content and 0.22 (slowly) to 1.06%/min (rapidly) maximum rate of in vitro digestion] for 7-d periods in a 4 × 4 Latin square. On d 7, blood was collected for 12 h postprandial with simultaneous blood flow measurement for determining the net portal appearance (NPA) of nutrients and hormones. The NPA of glucose, insulin, C-peptide, and glucose-dependent insulinotropic polypeptide (GIP) during 0-4 h postprandial were lower (P < 0.05) and those of butyrate and total SCFA were higher (P < 0.05) when pigs consumed the diet containing slowly digestible compared with rapidly digestible starch. The peak NPA of insulin occurred prior to that of glucose when pigs consumed diets containing rapidly digestible starch. The kinetics of insulin secretion had a linear positive relation with kinetics of NPA of glucose (R(2) = 0.50; P < 0.01). In conclusion, starch with high amylose and low in vitro digestibility decreases the kinetics of glucose absorption and insulin and GIP secretion and increases SCFA absorption and glucagon-like peptide-1 secretion. In conclusion, starch with high amylose content and a lower rate and extent of in vitro digestion decreased glucose absorption and insulin secretion and increased SCFA absorption.     

Influence of different levels and sources of resistant starch on faecal quality of dogs of various body sizes

In dry-extruded canine diets, starch ileal digestibility varies with the starch source, amount and processing parameters. Starch that escapes duodeno-ileal digestion can affect faecal quality by stimulating colonic bacterial fermentation. The aim of the present study was to assess the effect of various resistant starch (RS) sources and levels on the faecal score of dogs of different breeds and sizes. A total of twenty-one healthy adult female dogs (body weight ranging 5.0-30.6 kg) were used. The maintenance diet for the dogs was supplemented with increasing amounts of RS from two sources: high-amylose starch from maize (to 2.5, 4.3 and 7.4 % RS) and raw potato starch (to 7.4 and 11.4 % RS). Each level of RS was tested over a 7 d period followed by a 7 d washout period. Faecal scores were evaluated by one person using a scale ranging from 1 (for hard and dry faeces) to 5 (for liquid stools). Faeces were considered 'optimal' at scores of 2.5-3.0, 'acceptable' at scores of 3.0-3.75 and 'unacceptable' at scores >3.75. Small dogs showed very little sensitivity to RS based on the faecal score, while large dogs were quite responsive to RS supplementation. These results suggest that small dogs are poor models for assessing the effect of starch sources on ileal digestibility. They also indicate that a low RS content (strongly affected by source and processing) is an important factor for ensuring an optimal faecal score in large breed dogs.     

Effect of Microwave Cooking on the Starch and Protein Digestibility of Some Newly Released Moth Bean (Phaseolus aconitifolius Jacq.) Cultivars

The unsoaked, soaked and soaked-dehulled seeds of some newly released high yielding cultivars of moth bean (Jwala, RMO 225 and RMO 257) and one local variety commonly used by the farmers, were cooked till soft in the microwave oven for different standardized time periods and analysed for starch digestibility and protein digestibility. The starch digestibility of unprocessed moth bean varieties differed significantly (P<0.05) from 25.35 to 28.18 mg maltose released/g flour. The protein digestibility also differed significantly from 70.29 to 74.65% among all the four varieties. Soaking (12 h) and soaking-dehulling of seeds prior to cooking reduced the cooking time considerably. Microwave cooking appreciably improved the starch and protein digestibility of unsoaked, soaked and soaked-dehulled samples. However, maximum improvement in starch digestibility (from 27.28 to 62.57 mg maltose released/g flour) was noticed in soaked-dehulled and microwave cooked samples of Jwala variety and similarly, maximum improvement in protein digestibility (from 72.29 to 87.56%) was noticed in soaked-dehulled microwave cooked sample of RMO 225 variety.     

Compromised Hindgut Microbial Digestion,Rather Than Chemical Digestion in the Foregut,Leads to Decreased Nutrient Digestibility in Pigs Fed Low-Protein Diets

Background: Reduced nutrient digestibility due to low-protein (LP) diets occurring in the foregut or hindgut of pigs remains unclear. Methods: Growing barrows (21.7 ± 1.7 kg) were allotted into LP and high-protein (HP) diet treatments. Ileal digesta and feces were collected for in vitro cross-fermentation and microbial sequencing, and cross-feeding assessed nutrient digestibility. Results: No difference in foregut digesta flora and nutrient digestibility between treatments was observed. LP diet caused decreased total tract digestibility of dry matter (DM), organic matter (OM), gross energy (GE), neutral detergent fiber (NDF), and acid detergent fiber (ADF) compared with the HP diet (p < 0.05). The fermentation broth from LP diet-fed pigs induced less full fermentation digestion of DM, OM, crude protein, and GE than HP broth (p < 0.05). Additionally, LP broth fermentation presented lower fermentation gas and short-chain fatty acids (SCFAs) generation than HP group (p < 0.05). This situation above may be related to decreased abundances of Lachnospiraceae, Eubacterium_eligens_group, Roseburia, and Ruminococcaceae_UCG-009, which can efficiently ferment nutrients to produce SCFA. Conclusions: Change in the flora caused compromise in hindgut microbial fermentation digestion leads to decreased total tract nutrient digestibility in pigs fed an LP diet.     

Effects of viscosity and fermentability of dietary fibre on nutrient digestibility and digesta characteristics in ileal-cannulated grower pigs

Relative contributions of two functional properties, viscosity and fermentability of dietary fibre, on apparent ileal digestibility (AID), apparent total tract digestibility (ATTD), digesta passage rate, N retention and SCFA concentration have not been established. Thus, eight ileal-cannulated pigs randomised in a double 4 × 4 Latin square were fed four diets based on maize starch and casein supplemented with 5 % of actual fibre in a 2 × 2 factorial arrangement: low-fermentable, low-viscous cellulose (CEL); low-fermentable, high-viscous carboxymethylcellulose (CMC); high-fermentable, low-viscous oat β-glucan (LBG); high-fermentable, high-viscous oat β-glucan (HBG). Viscosity and fermentability interacted to affect (P < 0·001) digesta viscosity and AID and ATTD of nutrients. These properties tended to interact to affect (P < 0·10) digesta passage rate and butyrate. Pigs fed the CMC diet had the lowest (P < 0·05) digesta passage rate and the highest (P < 0·001) AID of energy, crude protein and DM, and ATTD of energy and DM. Post-ileal DM digestibility was highest (P < 0·001) for pigs fed the CEL and HBG diets. Post-ileal DM digestibility had a negative, curvilinear relationship with the AID of energy and crude protein (R2 0·85 and 0·72, respectively; P < 0·001). Digesta viscosity had a less strong relationship with the AID of energy and crude protein (R2 0·45 and 0·36, respectively; P < 0·001). In conclusion, high-viscous, low-fermentable dietary fibre increases the proportion of a diet that is digested in the small intestine by reducing digesta passage rate.