Caecal Digestion Research Articles

Minimal processed infant formula vs. conventional shows comparable protein quality and increased postprandial plasma amino acid kinetics in rats.

During industrial processing, heat treatments applied to infant formulas may affect protein digestion. Recently, innovative processing routes have been developed to produce minimally heat-processed infant formula. Our objective was to compare the in vivo protein digestion kinetics and protein quality of a minimally processed (T−) and a heat-treated (T+++) infant formula. Sixty-eight male Wistar rats (21 d) were fed with either a diet containing 40 % T− (n 30) or T+++ (n 30), or a milk protein control diet (n 8) during 2 weeks. T− and T+++ rats were then sequentially euthanised 0, 1, 2, 3 or 6 h (n 6/time point) after ingestion of a meal containing their experimental diet. Control rats were euthanised 6 h after ingestion of a protein-free meal to determine nitrogen and amino acid endogenous losses. Nitrogen and amino acid true caecal digestibility was high for both T− and T+++ diets (> 90 %), but a tendency towards higher nitrogen digestibility was observed for the T− diet (96·6 ± 3·1 %) compared with the T+++ diet (91·9 ± 5·4 %, P = 0·0891). This slightly increased digestibility led to a greater increase in total amino acid concentration in plasma after ingestion of the T− diet (P = 0·0010). Comparable protein quality between the two infant formulas was found with a digestible indispensable amino acid score of 0·8. In conclusion, this study showed that minimal processing routes to produce native infant formula do not modify protein quality but tend to enhance its true nitrogen digestibility and increase postprandial plasma amino acid kinetics in rats.

Caecal digestibility as an approximation of ileal protein digestibility evaluation in rats.

The rat model can be used to assess ileal protein digestibility rapidly and in first intention, but no standardised method exists. Our objective was to compare methods to assess protein digestibility, depending on collection site (ileum/caecum) and use of a non-absorbable marker. A meal containing either casein, gluten or pea protein and chromium oxide as non-absorbable marker was given to male Wistar rats and the entire digestive content was collected 6 h later. Total chromium recovery was incomplete and variable, depending on protein source. We observed no significant difference in digestibility between the methods for any of the protein sources tested. Although none of the methods tested is optimal, our results suggest that caecal digestibility can be used as a proxy of ileal digestibility in rats without using a non-absorbable marker. This simple method makes it possible to evaluate protein digestibility of new alternative protein sources for human consumption.

Protein and amino acid digestibility of 15N Spirulina in rats.

Spirulina is often used as dietary supplement for its protein content and quality. However, in vivo data on protein digestibility are lacking. This study aims to determine nitrogen and amino acid digestibility in rats. A secondary objective was to test the effect of sonication prior to ingestion to break cell walls. Wistar rats were fed a single test meal containing 15N Spirulina that was either sonicated (n = 11) or not (control, n = 13). Rats were euthanized 6h after the meal ingestion. Spirulina nitrogen digestibility was measured by assessment of 15N recovery in digestive contents. Amino acid digestibility was measured by quantification of the caecal amino acid content and their 15N enrichment. Real fecal nitrogen digestibility was 86.0 ± 0.7%, without any differences between groups. Mean 15N amino acid caecal digestibility was 82.8 ± 1.3%, and values ranged between 77.9 ± 1.9% for serine and 89.4 ± 1.0% for methionine. No effect of sonication was observed. The most limiting AA was histidine, with a chemical score of 0.98 and a PD-CAAS of 0.84. Lysine was also limiting in a lesser extent. The nitrogen and amino acid digestibility of Spirulina is relatively low, and showed no effect of prior sonication. Its amino acid composition is relatively well balanced but not enough to compensate for the poor digestibility.

15N and 2H Intrinsic Labeling Demonstrate That Real Digestibility in Rats of Proteins and Amino Acids from Sunflower Protein Isolate Is Almost as High as That of Goat Whey

Background:In the context of developing plant protein sources for humans, sunflower is a good candidate in its form as an oilseed coproduct. Objectives:We aimed to compare the real digestibility in rats of a sunflower isolate to that of goat whey protein. We also studied the efficiency of 15N and 2H intrinsic labeling in this assessment. Methods:Sunflower seeds and goat milk were labeled with 15N and M2H. Male Wistar rats (10 wk old) were fed a mealcontaining 12% of either sunflower isolate (n = 8) or whey (n = 8). Six hours after meal ingestion, protein and aminoacid digestibility were assessed by measuring nitrogen, hydrogen, and amino acids in the digesta, as well as isotopeenrichments in the bulk and individual amino acids. The differences between groups and isotopes were respectivelytested with an unpaired and a paired t test. Results:Protein isolate purity was 87% for whey and 94% for sunflower.2H and15N enrichments were, respectively, 0.12 atom % (AP) and 1.06 AP in sunflower isolate and 0.18 AP and 0.95 AP in whey. Fecal15N protein digestibility was 97.2±0.2% for whey and 95.1±0.5% for sunflower isolate. The use of2H resulted in a lower digestibility estimate than15N for whey (96.9±0.2%P<0.05) and sunflower (94.2±0.5%,P<0.01). For both isotopes, protein digestibility was about 2% higher for whey than for sunflower isolate. Mean15N amino acid caecal digestibility was 97.5±0.2% for whey and 96.3±0.2% for sunflower isolate. The values obtained with15N and2H resulted in significant differences ranging from –0.1% to 3.5%. The DIAAS was >1.0 for whey and 0.84 for sunflower (lysine). Conclusions:The protein and amino acid digestibility of sunflower isolate was high but its DIAAS reflected a moderate lysine imbalance. Despite slight differences with15N, deuterium produced comparable results, making it suitable for in vivo digestion studies.

Interactive effects of dietary fibre and lipid types modulate gastrointestinal flows and apparent digestibility of fatty acids in growing pigs.

A total of eight ileal and caecal cannulated Yorkshire barrows were used to determine the interactions of dietary fibre (DF) and lipid types on apparent digestibility of DM and fatty acids (FA) and FA flows in gastrointestinal segments. Pigs were offered four diets that contained either pectin or cellulose with or without beef tallow or maize oil in two Youden square designs (n 6). Each period lasted 15 d. Faeces, ileal and caecal contents were collected to determine apparent ileal digestibility (AID), apparent caecal digestibility and apparent total tract digestibility (ATTD) of dietary components. The interactions between DF and lipid types influenced (P &lt;0·05) the digestibility of DM and FA flows. The addition of maize oil decreased (P &lt;0·05) AID of DM in pectin diets, and the addition of beef tallow depressed (P &lt;0·001) ATTD of DM in cellulose diets. Dietary supplementation with beef tallow decreased (P &lt;0·05) the AID of FA in pectin-containing diets but had no effects in cellulose-containing diets. Dietary supplementation with beef tallow increased (P &lt;0·05) AID of SFA and PUFA and the flow of ileal oleic, vaccenic, linolenic and eicosadienoic acids and reduced the flow of faecal lauric, docosatetraenoic and docosapentaenoic acids in pectin- and cellulose-containing diets. In conclusion, the interaction between DF type and lipid saturation modulates digestibility of DM and lipids and FA flows but differs for soluble and insoluble fibre sources, SFA and unsaturated fatty acids and varies in different gastrointestinal segments.

Pregastric and caecal fermentation pattern in Syrian hamsters

Abstract Few studies have compared the pregastric and caecal digestion of hamsters. Mature Syrian hamsters (Mesocricetus auratus) were fed a diet containing crude protein and fibre at 225 and 64 g/kg, respectively. In the pregastric digesta, the pH, volatile fatty acids (VFA), lactate and ammonia N concentrations were 5.91±0.97, 43.1±12.9 μmol/g, 19.2±8.0 μmol/g and 2.46±1.16 mg/g, respectively. The corresponding values in the caecal contents were 6.41±0.25, 92.1±12.2 μmol/g, 6.9±1.0 μmol/g and 0.28±0.08 mg/g, respectively. Acetate was the primary VFA, followed by propionate in the forestomach and butyrate in the caecum. In the caecal contents, a very small amount of methane was produced. The number of total bacteria determined by real-time PCR averaged 2.31×109/g and 1.57×1010/g in the pregastric and caecal digesta, respectively. In the pregastric digesta, bifidobacteria and Bacteroides sp. were present at 1.57×107/g and 4.02×107/g, respectively. In the caecal contents, the numbers of bifidobacteria and Bacteroides sp. were 1.01×108/g and 1.46×108/g, respectively. The caecum appears to be more important in hamsters than the forestomach, both in terms of its greater size (3.39±0.63 g vs. 1.59±0.70 g) and greater microbial activity.

In situ caecal degradation of roughages in horses

The present study was carried out to evaluate the in situ degradation of dry matter (DM), neutral detergent fiber (NDF) and crude protein (CP) in roughages by the in situ caecal digestion technique in horses. The roughages evaluated were: Lucerne hay (Medicago sativa), peanut (Arachis pintoi cv. Amarillo), desmodio(Desmodium ovalifolium), stylo (Stylosanthes guianensis cv. Mineirão), pigeon pea (Cajanus cajan), lime-yellow pea (Macrotyloma axillare) and coastcross hay (Cynodon dactylon cv. coastcross). The assay was conducted in a complete randomized design with seven roughages and three replications. One mare with a cannula fitted in the caecum was used, fed diet consisting of coastcross hay (80%) and concentrate (20%) at 2.0% BW, four times a day. Nylon 6.5 × 20 cm bags were used with 45 μ/pore, containing 5.2 g DM/bag, inserting 3 or 4 bags in the caecum at the times of 2, 4, 6, 8, 12, 24 and 48 hours incubation. The caecum in situ degradability parameters of nutrients were obtained by Ørskov model. The DM degradability parameters of all the roughages were significant. There was no fit to the model for pigeon pea for CP and NDF and desmodio. Peanut, stylo and lime-yellow pea presented larger potentially degradable DM with values of 53, 46.5 and 40%, respectively, and higher values for the soluble fraction of 20, 21, 28.6%, with high degradability rates of 10.36, 20.26 and 14.8% h-1. Higher NDF degradation rates were observed in these foodstuffs with values of 9.1 and 11.3, 11.2% h-1, high potentially degradable fraction with values of 55, 51.8 and 47.2%, and greater CP degradation at 48 hours with values of 87, 95, and 94.8%. Peanut, stylo and lime-yellow pea presented potential for use in horses diets.

The effect of level and type of cereal non-starch polysaccharides on the performance, nutrient utilization and gut environment of pigs around weaning

The influence of non-starch polysaccharides (NSP) level and solubility on performance, digestion site and gut environment was investigated in 20 Swedish Yorkshire litters between 3 and 9 weeks of age. The litters were distributed among five diets based on cereals and cereal by-products. The control diet (C) had a medium content of NSP (147 g/kg dry matter (DM)), whereas diets H and Hi had a high content of NSP (188–250 g/kg DM), and diets L and Li had a low content of NSP (95–109 g/kg DM) after dilution with starch. The proportion of insoluble (i) NSP was higher in diet Hi and Li (0.80–0.85) than in diets C, H and L (0.68–0.73). The pigs offered diet Li showed the highest (P<0.05) feed intake and grew faster (P<0.05) than pigs offered diets C, L and H. In the post-weaning period feed:gain was highest for pigs offered the C and H diets and lower for pigs offered the low NSP diets and diet Hi. During week 6, the coefficient of caecal (CCAD) and total tract (CTTAD) apparent digestibility of organic matter (OM) was lower (P<0.05) in diet Hi compared to the other diets, and the CCAD and CTTAD of crude protein (CP) was higher (P<0.05) in diet L compared to the high NSP diets. During week 7, the CCAD and CTTAD of OM was lower (P<0.05) in diet Hi compared to the low NSP diets and diet C. The CCAD of CP and starch was higher (P<0.05) in diet L compared to the control diet. Diet L showed higher (P<0.05) values of digestible energy compared to the high NSP diets, both in the 6 and 7 weeks old piglets. NSP solubility influenced (P<0.05) the caecal digestibility of arabonixylans and total NSP in the 6 and 7 weeks old piglets, as well as the caecal digestibility of total dietary fibre in the 7 weeks old piglets. The content of total organic acids (OA) was linearly related to the pH level at the ileum ( R 2 = 0.70), caecum ( R 2 = 0.57) and colon ( R 2 = 0.83). The experimental diets altered the molar proportions of lactic acid and short chain fatty acids (SCFA), of total OA, as well as the molar proportions of acetic, propionic and butyric acids, of total SCFA, in the stomach, ileum, caecum and colon of the piglets. In conclusion, NSP solubility influenced the digestibility of cell wall polysaccharides at the caecum but not at the total tract. Diet Hi promoted production of lactic acid in the stomach and small intestine and butyric acid in the large intestine.

Fermentation Patterns in Rabbit Caecal Cultures Supplied with Plant Polysaccharides and Lactate

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Digestion and fermentation of proteins in rats fed keratin, albumin, cooked casein and antibiotics.

Dietary cooked casein promotes colon cancer in rats. We speculated and tested the hypothesis that cooking reduces the digestibility of casein, and increases the yield of bacterial metabolites, which are potential promoters of cancer. We investigated dietary means to manipulate nitrogen transfer and fermentation in the caecum. The caecal digestion of casein (cooked or not), keratin (hydrolysed or not) and bovine serum albumin (oxidized or not) was measured in rats. Protein fermentation was estimated by assaying caecal ammonia and branched-chain fatty acids. Keratin and cooked casein were digested to a very low extent, and were poorly fermented. Rats given cooked casein had 2-3 times more ammonia in their caecum than animals given the other proteins. Antibiotics (bacitracin, chlortetracycline, neomycin and spiramycin, at either 20 and 80 micrograms/ml water) decreased caecal ammonia in rats eating cooked casein, with spiramycin being most efficient. These data support the hypothesis given above, and provide ways to manipulate caecal ammonia.

Effect of fermentable carbohydrates on volatile fatty acids, ammonia and mineral absorption in the rat caecum.

The effects of poorly digested carbohydrates in the small intestine on caecal digestion and absorption have been studied in the rat. Even in diets lacking these carbohydrates, there was a noticeable production of volatile fatty acids (VFA) in the caecum. Except for cellulose, the carbohydrates (bran, pectin, guar-gum, crude potato-starch, lactose, lactulose) favoured considerable development of the caecum and enhanced the quantities of VFA present there. On reaching the caecum, they increased ammonia absorption as a result of a higher uptake of blood urea, even if a greater part of the urea nitrogen was used in bacterial protein synthesis. Arteriovenous differences in the caecum showed a considerable absorption of various electrolytes. VFA absorption seemed to be accompanied by a release of Cl- into the caecal contents and by absorption of the main cations, Na+ being absorbed along an unfavourable gradient between the plasma and the caecal contents.

Rôle de cinq souches de lactobacilles sur la dégradation des glucides chez le poulet monoxénique

Five strains of Lactobacillus were isolated in holoxenic roosters; two of these which had an alpha-amylase were inoculated separately into 5 groups of axenic chickens fed the same diet. Some differences among these 5 groups were noted. Lactobacillus proliferation varied between ten and a thousand-fold, depending on the strain, and for the same strain depending on whether the crop, caecum or faeces was examined. Amylolytic lactobacilli in vivo played a role in starch degradation in various ways related to the specific properties of their amylase. Lactic acid production in the crop was higher with the three strains producing the two lactic acid isomers than with the two strains producing only one of the isomers. Finally, monoxenic caecal digestion was different from that of both the axenic and the holoxenic.

Experimental study of digestion in Octopus vulgaris (Cephalopoda: Octopoda)*

Digestion in Octopus is very fast at the beginning and slows down progressively. At 18–19°C, the crop was empty 6 hours after the beginning of the meal, gastric digestion was achieved after 9 hours and caecal digestion after 12 hours. The digestive enzymes are mainly supplied by the digestive gland, where alternating phases of synthesis and release were observed. Absorption takes place in the digestive gland, in the digestive duct appendages, and in the caecum, where the lipids were first absorbed. At 14°C, all processes of digestion are distinctly slower. There was some evidence that digestion might also be affected by sex and sexual maturation.