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[The prececal and total intestinal nutrient digestibility and amino acid absorption of food yeasts in swine].

In a difference experiment the apparent precaecal (pc) and total intestinal (tot) nutrient digestibility and amino acid (AA) absorption of 5 yeasts (n-alkane yeasts Fermosin and Paprin, molasses/molasses distillers residue yeast, two sulfite waste liquor yeasts) were studied. The two n-alkane yeasts were very highly digested pc, the difference to tot digestibility is only small in most cases. In contrast to this, the pc and tot digestibility values of molasses/molasses distillers residue yeast differed considerably more. The probable reason for this is too hot drying due to which pc digestibility, particularly of the crude protein, and pc AA absorption are considerably reduced. In the two sulfite waste liquor yeasts, sulfite waste liquor residues containing lignin impair especially the crude carbohydrate digestibility and the energetic feed value; the better processing conditions of origin A, however, reduced considerably the negative effects. The results confirm that each yeast origin has its specific particularities, which have to be taken into consideration when they are used in feeding.

Amino Acids↗

[The energy metabolism of growing swine in the liveweight range of 10-50 kg. I. Study design, feed intake and digestibility].

Studies of the energy metabolism at maintenance and growth levels after the feeding of rations with a crude protein content of 17-24% and 44-47% resp. were carried out with hybrid pigs of line 150 in the live weight range between 10 and approximately 50 kg. This paper gives information on the methods and the outlay of the experiment and presents results concerning feed intake, live weight development and digestibility. Feed intake increased on average with growing live weight by 30-35 g DM/kg live weight. Feed conversion ranged from 1.2 to 1.8 kg DM/kg live weight gain in the first period and from 2.3 to 3.2 kg DM/kg live weight gain in the last period. The digestibility of the energy in the rations with a crude protein content of between 17 and 24% averaged 80% and that of the rations with a crude protein content of 44-47% averaged 86%. In the course of ontogenetic development the digestibility increased up to about 30 kg LW. The influence of the nutritional level on the level of digestibility was unequal in the experiments. In one experiment a decrease (1% unit) and in two experiments an increase (1-3% units) of the digestibility after the feeding of growth level in contrast to maintenance level could be observed. The change of rations with a varying protein content did not result in an influence on the digestibility level in comparison with the constant feeding of one ration.

Absorption↗

The influence of contamination with separate mycotoxins (aflatoxins, ochratoxin A, citrinin, patulin, penicillic acid or sterigmatocystin) on the in vitro dry matter and organic matter digestibilities of some roughages (berseem hay and wheat straw).

In vitro study on berseem hay and wheat straw was undertaken to investigate the the effect of mycotoxin contamination on dry matter and organic matter digestibilities. The data revealed a negative effect of most studied mycotoxins on the materials digestibility. Among the investigated mycotoxins, penicillic acid with its two concentrations (5 and 10 nmol) was the most negative, affecting digestibilities of both feed materials. Wheat straw digestibility was more influenced than berseem hay by the ochratoxin A, citrinin and sterigmatocystin (besides the penicillic acid) particularly with their high level (10 nmol). Yet, some mycotoxins act as antibiotics which may affect only the harmful flora but encourage the rumen microflora resulting in slight improvement of digestibility. The rumen conditions were able to metabolize or deform the used levels of all mycotoxins studied. Thus, there were no detectable residues of these mycotoxins in the digestion media after the in vitro fermentation.

Aflatoxins↗

Effect of age on seed digestion in parrots (Amazona aestiva).

The objective of this study was to compare the capacity of adult (more than 3 yr old) and young (less than 1 yr old) true parrots to digest seeds that are normally included in their diet in captivity, particularly soybean, sunflower, and corn. All the seeds were offered for 5 d with an interval of 15 d between different diets. The seeds of soybean and corn were boiled for 15 min and soaked in water at ambient temperature for 12 h before being fed to the birds. There were no differences in the digestibilities of crude protein and fats (ether extract) among animals, but the digestibilities of dry matter and crude fiber by the adult animals were higher than those of the young ones. The digestibility of carbohydrate (nitrogen-free extract) by adult birds was higher only for sunflower seeds. It is concluded that the capacity of parrots to digest fiber may change according to the age of the animal. Since the digestion of fiber depends on the action of microorganisms, these results suggest that the colonization of the gastrointestinal tract is delayed or very slow in young parrots.

Aging↗

Effects of dietary fibre on digesta passage, nutrient digestibility, and gastrointestinal tract morphology in the granivorous Mongolian gerbil (Meriones unguiculatus).

To investigate digestive tract performance in Mongolian gerbils (Meriones unguiculatus), food intake and digestibility, digesta passage rate, and gastrointestinal tract morphology were measured in captive animals fed low- or high-fibre diets. We used two markers (Co-ethylene diamine tetra-acetic acid for solutes and Cr-mordanted cell walls for particles) to measure differential passage rates of digesta fractions in order to test for the presence of a colonic separation mechanism (CSM). Although dry-matter intakes on the high-fibre diet did not differ from those on the low-fibre diet, digestibilities of dry matter, neutral-detergent fibre, acid-detergent fibre, crude protein, and crude fat were all significantly lower on the high-fibre diet. Gross energy intake on the high-fibre diet also did not differ from that on the low-fibre diet, but energy lost in faeces was much higher than on the low-fibre diet; thus, energy digestibility and digestible energy intake were significantly lower on the high-fibre diet. The lengths and dry-tissue masses of all segments of the gastrointestinal tract tended to enlarge in response to increased dietary fibre, but only the total tract contents, contents of the small intestine, and length and dry-tissue mass of the caecum increased significantly. The mean retention time (MRT) of the particle marker was significantly greater than that of the solute marker on the low-fibre but not the high-fibre diet; the solute/particle differential retention ratio was 0.62 on the low-fibre diet and 0.90 on the high-fibre diet. Thus, there was no evidence for selective retention of the solute marker on either diet. The MRT of the particle marker was significantly lower on the high-fibre diet and in the same direction as the MRT of the solute marker. These results suggest that the granivorous Mongolian gerbil has no CSM but can adjust its digestive tract capacity to accommodate greater quantities of low-quality food.

Animals↗

Influence of changes in lactase activity and small-intestinal mucosal growth on lactose digestion and absorption in preterm infants.

BACKGROUND: Feeding intolerance (ie, achieving and maintaining full enteral feedings) is a significant problem in preterm infants. A relation exists between feeding intolerance and incomplete lactose digestion. OBJECTIVES: We sought to identify the factors relating to lactose digestion and absorption, lactase activity, and small-intestinal mucosal growth. DESIGN: Lactose digestion and absorption, lactase-specific activity, and lumen-to-mucosa water flux as a measure of small-intestinal mucosal surface area were determined by using the triple-lumen perfusion technique on 2 occasions 3 wk apart in 10 preterm infants (x+/-SEM gestational age: 28.0+/-0.2 wk). RESULTS: Lactose digestion and absorption and lactase activity doubled between studies (P=0.035 and P=0.041, respectively). The change in digestion and absorption was related to lactase activity (P=0.034, R2=0.38). Lactase activity correlated with gestational age at birth (P=0.012, R2=0.51). The number of days of feeding explained 80% of the variability in small-intestinal mucosal surface area (P=0.001). CONCLUSIONS: To our knowledge, this is the first study to measure directly lactose digestion and absorption, lactase activity, and small-intestinal surface area in preterm infants. Changes in lactose absorption relate primarily to lactase activity rather than to mucosal growth. We showed directly a relation between enteral feeding and small-intestinal mucosal growth.

Digestion↗

Digestion of polysaccharides of potato in the small intestine of man.

Digestion and absorption from the small intestine of starch and nonstarch polysaccharides (NSP) (dietary fiber) from potato cooked and treated in various ways have been studied in ileostomy subjects. Test meals (300 g) of potato were fed following 24 h on a plant polysaccharide-free diet. Regardless of the treatment the potato had received, greater than 90% of NSP was recovered in ileostomy effluent. Starch from freshly cooked potato was well digested, only 3% being recovered; however, 12% from cooked and cooled potato escaped digestion in the small intestine. Digestibility of starch made resistant to alpha-amylase by cooling improved on reheating. Overall, 9, 18, and 14% of total carbohydrate fed was recovered from freshly cooked, cooled, and reheated potato, respectively. Digestibility of cooled potato was identical when eaten as large lumps or as finely sieved potato. In vitro studies with pancreatin also demonstrated incomplete digestion of cooled potato.

Adult↗

Strains and species of lactic acid bacteria in fermented milks (yogurts): effect on in vivo lactose digestion.

Lactose in yogurt with live bacteria is better tolerated than lactose in other dairy foods, partly because of the activity of microbial beta-galactosidase (beta-gal), which digests lactose in vivo. To evaluate the ability of different strains and species of lactic acid bacteria to digest lactose in vivo, yogurts (containing mixtures of strains of Streptococcus salivarius subsp thermophilus and Lactobacillus delbrueckii subsp bulgaricus) and fermented milks (containing individual species of S thermophilus, L bulgaricus, L acidophilus, or Bifidobacterium bifidus) that varied in microbial beta-gal activity were produced. Selected products were fed to healthy people who cannot digest lactose, and breath hydrogen production was monitored. All yogurts dramatically and similarly improved lactose digestion, regardless of their total or specific beta-gal activity. The response to fermented milks varied from marginal improvement with B bifidus milk to nearly complete lactose digestion with L bulgaricus milk. The results suggest that total beta-gal was not the limiting factor in promoting lactose digestion, perhaps because of a limited rate of intracellular substrate transport.

Adult↗

Metabolic effects of digestible and partially indigestible cornstarch: a study in the absorptive and postabsorptive periods in healthy humans.

To compare the effects of digestible (pregelatinized) and partially indigestible (retrograded) cornstarches on some metabolic indexes, we studied eight healthy volunteers during two periods separated by 1 wk. In each period, fasting volunteers consumed at 0800 the test meal containing either the digestible or partially indigestible cornstarch; blood and breath were sampled in the absorptive period for 8 h. To study its late effects, the same test meal as that served at 0800 was given again at 2200, and blood and breath were sampled for 3 h in the postabsorptive period the next morning, i.e., 10 h after ingestion of the test meal. In the absorptive period, blood glucose and insulin were significantly higher after ingestion of digestible cornstarch than after partially indigestible cornstarch. In the postabsorptive period concentrations of blood glucose, insulin, and fatty acids were not significantly different, whereas concentrations of blood acetate, breath hydrogen, methane, and 13CO2, and the respiratory quotient and satiety were significantly higher (P < 0.05) and concentrations of blood glycerol significantly lower (P < 0.05) after ingestion of partially indigestible cornstarch than after digestible cornstarch. We conclude that in healthy humans, digestion of partially indigestible cornstarch is slow in the small intestine and its colonic fermentation continues 10-13 h after its ingestion. Compared with pregelatinized cornstarch, the shift in starch digestion induced by retrogradation leads to a reduction in glycemic and insulinemic responses in the absorptive period and in lipolysis in the postabsorptive.

Adolescent↗

Digestibility of raw and cooked starches from legume seeds using the laboratory rat.

The in vivo digestibility and growth responses to diets containing raw and cooked legume starches were determined using male Wistar rats. These starches were obtained from seven legumes including smooth- and wrinkled-seeded field peas, navy beans, kidney beans, garbanzo beans, mung beans and lentils. Wheat and potato starch diets were fed for comparative purposes. With the exception of potato and the field pea starches, rats fed uncooked starch diets had higher weight gains than those fed cooked starch diets. The starches from wheat and all legumes, excluding the high-amylose wrinkled pea, were nearly 100% digestible but the legume starches reduced the digestibility of casein protein by 3 to 4%. Raw potato starch was shown to be only 57% digestible. The starches from potato and wrinkled pea reduced the digestibility of casein protein to 87% and gave high cecum weights. These characteristics were not altered by cooking the starch of wrinkled pea. The starches of smooth-seeded peas, lentils and all beans were highly digestible, showed no adverse effects on growth and were comparable to wheat starch in this evaluation.

Animals↗

Digestion and passage kinetics of chimpanzees fed high and low fiber diets and comparison with human data.

To investigate the digestive kinetics and fiber digestion of great apes, we conducted digestion trials on chimpanzees (Pan troglodytes) with diets of two fiber levels, one containing 34% neutral detergent fiber (NDF) and the other 14% NDF. Chimpanzees exhibited a response to fiber similar to that of humans. First, increases in the fiber concentration of the diet decreased mean transit time (MTT), hindgut turnover time (T) and the digestibility of fiber. Second, differences in MTT and T between the treatments and animals explained most of the variability in the digestibility of fiber components. Third, consistent with human data, the fiber marker passed more slowly than the liquid marker only when the high fiber diet was consumed. Fourth, individual variability, as in humans, was a significant factor affecting digestion and passage. Fifth, the MTT of chimpanzees was longer than that of humans. This result may be due to the apes' larger hindgut. In comparison with other hominoids, humans have smaller volumes in the gastrointestinal tract and hindgut. The gut proportions of modern humans, in combination with evidence from the fossil record, indicate that during its evolution the human lineage was able to overcome nutritional constraints imposed on body size increases in the great apes. We suggest that this advance was achieved through technological and social innovations that permitted early humans to achieve larger body size without lowering dietary quality.

Animals↗

Consumption of buckwheat protein lowers plasma cholesterol and raises fecal neutral sterols in cholesterol-Fed rats because of its low digestibility.

Buckwheat protein product (BWP) has a strong hypocholesterolemic activity in rats fed a cholesterol-enriched diet. In this study, we examined the influence of BWP on fecal excretion of sterols and nitrogen in rats fed a diet containing 5 g/kg cholesterol and 1.25 g/kg sodium cholate, and we examined whether the cholesterol-lowering activity of BWP is due to its low digestibility. In Experiment 1, rats fed BWP for 3 wk had significantly lower concentrations of plasma cholesterol and enhanced excretion of fecal total neutral sterols and nitrogen compared with rats fed casein. There was a significant correlation between fecal total neutral sterols and nitrogen (r = 0.89, P < 0.01). Fecal excretion of acidic sterols was unaffected by BWP. In Experiment 2, plasma cholesterol in rats fed trypsin-digested BWP for 2 wk was significantly higher than that in rats fed intact BWP. In Experiment 3, rats were fed BWP, low-molecular-weight fraction of the digest of BWP (LMF ) or high-molecular-weight fraction of the digest of BWP (HMF ) for 3 wk. Plasma cholesterol was lower in the BWP group than in the LMF group (P < 0.05), whereas that in the HMF group was intermediate. The in vitro digestibility of BWP with pepsin and pancreatin was significantly lower than that of casein. The results suggest that the cholesterol-lowering effect of BWP is mediated by higher fecal excretion of neutral sterols and that lower digestibility of BWP is at least partially responsible for the effect.

Animals↗

Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques.

Egg proteins contribute substantially to the daily nitrogen allowances in Western countries and are generally considered to be highly digestible. However, information is lacking on the true ileal digestibility of either raw or cooked egg protein. The recent availability of stable isotope-labeled egg protein allowed determination of the true ileal digestibility of egg protein by means of noninvasive tracer techniques. Five ileostomy patients were studied, once after ingestion of a test meal consisting of 25 g of cooked 13C- and 15N-labeled egg protein, and once after ingestion of the same test meal in raw form. Ileal effluents and breath samples were collected at regular intervals after consumption of the test meal and analyzed for 15N- and 13C-content, respectively. The true ileal digestibility of cooked and raw egg protein amounted to 90.9 +/- 0.8 and 51.3 +/- 9.8%, respectively. A significant negative correlation (r = -0.92, P < 0.001) was found between the 13C-recovery in breath and the recovery of exogenous N in the ileal effluents. In summary, using the 15N-dilution technique we demonstrated that the assimilation of cooked egg protein is efficient, albeit incomplete, and that the true ileal digestibility of egg protein is significantly enhanced by heat-pretreatment. A simple 13C-breath test technique furthermore proved to be a suitable alternative for the evaluation of the true ileal digestibility of egg protein.

Adult↗

Apparent digestibility of a debranched amylopectin-lipid complex and resistant starch incorporated into enteral formulas fed to ileal-cannulated dogs1.

The purpose of this study was to evaluate apparent digestibility in ileal-cannulated dogs fed enteral diets containing a debranched amylopectin-lipid complex (V-complex) or resistant starch. Six ileal-cannulated dogs were randomized into a replicated 3 x 3 Latin square design for determination of digestibility of three experimental treatments. Dietary treatments were as follows: 1) control; 2) V-complex; and 3) resistant starch. Diets were similar in chemical composition. Apparent digestibility of dry matter (DM), organic matter (OM) and carbohydrate by dogs fed the control diet was higher (P < 0.05) than for dogs consuming the other diets. Mean apparent digestibilities of carbohydrate for the control, V-complex and resistant starch diets were 89, 76 and 43%, respectively. Both DM and carbohydrate digestibility were lower (P < 0.05) for resistant starch compared with V-complex. Fecal dry and wet weights for dogs fed the control diet were lower (P < 0.05) than for those receiving either the resistant starch or V-complex treatments. Dogs fed the V-complex diet produced approximately 90 g less feces per day than dogs fed resistant starch. Dietary incorporation of V-complex to replace traditional carbohydrates may be beneficial for diabetic patients because of the decreased digestibility and subsequent glucose absorption rate. Furthermore, incorporation of resistant starch into enteral formulas may improve gastrointestinal tract health status as a result of increased fecal bulk, potential dilution of toxins in the intestinal lumen and greater production of short-chain fatty acids.

Amylopectin↗

Changing perspectives on aging and energy requirements: aging and digestive function in humans, dogs and cats.

When considering the question of energy balance, it is important to take into account energy provision and the ability of aging animals to digest macronutrients and thus obtain their maintenance energy requirement. A large number of studies have been conducted in humans in an effort to establish whether aging of the gastrointestinal tract has a significant effect on availability of dietary energy. The results of these studies have been conflicting, with indications that some aspects of gut functionality do decline with age, but little evidence overall to suggest that aging humans are at risk of energy deficit due to compromised digestive efficiency. A number of digestibility studies carried out with dogs confirm that there is no evidence of an age-related decline in digestive efficiency. This knowledge makes the determination of energy provision to senior dogs relatively straightforward to calculate. Many senior cats appear to exhibit quite a marked reduction in their ability to digest macronutrients, particularly fat, efficiently. Because this reduces the overall capacity to obtain energy from the diet, it is recommended that old cats should not routinely be offered reduced energy diets. For senior cats, the feeding regimen in later life should be to offer highly digestible diets that provide as much energy as adult maintenance rations.

Aged↗

Protein-bound D-amino acids, and to a lesser extent lysinoalanine, decrease true ileal protein digestibility in minipigs as determined with (15)N-labeling.

Heat and alkali treatment of food may increase the concentrations of protein-bound D-amino acids and cross-links such as lysinoalanine (LAL). To examine how protein treatment affects digestibility, purified test meals [total protein 150 g/kg dry matter (DM), 0.44 MJ/(kg BW(0.75). d)] were prepared, containing (g/kg DM) casein, 75; beta-lactoglobulin, 50; or wheat protein, 40. Each was (15)N-labeled. Test proteins were used either in their native form or after treatment for 6 or 24 h at 65 degrees C, pH 10.5-11.5. Each meal was fed to nine adult miniature pigs (twofold complete cross-classification). Chyme was collected continuously over 33 h postprandially via T-fistulas in the terminal ileum, and digestibilities of test proteins and individual L- and D-amino acids were calculated on the basis of recovery of (15)N and the respective amino acids in the chyme. Treatment of casein, beta-lactoglobulin or wheat protein for 24 h increased levels of D-amino acid residues. L-Asparagine and aspartate (L-Asx) were particularly susceptible; 14. 7 +/- 0.4, 11.7 +/- 0.2 and 11.0 +/- 0.9%, respectively, underwent racemization. LAL levels increased in parallel; 11.7 +/- 0.3, 13.6 +/- 0 and 14.8 +/- 0.0%, respectively, of total lysine was converted to LAL. At the same time, prececal protein digestibility was decreased by 13.4 +/- 2.3, 15.3 +/- 1.4 and 17.8 +/- 1.2% units, respectively (P < 0.05; mean +/- SEM, n = 9). Digestibility of individual L-amino acids decreased by 10-15%, but L-amino acids prone to peptic cleavage, such as L-phenylalanine and L-tyrosine, were not affected. Digestibilities of D-amino acids and LAL were approximately 35%. It seems that mainly D-amino acids, and to a lesser extent LAL, were responsible for lower digestibility by interfering with peptic cleavage.

Amino Acids↗

The effect of thermal processing and enzyme treatments of soybean meal on growth performance, ileal nutrient digestibilities, and chyme characteristics in broiler chicks.

Effects of thermal processing (toasting or extrusion) of untoasted soybean meal on growth performance, apparent ileal nutrient digestibilities, and chyme characteristics were studied in broiler chicks fed diets with soybean meal as the main protein source. Effects of increasing shear forces during extrusion as well as enzyme treatments (protease and carbohydrase) were also studied. When compared with toasting, extrusion significantly improved feed conversion ratio (1.56 vs 1.62) and apparent ileal digestibilities of CP and nonstarch polysaccharides (87.5 vs 82.2% and 26.7 vs 11.4%, respectively). Enzyme treatment improved apparent ileal digestibility of CP and nonstarch polysaccharide compared with no enzyme treatment (85.2 vs 83.7% and 20.6 vs 14.5%, respectively); however, enzyme treatments did not result in a better growth performance of the chicks. Among the enzyme treatments, no differences were found in growth performance and apparent ileal CP digestibility, whereas the carbohydrase significantly improved apparent ileal nonstarch polysaccharide digestibility compared with the other enzyme treatments. Extrusion of SBM at the highest shear level caused a significant increase in the water-holding capacity, chyme viscosity, and concentration of soluble nonstarch polysaccharides in the chyme compared with extrusion of SBM at lower shear levels. The increase in chyme viscosity did not affect growth performance, nor did it influence apparent ileal nutrient digestibilities.

Animals↗

Digestible sulfur amino acid requirement of starting turkeys.

Three experiments (a total of 1,020 poults) were conducted to determine the digestible sulfur amino acid (SAA) requirement for female turkey poults during the starter period. Poults were fed a standard corn-soybean meal diet (PC) that met or exceeded NRC recommendations (28% CP, 3,172 kcal MEn/kg) for 1 wk and were then randomly assigned to treatments until 22 d (Experiment 2 and 3) or 23 d (Experiment 1) of age. Dietary treatments included the PC diet and seven or nine titrated levels of methionine added to a basal corn-soybean meal diet, for a total of 0.50 to 1.33% total digestible SAA. The basal diet contained 18.4% intact crude protein. All diets contained 3,171 kcal MEn/kg. The true digestible SAA content of the basal diet without methionine additions was 0.50% based on digestibility assays of the corn and soybeans with cecectomized turkeys. Diets were formulated to contain 1.40% digestible lysine. Other amino acids were maintained at levels in relation to lysine based on previous research with turkeys and the Illinois Ideal Chick Protein. Broken-line analysis suggests that the digestible SAA requirement for female turkeys during the starter period is 0.76% for optimum body weight gain and 0.75% for optimal feed:gain at the energy levels used in these studies.

Amino Acids, Sulfur↗