[Food digestibility and N-metabolism in sheep fed concentrated feed at varying frequencies].
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The fundamentals of parenteral nutrition and the possibilities of oral nutrition with chemically defined diets are described. The possibilities are discussed against the background of a review of nutritional pathophysiology and the use of the available preparations set out.
Digestive intolerance to food proteins may occur in childhood as a result of a wide range of etiologic and pathophysiologic mechanisms. Cow milk protein intolerance is the most common form of food intolerance in children. Food allergy and food intolerance may be confused because both produce similar symptoms, especially in young children with clinical manifestations of food allergy localized to the gastrointestinal tract. On the other hand, food-sensitive enteropathy may be defined as the clinical food-related syndromes associated with an abnormal small intestinal mucosa. Although several foods have been reported to damage the small intestinal mucosa in infancy (soy, rice, fish, chicken meat, egg), cow milk-sensitive enteropathy is the most common cause. Whatever the mechanisms, digestive intolerance to food proteins with or without enteropathy is primarily a temporary condition of infancy, in contrast to most forms of food allergy. In children with these disorders, symptoms usually resolve by 1 to 3 years of age. The variation in prevalence rates of this disorder in different countries can be explained by different diagnostic criteria. The classic food-sensitive enteropathy syndromes with chronic diarrhea and failure to thrive in infancy have become rarer in some European countries, including Spain. Some risk factors for the development of these conditions appear to be early exposure to cow milk feedings, acute infectious diarrhea, and malnutrition. Breast-feeding appears to be at least partially protective.
At an average of 32 days after a modified Roux-en-y repositioning of rat small intestine, the mucosal mass, mucosal composition, in vivo absorption of galactose and the activity of maltase, sucrase and alkaline phosphatase were measured. In the gut segment with digestive secretions but without food (A) the only change was a decrease of sucrase activity which occurred most probably at the cellular level. In the gut segment with food and gastric juice and a reflux of digestive secretions (B) complex changes took place. An increase in mucosal mass was not accompanied by an increase in galactose absorption. There was a high increase of sucrase activity, a moderate increase of maltase activity and a tendency of the alkaline phosphatase activity to decrease. The changes (increase in mucosal mass and total enzyme activity, but no changes in activity at the cellular level) in the segment exposed to both digestive secretions and food (C) were compatible with a more proximal promotion of a distal gut segment.
The apparent digestibilities of organic matter, protein, lipid and carbohydrate of a laboratory chow were determined in young adult female rats fed ad libitum, after losing 40-50% body weight and prolonging the loss for up to 15 weeks, and while recovering the lost body weight during a second period of ad libitum food intake. During deprivation the animals increased the apparent digestibility of crude protein but there was no significant change in digestibility coefficients of lipid or carbohydrate in relation to treatments. When food was again offered ad libitum to the deprived animals they ate large amounts compared with their body weights but normal amounts when compared with their age peers. Apparent crude protein digestibility immediately returned to pre-deprivation values. No impairment of ability to ingest and digest quantities of food relative to age was detected.
Two strains of rats (Charles River CD and Lewis) were fed high-moisture (71% water) diets containing 50-300 mg acarbose/kg dry diet for 1-3 wk. Acarbose impaired carbohydrate digestion in both strains, as evidenced by increased fecal excretion and increased intestinal contents. For both strains the highest dose of acarbose tended to stimulate food intake, whereas an intermediate dose (100 mg/kg) inhibited food intake. The lowest dose (50 mg/kg) had no significant effect. In general the food intake-promoting effect of acarbose was more pronounced in CD rats, whereas the food intake-inhibiting effect of acarbose was more pronounced in Lewis rats. To determine whether increased intestinal bulk, due to undigested food, was responsible for the reduced food intake, another experiment was conducted in which Lewis rats were fed diets containing 5-25% cellulose. Although this level of cellulose should have increased fecal bulk to the same degree as acarbose, cellulose increased rather than decreased food intake. It is proposed that the presence of incompletely digested food in the digestive tract can inhibit food intake for several days. Because manipulating diet moisture altered energy intake without altering percentage of food excreted as feces, it is proposed that acarbose and diet moisture alter food intake by different mechanisms.
Caecectomized and sham-operated rats were fed a laboratory chow ad libitum and the effects of caecectomy on the digestibility of the food were studied. Compared with sham-operated controls, caecectomized rats showed a decrease in apparent digestibiltiy of organic matter from 77.8 to 73.0%, of crude protein from 83.0 to 79.4%, and of 'carbohydrate' from 74.6 to 69.0%. However, faecal water content increased from 41.6 to 54.8%. 51Cr-labelled EDTA was excreted faster in the faeces after caecectomy. The colon partly adapted to the loss of caecal mucosa by increased length and thus mucosal surface area. In a second concurrent experiment the effect of caecectomy on the apparent digestibility of food during food restriction was studied. Six caecectomized rats, comparable in all respects to those used in the first study, were fed the laboratory chow ad libitum for 3 weeks. They were then fed submaintenance amounts of food to achieve body weight losses of 40--50% and to maintain these low weights for 4 weeks. Finally, they were again fed ad libitum for 3 weeks. During the period of restriction the apparent digestibility of organic matter increased from 72.7 to 75.4%. This was largely due to the increased apparent digestibility of crude protein which rose from 78.4 to 81.9%. Digestibility coefficients returned to control values immediately upon refeeding ad libitum.
Regression techniques may be used to establish close relations between the crude fibre content and digestibility data of organic materials (total digestibility). It was shown from regression equations calculated for a number of feedingstuffs that the total digestibility of a feedstuff may be calculated, with a sufficient degree of accuracy, from the crude fibre content of the material. The range of variations from most of the digestibility data obtained for various feedstuffs, was clearly below the limit given (2.5%). When regression equations are used the variation limits should always be indicated for which they had been established. Differences within the different groups of feedstuffs are so small that in many instances, the same equation may generally be used for feedstuffs of the same group. Similarly, equations for calculating digestibility values may be derived on the basis of the lignin content of a material, although the range of variations will, in this case, be wider when compared with the crude fibre content. The reason for this must be seen in the greater uncertainty of the lignin method. Analogous regression equations may be found for the different conserving products of green feeds, in which certain alterations have to be made corresponding to the different methods of conserving used. On the one hand, these are accounted for by changes in the crude fibre content brought about by biochemical reactions during the conserving process on the other hand a special influence of conserving form can be observed. The content of digestible crude protein in green feeds can be established, with a high degree of accuracy, from the crude protein content of the material. The content of digestible organic matter can be calculated from the digestibility of organic matter and from the ash content of the material. The content of digestible organic matter is, in turn, closely related to the content of energetic feed units in a particular material.
For better understanding the mechanism of microbial strains promoting methane production, four strains Hungatella xylanolytica A5, Bacillus licheniformis B1, Paraclostridium benzoelyticum C2 and Advenella faeciporci E1 were inoculated into anaerobic digestion systems. After bioaugmentation, the cumulative methane production of A5, B1, C2 and E1 groups elevated by 11.68%, 8.20%, 18.21% and 15.67% compared to CK group, respectively. The metagenomic analysis revealed that the species diversity and uniformity of the experimental groups was improved, and hydrolytic acidifying bacteria, represented by Clostridiaceae, Anaerolineaceae and Oscillospiraceae, and methanogens, such as Methanotrichaceae and Methanobacteriaceae, were enriched. Meanwhile, the abundance of key genes in carbohydrate, pyruvate and methane metabolism was increased in the inoculated groups, providing reasonable reasons for more methane production. The strengthening mechanism of microbial strains in this study offered a theoretical foundation for selecting a suitable bioaugmentation strategy to solve the problems of slow start-up and low methane production in anaerobic digestion.
This study investigated how ethanol pretreatment (EP) enhances the resilience of high-solid anaerobic digestion against rapid organic loading shocks. Semi-continuous reactors fed with either untreated or EP-treated food waste were compared, and the underlying mechanisms were elucidated by integrating thermodynamic calculations with metagenomic analyses. At an organic loading rate of 6.0 g VS/(Lˑd), the control group (untreated) collapsed due to the accumulation of propionate and other longer-chain volatile fatty acids (VFAs), resulting in a methane yield decrease exceeding 70%. In contrast, the EP group maintained stability, exhibiting a methane yield decrease of less than 5%, with VFAs dominated by readily degradable acetate. Thermodynamic analysis confirmed that EP significantly lowered the energy barriers for VFA degradation. Metagenomic analysis revealed that both propionate/butyrate activation pathways (with lower energy cost or independence from acetyl-CoA) and syntrophic acetate oxidation were activated in the EP group, thereby avoiding the VFA metabolic stress observed in the control group. Furthermore, higher abundances of conductive type IV pili genes, Complex II, and archaeal V/A-type ATPase were detected in the EP group, suggesting the establishment of direct interspecies electron transfer and enhanced electron flux and energy capture efficiency. Moreover, under high loading conditions, only a few high-abundance metagenome-assembled genomes (MAGs) were detected in the control group, while multiple MAGs carrying identical VFA-degrading enzyme systems were identified in the EP group. The functionally redundant microbiota, unobstructed VFA metabolic pathways, and efficient electron transfer and energy supply collectively sustained the stability of the EP group under loading shocks.
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While local venous outflow was measured in anesthetized dogs, various constituents of intestinal chyme were placed in the jejunal lumen to identify those responsible for postprandial intestinal hyperemia. Digested food and its supernatant increased local blood flow, whereas its precipitate, undigested food, and pancreatic enzymes did not. In the jejunum bile alone had no effect, but it markedly enhanced the hyperemic effect of digested food. Bile in the ileal lumen, however, increased local blood flow. At physiological postprandial concentrations in the jejunum, glucose, and micellar solutions of oleic acid and monoolein increased flow, but taurocholate and 16 common dietary amino acids did not. The hyperemic effect of lipids required the presence of taurocholate. Of the 16 amino acids, only Glu and Asp increased flow at 10 times the physiological concentrations (28 and 20 mM, respectively). The study indicates that the constituents of chyme responsible for postprandial intestinal hyperemia are the hydrolytic products of food, especially those of carbohydrates and fats and that bile plays an important role in the hyperemia.
Fermentation of leafy food occurs in the enlarged saccus gastricus of the colobus monkey with the formation of volatile fatty acid, as in the rumen of ruminant animals. About half of the digestible organic matter and cellulose of the diet is digested in this way.
Fifty patients stricken by giardiosis were treated by a single dose administration of Tinidazole -- 50 mg./kg. for children and 2 g. for adults per os. Fifteen days after treatment, 84 0/0 of the patients had negative coprologic exams for giardiosis. The product was well-tolerated by the digestive tract as was demonstrated by a coprologic examination for digested food reside; however, minor digestive inconveniences were noted in 87 0/0 of the patients. There were no perturbations of hematologic or hepatic tests. This product would thus appear to be a treatment of choice in the management of giardiosis.
Crude fiber analysis does not accurately reflect the amount of dietary fiber in food materials, nor does it give a constant fraction of dietary fiber when used to compare sources in the diet. More accurate methods of estimating dietary fiber are compared. The neutral detergent method of Van Soest, modified for use with foods, was especially useful in measuring the insoluble fraction of dietary fiber. It not only provided a simple, quick method of analysis but also was useful in isolating dietary fiber for further experimentation. Water-holding capacity studies, trace mineral binding studies, and bile acid binding studies were run on the insoluble dietary fiber without interference from digestible food constituents.
Frequency of the labral brush movements of first, second, and fourth instars of Aedes aegypti (L.) and Aedes albopictus (Skuse) was studied comparatively in the laboratory. A frequency of 197 strokes per min for the first and second instars was observed in the former species compared to 118 strokes per min in the latter species. A faster ingestion rate of algal cells also was observed in first and second instars of Ae. aegypti (mean 57.5 cells per s) compared with first and second instars of Ae. albopictus (mean 22.4 cells per s). The digestive enzymes chymotrypsin (EC 3.4.21.1) and trypsin (EC 3.4.21.4) were more active in the peritrophic membrane (including food contents) than in the midgut epithelium of both species. Chymotrypsin activity in 11-d-old third and fourth instars of Ae. albopictus was 28 times higher than in the corresponding stadia of Ae. aegypti, indicating that the former species may have a superior enzymatic process for digesting food proteins.
A modified Roux-en-y repositioning of rat proximal small intestine resulted in a gut segment (A) exposed only to digestive secretions, but not to food and a gut segment (B) exposed to food, stomach juice and by reflux only to digestive secretions, and a third segment (C) exposed to both, food and digestive secretions. The changes in segment A were qualitatively very similar to those occurring after removal of luminal nutrition (intravenous feeding, self-emptying blind loop, and Thiry Vella loop). These findings support the hypothesis that the presence of luminal nutrition is a major factor regulating mucosal mass and enzyme activity in rat proximal small intestine. The changes in the luminal environment in segment B caused an increase in mucosal mass (in the proximal half only), an increase in sucrase activity which paralleled the increase in mucosal mass, and no change in activity of alkaline phosphatase which in fact was a decrease in activity ;at the cellular level'. Later on the net absorption of sodium and potassium was improved and the disappearance of galactose was unchanged when referred to unit length of small intestine.In segment C there was a small increase in mucosal mass, an increase in activity only for alkaline phosphatase, and an improvement of the net absorption of sodium without changes in the disappearance of galactose. These changes were compatible with a more proximal promotion of a distal gut segment.
1. The paper describes the development and construction of an apparatus for maintaining a normal microbial population of the rumen under strictly controlled conditions over long periods of time. 2. The apparatus is simple to construct and operate. It is possible to do four replicate experiments at the same time. 3. The results of three experiments are given. The experiments showed that when the steady-state was reached it could be maintained indefinitely, with the type and quantities of products of fermentation very similar to those in the rumen of donor animals, including the maintenance of normal protozoal populations for up to 49 d. 4. It was found that within wide ranges, the digestibility of rations and the output of products were independent of dilution rate. 5. Except for the lowest 'level of feeding', the digestibility was independent of the level of feeding. The output of products was proportional to the amount of food digested and was the same as would be expected in sheep on similar rations. 6. An experiment in which a ration of hay was changed to a mainly concentrate ration showed that the fermentation characteristics were determined mainly by the food given.