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Protein utilisation in response to caecal corn starch in ponies.

The influence of administering caecal corn starch (0.0, 0.2, 0.4 or 0.6 g/kg body weight/day) on protein utilisation in 4 ponies was analysed with a latin square experimental design. The basal diet was dehydrated alfalfa pellets. Determinations were made of nitrogen retention, protein and dry matter digestions, total plasma protein, plasma urea nitrogen, plasma ammonia and plasma-free amino acids. Twice daily administration of corn starch into the caecum resulted in an increased nitrogen retention (P less than 0.01). Maximum nitrogen retention was observed with the caecal administration of 0.4 g/kg bwt of corn starch/day. Nitrogen retention expressed as percentage of the nitrogen absorbed was significantly higher (P less than 0.01) when corn starch was caecally administered. Digestion coefficients for dry matter and protein tended to be higher in ponies receiving the corn starch. Values of blood urea nitrogen in ponies administered the 0.0, 0.2, 0.4 or 0.6 g levels were 7.74, 6.47, 5.36 and 7.39 mmol/litre, respectively. Total plasma protein concentration was not changed by treatment. A lower plasma ammonia level was observed at the 0.4 g/kg bwt treatment level when corn starch was administered via the caecum. A trend toward an increase in plasma essential amino acid concentrations of isoleucine, phenylalanine, leucine, arginine and threonine were observed with ponies receiving caecal corn starch. Likewise, non-essential amino acid concentrations of tyrosine, serine, proline and glycine were also elevated. A slight increase in glycine concentration was observed at the 0.2 g/kg bwt treatment level. These results suggest that the administration of corn starch into the caecum resulted in more efficient utilisation of nitrogen by the large intestine.

Amino Acids↗

Interaction of ruminal bacteria in the production and utilization of maltooligosaccharides from starch.

The degradation and utilization of starch by three amylolytic and one nonamylolytic species of ruminal bacteria were studied. Pure cultures of Streptococcus bovis JB1, Butyrivibrio fibrisolvens 49, and Bacteroides ruminicola D31d rapidly hydrolyzed starch and maltooligosaccharides accumulated. The major starch hydrolytic products detected in S. bovis cultures were glucose, maltose, maltotriose, and maltotetraose. In addition to these oligosaccharides, B. fibrisolvens cultures produced maltopentaose. The products of starch hydrolysis by B. ruminicola were even more complex, yielding glucose through maltotetraose, maltohexaose, and maltoheptaose but little maltopentaose. Selenomonas ruminantium HD4 grew poorly on starch, digested only a small portion of the available substrate, and generated no detectable oligosaccharides as a result of cultivation in starch containing medium. S. ruminantium was able to grow on a mixture of maltooligosaccharides and utilize those of lower degree (less than 10) of polymerization. A coculture system containing S. ruminantium as a dextrin-utilizing species and each of the three amylolytic bacteria was developed to test whether the products of starch hydrolysis were available for crossfeeding to another ruminal bacterium. Cocultures of S. ruminantium and S. bovis contained large numbers of S. bovis but relatively few S. ruminantium and exhibited little change in the pattern of maltooligosaccharides observed for pure cultures of S. bovis. In contrast, S. ruminantium was able to compete with B. fibrisolvens and B. ruminicola for these growth substrates. When grown with B. fibrisolvens, S. ruminantium grew to high numbers and maltooligosaccharides accumulated to a much lesser degree than in cultures of B. fibrisolvens alone. S. ruminantium-B. ruminicola cultures contained large numbers of both species, and maltooligosaccharides never accumulated in these cocultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Biochemical analysis of starch degradation by Ruminobacter amylophilus 70.

Ruminobacter amylophilus is an obligate anaerobe that uses only alpha-linked glucose molecules (i.e., maltose, maltodextrins, and starch) as a source of energy, making it an excellent model for the study of bacterial starch degradation. Constitutive amylase, amylopectinase, and pullulanase activities were found in intracellular and extracellular fractions of R. amylophilus. However, extracellular activities apparently resulted from cell lysis. Both soluble and membrane-bound polysaccharidase activities were detected. Most of the soluble polysaccharidase activity partitioned with the periplasmic cell fraction. No alpha-glucosidase or maltase activity was detected in either the cellular or extracellular fraction. In addition, intact cells of R. amylophilus bound U-14C-starch. This binding could be saturated and was constitutive and sensitive to proteinase K, indicating protein or protein complex mediation. Competition experiments showed that these starch-binding sites had equally high affinities for starch and maltodextrins larger than maltotriose. The sites had a reduced affinity for maltose and virtually no affinities for glucose and nonstarch polysaccharides. These findings suggest that R. amylophilus binds starch molecules to the cell surface as an initial step in transporting the molecule through the outer membrane and into the periplasmic space. Extracellular polysaccharides do not appear to be involved in starch degradation.

Amylases↗

Adhesion of Vibrio cholerae to granular starches.

Cholera is a severe diarrheal disease caused by specific serogroups of Vibrio cholerae that are pathogenic to humans. Cholera can become epidemic and deadly without adequate medical care. Appropriate rehydration therapy can reduce the mortality rate from as much as 50% of the affected individuals to <1%. Thus, oral rehydration therapy (ORT) is an important measure in the treatment of this disease. To further reduce the symptoms associated with cholera, improvements in oral rehydration solution (ORS) by starch incorporation were suggested. Here, we report that V. cholerae adheres to starch granules incorporated in ORS. Adhesion of 98% of the cells was observed within 2 min when cornstarch granules were used. Other starches showed varied adhesion rates, indicating that starch source and composition play an important role in the interaction of V. cholerae and starch granules. Sugars metabolized by V. cholerae showed a repressive effect on the adhesion process. The possible mechanisms involved are discussed. Comparing V. cholerae adhesion with the adhesion of other pathogens suggests the involvement of starch degradation capabilities. This adhesion to granular starch can be used to improve ORT.

Animals↗

Intracellular starch formation in corynebacteria.

Carrier, E. Bernard (Louisiana State University, Baton Rouge, La.) and C. S. McCleskey. Intracellular starch formation in cor-yne bacteria. J. Bacteriol. 83:1029-1036. 1962.-Cor-ynebacterium tritici, C. striatum, C. renale, and C. pseudodiphtheriticum produce an intracellular starch-like material when grown on native starches; glucose-1-phosphate, mono-, di-, and trisaccharides do not serve as substrates for intracellular starch formation. C. pseudotuberculosis and C. kutscheri produce intracellular starch from starch substrates and glucose-1-phosphate. C. diphtheriae produces starch from glucose-1-phosphate only.

Carbohydrate Metabolism↗

Degradation of starch and its hydrolytic products by oral bacteria.

Selected strains of oral bacteria were analyzed for their ability to degrade wheat starch, maltose, maltotriose, and maltoheptaose. S. sanguis IUOM-11M and JC804, S. mutans 6715, S. salivarius IUOM-8, A. viscosus IUOM-62, and A. naeslundii ATCC 12104 degraded all four substrates. S. mutans NCTC 10449 degraded starch, maltose, and maltotriose, while A. viscosus ATCC 15987 degraded starch and maltose, and S. sanguis SS34 degraded only maltose. L. casei IUOM-14 did not degrade any of the substrates. Analysis of starch degradation products from S. sanguis IUOM-11M and A. viscosus IUOM-62 demonstrated oligosaccharides, maltose, and trace amounts of glucose for the former and oligosaccharides, maltotriose, and maltose for the latter. S. sanguis IUOM-11M alpha-glucosidase (EC 3.2.1.20) demonstrated a pH optimum of 6.5 and greatly enhanced activity from maltose-cultured cells as compared with cells cultured in glucose or fructose. The presence of fructose in the growth medium prevented this enhancement of activity by maltose. Maltose inhibited sucrose-dependent synthesis of S. sanguis IUOM-11M insoluble polysaccharide and both primer-dependent and primer-independent synthesis of soluble polysaccharide. Maltoheptaose inhibited primer-dependent but not primer-independent soluble polysaccharide synthesis. Several oral bacteria have the ability to hydrolyze starch and to degrade further the products to acidogenic substrates. These products may also inhibit sucrose-dependent synthesis of polysaccharides, which enhances the production of the acidogenic substrate fructose. The results add further support to the growing body of evidence suggesting that caries-promoting properties of starch may be expressed only when starch is present in diets containing sucrose.

Actinomyces↗

Controlling electrophoretic trapping of circular DNA by addition of starch preparations to agarose gels.

Starch preparations were added to agarose gels to enhance the electrophoretic trapping of circular plasmid DNA. The critical voltages required to trap the open circular (OC) and the supercoiled (SC) forms of a 13.1-kbp plasmid were measured in gels composed of agarose and added starch preparations. Modified starch preparations reduced the critical voltage required to trap the OC form of the plasmid to approximately one-third of the control value (in 1% agarose gels). Amylose (a fraction of starch with a low amount of branching) also reduced the critical voltage to trap the OC form in a similar manner. The critical voltage to trap the SC form of the plasmid was not significantly reduced by the starch preparations. The capacity to trap OC DNA was increased by the addition of higher amounts of the starch preparations added to the gels. Field inversion gel etectrophoresis was used to characterize the length of the traps in the gels. The starch preparations and amylose increased the trap lengths approximately twofold. The increased trap length correlated with the decreased critical voltage required to trap the OC form of the 13.1-kbp plasmid.

Amylose↗

Synthesis and paste properties of octenyl succinic anhydride modified early Indica rice starch.

Octenyl succinic anhydride (OSA) modified early Indica rice starch was prepared in aqueous slurry systems using response surface methodology. The paste properties of the OSA starch were also investigated. Results indicated that the suitable parameters for the preparation of OSA starch from early Indica rice starch were as follows: reaction period 4 h, reaction temperature 33.4 degrees C, pH of reaction system 8.4, concentration of starch slurry 36.8% (in proportion to water, w/w), amount of OSA 3% (in proportion to starch, w/w). The degree of substitution was 0.0188 and the reaction efficiency was 81.0%. The results of paste properties showed that with increased OSA modification, the starch derivatives had higher paste clarity, decreased retrogradation and better freeze-thaw stability.

Biochemistry↗

Effect of grain sorghum hybrid on in vitro rate of starch disappearance and finishing performance of ruminants.

Forty-eight commercial grain sorghum hybrids were ranked on the basis of in vitro starch disappearance (IVSD) and starch content. Starch content ranged from 64.3 to 70.3% (P less than .01) and IVSD ranged from 5.2 to 6.3%/h (P less than .01). In the next year, 20 experimental grain sorghum hybrids consisting of 17 hybrids being developed for livestock diets and three for human diets were ranked according to IVSD, starch content, and CP content. In these samples, IVSD varied from 6.0 to 9.1%/h (P less than .05). Starch content and CP were not related to IVSD. Starch content was not correlated to CP content. Four of the original 48 grain sorghum hybrids, selected on the basis of IVSD (two fast and two slow), that differed in IVSD by 7.0% (6.5 to 7.0%/h), were fed for 133 d to steers (mean initial BW of 326 kg). The ADG of steers fed Hybrid A (fastest IVSD) was 9.0% faster than that of steers fed Hybrid D (slowest IVSD; 1.33 vs 1.22 kg, P = .06). Gain:feed ratio was positively correlated with IVSD across all treatments (R2 = .94). Hybrids A and D, another Hybrid, A1, and a bird-resistant hybrid (BR) were fed for 85 d to finishing lambs (mean initial BW of 28 kg). Lambs fed Hybrid A gained more efficiently (gain:feed) than those fed BR or A1 (.210 vs .188 and .184, P less than .05), and those fed D were intermediate (.200). Performance of sheep fed A1, with the fastest IVSD, and those fed BR, with the lowest IVSD, were similar, suggesting that factors other than IVSD affected lamb performance. Our data indicate that rate of grain sorghum starch digestion may influence feeding value of grain sorghum fed to cattle.

Animal Feed↗

Effect of substitution of starch for fiber and fat in isoenergetic diets on nutrient digestibility and reproductive performance of rabbits.

The optimal level of starch in diets for rabbit does was investigated. Five isoenergetic and isoproteic diets containing 26.6, 24.6, 19.0, 16.8, or 13.0% starch and 31.2, 33.4, 36.0, or 41.2% NDF, respectively (DM basis), were made by substitution of starch for NDF and fat. The effect of diet on nutrient digestibility was determined in fattening and nonlactating and lactating adult does using a total of 105 rabbits. Increasing dietary starch content linearly increased (P < .001) DM, GE, CP (P = .07), and starch digestibilities but decreased (P < .001) NDF digestibility. Nutrient digestibility was higher (P < .05), except for CP, in adult does than in fattening rabbits. Dry matter and GE digestibilities were higher (P = .08) for nonlactating than for lactating does. A lactation trial using 440 rabbit does was conducted over a 6-mo experimental period. Milk production and milk composition were measured in 70 lactations. A decrease in dietary starch content did not improve pup mortality before weaning but impaired (linear, P < .001) dry feed intake and pup growth from 21 d until weaning. Diet did not influence does' feed intake, milk DM, ether extract, and CP contents or prolificacy. However, diet had quadratic effects on milk production (P = .15), milk lactose content (P = .07), parturition interval (P = .02), and feed conversion efficiency (P = .02), expressed both per weight or number of pups weaned. Optimal values were reached for dietary starch and NDF contents at approximately 20 and 35.5% (DM basis), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Incidence of puberty in beef heifers fed high- or low-starch diets for different periods before breeding.

Spring-born Hereford x Angus heifers (n = 206) were used to determine effects of energy supplementation programs and amount of starch in the diet on incidence of puberty. In Exp. 1, heifers (205 +/- 5 kg; n = 68) grazing dormant native pasture were fed 0.9 kg/d (as-fed basis) of a 42% CP supplement from November until February 14. Heifers were stratified by weaning weight and allotted randomly to treatment before breeding (May to July). Treatments were 1) 0.9 kg (as-fed basis) of a 42% CP supplement/d and pasture (control); 2) a high-starch (HS) diet (73% corn; 53% starch) fed in a drylot for 60 d (HS-60); 3) a HS diet fed in drylot for 30 d (HS-30); or 4) a low-starch (LS) diet (49% corn; 37% starch) self-fed on pasture for 30 d (LS-30). The HS-60 and HS-30 heifers were limited-fed to gain 0.9 kg/d, and the LS-30 heifers had ad libitum access to the diet. High-starch-60 and LS-30 heifers were heavier (P < 0.05) than control and HS-30 heifers at the beginning of the breeding season. Thirty-one, 25, and 26% more HS-60 heifers were pubertal (P < 0.05) on May 1 compared with LS-30, HS-30, and control heifers, respectively. At puberty, HS-60 heifers were 24 and 22 d younger (P < 0.05) than LS-30 and control heifers, and 31 kg lighter (P < 0.01) than LS-30 heifers. In Exp. 2, heifers grazed dormant pasture and were fed 0.9 kg (as-fed basis) of a 42% CP supplement/d from weaning in October to late February; then heifers were assigned randomly to treatments for 60 d before the breeding season. In two years, control heifers (n = 46) grazed pasture and received 0.9 kg of SBM supplement/d; LS (n = 46) heifers were self-fed a distiller's grain and soybean hull-based diet in drylot; and HS heifers (n = 46) were limited-fed a corn-based diet in drylot. During treatment, HS and LS heifers had greater weight gains than control heifers. Pubertal BW (313 +/- 6 kg) was not influenced by treatment, but HS and LS heifers were younger (P < 0.03) than control heifers at puberty. During a 60-d breeding period, the incidence of puberty was greater (P < 0.05) for HS and LS heifers than for control heifers and was greater (P < 0.05) in HS than in LS heifers in Year 1. Feeding a LS or a HS diet for 30 d before breeding may be inadequate to stimulate puberty in beef heifers, but feeding a diet with a greater amount of starch for 60 d before breeding may increase the incidence of puberty during breeding of heifers that have inadequate yearling weight.

Animal Feed↗

Dietary soyabean oil depresses the apparent digestibility of fibre in trotters when substituted for an iso-energetic amount of corn starch or glucose.

The aim of the present study was to establish whether the inhibitory effect of fat feeding on fibre digestion has been underestimated due to the substitution of fat for corn starch. A high fat intake has been shown to lower total intestinal tract apparent digestibility of crude fibre in horses but, since fat was substituted for nonstructural carbohydrates, including starch, the specific effect of fat could not be ascertained. The possibility could not be excluded that starch also inhibits fibre digestibility, so that the fat effect observed earlier would have been underestimated. In this study, the intakes of iso-energetic amounts of soyabean oil, corn starch or glucose were compared as to fibre digestibility. Unlike starch, glucose is fully absorbed by the small intestine and, therefore, is not expected to influence fibre fermentation in the caecum and colon. Six trotters were fed rations high in soyabean oil (158 g/kg dry matter), corn starch (337 g/kg dry matter) or glucose (263 g/kg dry matter) according to a 3 x 3 Latin square design. Apparent crude fibre digestibility was similar for the rations with corn starch (mean +/- s.d., 70.7 +/- 3.06% of intake, n = 6) or glucose (71.0 +/- 1.90%), but was significantly depressed by fat feeding (56.5 +/- 7.65%). Similar observations were made for apparent digestibilities of neutral and acid detergent fibre and of cellulose. It was concluded that the addition of fat to the feed ration of horses has a specific inhibitory effect on fibre utilisation and, therefore, reduces the amount of energy provided by dietary fibre.

Animal Feed↗

Enzyme resistant starch fractions and dietary fibre.

Starch fractions that are more or less enzyme resistant may behave like dietary fibre, both physiologically and analytically. Ungelatinized granules from potatoes, high amylose maize and green bananas are poorly digested. Starch made resistant to amylase due to new covalent bindings, formed at heat treatment or present in starch derivatives used as food additives, may also be more or less undigestible. "Resistant starch" present in bread and corn flakes is probably retrograded amylose. It is undigestible in the small intestine, but readily degraded by the large bowel microflora. Amylose-lipid complexes seem to be completely absorbed in spite of their resistance to amylase degradation in vitro. Since undigestible starch fractions behave physiologically like non-starch polysaccharides, they should be included in the dietary fibre concept. "Resistant starch" is analysed as glucose based fibre with all current methods except one, which includes an initial DMSO solubilization step.

Amylases↗

Starch supplementation of grass harvested at two stages of maturity prior to ensiling: intake, digestion, and degradability by dairy cows.

The effects of the maturity of grass prior to ensiling and the supplementation of starch to grass silage on apparent digestibility, degradability, rumen content, and feed intake by dairy cows were investigated using a Latin square design. Treatments were silages from early or late cut grass with or without 4 kg of supplemental flaked corn starch. The silage from early cut grass contained more N and sugars than did the silage from late cut grass but was lower in neutral detergent fiber (NDF). Degradation characteristics were not different between the two silages. Apparent digestibilities of dry matter (DM), organic matter (OM), and N in the silage from late cut grass were lower than those in the silage from early cut grass, but NDF digestibility was not affected. Starch supplementation increased the lag phase for DM and OM in both silages, but the rate of degradation was decreased for NDF. Starch supplementation did not influence digestibilities of DM and OM in silage from early cut grass but decreased the digestibilities of DM and OM in silage from late cut grass. Crude protein and NDF digestibilities were decreased for silages from early and late cut grass. Starch supplementation increased NDF in the rumen of cows fed the silage from early cut grass, but NDF was not affected by starch supplementation for cows fed the silage from late cut grass. Rumen-degradable starch negatively influences degradability and apparent OM digestibility; the extent of the decrease is related to the maturity of the NDF.

Animal Feed↗

Comparative susceptibility of starch granules of double- and triple-mutants containing amylose-extender, waxy, sugary-1, sugary-2 and dull genes of maize inbred OH43 (Zea mays L.) to amylase.

Starch granules were prepared from 14 double- and 26 triple-mutants containing amylose-extender (ae), 14 double- and 18 triple-mutants containing waxy (wx), 15 double- and 20 triple-mutants containing sugary-1 (su1), 13 double- and 23 triple-mutants containing sugary-2 (su2), and 14 double- and 19 triple-mutants containing dull (du) of maize inbred Oh43 (Zea mays L.). The relative susceptibilities of these starch granules to fungal glucoamylase were determined and the starch granules were examined by scanning electron microscopy. A commercial normal maize starch was used as a control. Starch granules of the double- and triple-mutants containing su1 and su2 were digested two to eight times faster than normal. The ae gene reduced susceptibility and seems to be epistatic to su1 and su2. Starch granules of the double- and triple-mutants containing wx were digested about two times faster than normal and those containing shrunken-2 (sh2) were digested 1.2 to eight times faster than normal. Starch granules of triple-mutant combinations with opaque-2 (o2) showed digestion properties which were comparable to those of their respective monopaque double-mutant counterpart.

Glucan 1,4-alpha-Glucosidase↗

Some properties of starches of grain amaranths and several millets.

Starch granules were prepared from seeds of Amaranthus hypochondriacus L., A. caudatus L., proso millet, Japanese barnyard millet and foxtail millet. Amylose contents and the distribution of alpha-1,4 linked chain of amylopectin were determined by gel filtration of isoamylase-debranched starches. Some physical and chemical properties of the starches were also examined by scanning electron microscopy, X-ray diffractometry, photopastegraphy, and differential scanning calorimetry, together with starch-granule susceptibility to amylases. The existence of both normal and waxy types in the same species of a grain amaranth, A. hypochondriacus L., was confirmed. A. caudatas starches were identified to consist of mainly typical amylopectin and 5-7% amylose. The starches have some unique properties, namely, high starch-granule susceptibility values to amylases as well as those of A. hypochondriacus and unique pasting properties.

Amylases↗

Degradation of raw starch granules by alpha-amylase purified from culture of Aspergillus awamori KT-11.

Raw-starch-digesting alpha-amylase (Amyl III) was purified to an electrophoretically pure state from the extract of a koji culture of Aspergillus awamori KT-11 using wheat bran in the medium. The purified Amyl III digested not only soluble starch but also raw corn starch. The major products from the raw starch using Amyl III were maltotriose and maltose, although a small amount of glucose was produced. Amyl III acted on all raw starch granules that it has been tested on. However, it was considered that the action mode of the Amyl III on starch granules was different from that of glucoamylase judging from the observation of granules under a scanning electron microscope before and after enzyme reaction, and also from the reaction products. Glucoamylase (GA I) was also isolated and it was purified to an electrophoretically pure state from the extract. It was found that the electron micrographic features of the granules after treatment with the enzymes were quite different. A synergistic effect of Amyl III and GA I was observed for the digestion of raw starch granules.

Aspergillus↗

Inhibition of intestinal iron absorption by laundry starch.

The pathogenesis of iron deficiency anemia associated with amylophagia is usually attributed to dietary iron lack. However, large quantities of starch may inhibit intestinal iron absorption. Accordingly, studies were carried out to determine the effect of laundry starch on the intestinal absorption of inorganic and hemoglobin iron. In vitro, laundry starch bound 19 to 80% of the available 59FeSO4 and 34 to 68% of the available 59Fe-hemoglobin. Binding of both forms of iron was pH-dependent, with maximal binding at pH 7.0. In vivo, laundry starch significantly inhibited mucosal uptake of 59FeSO4 from isolated duodenal loops. In nonanemic rats, administration of laundry starch (100 mg) 1 hr before a 100-mug dose of 59FeSO4 significantly decreased the absorption of 59FeSO4, as compared to saline or low iron chow controls (6.2 +/- 2.0 versus 14.9 +/- 2.1 and -1.8 +/- 1.7, respectively, P less than 0.001). In anemic rats the absorption of either a 100-mug dose of 59FeSO4 or a 500-mug dose of 59Fe-hemoglobin was also significantly decreased by prior administration of laundry starch. The data obtained indicated that laundry starch (1) binds appreciable quantities of inorganic and hemoglobin iron in vitro; (2) inhibits the mucosal uptake or inorganic iron by isolated intestinal loops; (3) inhibits the intestinal absorption of inorganic iron in normal nonanemic rats, and (4) blunts the compensatory increase in inorganic and organic iron absorption in anemic rats.

Anemia, Hypochromic↗