Source Of Essential Amino Acids Research Articles

Effects of feeding cassava leaf meal on the growth of rabbits

Cassava leaf meal (CLM), prepared from leaves remaining after the harvest of cassava roots, contained (dry basis): 20·1% crude protein, 30·3% acid detergent fibre, 4·6 Mcal kg −1 gross energy, 1·16% calcium, 0·39 phosphorus and 84·0 mg kg −1 hydrocyanic acid. It was also found to be a good source of essential amino acids, except for methionine, and of trace minerals. Two feeding trials were conducted to study the effects of feeding CLM on the growth of rabbits. In each trial, 24 six-weeks-old crossbred rabbits were individually fed diets containing 0%, 20% and 40% CLM substituted for equal amounts of coconut oilcake in a 16% protein control diet. The results suggest that CLM could be used up to the 40% level in growing rabbit diets without any adverse effects on growth performance or carcass characteristics.

Hominid Dietary Selection Before Fire [and Comments and Reply

Control of fire was apparently acquired rather late in the course of hominid evolution. It is therefore necessary, in the study of dietary selection by early hominids, to consider the range of plants that would have proven inedible without cooking. Some plants contain toxins or digestibility-reducing compounds, and some plant constituents are indigestible. Cooking mitigates the impact of toxins and renders complex carbohydrates more digestible. Plant foods high in cellulose and/or starch are not readily digestible uncooked, and these constituents reduce the digestibility of other nutrients. Since nutrient intake is limited by the amount of food that can be processed per unit time, non-fire-using hominids should have attempted to increase nutrient intake by minimizing intake of these carbohydrates. Unlike animal sources of protein, plant materials generally lack a full complement of amino acids, and a variety of such materials must be ingested to obtain a balance of essential amino acids. Leaves and legumes, both possible sources of essential amino acids, may be ruled out as major suppliers of them for non-fire-using hominids-leaves because of their cellulose content and legumes because of their high frequency of toxic compounds. The limitations on the availability of plant protein strengthen the inference that some animal protein was ingested by early hominids on a regular basis. A ranking of plant parts as potential foodstuffs for non-fire-using hominids is proposed. When considered in conjunction with ecological factors, such a ranking should be helpful in generating models of hominid dietary selection before fire.

The utilization of coconut sap distillery by-products by broiler chicks

The utilization of coconut sap distillery by-products (CDB) by broiler chickens was investigated in three feeding experiments. CDB contained, on average (g 100 g −1 dry matter): 27·1 crude protein, 2·3 ether extract, 4·9 crude fibre, 10·3 ash and 55·4 nitrogen-free extract. However, considerable variation in crude-protein content, from 20·9 to 31·7%, was observed between batches of CDB. Amino acid analysis revealed CDB to be a good source of essential amino acids. In experiment 1 CDB was added to a commercial broiler finisher ration at 5 and 10% levels and compared with two commonly used animal protein supplements, namely local fish meal and skim-milk powder, added at similar levels. The performance of birds receiving diets supplemented with CDB was equal to or better than that of birds on diets supplemented with the other two protein sources. CDB was incorporated in broiler starter diets at levels of 8 and 12% in experiment 2, and at 10 and 15% in experiment 3. In both experiments CDB was used as a replacement for coconut oilcake and all diets were formulated to be isocaloric and isonitrogenous. The results indicate that CDB could be used in broiler diets up to 15%. The results were also suggestive of the presence of unidentified growth factor(s) in CDB.

A long-term metabolic balance study in young men to assess the nutritional quality of an isolated soy protein and beef proteins

To evaluate the capacity of an isolated soy protein to maintain long-term protein nutritional status in healthy young adult men, an 84-day metabolic balance experiment was conducted in eight subjects. The sole source of protein intake was provided by the isolated soy protein, given at a level of 0.8 g (N ՠ6.25) per kg per day. In a second and similar study, four young men received 0.8 g protein and three subjects 0.68 g protein per kg per day from beef proteins for 60 to 81 days. Body weight, nitrogen balance, blood chemistries, and body composition (whole body 40K) were monitored throughout each study. Body nitrogen balances were maintained within the range of N equilibrium in both diet groups. Body cell mass, as judged from 40K measurements, did not reveal any deterioration in protein nutritional status. These observations confirm the prediction, derived from previous short-term N balance studies, that the nutritional quality of isolated soy protein is high and that this plant protein can serve as the sole source of essential amino acids and nitrogen for protein maintenance in adults.

Chemical, Functional, and Nutritional Properties of Egusi (Colocynthis citrullus L.) Seed Protein Products

ABSTRACTEgusi (Colocynthis citrullus L.) kernels contain 52.0% oil, 28.4% protein (60% in defatted flour), 2.7% fiber, 3.6% ash, and 8.2% carbohydrate. They are good sources of essential amino acids, especially arginine, tryptophan and methionine, vitamins B1, B2, and niacin, and S, Ca, Mg, Mn, K, P, Fe, and Zn. The oil contains mostly oleic (15.9%) and linoleic (62.8%) acids. Protein isolates that differ in gel electrophoretic patterns and amino acid content can be prepared from the flour in one‐ or two‐step water and sodium hydroxide extractions. The water and oil holding capacities of the flour are 0.7 and 2.6 ml/g, respectively. Thick (mayonnaise‐type) emulsions form in the alkaline pH range and a stable foam forms at pH 5.0. Nutritionally, lysine is the most limiting amino acid (chemical score, 52.4).

Absorption of Keto-Analogues of Branched-Chain Amino Acids from Rat Small Intestine

The keto-analogues of essential amino acids provide a source of essential amino acids that contain no nitrogen, but little is known about the mechanism of keto-analogue intestinal absorption. Absorption of the keto-analogue of valine was compared with that of the corresponding amino acid valine by perfusing rat jejunum and ileum in vivo. In both ileum and jejunum, keto-valine was absorbed at rates only moderately below those of the amino acid valine when perfused at 1–50 mM. In the jejunum, absorption rates for keto-valine relative to valine ranged from 73% to 39% at perfusate concentrations of 1 mM and 25 mM, respectively. Similar results were obtained in the ileum. The absorption curve of keto-valine was nonlinear at low perfusate concentrations and linear at higher concentrations, consistent with both saturable transport and passive diffusion. In further studies, 3 mM keto-valine was perfused into jejunal segments. Twenty-five millimolar of the keto-analogues of isoleucine and phenylalanine inhibited keto-valine absorption by 43% and 50%, respectively, whereas 3 mM of the keto analogue of isoleucine did not. Sixty-seven millimolar valine and 56 mM glucose significantly increased keto-valine absorption by 30% and 57% respectively; there were corresponding fourfold and eightfold increments in water transport. The keto analogues of leucine and isoleucine were absorbed at the same rates as keto-valine when perfused at 3 mM and 25 mM. Arterial and mesentric venous blood was sampled after perfusing 25 mM of keto-leucine and keto-isoleucine. There was a significant release of the corresponding amino acids into mesentric venous blood compared with controls, which suggest partial transamination during absorption. The data indicate: (a) Keto-analogues of the branched-chain amino acids are absorbed at rates moderately below those of the corresponding amino acids; (b) keto-valine absorption is in part mediated throught a saturable mechanism; (c) keto-valine absorption is influenced by solvent drag; and (d) partial transamination occurs during keto-analogue absorption in the rat jejunum.

Utilization of processed pig hair in poultry diets

A commerically prepared sample of pig hair was evaluated in semi-purified and practical diets as a source of essential amino acids for poultry. Amino acid (total) supplementation of pig-hair protein in semi-purified diets indicated that the amino acids were utilized by poultry and that satisfactory performance was obtained when the protein was supplemented with the essential amino acids that analysis had shown to be lacking. The performance of broiler chickens fed on diets containing up to 6% pig hair, and of growing pullets fed on diets containing up to 9% of this material, suggests that properly processed pig hair can be used in rations along with other keratin proteins.

The absorption of the keto acid analogues of the branched chain amino acids from rat shall intestine

THE ABSORPTION OF THE KETO ACID ANALOGLIES OF THE BRANCHED CHAIN AMINO ACIDS FROM RAT SMALL INTESTINE, F. L. Weber, Jr., and S. Desk*, V.A. Hospital and the University of Kentucky School of Medicine, Lexington, Kentucky. The keto acid analogues (KAA's) of essential amino acids, given orally, are promising agents in the treatment of uremia, portal systemic encephslopathy, and urea cycle enzyme deficiencies. They provide a source of essential amino acids which contain no nitrogen. But, little is known about the mechanism of KAA intestinal absorption. The mechanism of absorption of the KM of valine (K-val) was compared to the corresponding amino acid valine (val) by perfusing rat jejunum and ileum in viva. Keto acids -were determined spectrophotometrically or by gas-liquid chromatography. In both ileum and jejunum K-val was absorbed at rates only moderately below those of the amino acid valwhen perfused at l-50 mM. In the jejunum, absorption rates for K-val relative to val ranged from 7339% at perfusate concentrations of 1 and 25 mM respective1Y. Similar results were obtained in the ileum. There was a plateauing in K-val absorption rates at higher perfusate concentrations suggesting saturable transport. In further studies, 3 ml+! K-vsl was perfused into jejunal segments. Twenty-five mM of the KAA's of isoleucine and phenylslanine (structural analogues of K-val), inhibited K-val absorption by 43 and 50% respectively while 3 mM of the KAA of isoleucine did not. Sixty-seven mu val and 56 mM glucose significantly increased K-val absorption by 30 and 57% respectively, while there were corresponding kfold and f&fold increments in water transport. The KAA's of leucine and isoleucine were absorbed at the ssme rates as K-val when perfused at 3 and 25 mM. Arterial and mesenteric venous blood was sampled after perfusing 25 mM of the branched chain KAA's. There was a significant release of the corresponding amino acids into mesenteric venous blood compared to controls suggesting partial transamination during absorption. The data indicate: (1) K-val absorption is in part mediated through a saturable mechanism, distinct from the val carrier. (2) K-val absorption is influenced by solvent drag. (3) Partial transsmination occurs during KAA absorption.

Periphyton production and grazing by chironomids in Alderfen Broad, Norfolk

SummaryThe standing crops of periphyton were measured on dead Typha stems and glass rods in a small, eutrophic lake from February to November. Chironomid larvae were also counted on the Typha stems; very few were present on the glass rods. The standing crop of periphyton on the Typha stems fell from 1.8 mg cm−2 in early April to nearly zero in November. On the glass rods the periphyton reached a peak of 1.93 mg cm−2 in late May and 1.94 mg cm−2 in July, thereafter falling to a steady level of 1.6 mg cm−2. The population of chironomids showed a peak in late May and then declined. The alimentary canals of chironomids collected fromTyphastems contained diatoms and filamentous algae so it appeared that chironomids were grazing down the periphyton. Chironomids moved on to theTyphastems in spring and returned to the mud in autumn. The periphyton is a richer source of essential amino acids than the mud, so that a movement from mud to reedstems in spring may increase the rates of growth and metamorphosis of the larvae.A crude production estimate gave a net primary production of periphyton of 170 mg dry wt m−2 day−1; the periphyton, however, would have contained bacteria and many small animals as well as algae.

Feeding and Nutrition of Insects Associated with Soybeans: 1. Growth and Development of the Mexican Bean Beetle, Epilachna varivestis,1 on Artificial Media

A semiliquid medium applied to layers of Cellucotton®, was readily accepted by 3rd- and 4th-stage larvae of the Mexican bean beetle, Epilachna varivestis Mulsant (Coleoptera: Coccinellidae). Larvae reared on this medium completed development and yielded normal adults. Tests were conducted with a total of 19 semiliquid (sol) and agar-base (gel) media differing in sucrose concentration, source of essential amino acids, and p H. A solcasein medium with 0.1M sucrose yielded the best results. This medium was used in routine rearings of the beetle, partially replacing fresh bean leaves. The solcasein medium was found extremely convenient in studies on host selection and nutrition of the Mexican bean beetle in its associations with soybeans.

Peptides as Sources of Essential Amino Acids for Lactic Streptococci

Summary Two strains of Streptococcus lactis , one of Streptococcus cremoris , and one of Streptococcus lactis var. maltigenes were shown to possess peptidases capable of hydrolyzing a number of commercially available dipeptides and two tripeptides into the constituent amino acids. The four test cultures exhibited similar hydrolytic ability toward the peptides under examination. If the C-terminal amino acid of the peptide was of d configuration, no hydrolysis occurred. Dipeptides in which one of the constituent amino acids was l-Ieucine or l-valine, when substituted for these amino acids in chemically defined media, were shown to fulflll the nutritional requirements of each of the four cultures for these essential acids. S. lactis var. maltigenes degraded the freed leucine and valine from such peptides to 3-methylbutanal and 2-methylpropanal, respectively. The possible role of peptides as precursors of flavor compounds in dairy products is discussed.

Studies on Amino Acid Inadequacy of Blood.

Summary(1) These studies further evaluate whole blood as sources of essential amino acids for protein depleted adult male rats. Human and canine blood again were rejected and failed to support repletion. Human blood supported rapid repletion when supplemented with 55 mg L-isoleucine and 15 mg DL-methionine per 120 mg of blood-N. Less than half these levels added to plasma supported repletion. Plasma alone permitted an intermediate rate of repletion. (2) Feeding normal dogs a non-protein diet and 150-375 mg N /kg/day as lyophilized human or dog blood did not increase the blood urea-N or NPN or produce negative N balance. Force-feeding 12-25 ml of citrated human blood increased blood urea-N of fasting rats. Supplementing the blood with isoleucine and methionine, however, did not reduce the blood urea-N. (3) Analysis of human blood, human plasma, and dog blood for 13 amino acids is reported.

The Influence of an Antibiotic, Animal Protein, Sex and Rearing Environment on Chick Growth

THE influence of antibiotics on chick growth has been established by such investigators as Moore et al. (1946), Stokstad and Jukes (1950), McGinnis et al. (1950) and Whitehill et al. (1950). The value of animal protein in the diet has been studied extensively. In addition to being a good source of essential amino acids, animal protein supplies vitamin B12 and one or more unidentified growth factors according to Sunde et al. (1950), Fuller et al. (1951) and Heuser and Norris (1951). These investigators found that animal protein improved growth even when vitamin B12 was added to a plant protein diet. Diets adequate in vitamin B12 generally support increased rates of growth when they are supplemented with an antibiotic.As reported by Robertson (1950), Kramke and Fritz (1951), Matterson and Singsen (1951) and McGinnis et al. (1951), diets which contained animal protein produced the highest body weights but all-plant protein diets …

Salivary mucin as a source of essential amino acids for the Lactobacillus acidophilus (Hadley).

Salivary mucin as a source of essential amino acids for the Lactobacillus acidophilus (Hadley).