Essential Amino Acid Requirements Research Articles

Exceeding Essential Amino Acid Requirements and Improving Their Balance as a Means to Minimize Heat Stress in Broilers

Response of broilers reared under summer conditions to feeds having essential amino acid (EAA) levels approximating 110% of their expected requirement was examined with both sexes. A commercial-type feeding regimen known to enable favorable performance under optimal conditions represented the control. Environmental conditions were sufficiently hot to depress performance but not cause death. Purified amino acids were supplemented to increase levels of limiting EAA and improve their overall balance without altering existing CP and ME. Live performance was not affected, but abdominal fat removed from the carcasses after processing significantly increased when the 110% level of EAA had been fed. Yield of the carcass without its abdominal fat, incidence of associated defects, and recovery of deboned breast meat were similar between the two dietary treatments. Both sexes responded similarly to the feed treatments. Improved amount and balance of effective amino acid intake likely increased the proportion of productive energy recovered from dietary ME; however, realization was as depot fat rather than as a benefit on live performance or muscle formation.

Different approaches to define individual amino acid requirements.

A full review of the strengths and limitations of the various methods used to define amino acid requirements is provided. The focus is on the recent development of carbon oxidation techniques such as indicator amino acid oxidation and 24-h amino acid balance to determine dietary indispensable (essential) amino acid needs in adults. All approaches depend on the change in a metabolic parameter in response to graded intake of the test amino acid. In humans, the within-subject variance is less than the between-subject variance, which has led to an appreciation of the need to study each subject across a range of intakes, above and below the mean requirement level. The data can then be analyzed using two-phase linear regression crossover and a precise population mean requirement can be determined. Several approaches have been used to define the variance of the mean requirement. Finally, a minimally invasive indicator amino acid oxidation model has been developed which allows the determination of dietary essential amino acid requirements in children and other vulnerable populations.

Phloem amino acids and the host plant range of the polyphagous aphid, Aphis fabae

AbstractThis study investigated the relationship between the essential amino acid requirement of the aphid Aphis fabae Scop. and the phloem sap amino acid composition of its host plants. The dietary amino acid requirement of A. fabae varied between clones. One or more of the eight clones of A. fabae tested displayed depressed larval survival, larval growth rate, or rm on diets lacking histidine, methionine, threonine, and valine, but none of the other five essential amino acids. The required amino acids corresponded closely to the essential amino acids that varied in relative concentrations among 16 plant species tested: histidine, threonine, tryptophan, and valine. It is suggested that the interclonal variation in the dietary requirements of an aphid species may contribute to the intraspecific variation in plant utilisation patterns. The phloem sap amino acid composition and sucrose : amino acid ratio did not differ consistently between host plant species of A. fabae and non‐host species, indicating that phloem amino acid composition is not an important factor in determining the host plant range of this aphid species.

Crude protein and essential amino acid requirements in chicks during the first week posthatch

Crude protein and essential amino acid requirements in chicks during the first week posthatch

Study of the effect of using different levels of tahinah (sesame butter) on the protein digestibility‐corrected amino acid score (PDCAAS) of chickpea dip

AbstractThis study was conducted to investigate the effect of using different proportions of tahinah (0–25%) on the protein digestibility‐corrected amino acid score (PDCAAS) of chickpea dip and to evaluate this parameter when chickpea dip is consumed with wheat bread. Protein quality was evaluated using the methods of amino acid score and true protein digestibility in weanling Sprague–Dawley rats. The levels of tahinah that provided the best true protein digestibility and protein digestibility‐corrected amino acid score were 20 and 25%. Values of true protein digestibility were significantly higher (P ≤ 0.05) than for the other types of chickpea dip (0.87 and 0.88 respectively). The consumption of wheat bread with chickpea dip led to a marked improvement in the true protein digestibility of the protein mixture (0.90); however, the protein digestibility‐corrected amino acid score did not change in the same manner owing to the relatively low amino acid score. It can be concluded that the addition of tahinah to chickpea led to an increase in the protein digestibility‐corrected amino acid score of chickpea dip (based on laboratory rat requirements for essential amino acids) and that the consumption of chickpea dip with bread led to an improvement in the protein digestibility of chickpea dip but not in the protein digestibility‐corrected amino acid score.© 2002 Society of Chemical Industry

An assessment of the efficacy of two lysine microencapsulation techniques to determine the quantitative lysine requirement of the South African abalone,Haliotis midaeL.

The quantification of the essential amino acid requirements of a species is a prerequisite to the formulation of biologically optimized diets. In this study, crystalline L-lysine was used in an attempt to determine the quantitative lysine requirement of juvenile Haliotis midae. Two microencapsulation techniques [gelatine/acacia and cellulose acetate phthalate (CAP)] were used to retard leaching of crystalline L-lysine incorporated into semipurified test diets. An assessment of the efficacy of the encapsulation techniques, revealed that despite effective lysine supplementation, H. midae fed semipurified test diets containing encapsulated crystalline L-lysine failed to promote significant improvements in either growth, feed or protein efficiency (P > 0.05). The failure of the crystalline L-lysine to illicit growth and nutritional responses is discussed.

Effect of L-malic and citric acids metabolism on the essential amino acid requirements for Oenococcus oeni growth.

The purpose of this work was to study the effect of L-malic and/or citric acids on Oenococcus oeni m growth in deficient nutritional conditions, and their roles as possible biosynthetic precursors of the essential amino acids. Bacterial cultures were performed in synthetic media. Bacterial growth rate was reduced or annulled when one amino acid was omitted from basal medium, especially for members of aspartate family, except lysine. The organic acids increased or restored the growth rates to the respective reference values. In each medium deficient in one essential amino acid, the L-malic acid utilization was accompanied by an increase of L-lactic acid concentration and accounted for approximately 100%l-malic acid consumed. D-lactic acid formation from glucose decreased in the medium without cysteine. Except for tyrosine, the recovery of glucose-citrate as D-lactic acid was lower than in the complete medium when asparagine, isoleucine or cysteine were excluded. The ethanol and acetate production was not modified. L-malic and citric acids favoured Oenococcus oeni m growth in nutritional stress conditions. Specifically citric acid was involved in the biosynthesis of the aspartate-derived essential amino acids and glucose in the cysteine biosynthesis. Such beneficial effect of l-malic and citric acids on amino acids requirements of Oenococcus oeni m have great significance considering the low amino acids concentration in wine.

The optimum dietary essential amino acid pattern for rainbow trout (Oncorhynchus mykiss), to maximize nitrogen retention and minimize nitrogen excretion

The optimum dietary essential amino acid (EAA) pattern for a given animal species is considered to be that EAA pattern which results in maximum nitrogen (N) retention for protein growth and minimum N excretion. In a series of two 8-week experiments, we investigated the optimum dietary EAA pattern for rainbow trout (Oncorhynchus mykiss). Experimental diets were fed to quadruplicate tanks of fish, using the equalized satiation feeding method. In the first experiment, we used the amino acid deletion method to arrive at an estimate of optimum dietary EAA pattern for rainbow trout. There were 11 dietary treatments: 1 diet with a control EAA pattern, and 10 other diets with 40% deletions of a single EAA from the control pattern. Based on N utilization data, an estimate of optimum dietary EAA pattern for rainbow trout was made. In the second experiment, we compared this dietary EAA pattern with three other estimates of optimum dietary EAA pattern for rainbow trout, based on 1) amino acid composition of rainbow trout whole-body protein, 2) EAA requirements for rainbow trout published by the National Research Council, and 3) EAA requirements for rainbow trout based on nonlinear regression analysis. Response variables included growth rate, feed efficiency ratio and N retention and excretion. The EAA pattern associated with EAA requirements as published by the National Research Council was found to result in the highest mean N retention and lowest mean N excretion, and so was considered the best estimate of optimum EAA pattern of those compared.

Protein digestibility using corrected amino acid score method (PDCAAS) of four types of mushrooms grown in Jordan.

This study was conducted to evaluate the protein quality of four types of edible mushrooms common in Jordan in terms of protein digestibility-corrected amino acid score (PDCAAS), which is a combination of the chemical score of the limiting amino acid multiplied by true digestibility of the protein. True protein digestibility values were low (61.4, 73.4, 52.6 and 80.5 for Terfezia claveryi, Pleurotus ostreatus, Tricholoma terrum and Agaricus macrosporus, respectively). Based on the essential amino acids pattern requirements for children, the limiting amino acids in P. ostreatus and A. macrosporus protein were sulphur-containing amino acids with chemical scores of 0.61 and 0.50, respectively. However, lysine was the limiting amino acid in the protein of T. claveryi and T. terreum with chemical scores of 0.71 and 0.67, respectively, and the PDCAAS was 0.43, 0.45, 0.35 and 0.40 for the mushrooms types, respectively. Considering the pattern of essential amino acid requirements of laboratory rats, the sulphur containing amino acids were the limiting amino acids in the protein of T. claveryi, P. ostreatus, T. terreum and A. macrosporus with chemical scores of 0.56, 0.30, 0.34 and 0.25, respectively. The PDCAAS were 0.34, 0.22. 0.17 and 0.20, respectively. It is concluded that the four mushroom types studied are of low protein quality.

Estimating digestible protein requirements of silver perch, Bidyanus bidyanus Mitchell

In this study, we estimated requirements for digestible protein, using intact protein sources, at one digestible energy content. Using digestibility data for silver perch (Bidyanus bidyanus Mitchell) for a large number of ingredients, we formulated a ‘summit’ diet to contain between 1.4 and 1.8 times the ‘expected requirements’ for digestible essential amino acids (based on requirements for channel catfish, Ictalurus punctatus Rafinesque). A ‘diluent’ diet was formulated to contain 0.4–0.5 times the expected requirements of digestible essential amino acids. Both ‘summit’ and ‘diluent’ diets contained similar digestible energy (14.7 MJ digestible energy kg−1 for the summit and 13.4 MJ digestible energy kg−1 for the diluent). Six diets were prepared with the following amounts of summit–diluent diets: 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100. A practical diet widely used by commercial farmers was also included as a control. Ten juvenile fish (2.1–2.6 g) were stocked into each experimental 70-L acrylic aquarium, and each dietary treatment was randomly assigned to five replicate aquaria. Fish were fed twice daily to apparent satiation for 54 days. Final individual fish weight ranged from 4–15.5 g. Results were analysed using intersecting linear regression analysis. The optimum digestible dietary protein for diets with 13.4–14.7 MJ digestible energy kg−1, after which protein deposition did not increase significantly, was 28%. Although this study did not determine requirements for individual amino acids, for diets with the digestible energy content used here, requirements for individual amino acids obviously did not exceed the content in the 28% protein diet. These contents are useful as an estimate of ‘recommended levels’ for silver perch diets with 13.4–14.7 MJ digestible energy kg−1. The proximate composition of fish was affected by diet. Whole body protein and moisture increased, whereas lipid content decreased with increasing dietary protein content (and increasing protein–energy ratio and decreasing lipid). Fish size was also affected by diet; however, the changes in whole carcass proximate composition also occurred for fish fed diets 60:40, 80:20 and the summit diet which were a similar final weight.

Amino acid composition and biological evaluation of the protein quality of high lysine barley genotypes.

The protein quality of high lysine barley genotypes Notch1 Notch2, Riso-1508 and Hiproly grown in Indian soil was evaluated by determining amino acid composition and also by rat growth and nitrogen balance studies. Protein and fat contents were found to be highest in Riso-1508. Lysine concentration (5.26 g/16g N) of Riso-1508 was also highest compared to the other high lysine genotypes. Rat feeding trials indicated that the growth promoting qualities of the proteins of genotype Riso-1508 were significantly (p < 0.05) higher than the low lysine barley genotype. The comparatively low lysine barley diet had more digestible protein than the high lysine barley diet. However, the BV and NPU of the high lysine barley were significantly (p < 0.05) higher. This improvement is of importance in meeting the essential amino acid requirements of man as well as other monogastric animals. The study showed that the high lysine barley harvested in Indian agroclimatic conditions retained high lysine quality.

The Protein Digestibility–Corrected Amino Acid Score

The protein digestibility-corrected amino acid score (PDCAAS) has been adopted by FAO/WHO as the preferred method for the measurement of the protein value in human nutrition. The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern. This scoring pattern is derived from the essential amino acid requirements of the preschool-age child. The chemical score obtained in this way is corrected for true fecal digestibility of the test protein. PDCAAS values higher than 100% are not accepted as such but are truncated to 100%. Although the principle of the PDCAAS method has been widely accepted, critical questions have been raised in the scientific community about a number of issues. These questions relate to 1) the validity of the preschool-age child amino acid requirement values, 2) the validity of correction for fecal instead of ileal digestibility and 3) the truncation of PDCAAS values to 100%. At the time of the adoption of the PDCAAS method, only a few studies had been performed on the amino acid requirements of the preschool-age child, and there is still a need for validation of the scoring pattern. Also, the scoring pattern does not include conditionally indispensable amino acids. These amino acids also contribute to the nutrition value of a protein. There is strong evidence that ileal, and not fecal, digestibility is the right parameter for correction of the amino acid score. The use of fecal digestibility overestimates the nutritional value of a protein, because amino acid nitrogen entering the colon is lost for protein synthesis in the body and is, at least in part, excreted in urine as ammonia. The truncation of PDCAAS values to 100% can be defended only for the limited number of situations in which the protein is to be used as the sole source of protein in the diet. For evaluation of the nutritional significance of proteins as part of mixed diets, the truncated value should not be used. In those cases, a more detailed evaluation of the contribution of the protein to the amino acid composition of the mixed diet is required. From such an evaluation, it appears that milk proteins are superior to plant proteins in cereal-based diets.

Digestibility of macronutrients, energy and amino acids, absorption of elements and absence of intestinal enteritis in Atlantic salmon, Salmo salar, fed diets with wheat gluten

Apparent digestibility coefficients (ADCs) of macronutrients and energy, and apparent absorption coefficients (AACs) of amino acids and elements were assessed in an experiment with 0.9 kg Atlantic salmon reared in saltwater tanks. Duplicate groups of fish were fed five diets, where 0, 6.25, 12.5, 25 and 50% of crude protein (CP) from fish meal (FM) was replaced with CP from wheat gluten (WG). In Experiment 2, triplicate groups of 0.9 kg salmon were fed a FM diet, a diet with 15% of CP from FM replaced with extracted, toasted soybean meal (SBM), and a diet with 35% of CP from WG, for 18 weeks. Experiment 2 was designed to determine whether WG caused pathological changes in the intestinal epithelium, and if a diet with 35% of CP from WG could support rapid growth. There was a trend toward increased ADC of fat and energy in the diets with WG, and the diet with 25% WG was ranked significantly higher than the FM control. The ADC of CP and AACs of all amino acids except alanine and lysine increased significantly with increasing proportion of dietary protein from WG, and the results indicate that absorption of individual amino acids from WG was between 94% and 100%. WG is low in lysine, but the results indicate that the requirement for lysine was nearly met and the requirement for other essential amino acids was met even with the highest WG inclusion level, due to high dietary protein concentration and the supplementary amino acid profile of FM. There was no reduced absorption of Ca, P or Mg in the salmon fed diets with WG. The absorption of Zn was higher in all the diets with WG than in the FM diet. The fish doubled their weight during Experiment 2, and there were no significant differences in growth among dietary treatments in salmon fed the WG, FM or SBM diets. No indication of intestinal pathology was seen in the salmon fed the FM or WG diets, while 60% of the examined fish fed SBM had SBM-induced changes in the mucosa of the posterior intestine.

The diet and nutrition of the Namaqua sandgrouse, an arid-zone granivore

The diet of the Namaqua sandgrouse, Pterocles namaqua, is described, and daily seed intake needed to meet limiting nutrient requirements during different stages of the annual cycle is estimated. Namaqua sandgrouse feed almost exclusively on seeds, mainly on those of protein-rich legumes. The energy content (17–24 kJ g−1) of selected seed species is less variable than protein (10–37%) and amino acid (0·11–4·52%) content. Energy is usually the first limiting factor for adults, especially females producing eggs. Essential amino acids appear to be more limiting than energy for growing chicks, suggesting that chicks may be more dependent on protein-rich legume seeds than adults. The dietary requirements for essential amino acids in developing chicks are similar to those of females producing eggs, suggesting that chick development is the most nutritionally demanding stage in the annual cycle of Namaqua sandgrouse.

Recent advances in European sea bass and gilthead sea bream nutrition

European sea bass (Dicentrarchus labrax) and gilthead sea bream(Sparus aurata) are amongst the most important finfish speciescultured in the Mediterranean region. Production of these species isnowadays a well-controlled process, but knowledge of their nutritionalrequirements is still very limited. Nevertheless, a considerable amountof data has been accumulated in recent years, and the purpose of thispaper is to review the recent advances on the nutritional requirementsof sea bass and sea bream. The optimum protein to energy ratio of thediets of sea bass and sea bream seem to be higher than for salmonids,and there is some evidence that high dietary lipid levels have nobeneficial effects on fish performances. Although the essential aminoacid requirements were estimated by the ideal protein method, data basedon the dose-response method is only available for a few amino acids.Essential fatty acid requirements were estimated for sea bream juvenilesbut data is lacking for sea bass. Vitamin and mineral requirements ofthese species are practically unknown. Although the importance ofbroodstock nutrition on gonadal development, spawning and egg quality isrecognized, few studies were done to elucidate these aspects. The recentdevelopment of microparticulate diets for larvae will contribute to theaccurate evaluation of their nutritional requirements.

Heat increment as affected by protein and amino acid nutrition

The activity of feeding and the metabolism caused by digestion and assimilation of food increase an animal's heat production. This increased heat production has been referred to as specific dynamic effect, specific dynamic action or heat increment (HI). HI is much larger when protein is a source of energy than when carbohydrate or fat are the sources of energy. HI for protein is much greater when the animal's ambient temperature is high than when it is low. Metabolisable energy is used more efficiently, thus having less HI, for maintenance than for production. A suggested explanation is that heat resulting from digestion and assimilation of food can substitute for the heat production in fasting when food provides energy equal to, or less than, maintenance requirements. When energy intake is large enough to support production, HI from anabolic processes becomes a waste product that cannot substitute for a fasting or maintenance function. The same rationale can be applied to the observation that dietary protein has a greater HI when an animal is at high temperatures. At low temperatures protein would be used for maintenance. At high temperatures the same amount of energy from protein would be enough to support production. As a result, HI of the protein would be increased at high temperatures. The high HI of protein or amino acids when at a high level in the diet can be at least partially explained. Protein synthesis requires a large amount of energy. Some energy is required to excrete nitrogenous waste. In addition, dietary protein stimulates protein turnover. Research findings have suggested that HI should be lowered by decreasing dietary protein. For non-ruminant animals this could be accomplished by discovering the essential amino acid requirements for an ideal protein. The ideal protein should result in a minimum HI. Research to date generally fails to document improved feed efficiency as a result of feeding an ideal protein.

Arginine and phenylalanine requirement of juvenile silver perch Bidyanus bidyanus and validation of the use of body amino acid composition for estimating individual amino acid requirements

An experiment was conducted in a closed system to quantify the arginine requirement of juvenile silver perch Bidyanus bidyanus. Five experimental diets were formulated to contain 40% crude protein with five graded levels of arginine. The diets contained casein and gelatine as protein sources supplemented with crystalline L-amino acids to simulate the reference amino acid profile (except for arginine) of silver perch tissue protein. The experiment lasted 12 weeks and, based on growth data using broken-line analysis, the arginine requirement of juvenile silver perch was found to be 2.7 g 100 g−1 dry diet (or 6.8% of protein). Based on whole-body amino acid composition, A/E ratios (essential amino acid/total essential amino acids + (cystine + tyrosine) × 1000) were estimated. Using the experimentally determined requirement for arginine and A/E ratios, the phenylalanine requirement of silver perch was predicted to be 5.5 g 100 g−1 protein. Another feeding trial was conducted to determine the phenylalanine require-ment of silver perch using a series of diets with various amounts of phenylalanine and a protocol similar to the previous one. It was found that the experimentally determined phenylalanine requirement of juvenile perch was similar to that predicted. The A/E ratios have been hitherto utilized for the estimation of essential amino acid requirements in three salmonids, common carp and channel catfish: the present findings extend the validity of the method to other fish species.

Quantitative dietary requirements of postlarval tiger shrimp, Penaeus monodon, for histidine, isoleucine, leucine, phenylalanine and tryptophan

The quantitative requirements of postlarvae Penaeus monodon for essential amino acids were determined through a series of feeding experiments. Test diets contained casein–gelatin as natural proteins supplemented with crystalline l-amino acids (CAAs) at levels based upon the tissue amino acid profile of postlarvae tiger shrimp. Each set of experimental diets contained graded levels of the test amino acid in a range below and above those found in shrimp muscle protein. The dietary CAA mixture was pre-coated with carboxymethylcellulose (CMC), and the diets were additionally bound with CMC, corn starch, and K-carrageenan to prevent leaching of amino acids and other nutrients. P. monodon postlarvae, PL 20, mean body weight of 20 mg, were randomly distributed to 30-l fiberglass tanks at a density of 10/tank and each group was fed a particular diet for 56 days. A one-way analysis of variance was used to determine if there were any significant differences in weight gain, survival, and feed conversion among the dietary treatments for each experiments. Regression analysis of the weight gain responses against dietary amino acid levels was used to estimate the amino acid requirements. The optimum dietary requirements for essential amino acids, in percent of the diet, were: 0.8% histidine, 1.01% isoleucine, 1.7% leucine, 1.4% phenylalanine, and 0.2% tryptophan. Expressed as percent of the dietary protein, the requirement values were: 2.2% histidine, 2.7% isoleucine, 4.3% leucine, 3.7% phenylalanine, and 0.5% tryptophan. This information is crucial in optimizing growth and feed efficiency and in developing cost-effective diets for P. monodon.

Estimates of essential amino acid requirements from dose‐response studies with rainbow trout and broiler chicken: Effect of mathematical model*

A total of 37 dose‐response experiments with essential amino acids performed with rainbow trout and broiler chicken were re‐evaluated with different mathematical approaches: an exponential model, a four‐parameter logistic function, the saturation kinetics model and the broken line approach. The different approaches were compared both with regard to the goodness of fit (r2 and sy.x) and with regard to the allowances which were derived regarding the optimal amino acid level in the diet. The experimental design, particularly the chosen range in dietary amino acid concentration was found to be important for the comparison of models. Amongst the non‐linear models, the four‐parameter logistic function and the saturation kinetics model appeared superior to the exponential approach, when the range in dietary amino acid concentration was very wide and included both a severely deficient basal level and a level that exceeded the needs of the animal by approximately the factor 2. In these cases, allowances derived from individual experiments were considerably different depending on the model. The allowances based on the exponential and the saturation kinetics approach were 27.7 and 20.7 g lysine/kg DM and 8.0 and 6.3 g methionine/kg DM, respectively, for rainbow trout. For other amino acids studied in rainbow trout the difference due to model was less. Consequently, the predicted ‘ideal protein’ for rainbow trout was considerably different depending on the model used. The maximum deviation found in different experiments with broiler chicken for the exponential vs. the saturation kinetics approach was 13.0 and 9.7 g lysine/kg and 11.4 and 8.2 g sulfur‐containing amino acids/kg, respectively. However, the more restricted the range in dietary concentration was, the lesser became the differences between the different non‐linear models. No definite recommendation can therefore be extracted regarding the most suitable, generally applicable mathematical model.

Preparation and functional properties of rice bran protein isolate.

Rice bran protein isolate (RBPI) containing approximately 92.0% protein was prepared from unstabilized and defatted rice bran using phytase and xylanase. The yield of RBPI increased from 34% to 74.6% through the use of the enzymatic treatment. Nitrogen solubilities of RBPI were 53, 8, 62, 78, 82, and 80% at pHs 2.0, 4.0, 6.0, 8.0, 10.0, and 12.0, respectively. Differential scanning calorimetry showed that RBPI had denaturation temperature of 83.4 degrees C with low endotherm (0.96 J/g of protein). RBPI had similar foaming properties in comparison to egg white. But emulsifying properties of RBPI were significantly lower than those of bovine serum albumin. The result of amino acid analysis showed that RBPI had a similar profile of essential amino acid requirements for 2-5-year-old children in comparison to that of casein and soy protein isolate.