Essential Amino Acid Requirements Research Articles

Growth and Clinical Variables in Nitrogen-Restricted Piglets Fed an Adjusted Essential Amino Acid Mix: Effects of Partially Intact Protein-Based Diets

BackgroundCurrent recommendations for protein levels in infant formula are intended to ensure that growth matches or exceeds growth of breastfed infants, but may provide a surplus of amino acids (AAs). Recent infant studies with AA-based formulas support specific adjustment of the essential amino acid (EAA) composition allowing for potential lowering of total protein levels. With the use of a combination of intact protein and free EAAs, we designed a formula that meets these adjusted EAA requirements for infants. ObjectiveOur objective was to test whether this adjusted formula is safe and supports growth in a protein-restricted piglet model, and whether it shows better growth than an isonitrogenous formula based on free AAs. MethodsTerm piglets (Landrace × Yorkshire × Duroc, n = 72) were fed 1 of 4 isoenergetic formulas containing 70% intact protein and 30% of an EAA mixture or a complete AA-based control for 20 d: standard formula (ST-100), ST-100 with 25% reduction in proteinaceous nitrogen (ST-75), ST-75 with an adjusted EAA composition (O-75), or a diet as O-75, given as a complete AA-based diet (O-75AA). ResultsAfter an initial adaptation period, ST-75 and O-75 pigs showed similar growth rates, both lower than ST-100 pigs (∼25 compared with 31 g · kg–1 · d–1, respectively). The O-75AA pigs showed further reduced growth rate (15 g · kg–1 · d–1) and fat proportion (both P < 0.05, relative to O-75). ConclusionsFormula based partly on intact protein is superior to AA-based formula in this experimental setting. The 25% lower, but EAA-adjusted, partially intact protein–based formula resulted in similar weight gain with a concomitant increased AA catabolism, compared with the standard 25% lower standard formula in artificially reared, protein-restricted piglets. Further studies should investigate if and how the specific EAA adjustments that allow for lowering of total protein levels will affect growth and body composition development in formula-fed infants.

Optimum Replacement Value of Fish Silage for Protein Source in Pacific White Shrimp Diets

Chemical and biological evaluations were undertaken to determine nutritive value of acid fish silage (FS) as a dietary protein source in the diet of Pacific white shrimp (Litopenaeus vannamei). Proximate composition, and amino acid profile of FS were determined for chemical evaluation; amino acid profile of FS was employed to predict its nutritive value against shrimp requirements for essential amino acids (EAA). Three biological evaluations of FS were conducted: (1) the attractability of the FS diets were compared with diets containing no FS; (2) a growth trial of 60 days was performed to determine the effects of replacing protein sources in the diet with FS, on the growth performance of the shrimp; (3) shrimp from the growth trial in the second biological experiment were evaluated to determine whether or not FS in the diet resulted in enhanced immune response against Vibrio parahemolyticus. Experimental diets were prepared containing 5 levels of FS replacing the combined fish meal and Acetes meal (kept at a constant ratio of 1:3): 0% FS (control), 12.5%, 25%, 37.5% and 50% FS replacement. For results of the chemical evaluation, the computed EAAI of FS was 98.5 indicating a well-balanced profile. In the attractability test using a custom-made setup, results showed that shrimp (1-2 g) were significantly more attracted to the diet containing 50% FS replacement than any other diet; the control and the other experimental diets were statistically similar in attractability. In the growth trial experiment, shrimp (average weight =0.01g) were fed diets of the same composition as that used for the attractability test. Results showed that weight gain (WG) and specific growth rate (SGR) of the FS-supplemented groups were significantly higher than the control group; however, 25% FS group did not significantly differ from that of the 37.5% FS. Feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate did not differ significantly among experimental groups. In the V. parahemolyticus challenge test, optimum FS replacement for immune enhancement was estimated to be 24.5% FS using a broken line model. In conclusion, the findings revealed that FS could serve as a feeding stimulant at 50% FS replacement. Likewise, FS could serve as an immunostimulant against V. parahaemolyticus in L. vannamei.

Amino acid composition and nutritional value evaluation of Chinese chestnut (Castanea mollissima Blume) and its protein subunit.

The amino acid composition, nutritional value and proteins subunit of chestnuts (Castanea mollissima Blume) from three regions of China (Henan, Hunan, and Guangdong) were investigated. Experimental results showed that the albumin fraction dominated the chestnut protein composition, but globulin and prolamin were nondetectable. All the Chinese chestnut proteins had a nutritionally balanced amino acid composition. Their amino acid score (AAS) could reach the FAO/WHO (2013) requirement for essential amino acids for older children, adolescents and adults. Leucine was the first limiting amino acid for all the Chinese chestnut protein isolates and digestible indispensable amino acid scores (DIAAS) were more than 90 (Leu). The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) spectra showed that different Chinese chestnut protein isolates had almost the same band components, which were mainly comprised of seven polypeptide segments with the molecular weights of (91–93) kDa, (70–72) kDa, (53–55) kDa, 37 kDa, (27–33) kDa, 20 kDa and (5–15) kDa. The amino acid compositions and the abundance of low molecular weight proteins indicated that Chinese chestnut could be utilized as a good source of plant protein for human nutrition.

Effects of amino acid composition in pig diet on odorous compounds and microbial characteristics of swine excreta

BackgroundMajor amino acids in pig diets are Lys, Met, Thr, and Trp, but little is known about the requirements for the other essential amino acids, especially on odorous compounds and microbial characteristics in feces of growing-finishing pigs. To this end, different levels of amino acid composition added to diets to investigate the effects of amino acid composition on microbial characteristics and odorous compounds concentration.MethodsA total eight (n = 8) barrows (Landrace × Yorkshire × Duroc) with an average bodyweight of 89.38 ± 3.3 kg were individually fed diets formulated by Korean Feeding Standards 2007 (old version) or 2012 (updated with ideal protein concept) in metabolism crates with two replication. After 15-day adaptation period, fresh faecal samples were collected directly from pigs every week for 4 weeks and analysed for total volatile fatty acids (VFA), phenols and indoles by using gas chromatography. The nitrogen was determined by Kjeldahl method. Bacterial communities were detected by using a 454 FLX titanium pyrosequencing system.ResultsLevel of VFA tended to be greater in 2012 than 2007 group. Among VFAs, 2012 group had greater (p < 0.05) level of short chain fatty acids (SCFA) than control.Concentration of odorous compounds in feces was also affected by amino acid composition in pig diet. Levels of ammonium and indoles tended to be higher in 2012 group when compared with 2007 group.Concentration of phenols, p-cresol, biochemical oxygen demand, and total Kjeldahl nitrogen, however, were lower (P < 0.05) in 2012 treatment group compare to 2007. The proportion of Firmicute phylum were decreased, while the Bacteriodetes phylum proportion increased and bacterial genera includingCoprococcus, Bacillus, and Bacteroides increased (p < 0.05) in 2012 compare to 2007 group.ConclusionResults from our current study indicates that well balanced amino acid composition reduces odor by modulating the gut microbial community. Administration of pig diet formulated with the ideal protein concept may help improve gut fermentation as well as reduce the odor causing compounds in pig manure.

Production of a high-nutritional-value functional food, the Update1 bread, with the supplementation of the wheat flour with high-protein-content raw food materials

AbstractDuring our research, we added extracted soya bean meal, egg-white powder, gluten, wheat sourdough, and bamboo fibre to wheat flour in order to increase the quantity of the essential amino acid and the biological value of the wheat protein, producing such a functional, health-protecting, health-preservative food product which is suitable to satisfy the essential amino acid requirements of humans, assuming normal nutrition. Furthermore, we could produce such a food, which, on the one hand, was suitable to confine or prevent the essential amino acid’s malnutrition symptoms, while, on the other hand, when applied alone, to meet the consumers’ needs. During our work, we determined the protein content and amino acid composition of the wheat flour, of the additives used in bread baking, and in the bread both baked with supplementation (Update1 bread) and without supplementation (normal bread), as well as the quantity of the Maillard reaction products (hydroxymethylfurfural). We calculated the biological value of the protein of different breads and evaluated the sensory characteristics of the produced functional food and the fortified bread, supplemented with high essential-amino-acid-containing additives.

Quinoa (Chenopodium quinoa Willd.) versus soja (Glycine max [L.] Merr.) en la nutrición humana: revisión sobre las características agroecológicas, de composición y tecnológicas

El diseño de alimentos funcionales a partir de productos vegetales muy estudiados como la soja (Glycine max [L.] Merr.) y la potencialización de productos ancestrales como la quinoa (Chenopodium quinoa Willd.) son estrategias factibles para contrarrestar la desnutrición mundial. El objetivo de la presente revisión es describir las características agroecológicas, de composición, nutricionales y tecnológicas de estas dos especies vegetales diferentes (leguminosa y pseudocereal), basado en las publicaciones previas. Se realizó una revisión en bases de datos (Scopus, Web of Science, Scielo) y se complementó con una búsqueda manual en Google Scholar y páginas web de instituciones acreditadas. Los estudios incluidos (n=117) en esta revisión muestran que la soja se adapta mejor a altitudes bajas (~1.000 m s. n. m.), mientras que la quinoa lo hace en un rango de mayores altitudes (500-4.000 m s. n. m.) con mayor tolerancia a heladas. Ambas son fuente de una alta calidad proteica por suplir los requerimientos de aminoácidos esenciales sugeridos para niños y adultos sin diferencias significativas (p&gt;0,05), particularmente triptófano y lisina y por los altos porcentajes de digestibilidad (&gt;70%). Sus concentraciones bajas de prolaminas y aceptables de Fe, Zn, Ca, daidzeína y genisteína los convierten en productos de interés para la industria alimentaria.

Progressive response of large intestinal bacterial community and fermentation to the stepwise decrease of dietary crude protein level in growing pigs.

The study aimed to determine the effects of reduction of dietary crude protein (CP) level with balanced essential amino acids (EAA) on intestinal bacteria and their metabolites of growing pigs. Forty pigs (initial BW 13.50±0.50kg, 45±2days of age) were randomly assigned to four dietary treatments containing CP levels at 20.00% (normal crude protein, NP); 17.16% (medium crude protein, MP); 15.30% (low crude protein, LP); and 13.90% (extremely low crude protein, ELP), respectively. Crystalline AAs were added to meet the EAA requirement of pigs. After 4-week feeding, eight pigs per treatment (n=8) were randomly selected and slaughtered for sampling of ileal, cecal, and colonic digesta and mucosa. Pigs with moderately reduced CP level had increased bacterial diversity, with the Shannon diversity indices for the colon digesta in the LP group and mucosa in the MP and LP groups significantly (P<0.05) higher than those in the NP and ELP groups. As the CP level reduces, the Bifidobacterium population were linearly decreased (P<0.05) both in ileum, cecum, and colon, and the ELP group had the lowest Bifidobacterium population in the cecum and colon, with its value significantly lower than NP and MP groups (P<0.05). However, the ELP group had the highest population of Escherichia coli in the colon, with its value significantly higher than the LP group (P<0.05). For bacterial metabolites, as CP level decreased, total short-chain fatty acid (T-SCFA), acetate, and butyrate were linearly increased (linear, P<0.05) in the ileum, while all SCFAs except formate in the cecum and T-SCFA and acetate in the colon, were linearly decreased (P<0.05). Reducing CP level led to a linear decrease of microbial crude protein (MCP) in the ileum (P<0.05) and ammonia in all intestine segments (P<0.05). The spermidine in cecum and total amines, cadaverine, methylamine, and spermidine in colon were shown a quadratic change (P<0.05) as dietary CP decreases, with the highest concentration in LP group. These findings suggest that moderate reduction of dietary CP level may benefit large intestinal bacterial community and its fermentation, which was negatively affected by extremely low CP diet.

Effect of total replacement of fishmeal by earthworm and Azolla filiculoides meals in the diets of Nile tilapia Oreochromis niloticus (Linnaeus, 1758) reared in concrete tanks

In order to eliminate use of fishmeal in aquafeeds, we evaluated the effect of total replacement of fish meal by a mixture of earthworm (Eisenia foetida) and aquatic fern Azolla filiculoides in the diets of Nile tilapia Oreochromis niloticus (Linnaeus, 1758). The experiment was conducted in O. niloticus fingerlings (initial mean weight = 5.6±0.2 g) for a period of 60 days. Five experimental diets isoproteic (30.4±0.6% protein) comprising control diet A0 and four test diets (A1 to A4) without fish meal were formulated. To satisfy essential amino acids requirements in test diets, the ratios 2:1; 1:1; 1:2; 1:5 between A. filiculoides and earthworm meals were used respectively in total replacement of fish meal. The diets were tested in triplicate. On termination of the experiment, the final mean weights in the test diets (10.79 to 11.94 g) were lower than 14.9 g obtained in group fed control diet (p&lt;0.05). The best growth performance and feed utilisation were obtained in fish fed test diets A1 and A4 (SGR = 1.25 and 1.26% day-1; FCR = 2.37 and 2.31 respectively). Excess of lysine in test diets was found to affect the feed utilisation.

Optimization of mold wheat bread fortified with soy flour, pea flour and whey protein concentrate.

The objective of this work was to study the effect of replacing a selected wheat flour for defatted soy flour, pea flour and whey protein concentrate on both dough rheological characteristics and the performance and nutritional quality of bread. A mixture design was used to analyze the combination of the ingredients. The optimization process suggested that a mixture containing 88.8% of wheat flour, 8.2% of defatted soy flour, 0.0% of pea flour and 3.0% of whey protein concentrate could be a good combination to achieve the best fortified-bread nutritional quality. The fortified bread resulted in high protein concentration, with an increase in dietary fiber content and higher calcium levels compared with those of control (wheat flour 100%). Regarding protein quality, available lysine content was significantly higher, thus contributing with the essential amino acid requirement.

Estimation of the dietary essential amino acid requirements of colliroja Astyanax fasciatus by using the ideal protein concept

Colliroja, Astyanax fasciatus, is a new aquaculture species, and information on its dietary essential amino acid requirements is lacking. The whole body composition of 120 farmed fish (16.2 ± 8.8 g) was determined to estimate the dietary essential amino acid requirement based on the ideal protein concept ((each essential amino acid/lysine) ×100), and the findings were correlated to the whole body essential amino acid content of Nile tilapia Oreochromis niloticus. The dietary essential amino acids, including cysteine and tyrosine, accounted for 5.46, 4.62, 1.16, 3.28, 5.63, 2.01, 2.59, 2.84, 4.66, 3.39, 0.65, and 3.51% of the total protein for lysine, arginine, histidine, isoleucine, leucine, methionine, methionine+tyrosine, phenylalanine, phenylalanine+tyrosine, threonine, tryptophan, and valine, respectively. There were positive linear and high correlations (r = 0.971) between the whole body amino acid profiles of colliroja and Nile tilapia. Thus, the whole body amino acid profile of colliroja might be used to estimate accurately the essential amino acid requirement.

Nutritional value of bee-collected pollens of hardy kiwi, Actinidia arguta (Actinidiaceae) and oak, Quercus sp. (Fagaceae)

Bee-collected pollens have gained attention as natural dietary supplement for human nutrition over the honeybee feed, and become important commercial hive products for beekeepers. Oak trees, Quercus sp. (Family: Fagaceae) and hardy kiwi, Actinidia arguta (Family: Actinidiaceae) are important pollen sources for honey bees. During collection and storage through the addition of nectar and salivary secretions the chemical composition of pollen is changed. We analyzed nutrient contents of bee collected oak and hardy kiwi pollens and compared with recommended requirement of essential amino acids for honey bee brood development. The results revealed that protein content was found 23.2% for oak and 26.5% for hardy kiwi pollen. All the determined essential amino acid contents of both oak and kiwi pollen satisfied the minimum individual amino acid requirement of honey bee. Threonine was present in marginal level in hardy kiwi pollen. Fat content of oak and hardy kiwi pollen were found 7 and 4.5% respectively. The higher value of polyunsaturated fatty acid/saturated fatty acid - stearic acid, lower AI and TI value, presence of essential fatty acid n-3 linolenic acid indicated these pollens as superior sources of fat. The most abundant mineral was found potassium in both the pollens followed by phosphorus. In contrast sodium content was found very less. In vitro digestibility of oak and kiwi pollen were found 69.5 and 37.8% suggesting the difficulty of nutrient uptake directly from pollen grains.

Complete replacement of fish meal by other animal protein sources on growth performance of Clarias gariepinus fingerlings

To completely replace the fish meal by a mixture of earthworm and maggot meals, experimental diets were tested during 42 days on Clarias gariepinus fingerlings. Five isoproteic and isoenergetic diets (40 % crude protein and 17.9 ± 0.3 kJ g−1) including the control diet (D1) based on fish meal, were formulated. All these diets satisfied the essential amino acids requirements of C. gariepinus fingerlings. These diets were tested on triplicate groups of 50 fishes (initial body weight: 3 ± 0.1 g) bred in tank (0.5 m3). The approximate ratios 2:5; 1:4; 1:12 and 0:1 between the earthworm meal and the maggot meal were used, respectively, to formulate four diets D2, D3, D4 and D5 without fish meal. After the feeding period, significant differences (P < 0.05) were observed on growth, feed utilization between control diet (D1) and test diets (D2–D5). Fish fed earthworm- and maggot-based diets were grown better than those fed the control diet. Survival and feed utilization were not significantly affected by the ratio between earthworm meal and maggot meal in the test diets. Lipid content was higher in carcass and fillet of fishes fed earthworm- and maggot meals-based diets than that of those fed fish meal-based diet. This study indicates that when the ratio 2:5 between the earthworm meal and the maggot meal is used to entirely replace fish meal and the ratio lysine/arginine of the diet is inferior to 1, the growth performances and feed utilization of Clarias gariepinus fingerlings are improved.

Influence of low protein diets on gene expression of digestive enzymes and hormone secretion in the gastrointestinal tract of young weaned piglets

To investigate dietary protein level effects on digestive mechanisms, weaned piglets were fed for 45 d with diets containing 20%, 17%, or 14% crude protein (CP) supplemented to meet requirements for essential amino acids. This article describes the influence of dietary protein on gastrointestinal hormones and expression of an array of digestive enzymes in the gastrointestinal tract and pancreas. Results indicated that there were no significant differences in expression of enzymes involved in carbohydrate digestion, except for maltase in the duodenum. In the jejunum, amylase expression in pigs fed 20% CP was much higher than that in pigs fed other diets (P<0.05) and maltase expression in those fed 17% CP was higher than that in other treatments (P<0.05). Although there were no remarkable differences in expression of aminopeptidase in the small intestine or carboxypeptidase in the pancreas (P>0.05), there was a trend towards higher expression of various proteases in pigs fed 17% CP. The duodenal expression of enteropeptidase in diets with 14% and 17% CP was significantly higher than that with 20% CP (P<0.05), but treatment differences did not existed in jejunum (P>0.05). The expression of GPR93 as a nutrient-responsive G protein-coupled receptor in 14% and 17% CP diets was significantly higher than that in 20% CP diet in the small intestine (P<0.05). The expressions of genes for pancreatic enzymes, lipase and elastase, were significantly higher in pigs fed diets with low CP, while similar trends occurred for carboxypeptidase, chymotrypsin and amylase. Conversely, the gastric expressions of pepsinogen A and progastricsin were lower with the 17% CP diet. Differences between treatments were found in the gastric antral contents of cholecystokinin and somatostatin: both increased in pigs fed 17% CP, accompanied by decreased content of motilin, which was also seen in plasma concentrations. These patterns were not reflected in duodenal contents. In general, 17% dietary CP was beneficial to the digestion of nutrient substance in the gastrointestinal tract.

Quantitative estimates of the optimal balance between digestible lysine and the true protein contents of broiler feeds

Typical poultry feed formulation models have been developed for meeting the minimum specifications of the essential amino acids (EAAs), ignoring the importance of providing precise levels of the non-essential amino acids (NEAAs) that are required for maximum performance. Including true protein (TP) values in these models in relation to EAAs can most accurately account for the requirements of all amino acids (AAs) in the ration (essential, non-essential and excess EAAs).Data from recent research reports on the digestible lysine (dLys) requirements for maximum weight gain and minimum feed conversion ratio (FCR) were compiled from the literature. dLys requirements and the TP contents of the feeds were recalculated based on common ingredient composition values. Broken-line linear (BLL) and broken-line quadratic (BLQ) models were fitted to the data and compared.The dLys requirements of broilers (g/kg diet) for body weight gain (BWG) and FCR were found to increase linearly as a function of the true and crude protein contents of the diet. These relationships were not affected by either age or sex. As chickens aged, the dLys requirements decreased. However, the dLys requirement to TP ratio did not change with age for BWG or FCR.For maximum BWG and minimum FCR, the dLys requirements were estimated from the prediction models to be 4.92% ± 0.51 and 5.58% ± 0.70 of the TP level of the diet, using the BLL models, respectively.The good linear relationship between the dLys requirement and TP level allows the prediction of the variables from each other for use in feed formulation to represent the requirements of both EAAs and NEAAs.The dietary dLys requirements were estimated to be lower using the BLL vs. the BLQ models.TP was a better predictor of dLys requirements than crude protein (higher R2 values).

Nutritional strategies to cope with reduced litter weight gain and total tract digestibility in lactating sows.

Twelve lactating sows were used to evaluate the effects of reducing dietary crude protein (CP) (14% vs. 12%) and increasing neutral detergent fibre (NDF) levels (18% vs. 22%) on litter performance, total tract apparent digestibility and manure composition in a 4×4 latin square arrangement during a 36-day lactation period. Diets were isoenergetic (2.9McalME/kg) and had similar total lysine content (0.9%). In addition, a second aim was to compare a reference external marker method (Cr2 O3 ) with an internal feed marker [acid-insoluble ash (AIA)] for the calculation of apparent total tract digestibility of nutrients in lactating sows. The reduction of dietary CP level in lactating sows had no effect on either live-weight or backfat thickness or apparent total tract digestibility of nutrients. However, the piglets' average daily gain (ADG) was reduced in low dietary CP diets, which suggests that sows reduced milk production due to an underestimation of certain essential amino acid requirements (e.g. valine). The increase of dietary NDF level did not affect sow and litter performance. Nevertheless, the total tract apparent digestibility of organic matter, CP and carbohydrates was reduced, and ether extract digestion was increased in high NDF compared to normal NDF diets equally balanced for ME and lysine content. The coefficients of total tract apparent digestibility of nutrients in lactating sows were greater when using AIA compared to Cr2 O3 marker, regardless of dietary CP or NDF level, but their coefficients of variation were lower in the former than in the latter. In lactating sows, a trade-off between litter performance and nutrient digestion is established when reducing dietary CP or increasing NDF levels while maintaining similar lysine content through synthetic amino acids and balancing metabolizable energy through dietary fat sources.

Essential amino acids: master regulators of nutrition and environmental footprint?

The environmental footprint of animal food production is considered several-fold greater than that of crops cultivation. Therefore, the choice between animal and vegetarian diets may have a relevant environmental impact. In such comparisons however, an often neglected issue is the nutritional value of foods. Previous estimates of nutrients’ environmental footprint had predominantly been based on either food raw weight or caloric content, not in respect to human requirements. Essential amino acids (EAAs) are key parameters in food quality assessment. We re-evaluated here the environmental footprint (expressed both as land use for production and as Green House Gas Emission (GHGE), of some animal and vegetal foods, titrated to provide EAAs amounts in respect to human requirements. Production of high-quality animal proteins, in amounts sufficient to match the Recommended Daily Allowances of all the EAAs, would require a land use and a GHGE approximately equal, greater o smaller (by only ±1-fold), than that necessary to produce vegetal proteins, except for soybeans, that exhibited the smallest footprint. This new analysis downsizes the common concept of a large advantage, in respect to environmental footprint, of crops vs. animal foods production, when human requirements of EAAs are used for reference.

Protein Needs of Physically Active Children.

Current Dietary Reference Intakes (DRI) for protein for children and youth require revision as they were derived primarily on nitrogen balance data in young children or extrapolated from adult values; did not account for the possible influence of above average physical activity; and did not set an upper tolerable level of intake. Revision of the protein DRIs requires new research that investigates: 1) long-term dose-response to identify protein and essential amino acid requirements of both sexes at various pubertal stages and under differing conditions of physical activity; 2) the acute protein needs (quantity and timing) following a single bout of exercise; 3) the potential adverse effects of chronic high intakes of protein; and 4) new measurement techniques (i.e., IAAO or stable isotope methodologies) to improve accuracy of protein needs. While active individuals may require protein in excess of current DRIs, most active Canadian children and youth have habitual protein intakes that exceed current recommendations.

Essential amino acids profile of differentially processed soy products and their efficiency in meeting daily requirement

Purpose – In the backdrop of declining per capita availability of pulses, soybean is the alternate source to address protein deficiency in India. The study aims to assess the efficiency of soy products available in the market for meeting the daily requirement of essential amino acids (EAAs). Design/methodology/approach – Extruded soy products, namely, soy nuggets, granules, soy flour manufactured from sprouts, spray-dried soy milk variants, ready-to-drink (RTD) soy beverage and silken tofu, were analysed for EAAs by high-performance liquid chromatography. In addition, efficiency of these products in terms of meeting the daily requirement of EAAs for an adult weighing 70 kg through a single serving (equivalent to 6 g protein) was also computed. Findings – Leucine was the most concentrated EAA in all the soy products, except in variants of soy milk. Total essential amino acids’ (TEAAs) content in soy flour was significantly higher compared to soy nuggets and granules. Spray-dried plain soymilk exhibited a significantly higher level of TEAAs content compared to flavoured variant and RTD soy beverage. Among all the products, silken tofu exhibited the highest concentration of TEAAs. RTD soy beverage was the most efficient product for meeting the daily requirement of isoleucine and valine, soy flour for aromatic amino acids and silken tofu for lysine and leucine. Originality/value – This work pertains to the determination of EAAs of commercial soy products and assesses their efficiency in terms of meeting the daily requirement of EAAs. This type of technical evaluation of soy products has not been conducted earlier.

Determination of digestible lysine and estimation of essential amino acid requirements for bullfrogs

The traditional method to determine the nutritional requirements of animals is based on individual dose–response experiments that are time consuming and costly. One alternative to establish the dietary protein profile is the use of the ideal ratio between essential amino acids and digestible lysine to estimate essential amino acid requirements. The objective of this study was to determine the digestible lysine requirement of bullfrogs and to estimate essential amino acid requirements based on the ideal ratio. The experimental design was completely randomized and consisted of five treatments and three replicates. Six hundred froglets with an initial mean weight of 51.53±1.91g, identified through an implanted transponder, were used. The experimental diet (30.42% digestible protein) was supplemented with five levels of lysine HCl (0, 0.7, 1.4, 2.1, and 2.8%), so that the diets contained 1.38, 2.11, 2.85, 3.65 and 4.39% digestible lysine. The performance variables were feed intake, weight gain, feed conversion, specific growth rate, protein efficiency ratio, protein retention efficiency, and body protein and lysine deposition. The optimum level of digestible lysine was obtained at the intersection of the ascending line with the response plateau. Weight gain increased until reaching 222.7g at 2.23% digestible lysine in the diet. The best feed conversion (1.4g/g) and body protein (48.28g) and lysine (4.07g) deposition were observed at 2.29%, 2.33% and 2.39% digestible lysine, respectively. The digestible lysine requirement of bullfrogs is 2.71% of dry weight or 8.91% of dietary digestible protein, a level that provides the highest protein retention efficiency. The requirements of the other digestible amino acids estimated based on the concept of the ideal ratio of essential amino acids are (of dry weight): 2.16% arginine; 0.94% histidine; 1.34% isoleucine, 2.39% leucine; 0.79% methionine; 1.31% phenylalanine; 1.34% threonine; 0.23% tryptophan; 1.58% valine; 0.36% cystine, and 1.07% tyrosine. Statement of RelevanceThe estimate requirement of digestible essential amino acid using the concept of the ideal ratio permits the elaboration of diets with an appropriate amino acid, maximizing growth, protein utilization efficiency and carcass quality for bullfrogs.

Effect of l‐glutamic acid supplementation on performance and nitrogen balance of broilers fed low protein diets

The aim of this study was to evaluate the effect of protein reduction and supplementation of l-glutamic acid in male broiler diets. A total of 648 chicks of the Cobb 500 strain were distributed in a completely randomized design with six treatments and six replications with eighteen birds per experimental unit. The study comprised pre-starter (1-7days), starter (8-21days), growth (22-35days) and final (36-45days) phases. The first treatment consisted of a control diet formulated according to the requirements of essential amino acids for each rearing phase. The second and third treatments had crude protein (CP) reduced by 1.8 and 3.6 percentage points (pp) in relation to the control diet respectively. In the fourth treatment, l-glutamic acid was added to provide the same glutamate level as the control diet, and in the last two treatments, the broilers were supplemented with 1 and 2pp of glutamate above that of the control diet respectively. The reduction in CP decreased the performance of broilers and the supplementation of l-glutamic acid did not influence performance when supplied in the diets with excess of glutamate. The lowest excreted nitrogen values were observed in the control diet, and treatments 2 and 3, respectively, in comparison with treatments with the use of l-glutamic acid (5 and 6). Retention efficiency of nitrogen was better in the control diet and in the treatment with a reduction of 1.8pp of CP. It was verified that the serum uric acid level decreased with the CP reduction. A reduction in CP levels of up to 21.3%, 18.8%, 18.32% and 17.57% is recommended in phases from 1 to 7, 8 to 21, 22 to 35 and at 36 to 42days, respectively, with a level of glutamate at 5.32%, 4.73%, 4.57%, 4.38%, also in these phases.