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Abstract The concept of a standardized reference diet (SRD) is used in laboratory model organisms to ensure nutritional control between studies and laboratories. Although models using the genetically identical, all female parthenogenetic marbled crayfish (Procambarus virginalis) are growing in popularity, research into nutrition in this species still has many knowledge gaps. To fast track the development of a SRD in terms of protein and amino acids (SRDprotein) for this species, we first analyzed the composition of its body amino acids to determine the ideal protein concept (IPC) of indispensable amino acids in wild-caught P. virginalis (which had an unusually high preponderance of leucine and arginine). Then, we strategically evaluated three common clusters of types of fish feed: (1) ornamental fish feed (SER) fortified with a naturally occurring alga (Spirulina). This type of feed was protein-high in arginine and leucine (SER + SPI) that fulfils the species’ IPC for iso-protein (~ 40%), iso-phosphorus (~ 0.8%) and near iso-energetic (~ 475 kcal 100 g−1); (2) freeze-dried live feed consisting of chironomid larvae (CHI) fortified with Spirulina (CHI + SPI) that fulfils the IPC for iso-protein (~ 46%), iso-phosphorus (~ 0.7%) and near iso-energetic (~ 405 kcal 100 g−1); and (3) a commercially standardized ‘starter diet’ for carnivorous fish larvae (FISH) and post-larval shrimps (SHRIMP) with iso-protein (~ 56%) and iso-phosphorus (~ 1.6%). A total of six diets, embracing a diverse range of proteinaceous feeds, were used in a 100-day ad libitum feeding and growth trial. The FISH group outperformed all the other groups (p 44% protein (tailored to deliver high arginine 3% and leucine 4%, followed by the usual lysine > 3.5% and methionine 1.2%) but also the lowest carbohydrate level (21%). For SRDprotein, our findings show that the FISH diet is ideal and suggest the possibilities of using a CHI + SPI diet for further optimization (more economic use of protein and phosphorus).

According to the theory of animal nutrition, the nutritional requirements of aquatic animals for feed protein and amino acids are the minimum requirements for feed protein and amino acids under the conditions of meeting animal growth performance and physiological health. The high crude protein content in aquatic feed not only violates animal nutrition theory, but also causes serious waste of feed resources, and significantly increases the nitrogen input into aquaculture water bodies. Therefore, it is necessary to develop low protein content and high-quality aquatic feed. This type of feed industry can be referred to as low protein aquatic feed that achieves the ideal protein model. The ideal protein model for aquatic animals is calculated and formulated based on the amount of digestible protein and amino acids in the feed, while also maintaining good amino acid balance. Constructing a database of protein and amino acid digestibility in feed raw materials is the technical core for developing ideal protein models for aquatic feed. The use of industrial enzymatic hydrolysis technology and microbial fermentation technology can significantly improve the digestibility and utilization of protein and amino acids in feed materials, or develop new feed materials with high digestibility of protein and amino acids. The application of such raw materials in feed is an important guarantee for the development of low protein content and high-quality aquatic feed. The quality standards for aquatic feed products are an important technical guarantee for the development of the aquatic feed industry and aquaculture industry. Therefore, the quality standards for aquatic feed products should also increase the technical indicators and content of digestible protein and amino acids in feed. [ABSTRACT FROM AUTHOR]

The concept of a standardized reference diet (SRD) is used in laboratory model organisms to ensure nutritional control between studies and laboratories. Although models using the genetically identical, all female parthenogenetic marbled crayfish (Procambarus virginalis) are growing in popularity, research into nutrition in this species still has many knowledge gaps. To fast track the development of a SRD in terms of protein and amino acids (SRDprotein) for this species, we first analyzed the composition of its body amino acids to determine the ideal protein concept (IPC) of indispensable amino acids in wild-caught P. virginalis (which had an unusually high preponderance of leucine and arginine). Then, we strategically evaluated three common clusters of types of fish feed: (1) ornamental fish feed (SER) fortified with a naturally occurring alga (Spirulina). This type of feed was protein-high in arginine and leucine (SER + SPI) that fulfils the species' IPC for iso-protein (~ 40%), iso-phosphorus (~ 0.8%) and near iso-energetic (~ 475 kcal 100 g−1); (2) freeze-dried live feed consisting of chironomid larvae (CHI) fortified with Spirulina (CHI + SPI) that fulfils the IPC for iso-protein (~ 46%), iso-phosphorus (~ 0.7%) and near iso-energetic (~ 405 kcal 100 g−1); and (3) a commercially standardized 'starter diet' for carnivorous fish larvae (FISH) and post-larval shrimps (SHRIMP) with iso-protein (~ 56%) and iso-phosphorus (~ 1.6%). A total of six diets, embracing a diverse range of proteinaceous feeds, were used in a 100-day ad libitum feeding and growth trial. The FISH group outperformed all the other groups (p < 0.05) and our exploratory multivariate analysis revealed an ideal demand of > 44% protein (tailored to deliver high arginine 3% and leucine 4%, followed by the usual lysine > 3.5% and methionine 1.2%) but also the lowest carbohydrate level (21%). For SRDprotein, our findings show that the FISH diet is ideal and suggest the possibilities of using a CHI + SPI diet for further optimization (more economic use of protein and phosphorus). [ABSTRACT FROM AUTHOR]

The complete quantitative essential amino acid (EAA) requirements of aquacultured animals are largely unknown except for a handful of species. This is problematic because formulation of least-cost diets for target animals demands precise knowledge of EAA requirements. One way of approximating EAA requirements is to use correlations between whole-body and/or muscle EAA profiles using essential to total EAA ratios (A/E ratios). This method requires a reference, quantified EAA requirement, usually lysine (Lys). To systematically evaluate the A/E ratio method, muscle AA profiles were measured in 10 species of teleost and whiteleg shrimp. In fish, Lys represented the dominant muscle EAA measured, ranging between 7.06 and 9.58 g/100 g protein, whereas, in shrimp, arginine (Arg) was quantified as the principal EAA. For non-EAA, glutamate (Glu) and glutamine were consistently the NEAA recorded at highest levels whereas, in shrimp, Glu + Gln was highest followed by aspartate (Asp) plus asparagine (Asn). Except for Arg, which was twice that of fish (P < 0.05), whiteleg shrimp expressed similar muscle A/E profiles. Strength of relationship between muscle EAA levels and known requirements were all strongly and positively correlated for non-salmonid species. When using Lys as the reference EAA there were few semblances between measured and estimated EAA requirements. [ABSTRACT FROM AUTHOR]

Abstract Background Exposure of broilers to litter microbiome may increase specific amino acid (AA) requirements towards activated immune responses. This may challenge the generality of the ideal protein (IP) concept, in which dietary essential AA to lysine ratios aimed to mimic presumably constant AA to lysine ratios in whole bird requirements. Therefore, we tested the effect of threonine, arginine and glutamine (TAG) supplementation to IP-based control diets (C) on performance, caecal microbiome composition, short-chain fatty acids and litter characteristics of broiler chickens placed on reused litter. Results Thirty-two pens with ten male broiler chickens each were used in a 2 × 2 factorial arrangement of two diet treatments (with or without TAG supplementation) and two litter treatments (placement on clean or reused litter) for 21 days (n = 8). Caecal contents were analysed for microbiome profile using percent guanine + cytosine (%G + C profile) method and short chain fatty acids. TAG-supplemented birds underperformed compared to C birds (P = 0.002), whereas birds placed on reused litter outperformed those on clean litter (P = 0.047). Diet, reused litter and their interaction impacted the %G + C profile at different ranges. Whilst TAG supplementation reduced bacterial abundance at %G + C 51–56 (P

Simple Summary: Broiler chicken production, providing valuable food products, has also been responsible for ammonia emissions which can lead to environmental pollution worldwide. Besides its economic and animal health advantages, feeding low protein diets can decrease the ammonia emission of broiler production. Even though low-protein diets balanced for amino acids have been used in practice, the ideal energy supply of broilers fed low-protein diets is not known. Therefore, our goal was to determine an ideal dietary energy-to-protein ratio of low-protein diets which does not compromise the production traits and carcass composition of the broilers. Based on our results, the 1.5% crude protein reduction in the diet while maintaining dietary energy constant did not negatively affect the production traits, increased the nitrogen retention, the breast meat yield, and decreased the drip loss of breast meat. Furthermore, the lowest concentration of total-N and uric acid-N in the excreta was obtained when isocaloric diets were fed. Although the low protein diets with reduced energy content led to lower final body weight of broilers, they did not affect the carcass composition, breast meat quality, nitrogen retention, and excreta composition compared to the control diet. This study shows the effects of feeding low protein (LP) diets with different energy-to-protein ratios were evaluated on the production parameters, carcass composition, meat quality, nitrogen retention, and excreta composition of broilers. A total of 576-day-old Ross 308 broilers were fed a control diet (C) and three LP diets containing 1.5% less crude protein than diet C for 41 days. The LP1 treatment was isocaloric with diet C, while the dietary apparent metabolizable energy corrected by nitrogen (AMEn) levels in the case of the LP2 and LP3 treatments were reduced by 1.5% and 3%, respectively. The LP diets were supplemented with six crystalline essential amino acids (AA) to meet the standardized ileal digestible AA requirements of broilers. The LP1 treatment did not affect the performance parameters of broilers and increased the breast meat yield, the nitrogen retention and decreased drip loss of breast meat and the total-N and uric acid-N nitrogen excretion of birds in comparison with the C group. Although the energy-reduced LP2 and LP3 diets resulted in lower final body weight, they did not affect the carcass composition, breast meat quality, nitrogen retention, and excreta composition of birds compared with the control treatment. [ABSTRACT FROM AUTHOR]

Background: Exposure of broilers to litter microbiome may increase specific amino acid (AA) requirements towards activated immune responses. This may challenge the generality of the ideal protein (IP) concept, in which dietary essential AA to lysine ratios aimed to mimic presumably constant AA to lysine ratios in whole bird requirements. Therefore, we tested the effect of threonine, arginine and glutamine (TAG) supplementation to IP-based control diets (C) on performance, caecal microbiome composition, short-chain fatty acids and litter characteristics of broiler chickens placed on reused litter. Results: Thirty-two pens with ten male broiler chickens each were used in a 2 × 2 factorial arrangement of two diet treatments (with or without TAG supplementation) and two litter treatments (placement on clean or reused litter) for 21 days (n = 8). Caecal contents were analysed for microbiome profile using percent guanine + cytosine (%G + C profile) method and short chain fatty acids. TAG-supplemented birds underperformed compared to C birds (P = 0.002), whereas birds placed on reused litter outperformed those on clean litter (P = 0.047). Diet, reused litter and their interaction impacted the %G + C profile at different ranges. Whilst TAG supplementation reduced bacterial abundance at %G + C 51–56 (P < 0.05), reused litter placement tended to reduce %G + C 23–31 and increase %G + C 56–59 (P < 0.10). However, TAG supplementation reduced bacterial abundance at %G + C 47–51 (P < 0.05) and increased caecal branched chain fatty acids on clean litter only (P = 0.025). Greater levels of propionic acid were observed for C birds placed on reused litter only (P = 0.008). Litter pH was greater for reused litter pens than clean litter pens at day 21 (P < 0.001). In addition, litter moisture content was less for TAG birds and reused litter pens compared to C birds (P = 0.041) and clean litter pens (P < 0.001), respectively. Conclusions: These data support the view that irrespective of performance benefits arising from bird placement on reused litter, TAG supplementation to IP-formulated baseline rations impaired growth, supported by the lowered abundance of caecal bacteria known to dominate in well-performing birds and greater levels of caecal branched chain fatty acids. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of threonine:digestible lysine ratio in the diet on the physiological variables and weight of organs of light laying hens. Two hundred and ten 47 week-old Dekalb White laying hens were distributed in a completely randomized design, with five levels of threonine (0.507; 0.552; 0.597; 0.642 and 0.677%) and seven replicates of six birds each. The experimental period was 10 weeks, totaling 62 days and more eight days for the animals to adapt. The physiological parameters of cloacal temperature (CT), respiratory rate (RR) and average surface temperature (AST) were recorded weekly (7:00 am, 10:00 am, 1:00 pm, 4:00 pm, and 7:00 pm); after solid and water fasting, the birds were slaughtered to assess the absolute weight of the organs. The time of day influenced (p < 0.05) the physiological parameters RR and AST, and CT showed a significant effect (p < 0.05) of increasing levels of digestible threonine. The total weight of the pancreas, proventriculus and lung showed a significant effect (p < 0.05) of the increase in the levels of digestible threonine. The respiratory rate is affected by the levels of threonine in the diet. The 0.687% level promoted hypertrophy of the pancreas, proventriculus and lung, promoting more significant activity of these organs. [ABSTRACT FROM AUTHOR]

Introduction Modern layer strains have high genetic potential for egg production, and may produce eggs for more than one laying cycle by inducing molting. Good egg production is obtained when adequate nutrition is provided, one of the most important nutrients is protein, particularly limited nutritional essential amino acid. Additionally, in layer flocks feed represents more than 70% of the cost of production. In this context, protein is one of the most costly nutrients and therefore there is a benefit in reducing any excess protein in the feed by making use of synthetic amino acids wherever feasible to reduce both the excess waste of nitrogen and the production cost. Synthetic amino acids such as methionine, lysine and threonine are commonly used in the poultry industry because those are limiting in diets based on cereal and soybean meal and are now readily available at a competitive cost. The essential amino acid, threonine, is the third limiting amino acid. Most of the previous research has been done on determining the amino acids requirements of laying hens in the first production cycle, and information on laying hens requirements in the second production cycle is very limited. As a result, the nutrient requirements of second-cycle hens are assumed to be similar to those observed in hens during the first laying cycle in the strain booklet guide and or NRC, 1994. The objective of this study was to determine the digestible Threonine (dig Thr) requirement of laying hen during the second production cycle fed wheat-soy diet as measured by laying performance.Materials and methods The birds that used for this experiment were selected from a flock that were molted at the 80wk of age on a non-fasting feeding program according to the molting recommendation by Hy-line W36 laying hens guide and had 103wk age. Hens were selected according to body weight and egg production. The pre-experimental period was two weeks for acclimatization. Basal diet were formulated according to the guidelines in the Hy-Line W-36 Commercial Management Guide (2016) according to the average pre-experimental period data; egg production less than of 80% and feed intake 98 g/b/d. Three hundred and eighty four layers were distributed to the 6 increasing levels of dig Thr 0.44, 0.46, 0.48, 0.50, 0.52 and 0.54%, with Thr-to-Lys ratio of 60, 63, 66, 69, 72 and 75%, respectively in a completely randomized design, with 8 replicates and 8 birds per experimental unit. The experiment lasted from 105 to 116 weeks of ages. All hens were weighed at the beginning and at the end of the experimental period. Birds were given artificial light (16L: 8D). Feed and water were provided ad libitum. Egg production (number and weight) and mortality were recorded daily, whereas feed consumption was measured every 4wks as feed disappearance. The daily intakes of Thr were calculated by multiplying the concentration of each in the experimental diet by feed conception. Digestible threonine requirement for optimal laying performance response parameters such as egg production (EP), egg mass (EM) and feed conversion ratio (FCR) to the daily dig Thr consumption by using NLIN procedure, through linear and quadratic broken-lines and quadratic polynomial regression fit models.Results and discussion The increasing dig Thr levels showed linear effect on egg weight, and quadratic effect on egg production (EP), egg mass (EM), and feed conversion ratio (FCR). The EP and EM increased and FCR improved linearly as dietary dig Thr levels increasing up to 0.48% (Thr-to-Lys ratio of 66%), and then EP and EM decreased and FCR deteriorate. The dig Thr requirements for the optimization of laying performance was depends on what parameter is taken into consideration for optimization and it is possible to compare models by their R2 and MAE. In this study, the model that provided the best fit was the quadratic polynomial regression model for EP, EM and FCR. The predicted dig Thr requirements with quadratic polynomial regression model for optimal EP, EM and FCR were 502, 505 and 517 mg/b/d, respectively. The dig Thr requirement to produce 1 g of EM was 9.57 mg. The optimum values estimated for FCR was slightly higher compared to those estimated for EP and EM.Conclusion The outcomes of the present study showed that, in the wheat-soy based diet formulated for second cycle of laying hen the threonine is a limited amino acid. The dig Thr requirements vary according on what parameter is taken into consideration for optimization. The dig Thr requirement for optimized FCR is higher than EP and EM. In the wheat-soy based diet formulated for second cycle of laying hen the level of digestible Thr 0.48% (Thr-to-Lys ratio of 66%) were recommended.

The objective of this study was to evaluate the effect of threonine:digestible lysine ratio in the diet on the physiological variables and weight of organs of light laying hens. Two hundred and ten 47 week-old Dekalb White laying hens were distributed in a completely randomized design, with five levels of threonine (0.507; 0.552; 0.597; 0.642 and 0.677%) and seven replicates of six birds each. The experimental period was 10 weeks, totaling 62 days and more eight days for the animals to adapt. The physiological parameters of cloacal temperature (CT), respiratory rate (RR) and average surface temperature (AST) were recorded weekly (7:00 am, 10:00 am, 1:00 pm, 4:00 pm, and 7:00 pm); after solid and water fasting, the birds were slaughtered to assess the absolute weight of the organs. The time of day influenced (p < 0.05) the physiological parameters RR and AST, and CT showed a significant effect (p < 0.05) of increasing levels of digestible threonine. The total weight of the pancreas, proventriculus and lung showed a significant effect (p < 0.05) of the increase in the levels of digestible threonine. The respiratory rate is affected by the levels of threonine in the diet. The 0.687% level promoted hypertrophy of the pancreas, proventriculus and lung, promoting more significant activity of these organs.

Simple Summary: Can urea nitrogen metabolite contribute to implementing the ideal protein concept in monogastric animals? This work aims to critically analyse how this metabolite can contribute to accurately implementing the ideal protein concept in monogastric animals, particularly in pig, poultry, and rabbit nutrition. This information will contribute to evaluating its potential and limitations as biomarker, as well as to standardizing the use of this metabolite in precise amino acidic monogastric nutrition. The ideal protein concept refers to dietary protein with an amino acid profile that exactly meets an animal's requirement. Low-quality protein levels in the diet have negative implications for productive and reproductive traits, and a protein oversupply is energetically costly and leads to an excessive N excretion, with potentially negative environmental impact. Urea Nitrogen (UN), which corresponds to the amount of nitrogen in the form of urea circulating in the bloodstream, is a metabolite that has been widely used to detect amino acid imbalances and deficiencies and protein requirements. This review aims to critically analyse how UN can contribute to accurately implementing the ideal protein concept in monogastric animals, particularly in pig, poultry, and rabbit nutrition (14,000 animals from 76 published trials). About 59, 37, and 4% of trials have been conducted in pigs, poultry, and rabbits, respectively. UN level was negatively correlated to main performance traits (Pearson Correlation Coefficient [PCC] of −0.98 and −0.76, for average daily gain and feed conversion ratio, respectively), and lower UN level was related to higher milk yield and concentration. High level of UN was positively correlated to N excretion (PCC = 0.99) and negatively correlated to protein retention (PCC = −0.99). Therefore, UN in blood seems to be a proper indicator of amino acid imbalance in monogastric animals. Great variability in the use of UN was observed in the literature, including uses as determination medium (blood, plasma, or serum), units, and feeding system used (ad libitum or restricted), among others. A standardization of the methods in each of the species, with the aim to harmonize comparison among works, is suggested. After review, UN measurement in plasma and, whenever possible, the utilization of the same nutritional methodology (ad libitum conditions or restriction with blood sampling after refeeding at standardised time) are recommended. More studies are necessary to know the potential of UN and other bioindicators for amino acid deficiencies evaluation to get closer to the ideal protein concept. [ABSTRACT FROM AUTHOR]

The paper emphasizes the importance of not only the quantitative but also qualitative composition of protein in nutrition. The authors propose protein classification into three main groups according to the concept of reference (ideal) protein. A mathematical model is examined to solve the task of rational mixture production upon the given profile of reference protein. Two variants of the criterion for formation of optimal composition are described. One of them presents the classical sum of squares of the residual for essential amino acid scores and 1. The second also presents the sum of squares of the residual for essential amino acid scores and 1 but with regard to only those amino acids, which scores are less than 1. The minima of these criteria at the set of variants for the content of ingredients are taken as targeted functions. The algorithm and the program of calculation were realized in the program environment Builder C++ 6.0. The macro flowchart of the algorithm is presented and detailed description of each block is given. The program interface before and after the start of the calculation module is shown. The main windows and interpretation of the presented data are described. An example of realization of the proposed mathematical apparatus when calculating a food model composition is given. Plant components (white kidney beans, flax, peanut, grit “Poltavskaya», dry red carrot) were used as an object of the research. Most plant proteins were incomplete. It is possible to regulate the chemical composition including correction of a protein profile by combination of plant raw materials. Analysis of alternative variants demonstrated that minimum essential amino acid score in the first composition was 0.79 (by the first criterion), in the second 1.0 (by the second criterion); the reference protein proportion in the mixture was 10.8 and 13.5, respectively, according to the first and second criterion. The comparative results by other quality indicators for protein in the mixture are also presented: the coefficient of amino acid score difference (CAASD), biological value (BV), coefficient of utility, essential amino acids index (IEAA).

This study shows the effects of feeding low protein (LP) diets with different energy-to-protein ratios were evaluated on the production parameters, carcass composition, meat quality, nitrogen retention, and excreta composition of broilers. A total of 576-day-old Ross 308 broilers were fed a control diet (C) and three LP diets containing 1.5% less crude protein than diet C for 41 days. The LP1 treatment was isocaloric with diet C, while the dietary apparent metabolizable energy corrected by nitrogen (AMEn) levels in the case of the LP2 and LP3 treatments were reduced by 1.5% and 3%, respectively. The LP diets were supplemented with six crystalline essential amino acids (AA) to meet the standardized ileal digestible AA requirements of broilers. The LP1 treatment did not affect the performance parameters of broilers and increased the breast meat yield, the nitrogen retention and decreased drip loss of breast meat and the total-N and uric acid-N nitrogen excretion of birds in comparison with the C group. Although the energy-reduced LP2 and LP3 diets resulted in lower final body weight, they did not affect the carcass composition, breast meat quality, nitrogen retention, and excreta composition of birds compared with the control treatment.

The current experiment was conducted to evaluate the effects of digestible threonine (dThr) on performance, egg quality, blood metabolites, and immune responses in laying hens fed a wheat-based diet during the second cycle. Also, dThr requirements were determined based on nutrient dose-response data. A total of 384, 105-week-old post-molt Hy-line-W36 laying hens were allocated to six groups, 0.02% increments, ranging from 0.44 to 0.54% dThr, with eight replicates/treatment and eight birds each, from 105 to 116 wk. By increasing, dThr levels improved egg weight with a linear trend (p

Abstract The objective of this study was to evaluate the effects of different levels of digestible lysine, at fixed amino acid ratios, in performance, blood parameters and diet digestibility of barrows from 15 to 30 kg. Fifty barrows of the Duroc breed with an average initial body weight of 14.95±3.22 kg were assigned to five treatments in a completely randomized experimental design with five replicates and of two animals per experimental unit. Treatments consisted of crude protein and lysine levels, maintaining a fixed ratio with the other digestible amino acids (8.4, 9.4, 10.4, 11.4, and 12.4 g kg–1lysine/kg of diet). The feed conversion decreased linearly according to lysine levels. The apparent digestibility coefficients of dry matter and crude protein increased linearly, and the same response was observed for serum total protein and urea. The results indicate that digestible lysine level for Duroc barrows in the starter phase is 12.4 g kg–1 of diet, as it improved feed conversion ratio and apparent nutrient digestibility.

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We recently described general principles for designing ideal protein structures stabilized by completely consistent local and nonlocal interactions. The principles relate secondary structure patterns to tertiary packing motifs and enable design of different protein topologies. To achieve fine control over protein shape and size within a particular topology, we have extended the design rules by systematically analyzing the codependencies between the lengths and packing geometry of successive secondary structure elements and the backbone torsion angles of the loop linking them. We demonstrate the control afforded by the resulting extended rule set by designing a series of proteins with the same fold but considerable variation in secondary structure length, loop geometry, β-strand registry, and overall shape. Solution NMR structures of four designed proteins for two different folds show that protein shape and size can be precisely controlled within a given protein fold. These extended design principles provide the foundation for custom design of protein structures performing desired functions.

ABSTRACT: Adequate pullet nutrition is essential to reach BW and suitable body composition for reproduction. An experiment was conducted to determine the effects of 4 dietary amino acid (AA) levels on BW, flock uniformity, body conformation, organ, leg, and feathering development of broiler breeder pullets during the rearing phase from 5 to 24 wk. A total of 1,360 Cobb-500 slow-feathering (SF) pullets were randomly placed in 16-floor pens with 85 females per pen. Diets with corn, soybean meal, and wheat-midds were formulated without protein restriction maintaining minimum ratios between essential AA and Lys on a digestible (dig) ideal basis. Treatments consisted of 4 dietary AA levels with 80% (low-AA), 90% (moderate-AA), 100% (standard-AA), and 110% (high-AA) of the Cobb-Vantress recommendations guided by dig Lys using balanced protein. Up to 4 wk, all pullets were fed a common starter crumble diet. Grower and developer mash diets were fed to pullets from 5 to 15 wk and from 16 to 24 wk, respectively. Pullets fed standard-AA and high-AA diets were heavier (P < 0.001) than those fed low-AA diets at 10, 15, and 20 wk of age. High-AA diets resulted in better (P = 0.040) flock uniformity at 10 wk. Pullets fed a high-AA diet had the highest (P = 0.041) relative breast weight at 20 wk of age and the lowest (P = 0.044) deposits of abdominal fat at 15 wk of age. Fleshing increased (P < 0.05) as AA content rise in the diet, while the relative shank length (P < 0.001) and the number of wing juvenile feathers (P = 0.004) decreased. Pullets fed the lowest dietary AA level had the longest (P = 0.007) small intestine relative to BW at 10 wk of age, but a smaller (P = 0.001) liver than those fed moderate and standard-AA diets at 20 wk of age. Dietary AA levels have important effects on pullet BW, fleshing, and organ development during rearing with potential reproductive performance impacts.

The ideal protein concept refers to dietary protein with an amino acid profile that exactly meets an animal’s requirement. Low-quality protein levels in the diet have negative implications for productive and reproductive traits, and a protein oversupply is energetically costly and leads to an excessive N excretion, with potentially negative environmental impact. Urea Nitrogen (UN), which corresponds to the amount of nitrogen in the form of urea circulating in the bloodstream, is a metabolite that has been widely used to detect amino acid imbalances and deficiencies and protein requirements. This review aims to critically analyse how UN can contribute to accurately implementing the ideal protein concept in monogastric animals, particularly in pig, poultry, and rabbit nutrition (14,000 animals from 76 published trials). About 59, 37, and 4% of trials have been conducted in pigs, poultry, and rabbits, respectively. UN level was negatively correlated to main performance traits (Pearson Correlation Coefficient [PCC] of −0.98 and −0.76, for average daily gain and feed conversion ratio, respectively), and lower UN level was related to higher milk yield and concentration. High level of UN was positively correlated to N excretion (PCC = 0.99) and negatively correlated to protein retention (PCC = −0.99). Therefore, UN in blood seems to be a proper indicator of amino acid imbalance in monogastric animals. Great variability in the use of UN was observed in the literature, including uses as determination medium (blood, plasma, or serum), units, and feeding system used (ad libitum or restricted), among others. A standardization of the methods in each of the species, with the aim to harmonize comparison among works, is suggested. After review, UN measurement in plasma and, whenever possible, the utilization of the same nutritional methodology (ad libitum conditions or restriction with blood sampling after refeeding at standardised time) are recommended. More studies are necessary to know the potential of UN and other bioindicators for amino acid deficiencies evaluation to get closer to the ideal protein concept.

Summary: This review, a summation of work presented at the Virtual 2020 Poultry Science Association Annual Meeting, addresses changes in laying hen performance and techniques to manage hens that require fine-tuning amino acid minimums. A look at past literature on amino acid responses in layers is presented. In addition, formulation trends are assessed with reference to sustainability. And finally, the rise of sustainable egg operations in the third world (e.g., One Egg) whereby vegetable protein for hens provides essential amino acids in the form of eggs to diets of people in poverty-stricken areas is discussed.A literature review in laying hens was conducted by assessing ideal protein citations, amino acid requirement citations, and 2 meta-analysis citations. It is concluded that as dietary CP trends downward that ideal protein research should continue to be conducted in diets that mimic practice, which are first limiting in Lys and are second limiting in the amino acid nutrient ratio in question. Furthermore, as CP continues to be lowered, care must be taken with the Leu nutrient minimum in the diet of hens whereby corn is the primary cereal, and subsequent assessments of Val and Ile in such diets warrant attention. Taken as a whole, meeting, rather than exceeding, amino acid needs of hens will allow for less dietary nitrogen inputs resulting in less environmental waste.

Precision nutrition in broilers requires tools capable of identifying amino acid imbalances individually or in groups, as well as knowledge on how more digestible proteins can be designed for innovative feeding programs adjusted to animals’ dynamic requirements. This work proposes two potential tools, combining traditional nutrition with biotechnological, metabolomic, computational and protein engineering knowledge, which can contribute to improving the precise amino acid nutrition of broilers in the future: (i) the use of serum uric nitrogen content as a rapid biomarker of amino acid imbalances, and (ii) the design and modeling of de novo proteins that are fully digestible and fit exactly to the animal’s requirements. Each application is illustrated with a case study. Case study 1 demonstrates that serum uric nitrogen can be a useful rapid indicator of individual or group amino acid deficiencies or imbalances when reducing dietary protein and adjusting the valine and arginine to lysine ratios in broilers. Case study 2 describes a stepwise approach to design an ideal protein, resulting in a potential amino acid sequence and structure prototype that is ideally adjusted to the requirements of the targeted animal, and is theoretically completely digestible. Both tools can open up new opportunities to form an integrated framework for precise amino acid nutrition in broilers, helping us to achieve more efficient, resilient, and sustainable production. This information can help to determine the exact ratio of amino acids that will improve the efficiency of the use of nitrogen by poultry.

The current experiment was conducted to evaluate the effects of digestible threonine (dThr) on performance, egg quality, blood metabolites, and immune responses in laying hens fed a wheat-based diet during the second cycle. Also, dThr requirements were determined based on nutrient dose-response data. A total of 384, 105-week-old post-molt Hy-line-W36 laying hens were allocated to six groups, 0.02% increments, ranging from 0.44 to 0.54% dThr, with eight replicates/treatment and eight birds each, from 105 to 116 wk. By increasing, dThr levels improved egg weight with a linear trend (p <.01), and egg production (EP), egg mass (EM), and feed conversion ratio (FCR) with quadratic trends (p <.05). Hens fed diet contained 0.48% dThr, dThr/digestible Lys (dLys) of 66% showed the best egg production traits. However, feed intake, egg quality traits, blood metabolites, and immune responses were unaffected by dThr levels. Based on the quadratic broken‐line regression models, the dThr requirements of laying hens during the second production cycle for optimised the EP, EM, and FCR were estimated at 507, 514, and 520 mg/hen per day, respectively. These values correspond to 9.84–10.1 mg/g of EM. It is concluded, in the laying hens fed a wheat-based diet during the second cycle, the dietary dThr level of 0.48%, dThr/dLys of 66%, and a daily intake of 520 mg dThr/bird are adequate for optimised performance. The amino acids requirements of laying hens vary depending on trait is considered for optimisation. The dThr requirement estimated for FCR was higher than those for EP and EM. In the laying hens that feed a wheat-based diet during the second cycle. A dietary digestible threonine concentration of 0.48% and a daily intake of digestible threonine 520 mg/bird are adequate for optimised performance. [ABSTRACT FROM AUTHOR]

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Abstract Background Major 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. Methods A 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. Results Level of VFA tended to be greater in 2012 than 2007 group. Among VFAs, 2012 group had greater (p

• Quails fed different tryptophan:lysine ratios showed genotype x environment interaction for slaughter weight, thigh + leg yield. • Genetic values varying according to the different tryptophan:lysine ratios in the diet. • Increasing of heritabilities and additive genetic variances estimates were observed according to the increasing of tryptophan:lysine. • Presence of genotype x environment interaction in the LF2 quails strains. Quails raised under different nutrition levels could lead to genetic variation affecting the genetic gain due to the genotype by environment (GxE) interaction. Thus, reaction norm models were carried out to evaluate the GxE interaction of two meat quails' strains (LF1 and LF2) raised under different tryptophan:lysine ratios for body weight and carcass traits. A total of 590 and 587 meat quails for LF1 and LF2, respectively, were raised under five different tryptophan:lysine ratios (0.15, 0.20, 0.25, 0.30 and 0.35) in final growth phase diet. The tryptophan:lysine ratios exhibited an important influence on the genetic parameters of body weight and carcass traits. Heritability and additive genetic variance estimates increased as tryptophan: lysine ratios increased, except for body weight at 28 and 35 days in LF2 strain. Lower correlation estimates and re-ranking of estimated breeding values were observed for slaughter weight, breast weight and thigh + leg yield in LF2 strain and for carcass yield in LF1 strain. It indicated a striking effect of amino acid ratios in quail carcass traits. The genetic evaluation and selection for carcass trait in quail strains raised under different tryptophan:lysine ratios should be considered in quail breeding programs. [ABSTRACT FROM AUTHOR]

Objective. To evaluate the reduction of crude protein levels, without altering the ratio of essential amino acids, of free-range chickens, of one at 42 days old. Materials and methods. Two trials were performed comprising the initial phase (one to 21 days) and growth (22 to 42 days). A total of 630 chicks of the Redbro line of one day old, were distributed in a completely randomized design with five treatments and six replicates of 21 birds each, totaling 30 experimental units consisting of a shelter area and corrals. The levels reduced of crude protein for the initial phase were: 21.5, 21.0, 20.5, 20.0 and 19.5% and for the growth phase: 19.0, 18.5, 18.0, 17.5 and 17.0%. In all the treatments were maintained the minimum ratio between essential amino acids and lysine. The performance characteristics evaluated were: weight gain, feed intake and feed conversion. Results. There was no effect (p>0.05) of the crude protein reduction for any of the variables in all phases, except for feed conversion (p<0.05) that improved with 18.20% in the growth phase. Conclusions. Crude protein levels for chickens of the Redbro line, can be reduced to 19.5% and 18.2% for the initial and growth phases, respectively, provided that the ideal amino acid ratios are maintained with digestible lysine and meet the requirements of limiting amino acids. [ABSTRACT FROM AUTHOR]

Abstract Given tilapia grown in the biofloc technology production system can consume the biofloc, it should be possible to optimize formulated diet protein content to account for nutrition derived from consuming biofloc. The present study, conducted in an outdoor biofloc technology production system, evaluated impacts on fish production indices, common microbial off-flavors, and water quality dynamics for hybrid tilapia (Oreochromis aureus × O. niloticus) fed diets formulated to contain 22.5%, 27.7%, and 32.3% digestible protein (DP) and 6% lipid. Fingerlings (32.2 ± 10.1 g/fish) were stocked in tanks (18.6 m2; 16.6 m3) in May 2016 at 25/m2 (29/m3) and grown for 5 months to market size. At harvest, fish fed the 22.5% DP diet were significantly smaller (518 g/fish) and had significantly higher feed conversion (1.5) than those fed the higher DP diets (553–564 g/fish and 1.4, respectively). Feed nitrogen input and nitrification rate increased linearly with increased DP. Results of this study suggest that by using ideal protein theory to formulate diets supplemented with the first four limiting amino acids (Lys, Met, Thr, Ile) digestible protein can be reduced from 32.3% to 27.7% without adversely affecting hybrid tilapia productivity indices. Market size distributions, nutrient retention, 2-methylisoborneol and geosmin off-flavors, and pond water quality dynamics in relation to diet DP also are discussed. Highlights • Dietary intact digestible protein for tilapia in the biofloc system may be reduced from 32.3% to 27.7%, but not to 22.5%. • Market-size frequency distribution of tilapia fed the 22.5% digestible protein diet was skewed toward smaller size classes. • Fillets of tilapia grown in an outdoor biofloc technology production system were tainted by 2-methylisoborneol and geosmin. [ABSTRACT FROM AUTHOR]

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Epigenetic changes regulate gene expression and depend of external factors, such as environment and nutrition. In pigs, several studies on protein nutrition have been performed to improve productive and reproductive traits. Indeed, these studies aimed not only to determine broad protein requirements but also pigs’ essential amino acids requirements. Moreover, recent studies tried to determine these nutritional requirements for each individual, which is known as protein precision nutrition. However, nutritional changes could affect different epigenetic mechanisms, modifying metabolic pathways both in a given individual and its offspring. Modifications in protein nutrition, such as change in the amino acid profile, increase or decrease in protein levels, or the addition of metabolites that condition protein requirements, could affect the regulation of some genes, such as myostatin, insulin growth factor, or genes controlling cholesterol and glucose metabolism pathways. This review summarizes the impact of most common protein nutritional strategies on epigenetic changes and describes their effects on regulation of gene expression in pigs. In a context where animal nutrition is shifting towards precision protein nutrition (PPN), further studies evaluating the effects of PPN on animal epigenetic are necessary.

We determined if ideal protein (IP) fishmeal-free (FMF) or all-plant protein (PP) diets of available ingredients satisfied production needs of hybrid striped bass (HSB; Morone chrysops x M. saxatilis) grown to market size in ponds managed according to industry practices, and if phytase (Phy) superdosing (20,000 FTUs) could alleviate inorganic phosphorus supplementation. An off-the-shelf commercial feed (COM), an IP control diet containing 16% fishmeal (FM), and four IP test diets with or without phytase superdosing (FMF, FMF + Phy, PP, PP + Phy) were evaluated. Inorganic phosphorus was excluded from phytase treated diets. Hybrid striped bass (averaging 344 g/fish) were stocked (5187 fish/ha) in 4 ponds/diet (0.1 ha) and grown for 5.5 months. Most responses of the five ideal protein diets did not differ significantly (P > 0.1) from the COM. Only net fish yield, weight gain, and FCR of the PP diet were less than those of the COM diet. Fish fed FMF and FMF + Phy diets had higher fish yields, mean weights, and gains than PP and PP + Phy diets. FMF ponds had fewer than expected large (907–1134 g) and more jumbo (>1135 g) fish and FMF + Phy ponds had fewer medium (680–906 g) and more large fish. PP ponds had fewer than expected jumbo fish. The COM diet resulted in larger livers (HSI), lower muscle ratio, but less feed phosphorus added to ponds compared to the FM diet. Absence of differences for other responses confirms the FM diet is a valid proxy for the COM diet. Phytase increased energy and protein retention of the PP diet but not the FMF diet. FM can be replaced with animal and/or plant proteins exclusively without major reductions in hybrid striped bass performance. The PP diet likely requires optimization of Met and branched chain amino acid levels to improve performance. Inorganic phosphorus can be replaced by diet phytase top-coating and judicious inclusion of phytate‑phosphorus without negative impact on HSB production. Phytase superdosing of the FMF and PP diets did not improve production variables but did improve mineral retentions, more so for the PP diet. Phytase superdosing reduced feed phosphorus fed by 60% and pond phosphorus loading by 40% but requires optimization of inclusion levels and economic evaluation before recommendation. • Hybrid striped bass can be grown to market size on an all-plant protein diet. • Dietary fishmeal was replaced totally by plant proteins or animal plus plant proteins. • Dietary inorganic P was replaced totally by phytase top-coating. • Dietary phytase reduced feed P fed by 60% and pond P loading by 40%. [ABSTRACT FROM AUTHOR]

ABSTRACT: The objective was to estimate the most appropriate digestible methionine + cysteine:lysine ratios for growing meat-type quails (Coturnix coturnix) from 1 to 21 days of age. Quails were fed with a basal ration deficient in digestible methionine + cysteine, with five levels of DL-methionine, in substitution of glutamic acid and starch, resulting in digestible methionine + cysteine:lysine ratios of 0.61, 0.66, 0.71, 0.76 and 0.81. Feed and methionine + cysteine intake, body weight gain, feed conversion and uniformity were assessed. From 1 to 7 days, an increasing linear effect was observed for feed and methionine + cysteine intake, body weight gain, and uniformity, and a linear decrease for feed conversion. From 8 to 14 days, the 0.70 methionine + cysteine: lysine ratio was the best for feed intake and body weight gain, and for uniformity, the 0.75 methionine + cysteine:lysine ratio was the most appropriate. For methionine + cysteine intake and feed conversion, an increasing and decreasing linear adjustment was observed, respectively. From 15 to 21 days, an increasing linear effect was observed for feed and methionine + cysteine intake and body weight gain; a decreasing linear effect was observed for feed conversion. The 0.81 ratio was the most efficient for feed conversion during all evaluated experimental periods. In conclusion, the 0.81 dietary methionine + cysteine:lysine ratio is the most appropriate for meat-type quails during the first 21 days of age.

ABSTRACT The poultry market has changed due to a higher consumer interest on products with differentiated organoleptic characteristics, making of free-range broiler production a promising activity. This experiment was conducted to determine the digestible lysine requirements of Redbro Cou Nu male and female chickens during the starter phase (one to 21 days of age). Six hundred and thirty Redbro Cou Nu broilers were distributed into 30 pens (21 chickens/pen) according to a randomized complete design in a 5 x 2 factorial arrangement, consisting of five levels of digestible lysine and two sexes, with three replicates (pens) per treatments. Diets with increasing digestible lysine levels (8.1, 9.5, 10.9, 12.3 and 13.7 g of digestible lysine per kg of diet) were offered ad libitum. The following performance traits were evaluated at the end of the experiment (d 21): feed intake, lysine intake, body weight gain, and feed conversion ratio. No interaction between dietary lysine level and sex was observed for the evaluated traits. The effect of sex was only detected on body weight gain, while effects of dietary lysine level were only detected on the feed intake. Males presented higher body weight gain than females. Lysine intake and body weight gain increased, and feed conversion ratio decreased as the level of dietary lysine increased. The best feed conversion ratio was obtained when birds were fed 12.95 g of digestible lysine per kg of diet.

Current experiment established different criteria to evaluate the requirements of digestible isoleucine for 22- and 42-day-old broilers by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means by Duncan’s test at 5% probability. A total of 1,920 Cobb 500 male broilers were used in an entirely randomized experimental design, with 6 treatments (6 digestible isoleucine levels: 0.6118; 0.6655; 0.7192; 0.7729; 0.8265 and 0.8802%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. Level 0.7192% of digestible isoleucine was considered standard. The digestible isoleucine level recommended for 22- and 42-day-old broilers is 0.7729%, corresponding to a digestible isoleucine:lysine ratio of 72%.

This study analysed the effects of digestible lysine on the performance parameters, morphometry and quality of the breast muscle (Pectoralis major) of Cobb 500 broiler chickens aged 21 and 42 days. Two completely randomized experiments were performed, with five treatments and eight replications of 30 birds per treatment. The diets were adjusted according to the nutritional requirements for each phase of poultry development, with digestible lysine levels during the initial phase (birds aged 1 to 21 days) at 1.12, 1.19, 1.25, 1.31, and 1.37% and during the final phase (22 to 42 days) at 0.97, 1.02, 1.08, 1.13, and 1.19%. During the initial phase, lysine supplementation had a significant effect (P<0.05) on weight gain and red content in breast meat, with 1.24% and 1.29% digestible lysine resulting in maximum weight gain and red content, respectively. No significant difference (P>0.05) was observed in breast muscle morphometry, carcass yield, performance, or meat quality in birds aged 22-42 days for the different levels of lysine, suggesting that the lowest level of lysine tested did not have a negative impact on production characteristics even though it was below the recommended levels for this species. In conclusion, 1.24% digestible lysine is recommended for maximum weight gain at the initial phase of broiler chicken development (1-21 days) and 0.97% is sufficient to meet the nutritional requirements of birds at the final phase (22-42 days) without compromising production performance. [ABSTRACT FROM AUTHOR]

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The evolution of the genetic improvement of broiler strains allowed significant gains in weight gain, breast yield and feed conversion, making the poultry industry one of the most competitive production chains in the country. Considering that nutrition is responsible for the largest portion of production costs, the formulation of balanced diets is of utmost importance to provide maximum food efficiency and better productive performance. The emergence of industrial amino acids at affordable prices, allowed the elaboration of rations based on the concept of ideal protein, which aims to reduce the crude protein content of rations and provide an amino acid profile that more closely meets the needs of poultry, thus improving nutrient utilization and decreasing the excretion of dietary nitrogen in the environment. These effects provide greater economic benefits to producers and less environmental pollution. However, in order for the objectives of the ideal protein concept to be achieved, it is important to have accurate knowledge of amino acid requirements, to meet the order of limitation, and to provide an adequate balance between nutritionally essential and non-essential amino acids. Therefore, the objective of this review was to demonstrate the importance of amino acids in the formulation of broiler diets, as well as an approach to the general aspects of the first limiting amino acids for birds, being methionine and lysine. [ABSTRACT FROM AUTHOR]

In previous work, we demonstrated that diets containing 40% digestible protein (DP) (45% crude protein) and 18% lipid supplemented with Met and Lys resulted in superior performance and nutrient retentions in hybrid striped bass (HSB) compared to less energy-dense diets when rearing HSB at temperatures similar to the summer growing period of the Southern U.S. The current work was aimed at vetting previous results in pond production of market-size HSB at commercial stocking densities to assess impacts on fish production indices and water quality parameters. Diets were formulated to contain digestible protein levels ranging from 41% to 35% DP and 15% crude lipid. The trial was conducted during the hottest portion of the growing season when impacts of feeding have the greatest influence on pond water quality. The 6-month pond (0.1 ha; 0.25 ac) study began with advanced juveniles (121.4 ± 3.21 g/fish; mean ± SD) in May 2013 and concluded with market sized fish in October 2013. Final fish size ranged from 448 ± 24 g to 1122 ± 46 g with food conversions ranging from 1.34–1.37. Results suggest that DP can be lowered from 41% DP to 35% DP by careful diet formulation while supplementing the first three limiting amino acids (Met, Lys Thr) without detrimental changes to body composition or nutrient retentions. Market size distributions, nutrient retention, and pond water quality dynamics in relation to test diets are also discussed. [ABSTRACT FROM AUTHOR]

The objective with this study was to determine the influence of the digestible arginine: lysine ratio in the diet of laying Japanese quails raised in hot weather on the physiological variables of thermoregulation, time in tonic immobility, behavior and nitrogen utilization. A total of 240 laying quails (Coturnix coturnix japonica) with 40 weeks of age were used in a completely randomized design with five treatments and six replications containing eight quails per experimental unit. The studied digestible arginine: lysine ratios were 110%; 120%, 130%, 140% and 150%, for 63 days divided into three periods of 21 days each. There was a quadratic effect (p < 0.05) for the variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface temperature gradient observed in the morning. In the afternoon, a quadratic effect (p < 0.05) of the arginine: lysine ratio was observed for variables average surface temperature, average body temperature, core to surface thermal gradient, ambient to surface thermal gradient, back temperature, head temperature and respiratory frequency. There was no significant effect (p > 0.05) of arginine: lysine ratios on the frequency of behaviors, except drinking and panting (p < 0.05), for which 130% ratio provided the lowest frequencies of these behaviors. There was a quadratic effect (p < 0.05) for the parameters of nitrogen retention, nitrogen excreted and nitrogen retention efficiency. Nitrogen intake and excreta moisture were not influenced by the different relationships studied (p > 0.05). The 130% arginine: lysine ratio corresponding to 0.131 g/kg/feed of arginine improves physiological responses related to thermoregulation and decreases the expression of behaviors correlated to heat stress, also meeting the best estimated ratio for nitrogen retention in the diet of quails laying Japanese raised in hot weather. • The arginine: lysine ratio alters physiological homeothermy responses. • Excess lysine and arginine decreases nitrogen retention and increases nitrogen excretion. • Arginine supplementation respecting the relationship with lysine benefits animal welfare. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of digestible lysine levels in diets with or without supplementation of industrial amino acids on performance, carcass characteristics and nitrogen excretion in broilers of 22 to 42 days of age. Birds were distributed in a completely randomized experimental design in a 4 × 2 factorial arrangement, with four digestible lysine levels (9.0, 10.0, 11.0 and 12.0 g/kg) and two methods to obtain the lysine levels (variation in the proportion of corn and soybean meal, without supplementation; or supplementation of industrial amino acids), eight replicates and 20 birds per replicate. There was an interaction effect on the performance characteristics and on the weights and yields of prime cuts. In both diets, feed conversion improved linearly as the lysine levels were increased. Feed intake; weight gain; carcass, thigh and drumstick weights; and boneless breast yield increased and abdominal fat reduced linearly as the lysine levels were increased in the unsupplemented diet. The lysine levels of the supplemented diets linearly reduced the yield of drumstick and quadratically reduced the yields of bone-in and boneless breast up to the estimated levels of 10.4 and 10.7 g/kg, respectively. Diets without supplementation increased the excretion and retention of nitrogen. The levels of 9.0 and 12.0 g/kg digestible lysine obtained with supplementation of industrial amino acids and without it, respectively, provide the best performance and yield of prime cuts in the birds. Diets in which the digestible lysine levels are obtained without supplementation provide better performance responses and carcass characteristics compared with supplemented diets.

The European pikeperch, Sander lucioperca (L.) is a valuable species in aquaculture, and its nutritious meat is highly regarded by consumers. The contents of indispensable dietary amino acids (IDAA) in pikeperch fillets is higher than in other fish species and exceed the adult recommended daily allowance of them. Increasingly, the fish meal and soya protein components of fish feed are being replaced with protein from brewer's yeast, Saccharomyces cerevisiae. The aim of this study was to determine the fatty acid profiles of juvenile pikeperch fed feeds supplemented with yeast extract and to determine the IDAA requirements of this species using the ideal protein method. It was demonstrated that supplementing feed with yeast extract did not have a significant impact on nutrient accumulation in the fish. Pikeperch requirements for exogenous amino acids is similar to that of rainbow trout at 26.2 g 100 g-1protein. Commercial feeds used in pikeperch culture contain sufficient quantities of essential amino acids.

Two experiments were carried out to evaluate the reduction of crude protein (CP) in diets supplemented with synthetic amino acids for piglets of 15 to 30 kg. In the performance assay (Exp I), 60 piglets with initial weight of 15.34±0.87 kg and final weight of 30.08±1.59 kg were distributed in a randomized block design with six replicates, five treatments and two animals per experimental unit. The treatments consisted of five diets in which the CP was reduced by 1.5 percentage points, resulting in low-protein diets (19.24, 17.74, 16.24, 14.74 and 13.24%), meeting the requirements of amino acids with inclusion of L-lysine, DL-methionine, L-threonine, L-tryptophan, L-valine and L-isoleucine. The average daily gain and feed conversion according to the Linear Response Plateau model (LRP) were estimated at 14.23 and 14.79% of CP, respectively. As the CP levels were reduced, there was an increase in the essential:non-essential amino acids ratio. The plasma urea concentration decreased linearly, indicating that there was a better use for amino acids with the CP reduction. In the nitrogen balance (Exp II), 30 crossbred barrow piglets with average weight of 21.69±4.46 kg were housed in metabolic cages, distributed in a completely randomized design with five treatments and six replicates, and the experimental unit consisted of a piglet. The biological protein value in the diets remained above the ideal (70%), in which the level of 13.24% CP corresponded to the highest value. There was no difference in levels of urea in blood and urine. Reduction of protein levels is efficient in decreasing the pollution effect in the excreta, with lower nitrogen excretion in feces and urine.

Two experiments were performed to determine the influence of threonine-lysine (Thr:Lys) ratio on requirements of digestible lysine (Lys) in low crude protein diets for broilers in the growth phase. In the first experiment, a total of 480 Cobb 500 male broilers were distributed in a completely randomized experimental design with four dietary Thr:Lysratio (57.0; 60.5; 64.0 and 67.5%) and with five replicates of 24 birds each. No significant differences were reported in weight gain, feed intake, poultry manure humidity, carcass and meat yields. However, the feed conversion was increased linearly as dietary Thr:Lysratio was increased. In the second experiment, a total of 400 Cobb 500 male broilers were distributed in a completely randomized experimental design with four digestibleLyslevels (1.005, 1.045, 1.085 and 1.125%), and with four replicates of 25 birds each. No significant differences were reported in performance, poultry litter humidity and carcass and meat yields. Lys levels of 1.005% and Thr:Lysat 57% were sufficient to maximize the performance and carcass yield of broilers during the growth phase when fed on low crude protein diets.

This study aimed to evaluate the performance of laying hens subjected to heavy semi-low crude protein (14.0%) and lysine levels while maintaining the same relation of digestible amino acid/ digestible lysine. A commercial line of 420 Isa Brown laying hens, in the period from 28 to 44 weeks of age, were distributed in 42 experimental plots. A completely randomized design with six treatments and seven replicates in four periods of 28 days/each was used. The treatments were: Control - Formulated according to the nutritional requirements proposed in the strain, containing 16.92% crude protein, 0.750% digestible lysine. Treatments 1 to 5, with crude protein levels of 14% and 0.600% of digestible lysine, 0.675%, 0.750%, 0.825% and 0.900%, respectively. The requirement of lysine, in relation to other digestible amino acids, can be estimated at 0.750% in diet with 14% crude protein, which corresponds to the average daily intake of 876 mg lysine dig. hen-1 day-1, without compromising the performance of hens.

A total of 1.500 male Cobb 500 broilers were used to determine the optimal digestible lysine level for 18 to 40-day-old broilers. The experimental period started when broilers were 18 days old and had an initial average weight of 737 ± 20 g. A completely randomized experimental design was applied, with five lysine levels, totaling five treatments with 10 replicates of 30 birds each. The experimental diets contained equal energy and protein levels, and 0.86, 0.95, 1.04, 1.13, and 1.22% digestible lysine. The following parameters were evaluated: average body weight at 40 days of age, daily weight gain, daily feed intake, feed conversion ratio, carcass yield and parts yield, and abdominal fat percentage. There was a quadratic effect (p

Current experiment established different criteria to evaluate the requirements of digestible valine for broilers from 22 and 42 days of age, by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means byDuncantest at 5% probability. A total of 1,920 Cobb 500 male broilers were used and distributed in an entirely randomized experimental design, with 6 treatments (6 digestible valine levels: 0.7192, 0.7729, 0.8265, 0.8802, 0.9339 and 0.9876%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. The level of 0.8265% digestible valine was considered standard. The inclusion of 0.816, 0.848 and 0.903% of digestible valine levels, corresponding to digestible valine:lysine ratios of approximately 76.00%, 79.00% and 84.12%, provided best feed intake, weight gain and feed conversion ratio, respectively for broiler from 22 to 42 days of age.

A 12-week trial was performed with rainbow trout ( Oncorhynchus mykiss) utilizing combinations of ingredients at two nutrient targets. Ingredient combinations were fishmeal-based diet (FMD), animal product-based diet (APD), plant product-based diet (PPD), novel plant-based diet (NPD) and potential future plant-based diet (FPD). Two nutrient concentrations were targeted: 1) to meet published amino acid targets for rainbow trout utilizing approximately 450 g/kg crude protein (400-420 g/kg digestible protein) and 2) to meet the amino acid targets based on ideal amino acid balance of trout muscle for Lys, Met and Thr utilizing approximately 400 g/kg crude protein (370-380 g/kg digestible protein). Interactive effects between ingredient combination and nutrient concentration occurred across all response variables. When diets were formulated to Target 1, fish consuming FMD and APD displayed better weight gain and feed conversion ratio (FCR) than plant-based diet, while graded effects were found within the plant-based treatments. When differing ingredient combinations were utilized and formulated to Target 2, fish grew equally well except for the NPD treatment which supported lower growth and higher FCR. Based on the data from the current experiment, one can completely remove fishmeal from trout feeds and reduce protein levels when dietary digestible amino acids are balanced. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of digestible lysine levels in diets with and without supplementation of industrial amino acids on performance and fat deposition in the carcass of broilers in the starter phase. One thousand four hundred and forty chickens with initial weight of 168.1±5.0 g were distributed in a completely randomized experimental design, in a 5 × 2 factorial arrangement, composed of five digestible lysine levels (10.0, 11.0, 12.0, 13.0 and 14.0 g/kg) and two types of diet (diet with different proportions of corn and soybean meal and diet supplemented with industrial amino acids to obtain the digestible lysine levels), with eight replications and 18 birds per replication. There was interaction effect only on weight gain and fat deposition in the birds. The lysine levels reduced feed intake linearly in both diets, but caused a linear increase in lysine intake. The lysine levels quadratically affected weight gain and feed conversion, which improved up to the estimated levels of 13.0 and 12.8 g/kg lysine, respectively, when the corn:soybean meal ratio of the diet changed. In the diets supplemented with amino acids, the lysine levels increased weight gain and improved feed conversion linearly. Regardless of the type of diet, protein deposition increased linearly, whereas fat deposition reduced also linearly, as the lysine levels in the diets were increased. The levels of 13.0 and 14.0 g/kg digestible lysine provide, respectively, the best performance in birds fed a diet in which the proportion of corn and soybean meal varies and a diet supplemented with industrial amino acids, in the period from 8 to 21 days of age.