Digestible Amino Acid Requirements Research Articles

Assessment of digestible amino acid requirement in White leghorn Layers based on production performance at low protein levels in diet

To understand the optimal requirement of d.lysine and threonine in White Leghorn (WL) layers (25-44 weeks), two independent experiments were executed. For the d. lysine study, birds (N=528) were categorized into eleven dietary groups (11×6×8) and were fed with two different protein levels (13.36 and 15.78%) each containing five concentrations of d. Lys. To optimize d. Thr, layers (N=390) were allotted to thirteen groups (13×5×6) in these diets were formulated by fixing the lysine concentrations at 0.65 and 0.60% with 13.36 and 15.78% protein levels respectively. Threonine was supplemented in both diets at graded levels of lysine. Basal diets with 0.70% lysine and 17% protein; threonine at 66% lysine served as corresponding controls. Egg production response to supplemental d. Lys was quadratic. Net feed efficiency and egg mass indices response were in both linear and quadratic. Supplementation of diets with Thr, the response of egg production was linear whereas, it was both linear and quadratic for economic parameters. In conclusion, supplementation of d. Lys at 0.65 and 0.60%; 69 and 72% d. Thr as % of d. Lys at low and high protein diets is optimal for better egg production with economic efficiency in WL layers in the tropics.

Hygienic pelleting can decrease Hubbard × Ross 708 apparent ileal amino acid digestibility, broiler performance, and increase digestible amino acid requirement

To reduce pathogenic bacteria such as Salmonella in feed and ensure a high-quality pellet, diets for broilers, turkeys, and breeders may be pelleted using high conditioning temperatures and extended times. However, increased conditioning temperature and time may alter amino acid conformation regarding secondary and tertiary structure, decrease digestibility and subsequent bird performance, and necessitate increased amino acid formulation density. The objective of this study was to evaluate increased conditioning temperature and exposure time within the pelleting process using a hygienizer (hygienic pelleting) in diets that vary in digestible lysine and corresponding amino acid ratio on Hubbard × Ross 708 starter broiler performance, apparent ileal amino acid digestibility (AIAAD), and requirement. A 5 × 2 factorial arrangement of treatments with 5 levels of digestible lysine (−20, −10%, 2019 Ross Broiler Starter Nutrition recommendation, +10, and +20%) and 2 techniques of pelleting (standard and hygienic) was utilized in a randomized complete block design. Standard pelleting utilized 77°C conditioning for 30 s and hygienic pelleting utilized 88°C conditioning for 60 s and 6-min retention time in a hygienizer. Each treatment was fed to 12 replicate pens of 10 male broiler Hubbard × Ross 708 chicks for a 21-day period. Standard pelleting and hygienic pelleting demonstrated a 1.19 and 1.37% digestible Lys requirement, respectively, using the 2 straight line, 1-breakpoint broken-line regression model. Performance data, AIAAD, and the broken-line regression model suggest an approximate 10% increase in digestible Lys and corresponding amino acid ratio relative to 2019 Ross Broiler Starter Nutrition Specifications for Hygienic Pelleting. Nutritionists should be cognizant that nutritional detriment may accompany procedures used to create hygienic pelleted feed.

Unresolved issues for amino acid digestibility in poultry nutrition

Summary The purpose of this article is to review and discuss several issues concerning amino acid digestibility in poultry nutrition which are not totally resolved. Some issues are more resolved than others. These issues are as follows: Which method should be used to determine amino acid digestibility? Are amino acid digestibility values determined with cecectomized roosters similar to and interchangeable with broiler chicken ileal digestibility values? Should apparent or standardized amino acid digestibility values be used in feed formulation (which is preferable?)? which type of basal endogenous amino acid correction should be used for standardized amino acid digestibility values? Which type of indigestible marker should be used and how should digestibility values be calculated when using a marker? What to do about the effect of bird age on amino acid digestibility in feed formulation? And, what values should be used for digestible amino acid requirements?

Total versus digestible amino acid requirements for growth and nutrient utilization of naked neck broilers during finishing phase

Total versus digestible amino acid requirements for growth and nutrient utilization of naked neck broilers during finishing phase

Amino acid requirements of broiler breeders at peak production for egg mass, body weight, and fertility

Two trials were conducted to determine the amino acid and protein requirements of broiler breeders at peak production. In trial 1, 32-wk-old Cobb 500 broiler breeders with similar BW were selected to determine the digestible amino acid requirement for daily product output (g of egg mass + g of BW gain/b/d) and feed conversion (g of feed/g of product) for Met, Phe, Arg, Ile, Lys, and CP in a 42-d production study. In trial 2, 30-wk-old Cobb 500 broiler breeders were selected to determine the digestible requirement for Met, Lys, Ile, Arg, Cys, Val, Trp, and Thr in a 70-d production study. Breeders were given a corn-soy basal diet plus crystalline amino acids with 8 graded levels of amino acids (10 birds per level), representing 40 to 130% of the highest suggested requirements reported in the literature. All other amino acids were maintained at 100% of their suggested requirement level. All breeders were inseminated weekly and fertility was determined. A third trial consisted of 41-wk-old colostomized hens randomly assigned to 1 of 2 diets differing only in the amount of Ile. Urine was collected after a 6-wk feeding period. The average digestible requirements per breeder per day for both product and feed/product ratio from trials 1 and 2 for Met, Cys, TSAA, Phe, Phe + Tyr, Trp, Arg, Ile, Lys, Val, Thr, and CP were 424, 477, 901, 689, 997, 252, 1,026, 830, 916, 799, 613 mg/d, and 20.0 g/d, respectively. The ideal profile for digestible Met, Cys, TSAA, Phe, Phe + Tyr, Trp, Arg, Ile, Lys, Val, and Thr was 46, 52, 98, 76, 108, 28, 112.0, 91, 100.0, 87, and 67%, respectively. A significant decrease in fertility was noted with increasing levels of Ile and Lys. Urine pH was significantly more alkaline in hens fed the higher level of Ile. It is suggested that adequate dietary Lys and Ile should be provided for maximum hatching egg production but an excess may affect fertility.

Evaluation of the use of feeding distillers dried grains with solubles in combination with canola meal on broiler performance and carcass characteristics

SUMMARY Distillers dried grains with solubles (DDGS) is an acceptable feed ingredient used as an alternative to corn or soybean meal in poultry diets. However, the unbalanced or low digestibility of amino acids in DDGS has been an issue and may be preventing its use at high levels. Canola meal (CM) contains high protein with well-balanced amino acids and can commonly be used as an economical alternative ingredient to soybean meal in poultry diets. Thus, the use of DDGS and CM together may improve the amino acid balance, performance, and carcass characteristics of broilers. An experiment was conducted to evaluate the use of DDGS in combination with CM in broiler diets. In a 3 × 2 factorial arrangement, 1,920 one-day-old male Heritage broilers were randomly assigned to 6 dietary treatments: 1) control (0% DDGS + 0% CM), 2) 6% DDGS + 0% CM, 3) 12% DDGS + 0% CM, 4) 0% DDGS + 7.5% CM, 5) 6% DDGS + 7.5% CM, and 6) 12% DDGS + 7.5% CM. Chicks (8 replicate pens, each with 40 chicks) were fed experimental diets from 0 to 48 d of age. The diets were formulated to be isocaloric and to meet the digestible amino acid requirements of the birds. Performance was evaluated at 14, 21, 35, and 48 d of age, and carcass characteristics were measured at 49 d of age. Overall (0 to 48 d of age), the inclusion of up to 12% DDGS in the diet did not significantly affect BW gain or feed intake, but it did negatively affect FE. The inclusion of 7.5% CM in the control diet did not significantly affect broiler performance; however, the diets containing 7.5% CM with 6 or 12% DDGS adversely affected performance as compared with the control diet. The inclusion of 7.5% CM in the diet of broilers negatively affected the carcass yield but positively affected the leg yield, regardless of the inclusion of DDGS. The inclusion of 12% DDGS in the diet of broilers increased the wing yield as compared with the nonsupplemented control diet. No interaction of DDGS and CM was observed in the carcass parameters measured, except for leg and wing yields. Thus, care should be taken when DDGS and CM are fed because negative effects on performance and carcass yield may be observed.

DESEMPENHO E MORFOMETRIA DUODENAL DE FRANGOS DE CORTE SUBMETIDOS A DIFERENTES NÍVEIS DE ENERGIA E PROGRAMAS DE ALIMENTAÇÃO DE 42 A 57 DIAS DE IDADE

This experiment was conducted to evaluate the use of different energy levels and amino acid recommendations on performance, carcass yield and intestinal morphometry of broilers from 42 to 57 days of age. We used 1,600 one-day old male broilers (Cobb 500) in a completely randomized design arranged in a 2x4 factorial scheme with 3,200 and 3,600 kcal ME/kg and four different feed programs. The metabolizable energy levels and the feed programs did not determine significant differences in carcass characteristics for choosing a level of energy or a feed program, thus the energy level and the recommendations of amino acids that determine the highest cost-benefit ratio should prevail. It was observed that 3,600 kcal ME/kg resulted in some improvement on performance and morphometry of the intestinal mucosa, also the fractioning of digestible amino acid requirements during two periods resulted in worse performance and intestinal villi height.KEYWORDS: Digestible amino acids; metabolizable energy; nutritional requirements; small intestine.

Reevaluation of digestible amino acid requirements of male and female broilers based on different ideal amino acids ratios in starter period

An experiment was conducted to reevaluate the digestible amino acid (AA) requirements of broilers based on different ideal amino acid ratios for male and female broiler chicks during the starter period (1–14 days). A total of 720 one-day-old feather sexed male and female broiler chicks were equally distributed to 12 dietary treatments with 4 replications per treatment and 15 chicks per replication. AA requirements were estimated based on digestible Lys requirement of 1.22 and 1.20 percent for male and female respectively, and different ideal AA ratios including Illinois Ideal Chick Protein (IICP), CVB, Feedstuff, NRC, ROSS and RPAN (Rhone Poulenc Animal Nutrition). Feed intake, body weight gain (BWG), and humeral immunity responses were measured for each pen at day 14 post hatch and feed:gain was calculated. Results of this study show that broiler chicks fed IICP diet had lower feed intake while broiler chicks fed ROSS and RPAN diets had lower BWG and feed:gain compared to other ideal amino acid profiles. When comparisons were made among chicks fed diets formulated with different ideal amino acid ratios, the most significant (p<0.05) performance improvements were observed by Feedstuff and CVB ratios. Feedstuff ratio had highest body weight gain and a better feed:gain (p<0.05) relative to all the other ratios for both genders. Digestible Lys, Met, Met+Cys, Thr, Ile, Arg, Trp, Leu and Val requirements for male and female broiler were estimated based on Feedstuff ratio to be 1.22, 0.54, 0.85, 0.73, 0.85, 1.34, 0.24, 1.62, 0.93 and 1.20, 0.53, 0.84, 0.72, 0.83, 1.32, 0.24, 1.60, 0.92 in starter period, respectively.

Use of combinations of canola meal and distillers dried grains with solubles in broiler starter diets

The development of the fuel ethanol industry has resulted in large quantities of distillers dried grains with solubles (DDGS). This can partially replace corn and soybean meal in broiler diets, but the amino acids in DDGS are not balanced. Canola meal (CM) is a good protein source with a high amino acid content, so the combined use of DDGS and CM may improve the amino acid balance. A study was conducted to evaluate the use of DDGS in combination with CM in broiler diets. In a 6 × 6 factorial arrangement, 1,080 one-day-old male broilers were randomly assigned to diets with 0, 5, 10, 15, 20, and 25% DDGS of known composition; within each level of DDGS, diets contained 0, 5, 10, 15, 20, or 25% CM from 0 to 18 d of age. Each treatment was replicated 6 times. Diets were formulated to meet digestible amino acid requirements and were fed as a 3.17-mm pellet. Body weight and feed consumption were measured at 18 d of age. In addition, feed bulk density and percentage of fines were evaluated. The DDGS and CM levels as well as their interaction significantly affected feed intake and BW (P < 0.05). Moreover, feed intake and BW declined dramatically with the increasing inclusion of CM. However, no significant difference was noted in FCR due to dietary DDGS and canola levels. Percentage of fines and diet bulk density were influenced significantly by dietary DDGS and CM levels as well as by their interaction. The percentage of fines increased with increasing combinations of DDGS and CM. However, the effect of dietary DDGS and canola concentrations on feed bulk density did not show a clear trend. By regression analysis, percentage of fines had a significant impact on feed intake and BW gain but failed to show any clear-cut relationship between bulk density and performance factors. Therefore, when DDGS and CM are used in combination, the total level of the 2 ingredients in the formulation should be considered.

Evaluation of Distillers Dried Grains with Solubles in Combination with Glycerin in Broiler Diets

2 Abstract: An experiment was conducted to evaluate the use of distillers dried grains with solubles (DDGS) combined with glycerin in broiler diets. In a 3×2 factorial arrangement, 600 one-day-old commercial strain Cobb 500 broilers were randomly assigned to experimental diets with 0, 15 and 30% DDGS of know n composition; within each level of DDGS the diets contained 0 or 5% glycerin, respectively, from 0-42 days of age. Diets were formulated to meet digestible amino acid requirements and were fed in pelleted form. Each dietary treatment was replicated 4 times. Body weight gain and feed consumption were measured and carcass characteristics were evaluated at 42 days of age. Inclusion of 30% DDGS had no adverse effect on body weight of chicks; however birds fed diets with 30% DDGS had greater feed intake and poorer feed conversion than birds fed the control diet at most age periods. This was highly correlated to the reduced pellet quality of diets containing the high levels of DDGS. Birds fed diets with 30% DDGS also had significantly reduced dressing percentage compared to birds fed the control diet with no DDGS. However, there was no adverse effect on breast meat yield related to the higher levels of DDGS inclusion. Addition of 5% glycerin from biodiesel production to the diets had no significant effect on body weight, feed intake, or feed conversion. There was no significant effect of the addition of glycerin on dressing percentage or yield of various carcass parts. With one minor exception, there was no significant interaction between addition of glycerin and level of DDGS in the diet, even though pellet quality declined when glycerin was added to the diets. Overall, the results of this study demonstrates that 15% DDGS of known nutritional quality can be utilized in diets for growing broilers with no adverse effects provided diets are formulated on a digestible amino acid basis and meet the nutritional requirements of the broiler. Higher levels may be tolerated but there may be a loss in feed conversion unless pellet quality can be improved. A loss in dressing percentage at higher levels of DDGS has been consistently noted in this and previous studies. Incorporation of 5 % glycerin from biodiesel production as a source of energy appears satisfactory.

Ideal Ratios of Isoleucine, Methionine, Methionine Plus Cystine, Threonine, Tryptophan, and Valine Relative to Lysine for White Leghorn-Type Laying Hens of Twenty-Eight to Thirty-Four Weeks of Age

Seven separate experiments were conducted with Hy-Line W-36 hens to determine the ideal ratio of Arg, Ile, Met, Met+Cys, Thr, Trp, and Val relative to Lys for maximal egg mass. The experiments were conducted simultaneously and were each designed as a randomized complete block design with 60 experimental units (each consisting of 1 cage with 2 hens) and 5 dietary treatments. The 35 assay diets were made from a common basal diet (2,987 kcal/kg of ME; 12.3% CP; 4.06% Ca, 0.47% nonphytate P), formulated using corn, soybean meal, and meat and bone meal. The true digestible amino acid contents in the basal diet were determined using the precision-fed assay with adult cecectomized roosters. Crystalline L-Arg (free base), L-Ile, L-Lys.HCl, DL-Met, L-Thr, L-Trp, and L-Val (considered 100% true digestible) were added to the basal diet at the expense of cornstarch to make the respective assayed amino acid first limiting and to yield 5 graded inclusions of the assayed amino acid. Hens were fed the assay diets from 26 to 34 wk of age, with the first 2 wk considered a depletion period. Egg production was recorded daily and egg weight was determined weekly on eggs collected over 48 h; egg mass was calculated as egg production x egg weight. The requirement for each amino acid was determined using the broken-line regression method. Consumption of Arg did not affect egg mass, thus a requirement could not be determined. The true digestible amino acid requirements used to calculate the ideal amino acid ratio for maximum egg mass were 426 mg/d of Ile, 538 mg/d of Lys, 253 mg/d of Met, 506 mg/d of Met+Cys, 414 mg/d of Thr, 120 mg/d of Trp, and 501 mg/d of Val. The ideal amino acid ratio for maximum egg mass was Ile 79%, Met 47%, Met+Cys 94%, Thr 77%, Trp 22%, and Val 93% on a true digestible basis relative to Lys. The ideal Met and Met+Cys ratios were verified in an ensuing identical experiment with 52- to 58-wk-old hens.

Efeito dos níveis de energia e programas de alimentação sobre a qualidade de carcaça e desempenho de frangos de corte abatidos tardiamente

This experiment was conducted to evaluate the use of different energy levels and amino acid recommendations on carcass and meat quality of broilers from 42 to 57 days of age. It was used 1,600 one-day old male broilers (Cobb) in a completely randomized design arranged in a factorial scheme 2x4 with 3,200 and 3,600 kcal ME kg-1 and four different feed programs. The experimental period was from 42 to 57 days of age. From 1 to 41 days of age all birds received the same diets based on corn and soybean meal. Data from carcass yield (output carcass, relation weight breast and thigh and overthigh with the carcass weight) and muscle quality (color, pH, cooking weight loss, shearing force, water holding capacity and sensorial analysis) and data from performance (weight gain, feed intake, feed:gain ratio and energy conversion) were evaluated. The energy levels and different feed programs did not determine differences on carcass meet quality to justify the choice of amino acid levels and need to consider the energy levels and amino acid recommendations to determine the best cost-benefit. It was observed that 3,600 kcal ME kg-1 resulted in some improvement on performance, and the partition of digestible amino acid requirements during two periods resulted in worst performance.

Efeito de diferentes níveis de energia e de programas de alimentação sobre o desempenho de frangos de corte abatidos tardiamente

O experimento foi realizado com o objetivo de avaliar diferentes níveis de energia metabolizável e de programas de alimentação sobre o desempenho de frangos de corte no período de 42 a 57 dias de idade. Foram utilizados 1.600 pintos machos da linhagem Cobb, em um delineamento inteiramente ao acaso, em esquema fatorial 2 x 4, composto de dois níveis de energia (3.200 e 3.600 kcal EM/kg) e quatro programas de alimentação (recomendações de aminoácidos). As aves foram alimentadas com ração à base de milho e farelo de soja até os 41 dias de idade, quando foram pesadas, homogeneizadas e separadas por tratamento, dando-se início ao fornecimento das rações experimentais. Foram avaliados dados de ganho de peso, consumo de ração e conversão alimentar ao final de cada período experimental, a conversão calórica e o índice de eficiência produtiva para todo o período experimental. O nível de 3.600 kcal EM/kg melhorou o desempenho das aves, mas o fracionamento das exigências de aminoácidos digestíveis em dois períodos piorou os resultados. O desempenho no período de 50 a 57 dias de idade indicou que o abate tardio deve ser antecipado em uma semana, pois, após os 49 dias de idade, ocorre piora na conversão alimentar.

Exigências de aminoácidos sulfurados digestíveis para suínos machos castrados e fêmeas de 15 a 30 kg

Cinqüenta leitões mestiços (Landrace x Large White), sendo 25 machos castrados e 25 fêmeas, na fase inicial de crescimento (15 a 30 kg), foram utilizados em um experimento visando determinar a exigência de aminoácidos sulfurados digestíveis. Os animais foram distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,502; 0,530; 0,558; 0,586 e 0,614% de metionina + cistina digestível), cinco repetições e dois animais, um macho e uma fêmea, por unidade experimental. Os níveis de metionina + cistina digestível da ração influenciaram de forma quadrática o ganho de peso diário (GPD) dos animais, que aumentou até o nível de 0,582%; a conversão alimentar (CA), que reduziu até o nível de 0,588%; e o consumo diário de ração (CDR), que aumentou até o nível de 0,579%. Os tratamentos influenciaram a deposição de gordura (DG), que variou de forma quadrática, reduzindo até o nível de 0,556%, mas não alteraram a deposição de proteína (DP). A exigência de aminoácidos sulfurados digestíveis para suínos machos castrados e fêmeas de 15 a 30 kg, para maior ganho de peso, é de 0,582% e, para menor conversão alimentar, de 0,588% de metionina + cistina digestível na ração, correspondendo a uma relação de 63% de metionina + cistina digestível:lisina digestível.

Pearl millet utilization in ccommercial laying hen diets formulated on a total or digestible amino acid basis

An experiment was carried out to evaluate the effect of replacing corn with pearl millet in commercial layer diets, formulated according to the minimal requirements for total and digestible amino acids. Two hundred and forty Lohmann LSL laying hens with 25 weeks of age were distributed in a completely randomized experimental design according to a 2 x 5 factorial arrangement with 3 replicates of 8 birds. Feed was formulated on two amino acid basis (total or digestible) according to Rostagno et al. (2000) and there were five pearl millet inclusion levels (0%, 25%, 50%, 75%, and 100%). Performance and egg quality were evaluated during five periods of 21 days.At the end of each period, feed intake, egg production, egg weight and feed conversion were evaluated. In the last three days of each period, the following egg quality parameters were evaluated: Haugh Unit, yolk pigmentation index, egg specific weight, shell percentage and shell thickness. Digestible amino acid requirements resulted in decreased feed intake (p<0.01) and increased production costs per mass of eggs (kg) or per dozen eggs (p<0.01) compared to total amino acid requirements. There was a linear reduction in feed intake, egg production, egg weight and yolk pigmentation index with increasing inclusion levels of pearl millet. Therefore, increasing levels of replacement of corn by pearl millet affected bird performance negatively. Besides, production costs were higher with increasing pearl millet levels.

A note on the performance and nitrogen output of broiler chickens fed diets with and without meat-and-bone meal formulated to total or digestible amino acid requirements

1. Effect of Dietary Protein Level and Type of Feed Formulation on Nitrogen Excretion of Broilers Reza Salahi Moghaddam, Shahriar Maghsoudlou, Yosef Mostafalou, Mohammad Hosein Shahir, Javad Bayat Koohsar Research on Animal Production CrossRef

A comparison of total and digestible amino acids in diets for broilers and layers

Eleven samples of food ingredients were analysed for their total and true digestible amino acid content, apparent metabolisable energy and other components. Large batches of these ingredients were retained for a broiler and a layer experiment. Four layer diets were formulated at 0.97 and 0.90 of total and digestible amino acid requirements for egg production using the analysed ingredients. Eight broiler diets were also formulated from 1.0 to 0.91 of total and digestible amino acid requirements in starter and finisher diets. Proximate and amino acid analyses and AME values were within the normal range for the 11 foodstuffs. Digestibility of amino acids was high with very few exceptions, e.g. cottonseed meal, meat and bone meal. Diets formulated on a total or digestible amino acid basis gave no differences in egg production parameters or broiler production parameters with no effect of level of inclusion. However, the main effects showed that diets formulated on a total compared to a digestible amino acid basis gave better growth rate and feed conversion efficiency in broilers. It was concluded that nutrient specifications for layers and broilers are not sufficiently precise to be able to differentiate between 1.97 and 0.90 of requirement for egg production or 1.0 and 0.91 for broiler growth. The use of digestible amino acids may be justified in diet formulations only when unusual protein concentrates with low amino acid digestibility values are used in large amounts.

Utilization of spent hen meal in diets for broiler chickens

Studies were conducted to evaluate spent hen meal (SHM) produced in commercial rendering plants as a nutrient source in diets for broiler chickens. Utilizing previously determined nutrient composition values, including digestible amino acid and TMEn content, diets were formulated to include 0, 5, 10, and 15% of SHM from three different locations. In the first experiment, conducted in battery pens from 1 to 21 d posthatch, diets were formulated with digestible amino acid requirements set at 90, 95, or 100% of NRC (1994) total amino acid requirements. In the second experiment, conducted in floor pens from 1 to 49 d posthatch, diets were formulated with digestible amino acid requirements set at 95% of NRC (1994) total amino acid requirements. Samples of birds from the second experiment were processed to determine the possible influence of SHM inclusion on carcass yield. Results of the present studies indicate that SHM from commercial rendering facilities can be utilized in diets for growing broiler chickens provided adjustments are made in nutrient content and digestibility. When formulated on the basis of digestible amino acid content, levels of SHM up to 10% appear acceptable based upon body weight, feed conversion, bone ash, and carcass yield. Higher inclusion rates generally reduced performance. It is apparent that differences in nutritional quality may exist among products produced by different rendering facilities; however, evaluation of products to assess nutrient quality may be difficult under commercial conditions. As more information is generated regarding typical amino acid content and digestibility of rendered SHM, the product may be used with greater confidence in commercial diets.

Lysine: Ideal protein in turkeys

This paper will review current and previous research related to our work on ideal proteins for turkeys. The concept of ideal protein is not new, but has not been researched in turkeys to any extent. Ideal proteins may be defined as the exact balance of amino acids needed for maximal growth. Ideal proteins are based on digestible amino acids. Several pieces of information need to be in place before one can actually run an experiment on the digestible amino acid requirements and ideal protein. The first of these is data on digestible amino acid content of feedstuffs for turkeys. The second necessity is a low protein diet that can be used to titrate the amino acids on a digestible basis. These requirements led us to formulate a very low protein starter diet (approximately 18% intact crude protein + amino acids) with corn and soybean meal that would support maximal growth. To formulate a diet at this crude protein level, it was necessary to use the ideal protein research from other species and previous research with turkeys. We now have an estimate of the ideal protein for turkeys. The future of this work and amino acid nutrition of turkeys will be reviewed.

A low-protein diet for turkey poults

A series of studies was conducted to determine whether a low-protein corn-soybean meal diet would support growth of turkeys similar to that supported by a standard diet. Three treatments administered in a series of experiments included: basal diet with essential amino acids (EAA), NaHCO3, and glutamic acid added at the expense of sucrose to bring the total protein up to 28% (+GLU); basal diet with EAA, NaHCO3, and sucrose added to bring the total protein content to 22% (+SUC); and a 28% crude protein standard diet that meets or exceeds NRC recommendations using intact protein sources (ST). Essential amino acid levels used in the experimental diets were based on an estimated ideal protein ratio for turkeys. The basal diet contained 18.4% intact CP from corn and soybean meal. All treatments were isocaloric with 3,172 to 3,192 kcal/kg. In all trials, the birds receiving +GLU and +SUC had adequate growth and feed:gain responses compared to birds receiving ST. The low protein basal diet with appropriate amino acid supplementation will allow for amino acid titrations to determine digestible amino acid requirements.