Amino Acid Density Research Articles

Protein source and nutrient density in the diets of male broilers from 8 to 21 d of age: Effects on small intestine morphology

In a companion study, high amino acid (AA) or apparent metabolizable energy (AME) densities in the diets of broilers from 8 to 21 d of age were found to improve feed conversion. A total of 1,120 male Ross × Ross 708 chicks were randomly allocated to 80 pens (8 treatments, 10 replications per treatment, 14 chicks per pen). A 2 × 2 × 2 factorial arrangement of treatments was used to investigate the interaction among the protein source (high distillers dried grains with solubles diet [hDDGS] or high meat and bone meal diet [hMBM]), AA density (moderate or high), and AME density (2,998 or 3,100 kcal/kg) of diets on small intestine morphology. Duodenum, jejunum, and ileum samples from 2 chicks per pen were collected and measured individually at 21 d. Jejunum sections were processed for histological analysis. Chicks fed hDDGS diets exhibited longer small intestines than did chicks fed hMBM diets. Particularly, when chicks were fed high AA density diets, jejuna were longer in groups fed hDDGS diets than groups fed hMBM diets. Dietary treatments did not affect jejunum villus height, width, area, crypt depth, villus to crypt ratio, goblet cell size, or cell density. In birds fed diets containing a moderate AA and a high AME density, jejunum muscle layers of chicks fed hDDGS diets were thicker than those fed hMBM diets. Chicks exhibited a lower feed conversion ratio (FCR) and a higher BW gain when their crypts were shorter. In conclusion, an hDDGS diet may facilitate small intestine longitudinal growth in broilers, which may subsequently improve dietary nutrient absorption. In addition, broiler chicks with shallow intestinal crypts exhibited better growth performance.

Effects of dietary amino acid density and metabolizable energy level on the growth and meat yield of summer-reared broilers

The effects of dietary amino acid (AA) density and AME on the growth and meat yield of summer-reared Cobb × Cobb 700 (CCB-700) broilers were evaluated. In addition, the responses of CCB-700 and Cobb × Cobb 500 (CCB-500) broilers to dietary AME levels (with low AA) were compared. All chicks were fed through a starter, grower, finisher, and withdrawal phase program. Grow-out performance, carcass traits, meat yield, and feed cost efficiency were evaluated using 2 separate 2-way ANOVA based on 2 separate 2 × 2 factorial arrangements of treatments. Each group includes 14 replicate pens with 14 chicks/replicate. Mortality was not affected by treatment; however, as compared with birds fed other diets, feeding CCB-700 broilers a low-AME and high-AA density diet decreased feed intake and BW on d 35, 42, and 54, and decreased carcass, breast, wing, front half, and back half weights on d 55. The CCB-500 broilers consumed more feed and gained more weight as compared with CCB-700 broilers at 14, 28, and 35 d of age. However, at 55 d of age, breast weight and wing yield were observed to be higher in the CCB-700 than in the CCB-500 broilers. However, the back half (drumstick and thigh) weights were lower in the CCB-700 than in the CCB-500 broilers. In conclusion, without affecting feed costs, broiler performance and carcass yield were affected by diet in both strains. More specifically, a higher AME diet and lower AA density increased the yield of all cut-up parts, except for legs, in summer-reared CCB-700 chicks.

Effects of protein source and nutrient density in the diets of male broilers from 8 to 21 days of age on their subsequent growth, blood constituents, and carcass compositions

The effects of protein source and amino acid (AA) and AME levels in the diets of male broilers from 8 to 21 d of age on subsequent growth and blood and carcass traits were investigated in the current study. Fourteen Ross × Ross 708 male broiler chicks were randomly allocated to each of 80 floor pens arranged in a randomized complete block design. Each diet contained 1 of 2 dietary protein sources (high inclusion of distillers dried grains with solubles or high inclusion of meat and bone meal), 1 of 2 AA densities (moderate or 10% higher), and 1 of 2 AME densities (2,998 or 3,100 kcal/kg). Experimental diets were fed from 8 to 21 d of age, and common diets from 1 to 7 and 21 to 55 d of age. The higher AME density in high inclusion of meat and bone meal diets increased serum triglyceride and cholesterol levels on d 20. The dietary inclusion of high inclusion of distillers dried grains with solubles or lower levels of AA increased high-density lipoprotein cholesterol on d 20. Feeding the high-AA-density diet decreased feed intake without affecting BW gain, which resulted in a lower feed conversion ratio (FCR). A high-AME-density diet lowered feed intake but increased BW gain, which resulted in a lower FCR from 8 to 21 d of age. Feed intake, BW gain, FCR from 21 to 54 d of age, and carcass weight on 42 and 55 d of age were not affected by treatments from 8 to 21 d of age. However, early dietary manipulation from 8 to 21 d of age affected fat and meat yield at 42 and 55 d of age. Moreover, a high-AME diet decreased feed cost per carcass weight gain from 8 to 55 d of age. In conclusion, high AA or AME densities during the grower phase, from d 8 to 21 of age, may improve growth during the grower feeding phase, but may also affect meat yield during the latter grow-out phases. Furthermore, high-AME diets from 8 to 21 d of age may save on feed costs for meat production.

Effects of dietary amino acid density regimens on growth performance and meat yield of Cobb × Cobb 700 broilers

SUMMARY The effects of dietary amino acid (AA) density on the performance and meat yield of Cobb × Cobb 700 broilers were evaluated in the current study. Cobb × Cobb 700 chicks, obtained from commercial hatchery, were fed either moderate- or high-AA-density diets within the starter (0 to 14 d, in crumbles), grower (14 to 28 d, in pellets), finisher (28 to 35 d, in pellets), and withdrawal (35 to 56 d, in pellets) phases of a grow-out program, for a total of 8 possible treatment combinations. Cobb × Cobb 500 birds, also from a commercial hatchery, were fed a moderate-AA-density diet and served as a reference. Before formulation of the experimental diets, the corn, soybean meal, and animal byproduct ingredients in the feed were analyzed for total AA concentration. At 42 and 56 d of age, live performance, meat yield, and feed cost efficiency were evaluated. Mortality, which averaged approximately 3%, was not affected by any treatments. Body weight on d 42 and 56 were not affected by AA density in the diets. Based on main effects of FCR, Cobb × Cobb 700 birds benefited greatly from being fed high-AA-density diets during the finisher and withdrawal feeding phases. Feeding Cobb × Cobb 700 moderate-AA-density diets throughout all feeding phases proved to be more economically efficient when compared with feeding high-AA-density diets at an early stage and a moderate-AA-density diet at a later stage. This is based on a lower feed cost to cut-up part value ratio observed on d 56. Although live performance and meat yield of Cobb × Cobb 700 broilers responded to high-AA-density diets, this diet did not result in the most cost-effective program.

Performance and carcass characteristics of Cobb × Cobb 500 slow-feathering male broilers fed on dietary programs having stepwise increases in ideal protein density

SUMMARY The Cobb × Cobb 500 slow-feathering male is a fast early-growth broiler grown under variable feeding programs and amino acid (AA) densities. An experiment was conducted using diets with increased ideal protein densities in a feeding program of 1 to 7 d, 8 to 21 d, 22 to 35d, and 36 to 42 d. Diets had ratios between essential digestible (D) AA and DLys (DAA:DLys) as follows: TSAA, 75%; DThr, 65%; DVal, 75% (from 1 to 7 d) and 77% (from 8 to 42 d); DIle, 67%; DArg, 104%; and DTrp, 17%. A completely randomized experimental design in a 3 × 3 factorial arrangement of 3 AA densities (low, moderate, and high) from 1 to 21 d (phase I) and 3 AA densities from 22 to 42 d (phase II) was used. The moderate dietary program was set with DLys at 1.26, 1.15, 1.05, and 0.95% from the prestarter to finisher phase. Replications per treatment were 30 from 1 to 21 d and 10 from 22 to 42 d. Birds fed the high-AA-density diets in phase I had the best BW gain at 35 and 42 d (P < 0.05) and the lowest FCR (P < 0.05) when combined with the high- or moderate-AA-density diets in phase II. The high- and moderateAA-density diets in phase I maximized BW gain at 42 d when combined with either the high- or moderate-AA-density diet in phase II (P < 0.05). Percentages of breast fillets, breast tenders, and thighs were not affected by treatment in phase I; however, breast fillet percentage was maximized with when the moderate- or high-AA-density diets (P < 0.05) were fed in phase II, whereas breast tenders and thighs were maximized only when the high-AA-density diets (P < 0.01) were fed in phase II. Commercial application will depend on ingredient costs and meat market prices at decision time based on the program that results in the lowest cost per sellable product.

Responses of Cobb×Cobb 500 slow feathering broilers to feeding programs with increasing amino acid densities

An evaluation of the effects of feeding programs with three amino acid (AA) densities given to males and females from a fast growth broiler breed was conducted. A total of 1200 Cobb×Cobb 500 broilers were distributed across 6 treatments in a 2×3 factorial arrangement (Sex×AA Density) with 8 replications of 25 birds per pen. Maize–soybean meal, provided from 1 to 7, 8 to 21, 22 to 35 and 36 to 42d of age, was formulated without crude protein restriction maintaining minimum ratios between essential AA and Lysine (Lys) in a true digestible (dig) basis as follows: total sulfur AA, 0.75; threonine, 0.65, valine, 0.75 (from 1 to 21d) and 0.78 (from 22 to 42d). Experimental treatments were Low (L), Moderate (M) and High (H) AA density diets with M having dig Lys of 1.25, 1.19, 1.09 and 1.05% in the pre-starter to withdrawal phases, respectively. Diets L and H had reductions and increases of 12% dig Lys in relation to the Moderate diet. There were no effects of treatments on mortality (P>0.05) and males had an overall better performance than females (P<0.001). No interactions were observed between Sex×AA density, with the exception of feed intake (1–42 days) and abdominal fat, which were further reduced with males as AA density increased than with females (P<0.01). Body weight gain was affected by AA density (P=0.0308) with birds fed L diets being lighter than those fed H and M diets. Feed conversion ratio (FCR) was improved (P<0.05) as AA density increased. Carcass and breast meat percentages were higher for females (P<0.01) and percent breast yield was highest for the H diet and lowest for the L diet, whereas the M diet was in between. Abdominal fat was reduced with H diet (P<0.05) for males but not for females. The decision making process to change AA density in the diet towards a higher density AA diet will depend on the price of feed ingredients and broiler meat.

Optimizing broiler performance using different amino acid density diets: What are the limits?

SUMMARY Broiler responses of economic interest, such as BW gain, FCR, and breast meat yield (BMY), can be optimized by increasing amino acid (AA) concentrations, improving the AA balance, or both. The AA requirements to maximize a response are lowest for BW gain, increased for FCR, and highest for BMY. A maximum performance response is reached when the response plateaus, whereas an optimal response is the one providing the highest return per input. These are usually not the same. Strategies used in linear feed formulation differ in how dietary AA are included in the diet; therefore, understanding how these strategies affect broiler responses is necessary to compare ultimate potential benefits. Minimum CP restrictions are still used even when TSAA, Lys, and Thr restrictions are set simultaneously, and AA requirements are presently expressed as either total or digestible. The use of ratios of essential AA to Lys is more popular now that synthetic Thr has become commercially available, and it will likely have an increase in use when l -valine and l -isoleucine have competitive prices. The present-day high-yield broiler has an increased responsiveness to AA density, especially for Lys, which contrasts with published requirements still in use. Increasing Lys and other AA at the beginning of the bird's life has been shown to have some positive carryover effects on performance in later periods; however, increasing the Lys and essential AA in broiler diets in the last phases of production allows compensation for BMY because of the continuous high allometric growth rate of breast muscle. Gains in performance are expected to result from increases in dietary AA density; however, the decision regarding what AA density to use will depend on the cost of feed relative to the market price of meat.

Effect of different amino acids density diets on lysine, methionine and protein efficiency in Arian broiler

The advantages provided by amino acid (AA) densities to broiler performance have been well documented, but little research has been reported on comparing the effect of different densities, i.e. high, medium, standard and low amino acid levels (HAA, MAA, SAA, and LAA), on protein and energy efficiency in broiler. This study evaluated the effects of the four different amino acid densities in a completely randomized experimental design on 800 male (10 replicates per treatment) broilers. All diets were isocaloric and isonitrogenous. In broilers receiving HAA, there had been a significant increase in body weight at Day 42. Feeding broilers with HAA diets significantly increased protein and energy intake in the grower period and during the overall study period (0–42 days of age) (P<0.05). There was a significant difference in efficiency of lysine and methionine during all time periods (P<0.05) and HAA levels were significantly higher than SAA. Protein efficiency ratio (PER) and energy efficiency ratio (EER) were not affected by an increase in AA density. AA levels had a significant effect on production efficiency factor (PEF). The results of this study suggest that additional lysine and methionine at 120% and other AA at 110% of National Research Council recommendations in starter and grower diets significantly improved body weight and PEF.

Predicted metabolizable energy density and amino acid profile of the crop contents of free‐living scarlet macaw chicks (Ara macao)

Hand rearing of neonates is a common practice for the propagation of psittacines. However, nutritional requirements for their growth and development are not well understood, and malnutrition is common. We analysed the amino acid (AA) profile of the crop contents of 19 free-living scarlet macaw (Ara macao) chicks, 19-59 days old. Predicted metabolizable energy (PME) density was 16.9 MJ/kg DM and true protein (total AA protein) 8.3 g/MJ PME. Crude protein (CP) was 10.0 g/MJ PME, lower than the requirements of 0- to 12-week-old leghorn chicks but not different than the requirements of growing budgerigars (Melopsittacus undulatus) and lovebirds (Agapornis spp.). The mean concentrations of leucine, isoleucine, threonine, lysine (Lys) and methionine on a PME basis were below the minimum requirements of 0- to 12-week-old leghorn-type chicks. The calculated PME density of the samples did not vary with age. However, there was a significant negative correlation between the average age of the chicks and the Lys concentration. We conclude that the lower CP and AA densities compared with poultry could result from a combination of (i) differences in the essential AA composition of the body tissues, (ii) adaptations that allow the birds to grow on low-protein food sources and (iii) suboptimal nutrition of these free-ranging chicks.

The effects of dietary amino acid density in broiler feed on carcass characteristics and meat quality

SUMMARY The advantages to broiler performance of feeding increased amino acid (AA) densities have been well documented, but minimal research has been reported on the effects of AA density on meat quality. In the current study, Ross × Ross 308 male broiler chicks were obtained from a commercial hatchery and fed diets with either deficient, low, high, or excessive dietary AA density during the finisher phase (28 to 42 d, in pellets). Broilers were slaughtered at 42 d of age and evaluated for live performance, carcass traits, breast and thigh composition, and breast and thigh meat quality. As expected, FCR decreased (P 0.05) existed among treatments with regard to final pH, cooking loss, shear force, proximate analysis, and average consumer acceptability of breast meat. The deficient AA diet yielded thigh meat with less (P < 0.05) moisture, less protein (P < 0.05), and more fat (P < 0.05) than thigh meat from all other treatments. In addition, the high and excessive AA treatments had higher (P < 0.05) concentrations of linoleic and linolenic acids in the thigh meat when compared with the deficient and low AA treatments, and thigh meat from the excessive AA treatment was more susceptible to oxidation (P < 0.05) than that from the deficient and low AA treatments. Overall, all 4 AA diets yielded high-quality breast and thigh meat, whereas the high AA diet yielded broilers with excellent live performance, carcass traits, and meat quality.

Dietary Apparent Metabolizable Energy and Amino Acid Density Effects on Growth and Carcass Traits of Heavy Broilers

Two experiments (EXP) were conducted to evaluate the interactive effects of dietary AME and amino acid (AA) density (total basis) on broiler chickens from 42 to 56 d of age. In EXP 1, diets were formulated to contain low AME (3,140 kcal/kg) and moderate AME (3,240 kcal/kg) in combination with moderate AA (16.2% CP, 0.88% Lys, and 0.75% TSAA) and high AA (18.0% CP, 0.98% Lys, and 0.83% TSAA) and fed to male broilers. Dietary treatments in EXP 2 were diets formulated to contain moderate AME (3,220 kcal/kg) and high AME (3,310 kcal/kg) combined with moderate and high AA concentrations used in EXP 1 and fed to male and female broilers. In general, dietary AME and AA did not interact to influence growth and meat yield responses. Broilers provided the low AME diet in EXP 1 consumed more feed and had poorer feed conversion but had higher total breast meat yield than birds fed the moderate AME diet. In EXP 2, broilers fed the high AME diet from 42 to 56 d had increased BW gain, decreased feed consumption, and improved feed conversion. Feeding the high AA diets in both EXP decreased feed consumption, improved feed conversion, and increased total breast meat yield. Nutritionists establishing nutritional programs for heavy broilers late in development from 2.5 to 3.6 kg may need to consider increasing AA density to optimize breast meat yield. Increasing the AME content of the diet improves feed conversion but not breast meat yield.

Live performance and environmental impact of broiler chickens fed diets varying in amino acids and phytase

This research examined the effects of decreasing dietary amino acid density (AAD) and potential interactions of AAD and phytase on growth and nitrogen (N) and phosphorus (P) excretion of broiler chickens. In experiment 1, diets were formulated to high (H) or moderate (M) AAD during prestarter (1–7 days), starter (8–19 days), and grower (20–35 days) resulting in the following dietary treatments: HHH, HHM, HMM, and MMM. The HHH feeding regimen improved (P≤0.05) body weight gain (BWG) and feed conversion (FCR) from 1 to 35 days of age, but increased (P≤0.05) N content of the excreta by 180 g/kg. In Experiment 2, three diets were fed from 36 to 49 days varying in AAD (H, M, and low, L) with (500 units/kg) or without supplemental phytase. Broilers fed a diet formulated to L AAD had high FCR. Increasing AAD increased (P≤0.05) N excretion by 0.56 and 0.80 g per bird compared with M and L AAD, respectively. Phytase supplementation reduced (P≤0.05) P excretion by 0.18 g per bird, but BWG and FCR were not affected. Dietary phytase and AAD did not interact to reduce N excretion. These results indicate that N excretion could be reduced with dietary manipulation, but effects on FCR should be considered.