Dietary Amino Acid Density Research Articles

Influence of dietary amino acid density, crude protein level, and feed scheduling on performance and carcass traits of Ross 708 female broilers slaughtered between 1.9 and 2.0 kg

Influence of dietary amino acid density, crude protein level, and feed scheduling on performance and carcass traits of Ross 708 female broilers slaughtered between 1.9 and 2.0 kg

Effects of Dietary Amino Acid Density and Exogenous Protease Inclusion on Growth Performance and Apparent Ileal Amino Acid Digestibility in Turkeys

Protein is one of the most expensive nutrients in poultry diets. In an effort to minimize feed costs, protein digestion and utilization by the animal must be carried out as effi­ciently as possible. The objective of this experiment was to evaluate the effects of dietary amino acid density and exogenous protease inclusion on growth performance and amino acid digestibility in turkey poults. Hybrid turkey poults (n = 780) were fed diets formulated to provide low (LAA) or adequate (AAA) amino acid density (approxi­mately 91 and 100% of the NRC4 recommended requirement for digestible Lys, respec­tively) with each diet being fed with or without an exogenous protease. Poults received experimental diets from d 1 to 42 of age. Growth performance metrics were calculated from pen weights and feed consumption was recorded throughout each experiment, and digestibility data were obtained from analysis of ileal contents. Data were analyzed using SAS 9.4 with pen as the experimental unit and pen location as the blocking factor. For the overall experiment (d 0 to 42), poults fed AAA diets had improved (P < 0.01) ADG, ADFI, and feed conversion ratio (FCR) compared to those fed LAA diets. There was no difference (P > 0.14) in poult performance due to protease inclusion. There was an amino acid density × protease interaction (P = 0.01) for apparent ileal amino acid digestibility (AIAAD) of Trp. There was no difference in AIAAD coefficients of Trp in the LAA diets with or without protease. However, in the AAA diets, poults not receiving protease had greater AIAAD of Trp than those consuming protease. There was no difference (P > 0.09) in AIAAD coefficients of Arg, Met, Cys, Thr, Ile, Leu, Lys, or Val due to dietary amino acid density or protease inclusion. Greater amino acid density improved growth performance in poults up to 42 d of age. No improvement in growth performance was observed when poults were fed an exogenous protease in the starter phase, although protease inclusion increased ADG by 5.3% and ADFI by 4.1% during the grower phase. There was no benefit of increased dietary amino acid density or protease inclusion on AIAAD in poults.

Interactive effects of dietary amino acid density and environmental temperature on growth performance and expression of selected amino acid transporters, water channels, and stress-related transcripts

Exposure to heat stress (HS) is one of the challenges facing the broiler industry worldwide. Various nutritional strategies have been suggested, such as altering dietary concentrations of some nutrients. Thus, we evaluated feeding different amino acid (AA) densities on live performance, Pectoralis (P.) muscles, and expression of selected AA transporters, water channels, and stress-related transcripts in a fast-growing broiler strain. Ross 308 chicks (n = 576) were randomly assigned to 4 dietary treatments (24 reps, 6 chicks per rep), differing in AA density (110, 100, 90, and 80% of a breeder's AA specifications). During 24 to 36 days of age, half of the birds were kept at a thermoneutral (TN) temperature of 20°C, whereas the other half were subjected to HS at 32° C for 8 h daily, making the treatment design a 4 × 2. The results revealed no interaction between housing temperature and AA density on growth performance or P. muscles weights. Feeding 80% AAs depressed BWG, FCR, and P. muscles at 36 d (P < 0.001). There was an interaction (P < 0.001) between AA density and temperature on the expression of all examined genes. Reducing the AA density beyond 100% upregulated the expression of AA transporter (CAT1, B0AT, b0,+AT, SNAT1, LAT1), HSP70, HSP90, glucocorticoid receptor (GR), and AQP3 in the TN birds’ jejunum. Whereas in the HS birds, inconsistent expressions were observed in the jejunum, of which CAT1, B0AT, and LAT1 were markedly downregulated as AA density was reduced. In P. major of TN birds, reducing AA density resulted in upregulating the expression of all AA transporters, HSP70, GR, and AQP1, while downregulating HSP90 and AQP9. In contrast, AA reduction markedly downregulated CAT1, B0AT, and LAT1 in the P. major of HS birds. These findings indicate that the dietary AA level alters the expression of various genes involved in AA uptake, protein folding, and water transport. The magnitude of alteration is also dependent on the housing temperature. Furthermore, the results highlight the importance of adequate AA nutrition for fast-growing chickens under HS.

Effects of dietary amino acid density and exogenous protease inclusion on growth performance and apparent ileal amino acid digestibility in poultry

Two experiments were conducted to evaluate the effects of dietary amino acid density and exogenous protease inclusion on growth performance and amino acid digestibility in poultry. In experiment 1, Cobb 500 broiler chicks (n = 480) were fed to 21 d of age. Treatments were arranged as a 2 × 4 factorial design with main effects of commercial protease (with or without) and amino acid density which corresponded to approximately 95, 97.5, 100, or 102.5% of breeder recommendations for digestible Lys. In experiment 2, hybrid turkey poults (n = 780) were fed diets formulated to provide low or adequate amino acid density (approximately 91 and 100% of the NRC-recommended requirement for digestible Lys, respectively) with each diet being fed with or without an exogenous protease. Poults received experimental diets from day 1 to 42 of age. Growth performance metrics were calculated from pen weights and feed consumption recorded throughout each experiment, and digestibility data were obtained from analysis of ileal contents. Data were analyzed using SAS 9.4 with pen as the experimental unit and pen location as the blocking factor. Results of these experiments demonstrated broilers fed 1.12 and 1.21% digestible Lys diets with added protease had a 2-point improvement in feed conversion ratio ( FCR ) compared with chicks fed these diets without protease. Increasing amino acid density improved FCR in broilers and poults and improved BW, ADG, and ADFI in poults. There was no evidence that added protease had an effect on BW, ADG, or ADFI in broilers or poults. Finally, ileal amino acid digestibility was not affected by amino acid density or protease inclusion for either 20-day-old broiler chicks or 42-day-old turkey poults.

Effects of Dietary Amino Acid Density and Exogenous Protease Inclusion on Growth Performance and Apparent Ileal AA Digestibility in Broilers

Effects of Dietary Amino Acid Density and Exogenous Protease Inclusion on Growth Performance and Apparent Ileal AA Digestibility in Broilers

Growth performance, carcass characteristics, ileal microbiota, and amino acid digestibility of broilers fed diets varying in supplemental copper concentrations and amino acid density from 1 to 32 d of age

Summary Two experiments were designed to determine interactive effects of supplemental dietary Cu and amino acid (AA) density on growth performance, processing characteristics, ileal microflora, and AA digestibility of broilers. In experiment 1, 8 dietary treatments were used, consisting of a factorial arrangement of 3 Cu programs providing Cu concentrations of 135-135-135, 270-135-135, or 270-270-135 mg/kg in starter, grower, and finisher periods, formulated at moderate or low AA density, positive and negative controls. The Cu source was tribasic Cu chloride. In both experiments, control birds were provided with diets formulated to moderate AA density and approximately 13 mg/kg Cu. Broilers fed positive control diets were unvaccinated and received diets containing a coccidiostat, while all other birds were vaccinated against coccidiosis. The results indicated that feeding high concentrations of dietary Cu may decrease feed conversion ratio through reduced feed intake. This led to reduced carcass weight and yield, but did not affect breast meat weight and yield. No differences were observed for microflora composition. Experiment 2 evaluated apparent ileal AA digestibility and used 6 dietary treatments, consisting of positive and negative controls and a factorial of either 135 or 270 mg/kg Cu and low or moderate AA density. Copper treatments reduced Cys digestibility compared with negative control–fed birds, and only Trp digestibility was increased with Cu supplementation. These studies indicate that feeding high concentrations of Cu may enhance growth performance but did not improve digestibility of most AA or alter microflora profile.

Effects of reducing dietary amino acid density and stocking density on growth performance, carcass characteristics, meat quality, and occurrence of white striping in broiler chickens

A 49-day trial was conducted to determine the impact of dietary amino acid (AA) density and stocking density (SD) on growth performance, carcass traits, meat quality, and white striping (WS) occurrence in broiler chickens. Two hundred eighty-eight Ross 308 male broilers consisting of 6 replicate cages with 8 broilers per replicate were used. Treatments were arranged in a 3 × 2 factorial and consisted of 3 AA densities (normal, 10, or 20% lower than normal) and 2 different SD (high 35 kg/m2 or low 26 kg/m2). Breasts were classified as normal, moderate, and severe for WS. Data were analyzed as a completely randomized design using the GLM procedure. Decreasing AA density decreased overall growth performance, carcass, breast yields, and fillet dimensions linearly, while leg and rib cage yields increased linearly (P < 0.01). High SD decreased hot carcass, breast, wings, and rib cage weights in birds fed normal AA diets (P < 0.05). High SD increased the length of breast fillet (P < 0.05). Cooking loss, breast lightness (L∗), and redness (a∗) at 48 h postmortem increased linearly with decreasing AA density, while ultimate breast pH (pHu) and nitrogen content decreased linearly (P < 0.05). The occurrence of normal, moderate, and severe WS fillets was 45.3, 49.1, and 5.6%, respectively. As the dietary AA density decreased, the occurrence of no WS breast fillets increased linearly, whereas the occurrence of moderate WS fillets and mean WS score decreased linearly (P < 0.05). SD did not affect the occurrence of WS. Severe WS fillets were heavier and had higher cranial thickness, pHu, and fat content and lower yellowness (P < 0.05), but water-holding capacity, nitrogen content, L∗, and a∗ value did not differ among different WS scores. Taken together, WS occurrence and severity increased with higher growth rate. Growth depression created by lowering dietary AA density regardless of SD resulted in a decrease in mean WS score, but it also compromised the growth and meat quality.

Effect of pullet body weight and hen dietary amino acid treatments on their progeny fed high and low amino acid diets

Four studies were conducted on Cobb 700 broilers to evaluate the dietary protein and any maternal effects on live production and processing parameters. Day-old Cobb 700 broiler breeder pullets were reared to conform to 2 different BW curves (control BW and increased BW) with 8 replicate pens per treatment. Birds were fed common diets from 1 d of age until first egg (24 wk). At 24 wk, 12 pens of each pullet treatment were given different amino acid (AA) diets (low = 14% CP, high = 15% CP). The performance of female and male progeny from 32 and 45 wk hens were evaluated on low AA and high AA density diets. The 4 progeny trial designs were identical factorial 2 × 2 × 2 designs, with 2 pullet BW curves (control BW and increased BW), 2 dam CP diet levels (low and high), and 2 progeny CP diets (low and high), with 6 replicates each containing 18 birds, for a total of 108 broiler progeny per treatment. Broiler chickens on the higher AA density feed exhibited consistent improvement in mid-growth BW and FCR and white meat yield percentage. Some maternal effects were noted, including increased carcass yield in female broilers from 32 wk old hens. There were 3-way interactions of pullet BW × hen dietary AA × progeny dietary AA treatments for female progeny carcass yield (from 32-week-old hens) and male tender yield (from 45-week-old hens). There were 2-way interactions of pullet BW x hen dietary AA treatments effect on female and male progeny drumstick yield from 32-week-old hens, pullet BW × progeny dietary AA treatments effect on male 27 d BW from 32-week-old hens, and hen dietary AA × progeny dietary AA treatments effect on male thigh yield from 45-week-old hen. The epigenetic effects of maternal pullet BW and dietary AA treatments were seen in processing yields suggesting, the need of dietary CP changes of the progeny.

Effects of Dietary Amino Acid Regimens on Live Performance and Processing Characteristics of Cobb MV × 700 Male and Female Broilers

The magnitude and timing of broiler responses to dietary amino acid (AA) density can vary between sexes and among genetic lines. Two experiments (Exp) were conducted to determine the responsiveness of Cobb MV × 700 broilers to changes in dietary AA density. In Exp 1, low (L), medium (M), and high (H) AA density diets were maintained across starter and grower phases in a 28 d growth performance trial (all males). In Exp 2, combinations of L, M, and H-AA density diets were varied across 4 feeding phases to evaluate the effect of 6 AA feeding regimens (HHHH, HHHM, HHMM, HMMM, MMMM, and HHLL) on growth performance, carcass composition, and breast muscle myopathies of broilers reared sex-separately. Body weight gain, feed intake (FI), and FCR responded positively to increased AA density during the starter and grower phases (0 to 28 d) of Exp 1. In Exp 2, broiler responses to AA density from 0 to 28 d diminished by the conclusion of the finisher phase (day 35), and FCR was the only measurement influenced by dietary AA density through day 46. Carcass characteristics and breast muscle myopathies were unaffected by AA density, with the exception of fat pad percentage, which decreased with increasing AA density. These data indicate that Cobb MV × 700 broilers may be less responsive to dietary AA density than other high-yielding broiler strains and further research to establish digestible AA:Lys ratios or dietary energy concentrations that optimize responses to increased AA density are warranted.

Reducing protein and supplementing crystalline amino acids, to alter dietary amino acid profiles in birds challenged for subclinical necrotic enteritis

Necrotic enteritis (NE) is an infection of the gastrointestinal tract and is estimated to cost the global poultry industry billions of dollars annually. A study was conducted to examine whether reducing the crude protein might offset the severity of NE in broilers experimentally challenged with Eimeria spp. on day 9 and Clostridium perfringens on days 14 and 15. Furthermore, increasing the dietary amino acid (AA) density of the diet was also examined owing to identified benefits of improving performance compromised from low protein (LP) diets or NE. A 2 × 2 × 3 factorial arrangement of treatments at 6 replicates per treatment was used with 972 Ross 308 cockerels fed wheat-sorghum-soy-based diets to 35 D. Factors were NE challenge: no or yes; protein: standard (SP) or LP; and AA density: 100% AA, 115% with only essential AA (115% EAA) increased, and 115% AA with both essential and nonessential AA (115% AA) increased. The performance was measured in grower (days 7–21), finisher (days 21–35), and overall (day 7–35) periods. In addition, on day 16, intestinal lesion score and cecal short-chain fatty acids were measured. Only in nonchallenged birds fed LP diets, 115% AA increased grower feed intake (P < 0.01) and body weight gain (P < 0.05) compared to 115% EAA treatments. Challenge increased jejunal lesions (P < 0.001) with no difference between dietary treatments. Finisher body weight gain was greater in nonchallenged birds fed the 115% AA diets than in challenged birds (P < 0.05). Feeding diets with higher nonessential AA encouraged faster recovery from NE challenge. When fed the SP diets, NE challenge increased cecal butyric acid (P < 0.01) and total short-chain fatty acids (P < 0.05). The nutrient matrix used in LP diets does not favor beneficial butyric acid–producing bacteria. Using LP diets to mitigate NE severity does not offset the predisposing effect of E. spp. when attacking the gastrointestinal tract, and NE recovery is favored when feeding SP diets or additional AA.

Effects of dietary amino acid density and feed allocation during the starter period on 41 days of age growth performance and processing characteristics of broiler chickens given coccidiosis vaccination at hatch

A study was conducted to determine if increasing digestible (dig) amino acid (AA) density or feed allocation of starter diets fed to broilers receiving coccidiosis vaccination can ameliorate poor cumulative growth performance and reduce meat yield. A total of 1,600 Yield Plus Ross × Ross 708 male broilers were assigned to a 2 × 3 factorial arrangement of dig AA density [moderate (1.15% dig Lys) and high (1.25% dig Lys)] and feed allotment (0.45, 0.73, and 1.00kg/bird) with 2 positive control treatments during the starter period. Diets were formulated to essential AA ratios relative to dig Lys. Vaccinated birds received a 1x dosage of Coccivac- B52 prior to placement, whereas non-vaccinated birds in the positive control groups were fed diets containing diclazuril. Following consumption of the starter diets, birds were provided common grower and finisher diets. Broilers fed the high AA density diet during the starter period had higher cumulative BW gain and lower cumulative feed conversion ratios (P < 0.05) than those fed the moderate AA density diet. Broilers fed the high AA density diet had heavier (P ≤ 0.005) carcass and total breast weights than birds fed the moderate AA density diet. Broilers fed a starter allotment of 1.00kg/bird produced heavier carcass weights (P ≤ 0.006) than did birds provided lower allotments. Additionally, broilers fed the high AA density diet had a greater percentage of 0 scores (P = 0.005) for the upper intestinal region during scoring. Results from this study indicated that feeding the high AA density diet at higher feed allotments during the starter period resulted in increased AA intake, which supported the bird through the vaccine challenge and enhanced the cumulative growth and meat yield.

Effects of Dietary Energy and Amino Acid Density During Finisher and Withdrawal Phases on Live Performance and Carcass Characteristics of Cobb MV × 700 Broilers

SUMMARY Meeting dietary energy needs of broilers accounts for the largest proportion of feed costs, and energy has long been identified as a driver of feed intake (FI) in poultry. Dietary energy content can also influence responses of broilers to dietary amino acids (AA). Therefore, 2 experiments (Exp) were conducted to determine the effects of energy density in the finisher (29–36 d) and withdrawal (37–46 d) diets on Cobb MV × 700 broiler performance and processing characteristics. Treatments in Exp 1 were a factorial arrangement of sex and energy density [low (LE), medium (ME), and high energy (HE)], whereas treatments in Exp 2 were a factorial arrangement of energy (LE, ME, and HE) and AA density [medium AA (MAA) or high AA (HAA)]. In Exp 1, no energy or energy × sex interactions were observed on overall (29–46 d) live performance or processing measurements of broilers. In Exp 2, energy density had no effect on overall live performance or carcass composition. Birds fed MAA diets had higher FI and body weight gain than birds fed the HAA diets during the overall experimental period. Processed part weights and yields were unaffected by AA density, except for pectoralis minor yields, which were higher for birds fed HAA than for those fed MAA diets. These data indicated that changes in 29–46 d energy density of the magnitude used in this study did not influence responses of Cobb MV × 700 broilers to varying AA levels.

Digestible lysine concentrations and amino acid densities influence growth performance and carcass traits in broiler chickens from 14 to 35 days post-hatch

The present study was conducted to evaluate the responses of growth performance and carcass traits in Cobb MV × 500 fast feathering broiler chickens fed maize, soybean meal (SBM) and peanut meal based diets containing different levels of digestible (dig) lysine (Lys). Dietary treatments consisted of 6 concentrations of dig Lys that ranged from 8.4 to 12.9 g/kg in increments of 0.9 g/kg. Two control diets with the medium level of dig Lys concentration of 11.1 g/kg were included where the positive control (PC) diet was a typical commercial diet based on maize and SBM and the negative control (NC) diet replaced part of SBM with100 g/kg peanut meal to allow higher supplementations of feed grade amino acids. Each of the eight experimental diets were offered to either male or female broiler chickens to form 16 experimental treatments and each treatment included 6 floor pens with 12 birds per pen. Broiler chickens were offered experimental diets from 14 to 35 days post-hatch. All diets were balanced with essential amino acids (EAA) by using ideal protein ratio approach and were offered to broiler chickens from 14 to 35 days post-hatch. Predictably, male broiler chickens had better weight gain (WG), feed intake (FI), feed conversion ratio (FCR) and breast meat yield (P < 0.001) than female birds. Sex did not influence yield of wings (P = 0.174) and thighs (P = 0.243). There were no interactions between sex and dietary dig Lys levels on growth performance and linear improvements were observed for live body weight (BW), WG and FCR. By comparing three mathematical models, in female birds, the dig Lys requirement was estimated at 11.5 g/kg for optimal WG and 12.1 g/kg for FCR. In male broiler chickens, the dig Lys requirement was estimated at 10.3 g/kg for optimal WG and 12.2 g/kg for FCR. The results suggested that modern broilers are highly responsive to dietary amino acid (AA) density and regular evaluations of AA requirements are needed because of genetic progress of modern broiler chickens.

Effect of dietary amino acid density on broiler breeder reproductive performance

The effects of 3 dietary amino acid (AA) profiles during lay on reproductive performance of broiler breeders were investigated. A flock of 2,376 Ross 708 female broiler breeders were randomly divided into 3 treatments with 12 replicates of 66 females per replicate, and fed 2 breeder feed phases (breeder 1: 25 to 36 wk; breeder 2: 37 to 60 wk) which were formulated to 3 different AA densities (Aviagen advice = control; 10% increased AA in Aviagen advice = high-AA; and estimated AA needs for maintenance, growth, and egg mass = estimated-AA). No differences in total or hatching egg production due to dietary treatments were observed. Hens fed high-AA had a higher incidence of double-yolk eggs. During the second phase of lay, hens fed estimated-AA had lower livability compared to the other treatments. Hens fed estimated-AA also laid smaller eggs compared to control and high-AA fed birds. Back feather cover deteriorated as hens grew older, and hens fed the estimated-AA diets had poorer feather cover from 41 wk onward. Overall, these results suggest that feeding higher AA levels than Aviagen recommendations presented no benefit in reproductive performance or feather quality. The estimated-AA feeding approach supported laying performance similar as other treatments, although affected egg weight and back feather cover.

Box-Behnken optimisation of growth performance, plasma metabolites and carcass traits as influenced by dietary energy, amino acid and starch to lipid ratios in broiler chickens.

A Box-Behnken designed study was completed to predict growth performance, carcass characteristics and plasma hormone and metabolite levels as influenced by dietary energy, amino acid densities and starch to lipid ratios in male broiler chickens. The design comprised three dietary energy densities (11.25, 12.375 and 13.5 MJ/kg), three digestible lysine concentrations (9.2, 10.65 and 12.1 g/kg) and three starch to lipid ratios (4.5, 12.25 and 20.0) in broiler diets based on maize and soybean meal. Each of thirteen dietary treatments was offered to 10 replicates of 15 birds per replicate floor pen or a total of 1,950 Ross 308 male broiler chickens from 21 to 35 days post-hatch. Increasing dietary energy decreased feed intake with a quadratic relationship between feed intake and dietary standardised ileal digestible (SID) Lys concentrations, where increasing SID Lys initially increased and then depressed feed intake. Increasing dietary amino acid density increased body weight gain and carcass weight; however, dietary energy did not influence body weight gain, carcass and breast meat weight. Feed efficiency was positively influenced by energy and amino acid densities but negatively influenced by starch to lipid ratios and energy and amino acids had more pronounced impacts than starch to lipid ratios. This study indicated that both energy and amino acid densities regulate feed intakes in broiler chickens. Body weight gain of modern broiler chickens is more responsive to amino acid densities; nevertheless, dietary energy density continues to play an important role in protein utilisation, as reflected in significantly reduced plasma uric acid levels.

Effects of reduced dietary energy and amino acid density on Pectoralis major myopathies in broiler chickens at 36 and 49 days of age

Two experiments (Exp) were conducted to determine if reductions in the incidence and severity of wooden breast (WB) and white striping (WS) may be obtained by reducing dietary nutrient density. In each Exp, Yield Plus × Ross 708 male broiler chicks were placed into 63 pens (22 birds/pen). All birds received an identical prestarter diet until 7 d of age, after which time each pen was randomly assigned to 1 of the following 7 dietary treatments (TRT) for the starter (8 to 14 d), grower (15 to 24 d), finisher 1 (Exp 1: 26 to 35 d; Exp 2: 26 to 42 d), and withdrawal (Exp 2: 43 to 48 d) phases: 1) 100% of primary breeder recommendations for digestible amino acid and metabolizable energy density throughout Exp; 2) 95% of TRT 1 until 14 d of age, then as TRT 1; 3) 95% of TRT 1 until 24 d of age, then as TRT 1; 4) 95% of TRT 1 throughout Exp; 5) 90% of TRT 1 until 14 d of age, then as TRT 1; 6) 90% of TRT 1 until 24 d of age, then as TRT 1; 7) 90% of TRT 1 throughout Exp. At 36 d (Exp 1) and 49 d (Exp 2), 18 birds per pen were processed and evaluated for WS and WB. In Exp 1, reduced dietary density in the starter phase (TRT 2 and TRT 5) resulted in increased (P ≤ 0.05) incidences of severe WB (32.9% and 34.7%) relative to TRT 1 (18.2%). In Exp 2, broilers assigned to TRT 7 had reduced (P < 0.01) incidences of severe WB (20.8%) and WS (42.3%) relative to the control (WB: 36.5%; WS: 64.5%). In both Exp, plasma creatine kinase and lactate dehydrogenase increased (P ≤ 0.05) with increasing scores for WB and WS. Reducing dietary nutrient density from 8 to 14 d may exacerbate fillet myopathies in broilers reared to 35 d of age. Although reducing dietary energy and amino acid density to 90% of recommendations from 1 to 48 d reduced the severity of myopathies, these reductions occurred with compromises in live performance. Altogether, these results indicated that concurrent manipulation of dietary amino acid and energy density is not a viable practical solution for breast myopathies.

Effects of dietary copper and amino acid density on growth performance, apparent metabolizable energy, and nutrient digestibility in Eimeria acervulina-challenged broilers

The objective of this experiment was to evaluate the influence of copper supplementation in diets varying in amino acid (AA) density on growth performance, apparent metabolizable energy (AMEn), apparent ileal nutrient digestibility (AID), and plasma carotenoids in broilers infected with Eimeria acervulina. Ross 308 male broilers (480 total) were housed in battery cages and allotted to 8 experimental treatments in a factorial arrangement of 2 dietary AA densities [1.00% (LAA) or 1.20% (HAA) digestible Lys], 2 supplemental copper concentrations (zero or 116 mg/kg), and 2 E. acervulina infection states (uninfected or infected). Essential AA ratios relative to digestible Lys were similar in both the LAA and HAA diets, and copper was provided by 200 mg/kg of tribasic copper chloride (58% copper). Chicks received experimental diets from 2 to 21 d post hatch and 6 replicate cages of 10 birds per cage were assigned to each treatment. Broilers were inoculated with zero or 6.3 × 105 sporulated E. acervulina oocysts at 15 d and blood and ileal digesta were collected at 21 days. From 2 to 15 d, body weight gain and G:F of broilers were improved (P < 0.05) with increasing AA density, and an AA density × copper interaction was observed (P < 0.05) for feed intake. Eimeria infection reduced (P < 0.05) plasma carotenoids, growth performance, dietary AMEn, and AID of organic matter, nitrogen, and total AA. There were no interactive effects of dietary treatments with E. acervulina infection on broiler growth performance or dietary AMEn. An AA density × copper supplementation interaction was observed (P < 0.05) for AID of total AA, whereby copper supplementation increased AID of total AA for birds fed the LAA diet and decreased AID of total AA for birds fed the HAA diet. In summary, E. acervulina-induced reductions in nutrient digestibility were dependent on dietary copper and AA status, but changes in digestibility had minimal impact on growth performance of broilers during the E. acervulina infection period.

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 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.