Performance and economic evaluation of feeding programs varying in energy and protein densities for broiler grillers

Transcription

1 C 2015 Poultry Science Association Inc. Performance and economic evaluation of feeding programs varying in energy and protein densities for broiler grillers V. Basurco, S. L. Vieira,,1 N. C. Serafini, G. O. Santiago, C. R. Angel, and R. Gonzalez-Esquerra San Fernando, Av. Republica De Panama, 4295, Lima, Peru; Department of Zootechny, Federal University of Rio Grande do Sul, Av. Bento Gonçalves 7712, Porto Alegre, RS, Brazil ; Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA 20742; and Novus do Brasil, Al. Venus, 512, Indaiatuba, SP, Brazil Primary Audience: Nutritionists, Researchers SUMMARY A study was conducted to evaluate field performance and economic impacts of feeding diets varying in AME and amino acid (AA) densities to Cobb 500 female broiler grillers (eviscerated carcass averaging 1.0 kg). Corn soy diets were fed to birds in a factorial arrangement of 3 AME (low, moderate, and high) by 3 AA densities (low, moderate, and high). Differences in AA and AME average values were of 10 and 1.5%, respectively. Treatments had 8 replications of 40 birds allocated in floor pens. Live performance was significantly improved in parallel with increases in AME and AA; however, carcass yield increased and abdominal fat was reduced only when AA was increased (P < 0.05). Gross margins (GM) for each treatment were calculated using scenarios of high and low market costs for corn, soybean meal, as well as for carcass prices. Costs were classified as variable [costs of feeding (CF), fixed farm costs (FFC), and fixed processing costs (FPC)] and their behavior in response to nutritional density was studied. All cost components, (CF, FFC, and FPC) decreased as AME increased, which resulted in the lowest total costs (TC) for the highest AME diets in all scenarios tested, as well as the greatest GM for those dietary programs. In contrast to AME, cost components moved in opposite directions in response to AA density whereby, in 4 out of 7 scenarios, optimizing CF did not result in greater GM. The present study was conducted with low-weight carcasses and, therefore, conclusions made from the presented data are restricted to this type of product. It is concluded that when broiler grillers are objects of study, the use of CF as the sole criteria to choose an optimal feeding program, without considering significant fixed costs present along the production and meat processing chains, tends to underestimate the economic potential of increasing nutrient density. Key words: amino acid, broiler, griller, metabolizable energy 2015 J. Appl. Poult. Res. 24: Corresponding author: slvieira@ufrgs.br

2 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS 305 DESCRIPTION OF THE PROBLEM Dietary density impacts broiler production parameters related to meat output, and therefore total revenue. Improvements in BW gain, FCR, and breast meat yields of broilers at different ages have been reported with increased amino acids (AA) andame n diet densities [1 4]. Increasing the proportions of protein and energy in broiler feeds is associated with increased costs because of the greater need for more expensive protein and energy-rich ingredients. Costs of major feed ingredients, such as soybean meal (SBM), corn, as well as vegetable fats are typically volatile and have dramatically increased in the last few years. Market prices peaked in 2008 and then declined in 2009 and 2010 but without returning to prices seen prior to the 2007, and moved sharply upward again in 2011 [5]. Performance changes obtained in response to increasing nutrient density usually follow a response-curve of decreasing returns for a number of parameters of economic significance, whereas formulating at higher nutrient densities results in more expensive diets. Given that relationship, the dietary density that yields optimal overall profitability is attained at the point whereby the incremental production obtained by dietary manipulations maximize the difference between total revenue (TR) and total costs (TC). Typically, costs of feeding (CF) correspond to the major component of TC per kilogram meat. Still, fixed farm costs (FFC) and fixed processing costs (FPC) have a significant contribution. Optimizing nutritional programs to the lowest possible CF without accounting for those incurred from the farm through the processing and marketing of chicken meat is commonly observed in a number of industries. For the purpose of this discussion, CF include the proportion of the TC per kilogram meat attributed to the costs of feed ingredients delivered at the feed mill, the costs of manufacturing them into chicken feed, and the costs of transporting such feed to the farm where it would be finally consumed by the birds. Normally, such cost component is of variable nature behaving in an inverse quadratic manner in response to gradual increases in nutrient density. As dietary density increases and performance improves, the response curve eventually reaches a point where better performance results in greater CF. In contrast, a significant portion of the TC per kilogram carcass is attributed to farm costs (i.e., FFC) and costs during processing (i.e., FPC) many of which can be of fixed nature. Unlike variable costs, fixed costs per kilogram meat always drop in response of increasing carcass weight. For instance, the cost of a 1-day-old chick is diluted per kilogram meat in a large relative to a small carcass. To a certain extent, 1- day-old chick, vaccination, labor, live bird transportation, farm depreciation/amortization, and so on, as well as many meat processing costs are of a fixed nature. As these costs components can move in different directions in response to dietary density and performance improvements, optimizing to lowest CF may not necessarily optimize profitability. Research work assessing the economic impact of nutrient density in modern broilers has mainly used male broilers heavier than 2.0 kg at processing and having meat yields, especially breast meat, as their main targets [6 8]. Low BW eviscerated broiler chicken carcasses, usually referred as broiler grillers or young chickens, are grown around the world to serve a variety of markets and are a main product in the Middle East market. These are eviscerated carcasses without head, neck, feet, and giblets and are usually sold by the unit. Around one-third of all Brazilian chicken exports are yearly delivered to that region, a volume slightly superior to 1 million metric tons in 2013 [9]. Broiler grillers are presently marketed with carcass weights ranging from 1.0 to 1.2 kg, which, therefore, demand live birds having BW between 1.5 and 1.7 kg. Official data is not completely available, but it is expected that broilers processed for the griller market are usually female chickens processed at very early ages. The current study is aimed at evaluating growth responses, eviscerated carcass yields, and economic responses of feeding programs varying in AME and AA densities fed to female broilers processed at an age delivering body weights similar to those destined to the broiler griller market. It was also its objective to illustrate the impact of considering variable and fixed

3 306 JAPR: Research Report costs in choosing the nutritional strategy that maximizes economic return. MATERIALS AND METHODS Bird Husbandry Procedures adopted throughout this study were approved by the Ethics and Research Committee of the Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. A total of two thousand, eight hundred eighty 1-dayold slow-feathering Cobb Cobb 500 female broiler chicks, vaccinated for Marek s disease at the hatchery, were randomly distributed into 72 pens ( m; birds/m 2 ). Each pen had reused rice hulls as bedding and was equipped with 1 tube feeder with 15-kg capacity and 3 nipple drinkers. Average temperature was 32 C at placement and was reduced to provide bird comfort throughout the study with the use of thermostatically controlled heaters, as well as fans and foggers. Lighting was continuous until 7 d age and a 12L:12 D cycle was used afterwards. Birds had ad libitum access to water and mash feeds. Diets were formulated on a true digestibility basis using published values as reference for nutrients that did not vary with the feeding treatments [10]. Treatments Treatments were distributed in a 3-phase feeding program: 1 to 7 d (prestarter), 8 to 18d(starter),and19to29dage(grower finisher) (Tables 1, 2, and 3). Study diets were formulated using average nutrient and AME n allowances data obtained from a representative number of Brazilian nutritionists responding to a survey on dietary programs used in their commercial operations. Data originated from this survey was reported as digestible (dig) ratios of essential AA to Lys as well as AME n used in feeding programs in these operations. Averaged survey values were used to formulate moderate diets (M) having dig Lys at 1.28, 1.22, and 1.07%; and AME at 3,050, 3,100, and 3,200 kcal/kg feed, respectively in the prestarters fed from 1 to 7 d, starters fed from 8 to 21 d, and grower-finisher diets fed from 22 to 29 d. High (H) and low(l) feeding programs were formulated such that ideally balanced protein (IP)and AME n were increased or decreased in comparison to the M diets in 10% for IP and 1.5% for AME n. These ranges were used because they represented the minimum and maximum found in the survey. Minerals and vitamins were common to all diets. Ideal AA ratios were 0.80 for total sulfur AA, 0.65 for Thr, 0.75 for Val, 0.65 for Ile, 1.04 for, Arg, and 0.17 for Trp from 1 to 18 d. From 19 to 29 d ratios were the same with exception of 0.78 for Val and 0.67 for Ile. The study had a factorial arrangement of 9 treatments having 3 IP diets (IPD)by3AME n diets (AMED). Study diets were provided to 8 replicate pens of 40 birds each (14.7 birds/m 2 ). Analyses of AA in ingredients and diets were conducted using an HPLC auto analyzer and employed performic acid oxidation of the feed sample prior to acid hydrolysis (AOAC [11]). Analysis of 2-hydroxy-4 methylthiobutanoic acid was also done using HPLC [12]. Measurements Data obtained for BW gain (BWG), feed intake (FI), and FCR corrected for the weight of dead birds was determined at 7, 18, and 29 d. Mortality was recorded daily. At 29 d, 7 birds were randomly obtained from each pen, fasted for 8 h, and individually weighed for in-line processing. Birds were electrically stunned with 45 V for 3 s and then bled for 3 min after a jugular vein cut, being then scalded at 60 Cfor 45 s with feathers being mechanically plucked afterwards. Evisceration was manual (lungs remained in the carcass) and carcasses were immediately immersed in slush ice for approximately 3 h. Eviscerated carcasses were hung for 3 min to remove excess water prior to their individual weighing, then abdominal fat was manually removed. For the sake of data recording and statistical analyses, carcass yield was expressed relatively to live weight, whereas abdominal fat was expressed as a proportion of the eviscerated carcass. Economic Analyses Study diets were formulated using leastcost feed formulation software considering

4 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS 307 Table 1. Ingredient and nutrient composition of diets having varying levels of AME and ideally balanced protein (IP) fed to broilers from 1 to 7 d age. Low AME Moderate AME High AME Item Low IP Moderate IP High IP Low IP Moderate IP High IP Low IP Moderate IP High IP Ingredient, % Corn 7.8% Soybean meal (SBM) 45.0% Soybean oil Dicalcium phosphate Limestone Sodium bicarbonate Methionine hydroxy analogue Biolysine Common salt Choline chloride 60.0% L-Threonine 98.5% Vitamin and mineral mix Diet cost R$/kg Energy and nutrient composition, % or as noted 5 AME, kcal/kg 3,004 3,004 3,004 3,050 3,050 3,050 3,096 3,096 3,096 CP 20.7 (20.4) 22.9 (22.7) 25.1 (25.4) 20.7 (20.3) 22.9 (23.2) 25.1 (25.4) 20.7 (20.3) 22.9 (23.2) 25.1 (24.9) Ca Average P Na Choline chloride, mg/kg 1,700 1,700 1,700 1,700 1,700 1,700 1,700 1,700 1,700 Dig Lys Dig TSAA Dig Thr Dig Val Total Lys 1.27 (1.23) 1.41 (1.37) 1.55 (1.56) 1.27 (1.29) 1.41 (1.45) 1.55 (1.60) 1.27 (1.30) 1.41 (1.42) 1.55 (1.56) Total TSAA 0.99 (1.03) 1.09 (1.07) 1.20 (1.22) 0.99 (0.95) 1.09 (1.06) 1.20 (1.22) 0.99 (0.99) 1.09 (1.09) 1.20 (1.18) Total Thr 0.83 (0.82) 0.93 (0.90) 1.03 (0.99) 0.84 (0.86) 0.93 (0.90) 1.03 (0.98) 0.84 (0.85) 0.93 (0.90) 1.03 (0.98) Total Val 0.95 (0.95) 1.06 (1.09) 1.17 (1.20) 0.95 (0.93) 1.06 (1.08) 1.17 (1.18) 0.95 (0.94) 1.06 (1.09) 1.17 (1.15) Total Ile 0.88 (0.85) 0.99 (0.98) 1.10 (1.09) 0.88 (0.86) 0.99 (1.01) 1.10 (1.11) 0.88 (0.84) 0.99 (0.99) 1.10 (1.07) 1 Novus International, St. Louis, MO, contains 84% hydroxy methyl butanoic acid and 12% calcium. 2 Evonik Industries AG, Hanau, Germany, contains 50.7% L-Lys as L-Lys sulfate; 0.3% Thr, 0.1% Trp, 0.1% TSAA 0.2%, 0.5% Leu, 0.6% Arg, 0.3% Ile, and 0.4% Val. 3 Composition per kg of feed: vitamin A, 8,000 UI; vitamin D3, 2,000 UI; vitamin E, 30 UI; vitamin K3, 2 mg; thiamine, 2 mg; riboflavin, 6 mg; pyridoxine, 2.5 mg; cyanocobalamin, mg, pantothenic acid, 15 mg; niacin, 35 mg; folic acid, 1 mg; biotin, 0.08 mg; iron, 40 mg; zinc, 80 mg; manganese, 80 mg; copper, 10 mg; iodine, 0.7 mg; selenium, 0.3 mg; sodium monensin 40% (Coban 100, Elanco Animal Health, Greenfield, IN). 4 Prices [Brazilian Real (R$) per kilogram] used during formulation were: corn: 0.48; SBM: 0.80; soybean oil: 2.38; dicalcium phosphate: 1.10; limestone: 0.12; sodium bicarbonate: 0.91; MHA 84%: 8.08; Biolys 50.7%: 2.23; salt: 0.33; vitamin premix: 15.19; choline chloride 60%: 2.31; L-threonine 98.5%: 4.61; vitamin and mineral mix: By the time this paper was written, exchange rate was 2.35 R$ per 1 U$. 5 Analyzed values in parentheses.

5 308 JAPR: Research Report Table 2. Ingredient and nutrient composition of diets having varying levels of AME and ideally balanced protein (IP) fed to broilers from 8 to 18 d age. Low AME Moderate AME High AME Item Low IP Moderate IP High IP Low IP Moderate IP High IP Low IP Moderate IP High IP Ingredient, % Corn 7.8% Soybean meal (SBM) 45.0% Soybean oil Dicalcium phosphate Limestone Sodium bicarbonate Methionine hydroxy analogue Biolysine Common salt Choline chloride 60.0% L-Threonine 98.5% Vitamin and mineral mix Diet cost R$/kg Energy and nutrient composition, % or as noted 5 AME, kcal/kg 3,054 3,054 3,054 3,100 3,100 3,100 3,147 3,147 3,147 CP 19.8 (19.9) 21.9 (21.9) 23.9 (23.8) 19.8 (19.9) 21.8 (21.9) 23.9 (24.3) 19.7 (19.4) 21.8 (21.7) 23.9 (25.9) Ca Average P Na Choline chloride, mg/kg 1,650 1,650 1,650 1,650 1,650 1,650 1,650 1,650 1,650 Dig Lys Dig TSAA Dig Thr Dig Val Total Lys 1.21 (1.22) 1.34 (1.35) 1.47 (1.49) 1.21 (1.24) 1.34 (1.38) 1.47 (1.45) 1.21 (1.23) 1.34 (1.32) 1.47 (1.50) Total TSAA 0.94 (0.96) 1.04 (0.99) 1.14 (1.08) 0.94 (0.98) 1.04 (1.03) 1.14 (1.13) 0.94 (0.89) 1.04 (0.99) 1.14 (1.17) Total Thr 0.79 (0.79) 0.89 (0.88) 0.98 (0.96) 0.79 (0.75) 0.89 (0.86) 0.98 (0.95) 0.79 (0.75) 0.89 (0.86) 0.98 (0.96) Total Val 0.90 (0.94) 1.01 (0.99) 1.12 (1.09) 0.90 (0.87) 1.01 (0.98) 1.12 (1.09) 0.91 (0.88) 1.01 (1.01) 1.12 (1.13) Total Ile 0.83 (0.85) 0.94 (0.90) 1.04 (1.01) 0.83 (0.80) 0.94 (0.90) 1.05 (1.02) 0.84 (0.81) 0.94 (0.94) 1.05 (1.06) 1 Novus International, St. Louis, MO, contains 84% hydroxy methyl butanoic acid and 12% calcium. 2 Evonik Industries AG, Hanau, Germany, contains 50.7% L-Lys as L-Lys sulfate; 0.3% Thr, 0.1% Trp, 0.1% TSAA 0.2%, 0.5% Leu, 0.6% Arg, 0.3% Ile, and 0.4% Val. 3 Composition per kg of feed: vitamin A, 8,000 UI; vitamin D3, 2,000 UI; vitamin E, 30 UI; vitamin K3, 2 mg; thiamine, 2 mg; riboflavin, 6 mg; pyridoxine, 2.5 mg; cyanocobalamin, mg, pantothenic acid, 15 mg; niacin, 35 mg; folic acid, 1 mg; biotin, 0.08 mg; iron, 40 mg; zinc, 80 mg; manganese, 80 mg; copper, 10 mg; iodine, 0.7 mg; selenium, 0.3 mg; sodium monensin 40% (Coban 100, Elanco Animal Health, Greenfield, IN). 4 Prices [Brazilian Real (R$, per kilogram] used during formulation were: corn: 0.48; SBM: 0.80; soybean oil: 2.38; dicalcium phosphate: 1.10; limestone: 0.12; sodium bicarbonate: 0.91; MHA 84%: 8.08; Biolys 50.7%: 2.23; salt: 0.33; vitamin premix: 15.19; choline chloride 60%: 2.31; L-threonine 98.5%: 4.61; vitamin and mineral mix: By the time this paper was written, exchange rate was 2.35 R$ per 1 U$. 5 Analyzed values in parentheses.

6 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS 309 Table 3. Ingredient and nutrient composition of diets having varying levels of AME and ideally balanced protein (IP) fed to broilers from 19 to 29 d age. Low AME Moderate AME High AME Item Low IP Moderate IP High IP Low IP Moderate IP High IP Low IP Moderate IP High IP Ingredient, % Corn 7.8% Soybean meal (SBM), 45.0% Soybean oil Dicalcium phosphate Limestone Sodium bicarbonate Methionine hydroxy analogue Biolysine Common salt Choline chloride 60.0% L-Threonine 98.5% Vitamin and mineral mix Diet cost R$/kg Energy and nutrient composition, % or as noted 5 AME, kcal/kg 3,152 3,152 3,152 3,200 3,200 3,200 3,248 3,248 3,248 CP 17.5 (17.3) 19.3 (19.0) 21.1 (20.9) 17.5 (17.2) 19.3 (18.9) 21.1 (20.9) 17.4 (17.5) 19.3 (18.7) 21.1 (21.2) Ca Average P Na Choline chloride, mg/kg 1,600 1,600 1,600 1,600 1,600 1,600 1,600 1,600 1,600 Dig Lys Dig TSAA Dig Thr Dig Val Total Lys 1.06 (1.06) 1.18 (1.23) 1.29 (1.32) 1.06 (1.08) 1.18 (1.20) 1.29 (1.33) 1.06 (1.10) 1.18 (1.22) 1.29 (1.32) Total TSAA 0.83 (0.84) 0.92 (0.89) 1.01 (1.03) 0.83 (0.79) 0.92 (0.88) 1.01 (0.97) 0.83 (0.79) 0.92 (0.93) 1.01 (0.97) Total Thr 0.71 (0.74) 0.79 (0.77) 0.88 (0.84) 0.71 (0.68) 0.80 (0.82) 0.88 (0.85) 0.71 (0.68) 0.80 (0.82) 0.88 (0.84) Total Val 0.79 (0.80) 0.88 (0.90) 0.97 (1.01) 0.79 (0.82) 0.88 (0.89) 0.97 (0.99) 0.79 (0.83) 0.88 (0.87) 0.97 (0.97) Total Ile 0.72 (0.73) 0.81 (0.80) 0.90 (0.91) 0.72 (0.71) 0.81 (0.80) 0.90 (0.90) 0.72 (0.75) 0.81 (0.79) 0.91 (0.90) 1 Novus International, St. Louis, MO, contains 84% hydroxy methyl butanoic acid and 12% calcium. 2 Evonik Industries AG, Hanau, Germany, contains 50.7% L-Lys as L-Lys sulfate; 0.3% Thr, 0.1% Trp, 0.1% TSAA 0.2%, 0.5% Leu, 0.6% Arg, 0.3% Ile, and 0.4% Val. 3 Composition per kg of feed: vitamin A, 8,000 UI; vitamin D3, 2,000 UI; vitamin E, 30 UI; vitamin K3, 2 mg; thiamine, 2 mg; riboflavin, 6 mg; pyridoxine, 2.5 mg; cyanocobalamin, mg, pantothenic acid, 15 mg; niacin, 35 mg; folic acid, 1 mg; biotin, 0.08 mg; iron, 40 mg; zinc, 80 mg; manganese, 80 mg; copper, 10 mg; iodine, 0.7 mg; selenium, 0.3 mg; sodium monensin 40% (Coban 100, Elanco Animal Health, Greenfield, IN). 4 Prices [Brazilian Real (R$) per kilogram] used during formulation were: corn: 0.48; SBM: 0.80; soybean oil: 2.38; dicalcium phosphate: 1.10; limestone: 0.12; sodium bicarbonate: 0.91; MHA 84%: 8.08; Biolys 50.7%: 2.23; salt: 0.33; vitamin premix: 15.19; choline chloride 60%: 2.31; L-threonine 98.5%: 4.61; vitamin and mineral mix: By the time this paper was written, exchange rate was 2.35 R$ per 1 U$. 5 Analyzed values in parentheses.

7 310 JAPR: Research Report ingredient market prices observed in the south of Brazil as of July Study diets, live performance and carcass data were filled into a spreadsheet per dietary treatment and feeding phase to compose a calculator that could estimate CF, FFC, FPC, and gross margin (GM). The above-mentioned costs and other market values utilized to economic estimations were established as an average of the integrations included in the survey as stated previously. CF was obtained by pooling the cost of all feed ingredients consumed by birds under a particular treatment, plus an operational feed mill cost of U$ 8/metric ton (MT). A feed transportation cost to the farm of U$ 5/MT was added. Performance and carcass data were used to calculate the contribution of CF as per-kilogram carcass. All farm costs were considered as fixed, and therefore FFC included labor at the farm, veterinary services, vaccines, maintenance of farm equipment, as well as barn depreciation and amortization. For the purpose of this exercise, FFC were considered at U$ 0.6/bird irrespective of bird size. All processing costs were also considered as fixed and included labor, transportation to the processing plant, equipment Table 4. Ingredient and carcass market prices used during the analyses of various scenarios (U$/MT) 1. Item High Average Low Corn SBM Eviscerated carcass 1,600 1,300 1,000 1 Scenarios were chosen using oscillations in Brazilian prices of 2012 and 2013 as guidelines. maintenance, depreciation, and amortization. Altogether, FPC added up to U$ 0.420/bird at the farm gate. A loss of 1.5% in total carcass output was imposed across treatments representing bird losses during transportation from the farm gate to the processing plant. By imposing scenarios of high or low corn or soybean meal prices (Table 4), TC/kilogram carcass was further calculated (TC = CF + FFC + FPC). Scenarios of high or low carcass prices (Table 4; U$/kg carcass) were considered while estimating total revenue (TR). For each scenario studied, GM was obtained by the equation GM = TR TC. In all cases, when the sensitivity of the system was affected by one isolated factor studied (high or low carcass or ingredient market prices), all others elements were kept at average prices. Table 5. Growth performance of broilers fed diets having varying levels of AME and ideally balanced protein (IP) from 1 to 29 d age 1. BW gain, g FCR 2 Feed intake, g Treatment 1to7d 1to18d 1to29d 1to7d 1to18d 1to29d 1to7d 1to18d 1to29d IP High 134 a 666 a 1,502 a a a a 141 b 862 b 2,185 c Moderate a 665 a 1,491 a,b b b b 145 a,b 882 a 2,245 b Low 128 b 645 b 1,478 b c c c 148 a 897 a 2,295 a AME High a 1,502 a a a a ,221 b Moderate b 1,487 a,b a b b ,243 a,b Low b 1,484 b b c c ,261 a SEM Main effect (P-value) IP density <0.001 <0.001 < <0.001 <0.001 AME <0.001 <0.001 < IP AME a c Means within a column not sharing a common superscript are different (P < 0.05). 1 Means are based on 8 replicates of 40 birds/treatment at the beginning of the study. 2 FCR corrected for the weight of dead birds. 3 Moderate IP treatments were formulated with 1.28, 1.22 and 1.07% digestible (dig) Lys from first to last diet, whereas high and low were 10% higher and lower in dig Lys with minimum ratios of: TSAA 0.80; Thr 0.65; Val 0.75, Ile 0.65 from 1 to 21 d and Val 0.78 and Ile 0.67 from 21 to 29 d; Arg 1.04 and Trp 0.17 were the same from 1 to 29 d; high, moderate, and low AME treatments had 3,147, 3,100, and 3,054 kcal/kg, respectively.

8 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS 311 Statistical Analysis Data were submitted to a 2-way ANOVA using the GLM procedure of SAS [13]. Significance was accepted at the P 0.05, and mean differences were separated using Tukey s Honest Significant Difference Test [14]. Mortality and carcass data were arcsine transformed prior to statistical analysis. RESULTS AND DISCUSSION Live Performance and Carcass Yields Analyzed AA of the study diets was in an acceptable range as expected from feed formulation. This is presented for the first 5 limiting AA in Tables 1, 2 and 3. Increased BWG was observed when birds were fed H and M compared to L IPD from 1to7d(P < 0.002), 1 to 18 d (P < 0.001) and1to29d(p < 0.003) (Table 5). Feeding H AMED from 1 to 18 d (P < 0.002) resulted in higher BWG when compared to M and L AMED Table 6. Interaction for FCR and feed intake (FI) of broilers fed diets having varying levels of AME and ideally balanced protein (IP) fed to broilers 1. Treatment FCR FI, g 1to18d 1to18d IP AME High High a 845 c High Moderate b 852 b,c High Low c,d 888 a,b Moderate 2 High b,c 886 b,c Moderate Moderate b,c 877 a,b,c Moderate Low c,d 881 a Low High d 891 a Low Moderate e 910 a Low Low e 887 a,b SEM P-value a e Means within a column not sharing a common superscript are different (P < 0.05). 1 Means are from each of 8 replicate pens of 40 birds at the beginning of the study. 2 Moderate IP treatments were formulated with 1.28, 1.22, and 1.07% digestible (dig) Lys from first to last diet, whereas high and low were 10% higher and lower in dig Lys with minimum ratios: TSAA 0.80; Thr 0.65; Arg 1.04 and Trp Val and Ile were 0.75 and 0.65 from 1 to 21 d and 0.78 and 0.67 from 21 to 29 d; high, moderate, and low AME treatments had 3,147, 3,100, and 3,054 kcal/kg, respectively. whereas feeding H and M AMED were without difference from 1 to 29 d (P < 0.024). Improvements in FCR were observed (P < 0.001) as IPD increased gradually for each one of the 3 levels as well as for AMED (P < 0.001) in the 3 growth periods. Gradual increases in FI from H to L IPD were observed from 1 to 7 d (P < 0.002), 1 to 18d(P < 0.001) and 1 to 29 d (P < 0.001). Mean FI between H and M IPD as well as between M and L IPD, however, were not significantly different in the periods from 1 to 7 and 1 to 18 d, respectively. Decreases in FI were also observed when comparison was done between birds fed H and L AMED from 1 to 29 d (P < 0.009). An interaction was observed from 1 to 18 d for FCR (P < 0.001) and FI (P < 0.005) (Table 6), which showed that the increases observed in FCR and FI as IPD and AMED were reduced did not follow when M and L AMED were fed along with L IPD. Mortality (data not shown) was not different between treatments (P > 0.05). Table 7. Carcass weight and yield of broilers fed diets having varying levels of AME and ideally balanced protein (IP) fed to broilers from 1 to 29 d age 1. Carcass 2 Abdominal fat Treatment g % g % IP High 1, a,b a Moderate 3 1, a b Low 1, b c AME High 1, Moderate 1, Low 1, SEM Main effect (P-value) IP <0.001 <0.001 AME IP AME a c Means within a column not sharing a common superscript are different (P < 0.05). 1 Means are from each of 8 replicate pens of 40 birds at the beginning of the study. 2 Eviscerated carcass without feet or head and abdominal fat are means of 8 birds from each of 8 replicates/treatment. 3 Moderate IP treatments were formulated with 1.28, 1.22, and 1.07% digestible (dig) Lys from first to last diet, whereas high and low were 10% higher and lower in dig Lys with minimum ratios: TSAA 0.80; Thr 0.65; Arg 1.04 and Trp Val and Ile were 0.75 and 0.65 from 1 to 21 d and 0.78 and 0.67 from 21 to 29 d; high, moderate, and low AME treatments had 3,147, 3,100, and 3,054 kcal/kg, respectively.

9 312 JAPR: Research Report Birds sampled for carcass analyses had similarbw(table5) and did not reflect BW gain differences at 29 d age. Still, an increased yield of whole carcass as percentage of live bird was observed for birds fed H and M IPD when compared to L IPD (P < 0.033) (Table 7), which occurred with a concurrent reduction in abdominal fat (P < 0.001). Abdominal fat as percentage of eviscerated carcass was lowest (P < 0.001) in H IPD (Table 7). A higher AA density typically causes an increase in breast meat yield because of increased lean muscle tissue [7] and consequently reduction in the fat deposition. Diets with high AME probably used the energy in excess for accumulation as abdominal and carcass fat. In the present study, feeding H IPD improved BWG and reduced FI and percent carcass fat when compared to L IPD as it was found by other researchers when conducting studies having similar changes in AA densities, but using heavier broilers [1, 7, 8, 15]. Feeding H AMD also improved BWG whereas reductions in FCR, FI, and percentage of abdominal fat were observed when compared to L AMD. Effects of AME in the present study were similar to those from others that evaluated the way broilers respond to variation in dietary AME [16, 17]. In the present study, broilers adjusted their feed intake as dietary AA concentration was reduced within each AME level, which probably impacted the abdominal fat content in their carcasses. Economic Analysis Calculating all cost components and how they change in an integrated broiler operation is complex and beyond the scope of this study. For the purpose of discussing the nature of key costs components in choosing the optimal nutritional density, the current study assumed that the farm and processing costs were the most significant ones in a regular Brazilian broiler chicken operation. Also, it was assumed that these costs were of a fixed nature in the context of the system studied, which had relatively small differences in live weight (maximum of 24 g BW) and carcass performance (maximum of 15 g BW) attained by the dietary treatments tested herein. This assumption implies that all factors considered at the farm and at the processing facilities remained the same in spite of the rather small BW carcass weight differences mentioned above. For the purpose of calculating TR, it was also assumed that prices were constant across carcass weight categories in spite of relatively small differences among them. Within all scenarios tested the cost components moved following the same trends in response to increments in AME density. Thus, conclusions drawn from either CF or GM favored the use of H AME diets in all cases. However, that was not the case for IP diets since, in 4 out of the 6 scenarios tested, the IP program that minimized CF was different from the one that Table 8. Economic sensitivity analyses of carcass production of broilers fed diets varying in AME and ideally balanced protein (IP) from 1 to 29 d age 1. U$/kg carcass 2 IP AME Low Moderate High Low Moderate High Cost of feeding Fixed farm costs Fixed processing costs Total fixed cost Total cost Gross margin Moderate IP treatments were formulated with 1.28, 1.22, and 1.07% digestible (dig) Lys from first to last diet, whereas high and low were 10% higher and lower in dig Lys with minimum ratios of: TSAA 0.80; Thr 0.65; Val 0.75, Ile 0.65 from 1 to 21 d and Val 0.78 and Ile 0.67 from 21 to 29 d; Arg 1.04 and Trp 0.17 were the same from 1 to 29 d; High, moderate, and low AME treatments had 3,147, 3,100, and 3,054 kcal/kg, respectively. 2 Cost of feeding (CF) = feed ingredients plus mill and transportation in a total of U$ 1.3/kg; fixed farm costs (FFC) = U$ 0.6/bird; fixed processing costs (FPC) = U$ 0.42/bird at farm gate; TC = CF + FFC + FPC; total revenue (TR) = high, moderate, and low carcass market prices = U$ 1.6, 1.3, and 1.0 per kg, respectively.

10 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS 313 Table 9. Economic sensitivity analyses under several price scenarios 1,2. Protein density Energy density Protein density Energy density U$/kg carcass Low Moderate High Low Moderate High Low Moderate High Low Moderate High High Corn Prices Low Corn Prices Cost of feeding Total cost Gross margin High Soybean Meal (SBM) Prices Low SBM Prices Cost of feeding Total cost Gross margin High Carcass Prices Low Carcass Prices Cost of feeding Total cost Gross margin When the price of one factor was tested, prices of all the others ingredients and/or eviscerated carcass were kept at average. 2 Moderate treatments were formulated with 1.28, 1.22, and 1.07% digestible (dig) Lys from first to last diet, whereas high and low were 10% higher and lower in dig Lys with minimum ratios of: TSAA 0.80; Thr 0.65; Val 0.75, Ile 0.65 from 1 to 21 d and Val 0.78 and Ile 0.67 from 21 to 29 d; Arg 1.04 and Trp 0.17 were the same from 1 to 29 d; High, moderate, and low AME treatments had 3,147, 3,100, and 3,054 kcal/kg, respectively. 3 Cost of feeding (CF) = feed ingredients plus mill and transportation in a total of U$ 1.3/kg; fixed farm costs (FFC) = U$ 0.6/bird; fixed processing costs (FPC) = U$ 0.42/bird at farm gate; TC = CF + FFC + FPC; total revenue (TR) = high, moderate, and low carcass market prices = U$ 1.6, 1.3, and 1.0 per kg, respectively.

11 314 JAPR: Research Report maximized GM. In this particular setting it can be observed from Table 8 that 41.6% of TC was a variable component (i.e., CF) and 58.4% was fixed (34.4 and 24.0% for FFC and FPC, respectively). Thus, both cost types had a significant contribution to TC, but they did not necessarily changed in the same direction as well as in the magnitude of response to nutrient density. Therefore, the nutrient density that maximizes GM is not necessarily the one that minimizes FFC. Based on data presented in Table 9 it can be stated that Cobb Cobb 500 female broiler grillers benefited significantly from increasing protein and energy density, such that M and H IPD as well as H AME diets generally provided best GM. Because it is the largest proportion of broiler production costs it is usual to target CF as the main criteria to implement nutrient density strategies. However, although this simplifies cost calculation, it underestimates the potential of higher density diets if significant fixed components are present along the production chain. Adding fixed costs from the farm (i.e., FFC) and from the processing plant (i.e., FPC) in the estimation of total production cost provides more precise information to estimate the optimal nutrient density as per economic considerations. CONCLUSIONS AND APPLICATIONS 1. To the best of our knowledge, this study is unique in that it deals with the economic responses of low-bw Cobb x Cobb 500 female broiler grillers to various AA and AME densities in commercial-type diets. 2. The present study illustrates the opportunity of making better decisions and reducing costs by integrating information along the production system, a practice that could be greatly facilitated by using models. 3. This study suggests that, when determining gross profit margins in griller production, only considering feed formulation costs or optimum nutrient densities can lead to incorrect conclusions. REFERENCES AND NOTES 1. Dozier, W. A., III, A. Corzo, M. T. Kidd, and S. L. Branton Dietary apparent metabolizable energy and amino acid density effects on growth and carcass traits of heavy broilers. J. Appl. Poult. Res. 16: Dozier, W. A., III, C. J. Price, M. T. Kidd, C. Corzo, J. Anderson, and S. L. Branton Growth performance, meat yield, and economic responses of broilers fed diets varying in metabolizable energy from thirty to fifty-nine days of age. J. Appl. Poult. Res. 15: Dozier, W. A., III, R. W. Gordon, J. Anderson, M. T. Kidd, A. Corzo, and S. L. Branton Growth and meat yield and economic responses of broilers provided threeand four-phase regimens formulated to moderate and high nutrient density during a 56 day production period. J. Appl. Poult. Res. 15: Kidd, M. T., A. Corzo, D. Hoehler, E. R. Miller, and W. A. Dozier, III Broiler responsiveness (Ross x 708) to diets varying in amino acid density. Poult. Sci. 84: Rosegrant, M. W., S. Tokgoz, and P. Bhandary The new normal? A tighter global agricultural supply and demand relation and its implications for food security. Am. J. Agric. Econ. 95: Leeson, S., and G. Lopez Response of broiler breeders to low-protein diets: offspring performance. Poult. Sci. 74: Corzo, A., M. W. Schilling, R. E. Loar, II, L. Mejia, L. C. G. S. Barbosa, and M. T. Kidd Responses of Cobb x Cobb 500 broilers to dietary amino acid density regimens. J. Appl. Poult. Res. 19: Lilly, R. A., M. W. Schilling, J. L. Silva, J. M. Martin, and A. Corzo The effects of dietary amino acid density in broilers feed on carcass characteristics and meat quality. J. Appl. Poult. Res. 20: ABPA (Associação Brasileira de Proteína Animal) União Brasileira de Avicultura, relatório anual da UBABEF Accessed Jul ca705e70f0cb110ae3aed67d29c8842.pdf /japr/ pfv030.html. 10. Rostagno, H. S., L. F. T. Albino, J. L. Donzele, P. C. Gomes, R. F. Oliveira, D. C. Lopes, A. S. Ferreira, S. L. T. Barreto, and P. F. Euclides in Tabelas Brasileiras para Aves e Suínos. Composição de Alimentos e Exigências Nutricionais, 3rd ed. UFV, Viçosa, MG, Brazil. 11. AOAC International Official Methods of Analysis of AOAC International. 16th ed. AOAC Int., Arlington, VA. 12. Ontiveros, R. R., W. D. Shermer, and R. A. Berner An HPLC method for determination of 2-hydroxy-4- (methylthio) butanoic acid (HMB) in supplemental animal feeds. J. Agric. Food Chem. 35: SAS User s Guide Version 9.2 ed. SAS Inst. Inc., Cary, NC. 14. Tukey, J The philosophy of multiple comparisons. Stat. Sci. 6: Taschetto, D., S. L. Vieira, R. Angel, A. Favero, and R. A. Cruz Responses of Cobb x Cobb 500 slow feathering broilers to feeding programs with increasing amino acid densities. Livestock Sci. 146:

12 BASURCO ET AL.: ENERGY AND PROTEIN FOR BROILERS Hidalgo, M. A., W. A. Dozier, III, A. J. Davis, and R. W. Gordon Live performance and meat yield responses of broilers to progressive concentrations of dietary energy maintained at a constant metabolizable energy-tocrude protein ratio. J. Appl. Poult. Res. 13: Dozier, W. A., III, M. T. Kidd, A. Corzo, J. Anderson, and S. L. Branton Growth, meat yield, and economic responses of Ross x Ross 708 broilers provided diets varying in amino acid density from 36 to 59 days of age. J. Appl. Poult. Res. 15: