Apparent metabolizable energy and ileal amino acid digestibility of commercial soybean meals of different origins in broilers

We studied the chemical composition and the in vivo AMEn content and apparent (AID) and standardized (SID) ileal digestibility of CP and amino acids (AA) of 27 samples of soybean meals (SBM) from Argentina (ARG), Brazil (BRA), and USA, collected in Spain. On 88% DM basis, the BRA meals had more CP (46.9 vs. 46.0 and 45.9%; P < 0.05) and less sucrose (5.21 vs. 6.28 and 6.47%; P < 0.001) and stachyose (4.20 vs. 4.66 and 4.78%; P < 0.05) than the USA and ARG meals. Urease activity, protein dispersibility index, KOH protein solubility, and trypsin inhibitor activity values, were higher for the USA meals than for the South American meals (P < 0.05). In the in vivo trial, broilers received a common crumble diet from 0 to 16 d of age and then, their respective experimental diets (53% of a N-free diet and 47% of each of the 27 SBM tested) in mash form, for 5 d. The AMEn (2,334 vs. 2,282 and 2,277 kcal/kg; P = 0.062) and the AID (87.3 vs. 86.7 and 86.4%; P = 0.054) and SID (91.9 vs. 91.2 and 90.8%; P < 0.05) of the protein, were greater for the USA meals than for the ARG and BRA meals. In fact, the SID of Lys (93.5 vs. 93.0 and 92.1%; P < 0.001) and of the sum of Lys, Met, Thr, Trp, and Cys (91.4 vs. 91.0 and 90.2%; P < 0.05) were greater for the USA meals than for the ARG and BRA meals. In summary, the chemical composition, protein quality indicators, AMEn content, and ileal digestibility of the CP and the AA of the SBM, varied with the country of origin of the soybeans. In order to increase the accuracy of the feed formulation process, the composition and nutrient content of commercial batches of SBM, by country of origin should be controlled and periodically updated.

Teaching the principles of least-cost poultry feed formulation utilizing the Solver function within a computer software workbook

A Microsoft Excel workbook, User-Friendly Feed Formulation with Data from Australia (UffdAu.xlsm), has been developed for teaching feed formulation techniques to tertiary level, university students. It runs under both Microsoft Windows and Apple iOS operating systems. The example ingredient composition matrix is based on the Australian Feed Ingredient Database to illustrate the biological and econometric principles of least-cost feed formulation. The nutrient data are based roughly on recent primary breeder company recommendations. The workbook is easily adapted to appropriate ingredients, nutrients, and prices most relevant to the students, wherever it is used. The workbook uses the linear routines of Excel's Solver add-in under the Data heading in the header Ribbon. There is a worksheet illustrating how to adapt non-linear responses such as exogenous enzymes to typical linear models using a step function. Additional worksheets illustrate how proximate analysis can be interpreted in modern analytical chemistry terms and, how various feed energy measures are related to feed composition. UffdAu.xlsm is available free of charge from the Poultry Hub Australia website (https://www.poultryhub.org).

Influence of extruded soybean meal with varying fat and oleic acid content on nitrogen-corrected apparent metabolizable energy in broilers

High oleic (HO) soybeans may serve as a value-added feed ingredient; providing amino acids and estimating their dietary energy value for broilers is essential. In this study, we determined the apparent metabolizable energy (AME), AME corrected for zero nitrogen retention (AMEn), digestibility, and nitrogen (N) retention of HO full-fat (HO-FF) soybean as compared to solvent-extracted soybean meal (SE-SBM), normal oleic full-fat (NO-FF) and extruded expeller (NO-EE) soybean. A total of 240 Ross-708 male broilers were selected, with 8 replicates per treatment and 6 chicks per cage. The AME and AMEn were estimated using the difference method with a 30% inclusion of test ingredients using a corn-soy reference diet with partial and total excreta collection. The index method with partial excreta collection used titanium dioxide as an inert marker. The same starter diet was provided for all birds for 14 d, followed by the reference and assay diets for the next 6 adaptation days. Total excreta were collected twice a day for 3 d. The AME and AMEn values determined for the HO-FF and NO-FF were higher (P < 0.001) than the NO-EE and SE-SBM. The AME of SE-SBM and NO-EE were similar with both methods, but the AMEn of SE-SBM was lower than the NO-EE only with the partial collection method. The agreement between AME and AMEn values determined by partial and total excreta collection analysis was 98%. Data from the total excreta collection method yielded higher AME and AMEn values (P < 0.001) than those from the partial collection method. In summary, HO-FF and NO-FF soybean meals had similar AME and AMEn values. The HO-FF soybean had 39 and 24% higher AME and AMEn than SE-SBM. Hence, high oleic full-fat soybean meal could serve as a valuable alternative feed ingredient to conventional SE-SBM meals in broiler diets, providing additional energy while providing amino acids and more oleic acid to enrich poultry meat products.

Prediction equations of the metabolizable energy in corn developed by chemical composition and enzymatic hydrolysate gross energy for roosters

Two experiments were conducted to establish the prediction equations for AME and TME of corn based on chemical composition and enzymatic hydrolysate gross energy (EHGE) in roosters. In experiment 1, eighty 32-wk-old Hy-line Brown roosters with an average body weight of 2.55 ± 0.21 kg were randomly assigned to 10 diet treatments in a completely randomized design to determine AME and TME by the force-feeding method. Each treatment had 8 replicates with 1 bird per replicate. The 10 test diets used in the experiment were formulated with corn (including 96.10%) as the sole source of energy. In experiment 2, the EHGE of 14 corn samples was measured by the computer-controlled simulated digestion system (CCSDS) with 5 replicates of each sample. The average AME and TME values of corn were 14.58 and 16.46 MJ/kg DM, respectively. The EHGE of 14 corn samples ranged from 14.66 to 15.89 (the mean was 15.24) MJ/kg DM. The best-fit equations for corn based on chemical composition were AME (MJ/kg DM) = 14.5504 + 0.1166 × ether extract (EE) + 0.5058 × Ash - 0.0957 × neutral detergent fiber (NDF) (R2 = 0.8194, residual standard deviation (RSD) = 0.0860, P < 0.01) and TME (MJ/kg DM) = 16.0625 + 0.1314 × EE + 0.4725 × Ash - 0.0872 × NDF (R2 = 0.7867, RSD = 0.0860, P < 0.01). The best-fit equations for corn based on EHGE were AME (MJ/kg DM) = 7.8883 + 0.4568 × EHGE (R2 = 0.8587, RSD = 0.0693, P < 0.01) and TME (MJ/kg DM) = 10.0099 + 0.4228 × EHGE (R2 = 0.8720, RSD = 0.0608, P < 0.01). The differences between determined and predicted values from equations established based on EHGE were lower than those observed from chemical composition equations. These results indicated that EHGE measured with CCSDS could predict the AME and TME of corn for roosters with high accuracy.

Effects of lysolecithins on performance, egg quality, blood profiles and liver histopathology in late-phase laying hens

1. This study investigated the effects of lysolecithins (LL) on performance, egg quality, blood profiles, relative organ weight and liver histopathology in laying hens.2. A total of 480 healthy 65-week-old Lohmann laying hens were randomly allocated into four treatments in a 2 × 2 factorial arrangement design with two levels of energy (AMEn, 11.08 MJ/kg and 12.94 MJ/kg) and two levels of LL (0 and 0.05%).3. Birds fed high energy diets had lower (P < 0.05) average daily intake and feed conversion rate during weeks 0-4, 5-8 and 0-8, but higher (P < 0.05) average egg weight (AEW) during trial weeks 0-4. There was an interaction in (P < 0.05) AEW during trial weeks 0-14 and 0-8 for energy and LL. The high energy diets increased yolk colour at the end of weeks 2 and 4, while addition of LL increased albumen height at the end of week 2. There was an interaction (P < 0.05) in yolk colour between energy and LL at the end of week 2. There was an interaction (P < 0.05) in serum superoxide dismutase and LDL-C throughout the experiment.4. The high energy diets increased (P < 0.05) the relative weight of abdominal fat compared with low energy diets. The high energy diets increased (P < 0.05) liver ether extract content and liver pathological injury score compared with low energy diets at the end of week 8, while the addition of LL decreased (P < 0.05) liver pathological injury score.5. The supplementation of LL in high energy diets could alleviate some negative effects on liver injury in late laying hens.

Dietary crude protein reductions in wheat-based diets with two energy densities compromised performance of broiler chickens from 15 to 36 days post-hatch

This study was designed to investigate the impacts of 2 energy densities (13.0 and 12.5 MJ/kg ME) in wheat-based diets with 3 tiers of CP concentrations (210, 190, and 170 g/kg) on the performance of broiler chickens. The parameters assessed included growth performance (15-36 d posthatch), carcass traits, nutrient utilization, starch-protein digestive dynamics, apparent ileal amino acid digestibility coefficients, and the free amino acid and ammonia (NH3) concentrations in systemic plasma. Also, the feasibility of substituting soybean meal with canola meal in 190 g/kg CP diets was investigated. The dietary CP reduction from 210 to 170 g/kg significantly compromised weight gain by 12.4% (1,890 vs. 2158 g/bird) and FCR by 5.33% (1.501 vs. 1.425). The 0.5 MJ energy density reduction compromised FCR by 3.25% (1.525 vs. 1.477; P = 0.013) in birds offered 170 g/kg CP diets. Reducing dietary CP and energy densities interactively influenced (P = 0.027) apparent metabolizable energy (AME) and nitrogen corrected metabolizable energy (AMEn) (P = 0.022) such that reducing dietary CP increased these parameters but reducing dietary energy densities decreased AME and AMEn. The 150 g/kg canola meal inclusion with the elimination of soybean meal displayed some promise. Dietary CP reductions (and increased nonbound amino acid inclusions) linearly associated with increased plasma ammonia (NH3) concentrations (r = -0.607; P = 0.010) and plasma NH3 was linearly related to depressed weight gains (r = -0.565; P = 0.018). The association of dietary non-protein-bound amino acid (NPBAA) inclusions and elevated plasma NH3 concentrations have profound implications for the successful development of reduced-CP, wheat-based broiler diets.

Determination of prediction equations for apparent metabolizable energy corrected for nitrogen of corn gluten meal and canola meal in broilers

The objectives of this experiment were to determine the AMEn content of different samples of corn gluten meal (CGM) and canola meal (CM) by a reference diet method and to develop prediction equations based on the chemical composition to estimate the AMEn value of CGM and CM in broilers. A total of 300 one-day-old male broiler chicks were randomly assigned to fifteen treatments (14 experimental diet and 1 reference diet) with 4 replicates of each with 5 birds per replicate. At first, birds were fed a starter diet from 0 to 10 d of age, and then, a grower diet from 11 to 23 d of age. To determine the AMEn content, the test diet consisted of 60% reference diet, 38% each test CGM or CM, and 2% minor ingredients. To adaptation, the broilers were fed experimental diets for 4 d, and then feces were collected on 28 d. The gross energy values and chemical compositions among the CGM and CM from different origins were significantly different. The AMEn values of the CGM samples varied from 3,123 to 3,918 kcal/kg, and for the CM, the range was from 1,578 to 2,109 kcal/kg. At the end of the experiment, data were analyzed with SPSS software, and a regression equation was obtained based on the chemical composition. The best equations were selected based on the standard of prediction and regression adjusted R². The equation, AMEn = 49.196 × CP + 80.87 × EE (SEP 180.99; adjusted R² 0.97), was selected to predict the AMEn value of CGM, and the equation, AMEn = 631.55 × EE + 16.716 × CP (SEP 55.3; adjusted R² 0.94), was selected to predict the AMEn value of CM.

Broiler Age Influences the Apparent Metabolizable Energy of Soybean Meal and Canola Meal

The effects of broiler age on the apparent metabolizable energy (AME) and nitrogen-corrected AME (AMEn) of soybean meal (SBM) and canola meal (CM) were examined. A corn-SBM basal diet was developed, and two test diets were formulated by substituting (w/w) 300 g/kg of the basal diet with SBM or CM. Six groups of broiler chickens, aged 1−7, 8−14, 15−21, 22−28, 29−35 or 36−42 d post-hatch, were utilized. Each diet, in pellet form, was randomly allocated to six replicate cages in each age group. Except for the 1−7 d age group, the birds were fed a starter (d 1−21) and/or a finisher (d 22−35) diet prior to the introduction of the experimental diets. The number of birds per cage was 10 (d 1−7), 8 (d 8−14) and 6 (d 15−42). The AME and AMEn of SBM and CM were determined by total excreta collection. The data for each protein source were subjected to orthogonal polynomial contrasts using the General Linear Models procedure. Bird age decreased the retention of dry matter quadratically (p < 0.001) for both SBM and CM. The retention of nitrogen decreased linearly (p < 0.001) with the advancing age of broilers for SBM and CM. The AMEn of SBM and CM decreased quadratically (p < 0.001) as the birds grew older. The highest AMEn was observed during week 1 for both SBM and CM, then declined until week 3, followed by increases thereafter. The current results showed that the age of broiler chickens influenced the AMEn of SBM and CM and supported the use of age-dependent AMEn of feed ingredients in diet formulations.

Comparative study of apparent metabolizable energy and net energy values of dephenolized cottonseed proteins for laying hens

Optimizing the energy utilization of nutrients and ensuring maximum benefits are continuous goals for livestock producers. The net energy (NE) value of feed reflects its nutritional value in the precision feeding system. An experiment was conducted to determine the apparent metabolizable energy (AME) and NE values of 3 types of dephenolized cottonseed protein (DCP) for Hy Line Brown hens aged 42 to 45 weeks using the reference diet substitution method. A reference diet based on corn soybean meal was used to meet the nutritional needs of Hy Line Brown laying hens. To render the crude protein and energy values of the 3 test diets similar, 10.5%, 12%, and 16% of the gross energy yielding ingredients from the reference diet were replaced with DCP 1, DCP 2, and DCP 3, respectively. The birds were fed 4 diets during a 7-d adaptation period. After the dietary adaptation period, 2 birds per replicate from each treatment group were placed in an individual open circuit respiratory calorimetry chamber for a 3-d experimental period. Daily O₂ consumption and CO₂ production were recorded, and excreta samples were collected. The AME values of DCP 1, DCP 2, and DCP 3 were 3,049.05, 2,820.13, and 2,982.31 kcal/kg of dry matter (DM), respectively. The NE values of DCP 1, DCP 2, DCP 3 were 1,475.77, 1,910.31, and 1,905.37 kcal/kg of DM, respectively, and the NE:AME ratios were 48.40%, 67.74%, and 63.89%, respectively. Our data show that the AME value of DCP does not reflect the nutritional value of the feed. The NE value of DCP with a high ME value was not necessarily high.

Influence of Broiler Age on the Apparent Metabolizable Energy of Cereal Grains Determined Using the Substitution Method

Simple Summary

Knowledge of the metabolizable energy content of cereal grains is critical for their economical and sustainable use and precise poultry feed formulation. The current practice in the feed industry is to use the apparent metabolizable energy (AME) or nitrogen-corrected AME (AMEn) values of ingredients from prediction equations or reference tables, which have been estimated using (5-week-old birds). Several factors, including age, ingredient type, and methodology, can affect the AMEn value of ingredients in poultry. Currently, there are no data available on the age effect, from hatch to 6 weeks of age, on the AMEn of grains in broilers. The aim of the present study was to investigate the influence of age on the AMEn of wheat, sorghum, barley, and corn from hatching to day 42 using the substitution method. The results showed that the age influence on the AMEn of cereal grains was grain dependent. In wheat and sorghum, AMEn was influenced by age, while the AMEn of barley and corn were unaffected. Poultry nutritionists might need to consider age-dependent AME or AMEn values for some grains in feed formulations.

Abstract

The present study investigated the influence of broiler age on the AMEn of wheat, sorghum, barley, and corn using the substitution method at six different ages (days 7, 14, 21, 28, 35, and 42). A corn-soybean meal basal diet was formulated and, the test diets were developed by replacing (w/w) 300 g/kg of the basal diet with wheat, sorghum, barley, or corn. Bird age influenced (p < 0.001) the AMEn of wheat and sorghum but had no effect (p > 0.05) on those of barley and corn. The AMEn of wheat increased with age (p < 0.001) from 12.53 MJ/kg DM in week 1 to 14.55 MJ/kg DM in week 2, then declined subsequently, but no linear or quadratic responses were observed. The AMEn of sorghum demonstrated a quadratic response (p < 0.05), increasing from 12.84 MJ/kg DM in week 1 to 13.95 MJ/kg DM in week 2, and then plateauing to week 6. Overall, the present results suggest that the effect of broiler age on the AMEn varies depending on the grain type. The current data suggest that the application of age-dependent AME or AMEn of wheat and sorghum will lead to more precise feed formulations.

The Impact of Genotype and Age on Energy and Protein Utilization in Individually Housed Brown Laying Hens

Simple Summary

An investigation into whether the nutrient requirement of egg-laying hens has changed with genotype improvements was conducted. This study compared the response of individually housed laying hens of two different genotypes and ages. The strains used were a heritage breed in mid-lay and a modern breed at peak production. Energy was utilized with the same efficiency by both strains. All hens were able to adjust their feed intake to ensure that their energy requirements were met. The modern strain utilized protein slightly more efficiently than the heritage strain. It is unlikely that the nutrient requirements of modern layer strains have increased. More likely, requirements have decreased because modern hens are lighter and have a lower daily egg output (lay smaller eggs) despite their higher lifetime egg output. Regardless, feeding programs need to be adjusted for economic reasons and depend on achievable feed intakes under particular circumstances.

Abstract

Responses to dietary energy and protein levels were compared between two egg-laying genotypes. Individually housed hens of a historic strain (HS) and a modern strain (MS) were compared. In Experiment 1 (Exp.1), four levels of true metabolizable energy, corrected for zero nitrogen retention (TME_n) and four levels of total lysine, were offered from 30 to 40 weeks of age. In Experiment 2 (Exp.2), three levels of apparent metabolizable energy, corrected for zero nitrogen retention (AME_n) and four levels of standardized ileal digestible lysine (SID Lys), were fed from 20 to 30 weeks of age. A randomized factorial block design (4 × 4 Exp.1 and 3 × 4 Exp.2) was applied. Energy utilization for egg output (EO) did not differ (NS), and both strains maintained a constant kJ intake (NS). The efficiency of SID Lys utilization for EO differed, with the MS being the more efficient (p < 0.034). A single model could be used to predict feed intake, using BW, EO, AME_n and SID Lys (r = 0.716). In conclusion, it is unlikely that the requirements of modern layer strains have increased. However, feeding programs should be adjusted for economic reasons and are dependent upon achievable feed intake under particular circumstances.

Feeding guanidinoacetic acid to broiler chickens can compensate for low dietary metabolisable energy formulation

1. This study compared the responses of broilers to diets supplemented with the same level of guanidinoacetic acid (GAA) but formulated to have different N-corrected apparent metabolisable energy (AMEn) contents. The study involved 1280, one-day-old Ross 308 broilers, in 64 pens comprising 32 pens of males and 32 pens females, (20 birds in each) aged from 0 to 42 days.2. Commercial AME levels of 12.55 MJ/kg, 12.97 MJ/kg and 13.18 MJ/kg in the starter, grower and finisher diets, respectively, were set for the positive control (PC) feed. Four dietary treatments were prepared: PC (as above); negative control 1 (NC; PC - 0.21 MJ ME /kg); NC1+ 0.06% GAA; NC2 (PC - 0.42 MJ ME/kg + 0.06% GAA). Each diet was provided in 16 pens (eight male and eight female), following randomisation.3. Overall, birds fed NC1 had lower feed intakes (FI) compared to birds fed the PC and NC2+GAA, lower weight gain (WG) compared to all the other diets and lower final body weight than birds fed the GAA diets (P<0.05). There was a diet x sex interaction (P=0.039), whereby feeding NC+GAA to female birds improved feed efficiency compared to being fed NC2 and NC1+GAA, but not in males. Birds fed diets with GAA had a higher poultry efficiency factor (P < 0.001) than those fed NC1.4. There were no effects of treatment or sex on litter moisture, footpad score, white striping, wooden breast, AMEn, dry matter and fat retention (P>0.05). However, the diet NC1+GAA had 11.2% higher nitrogen retention coefficient compared to the NC1 diet (P=0.038).6. Overall, the results implied that lower performance induced by a reduction of dietary AMEn in the range of 0.21 to 0.42 MJ/kg was more than compensated by supplementing 600 g/t GAA to the feed.

An investigation into the influence of age on the standardized amino acid digestibility of wheat and sorghum in broilers

Standardized ileal digestibility coefficients (SIDC) of nitrogen (N) and amino acids (AA) in wheat and sorghum at 6 different ages (d 7, 14, 21, 28, 35, and 42) of broilers were determined. Two assay diets were formulated to contain 93.8% of each grain as the sole source of AA in the diet. Titanium dioxide (0.5%) was added as an indigestible marker. Each assay diet was fed to 6 replicate cages housing 14 (d 7), 12 (d 14), 10 (d 21), 8 (d 28), 8 (d 35), and 6 (d 42) birds per cage for 4 d prior to ileal digesta collection. The apparent ileal digestibility coefficients (AIDC) were standardized by using the age-appropriate basal endogenous AA losses. In the case of wheat, AIDC of N and all AA increased (linear or quadratic, P < 0.05 to 0.001) with advancing age. No age effect was noticed on the SIDC of N, average of indispensable (IAA) and dispensable AA (DAA), though the average of total AA (TAA) tended (linear, P = 0.09) to increase as birds grew older. In sorghum, the AIDC of N, average of IAA and DAA were unaffected (P > 0.05) by age. The SIDC of N, average SIDC of IAA, DAA and TAA were higher at d 7, reduced at d 14 and then plateaued. Among the IAA, the SIDC of Arg, His, Ile, Leu, Lys, Thr, Val, and the SIDC of all individual DAA (except Cys) decreased with age (linear or quadratic, P < 0.05 to 0.001) with higher values at d 7. The higher SIDC values determined at d 7 were due to higher EAA losses during wk 1. The results showed that broiler age influences AA digestibility and this may need be considered in practical feed formulations. The age effect is variable depending on the grain type and specific AA.

Comparison of methodologies to determine the apparent ileal amino acid digestibility of maize, wheat, lupins, and peas for broiler chickens

The influence of method (direct vs difference method) used to determine the apparent ileal digestibility coefficient (AIDC) of amino acids in two cereals (maize and wheat) and two grain legumes (Australian sweet lupins and peas) was investigated. For the direct method, the test ingredients were incorporated as the sole source of protein in assay diets. The assay diets used in the difference method were formulated by substituting the cereals and legumes for 50 and 25% (w/w), respectively, of a maize-soy basal diet. Each diet contained 3 g/kg titanium dioxide as an indigestible marker and were offered ad libitum to four replicate cages of broilers (four birds/cage) from d 28 to d 35 post-hatching. On d 35, digesta were collected from the terminal ileum and the AIDC of amino acids were calculated using marker ratios in the diet and digesta. Except for histidine, methionine, cysteine and tyrosine, the main effect of methods was found to be significant (P<0.05 to 0.001) for the AIDC of all amino acids. The main effect of the ingredients was significant (P<0.05 to 0.001) for all amino acids, except for histidine, aspartic acid and serine. Interactions (P<0.05) between ingredients and method were observed only for leucine, lysine, proline and serine. The AIDC of amino acids, determined by the difference method, was found to be distinctly higher than those determined by the direct method. This suggested that the direct method underestimated amino acid digestibility in low and medium protein ingredients.

Application of Apparent Metabolizable Energy versus Nitrogen-Corrected Apparent Metabolizable Energy in Poultry Feed Formulations: A Continuing Conundrum

Simple Summary

Despite some limitations, the metabolizable energy system has been extensively used for describing the available energy in ingredients and for formulating complete poultry feeds. Three methods, namely direct, difference (substitution), and regression, or modifications thereof, have been employed to measure the apparent metabolizable energy (AME) of feeds and ingredients for poultry. The AME of feed ingredients are often corrected for zero nitrogen (N) retention to estimate the N-corrected AME (AMEn). Although the need for N-retention corrections has been intensely debated and challenged ever since the advent of the AME system, no definitive conclusion has been reached and the majority of poultry diets today are formulated to meet the requirements for AMEn rather than AME. There is limited information on the effect of zero N-retention correction on the energy value of major protein sources. The aim of this investigation was to understand the consequences of correction to zero N retention to the energy values of samples of several protein sources differing in protein quality. Based on the data presented herein, correcting AME values to zero N retention for modern fast-growing broilers penalizes the energy value of all major protein sources and is of higher magnitude for ingredients with higher protein quality.

Abstract

In the present investigation, N retention, AME, and AMEn data from six energy evaluation assays, involving four protein sources (soybean meal, full-fat soybean, rapeseed meal and maize distiller’s dried grains with solubles [DDGS]), are reported. The correction for zero N retention, reduced the AME value of soybean meal samples from different origins from 9.9 to 17.8% with increasing N retention. The magnitude of AME penalization in full-fat soybean samples, imposed by zero N correction, increased from 1.90 to 9.64% with increasing N retention. The Δ AME (AME minus AMEn) in rapeseed meal samples increased from 0.70 to 1.09 MJ/kg as N-retention increased. In maize DDGS samples, the correction for zero N retention increased the magnitude of AME penalization from 5.44 to 8.21% with increasing N retention. For all protein sources, positive correlations (p < 0.001; r = 0.831 to 0.991) were observed between the N retention and Δ AME. The present data confirms that correcting AME values to zero N retention for modern broilers penalizes the energy value of protein sources and is of higher magnitude for ingredients with higher protein quality. Feed formulation based on uncorrected AME values could benefit least cost broiler feed formulations and merits further investigation.

The effect of a heat-stable xylanase on digesta viscosity, apparent metabolizable energy and growth performance of broiler chicks fed a wheat-based diet

Feed costs represent a significant portion of the cost of poultry production. This study, in 3 experiments, was conducted to evaluate the effectiveness of a heat-stable xylanase (XYL) as a dietary supplement and its effect on digesta viscosity, nitrogen-corrected apparent metabolizable energy (AME_n), and live performance in broiler chicks. Experiment 1: the objective was to determine the effects of the amount and type of enzyme supplementation on digesta viscosity, AME_n, and bird performance using 7 diets. The dietary treatments were: no supplementation (C), 5 levels of XYL (1 to 16 ppm), or supplementation with a carbohydrase cocktail (CC). Experiment 2: the objective was to determine the interaction of the dietary XYL and the energy content of the feed. There were 2 levels of XYL (0 and 20 ppm) and 3 dietary energy levels (2,770, 2,920, and 3,070 kcal/kg ME). Experiment 3: the objective was to determine the interaction of the dietary XYL and feed form. The treatments were: 5 levels of XYL (0 to 40 ppm) and 2 feed forms (mash and crumble). Broiler chicks were reared in battery cages to 21 d. Statistical analysis of the data was completed using Proc GLM of SAS (9.2) (SAS Institute, Cary, NC).

In experiment 1, increasing XYL (0 to 16 ppm) resulted in a decrease in digesta viscosity and an increase in AME_n. The XYL included as low as 1 ppm resulted in a significant increase in AME_n which reached 5% with 16 ppm XYL. In contrast, increase in BWG (4%) above values with the basal diet was greatest with 1 ppm XYL. In experiment 2, the caloric content of the diet influenced the increase in AME_n with inclusion of XYL, 8% and 6% increases with 2,920 kcal/kg and 3,070 kcal/kg diets, respectively. Without addition of XYL, BWG was significantly lower when fed the diet with the highest energy content. In experiment 3, feed form x XYL influenced the effect of XYL on BWG. The BWG was greater when birds were fed the crumble diet with XYL vs when they were fed the mash feed with XYL. The xylanase proved effective for broilers to 21 d when fed the diets used herein with changes in digesta viscosity, increased dietary AME_n, and improved bird performance represented by either BW gain or FCR.

Influence of the energy and digestible lysine contents of the diet on performance and egg quality traits of brown-egg laying hens from 19 to 59 weeks of age

The influence of nutrient density and standardized ileal digestible lys (DLys) content of the diet on egg production and egg quality traits, was studied in brown-egg laying hens from 19 to 59 wk of age. The experimental design was completely randomized with eight treatments arranged as a 2×4 factorial with two AMEn concentrations (2,680 and 2,780 kcal/kg) and four levels of DLys (0.68, 0.72, 0.76, and 0.80%). Each treatment was replicated nine times and the experimental unit was a cage with nine hens. Hen production, egg components (proportion of albumen, yolk, and shell), egg quality traits (Haugh units, egg shell strength, and incidence of broken, dirty, and shell-less eggs) were measured by period (28 d) and cumulatively. Data were analyzed as a completely randomized design with energy concentration, level of DLys, and their interactions as main effects. In addition, the effects of the level of DLys on the variables studied, were partitioned into its linear and quadratic components. No interactions between AMEn and DLys content of the diet were detected for any of the traits studied and therefore, only main effects are presented. An increase in the AMEn concentration of the diet from 2,680 to 2,780 kcal/kg increased energy intake (P < 0.05) and egg weight (P < 0.001) and improved feed conversion ratio (P < 0.05). An Increase in DLys from 0.68 to 0.80% did not affect the number of eggs produced but increased linearly egg weight (P < 0.01) and egg mass production (P < 0.05). Diet did not affect egg quality. In conclusion, an increase in the AMEn content of the diet from 2,680 to 2,780 kcal/kg increased egg weight and improved feed efficiency. Laying hens require no more than 744 mg DLys/d (corresponding to 0.68% DLys) to optimize egg production. However, when the objective is to maximize egg weight, hens should consume at least 843 mg DLys/d (corresponding to 0.76% D Lys).

Apparent metabolizable energy of cereal grains for broiler chickens is influenced by age

The current study was conducted to investigate the influence of broiler age on the AME and AMEn of 4 common cereal grains (wheat, sorghum, barley, and corn). Four experimental diets with the same inclusion (962 g/kg) of each grain were developed and fed to groups of broiler chickens aged 1 to 7, 8 to 14, 15 to 21, 22 to 28, 29 to 35, or 36 to 42 d post-hatch. Each diet, in pellet form, was randomly allocated to 6 replicate cages in each age group. Except for the 0 to 7 d age group, the birds were fed a starter (d 0-21) and/or a finisher (d 21-35) diet before the introduction of experimental diets. The number of birds per cage were 10 (d 1-7) and 8 (d 8-42). Excreta were collected over the last 4 d of each age period. The AME and AMEn of the grains were determined by the total excreta collection. Bird age influenced (P < 0.001) the AME and AMEn of all cereal grains. The AMEn of wheat declined quadratically (P < 0.01) with advancing age, from 3,461 kcal/kg in wk 1 to 3,219 kcal/kg in wk 2 and then plateaued. The AMEn of sorghum grain declined linearly (P < 0.001) with advancing age, from 3,762 kcal/kg in wk 1 to 3,614 kcal/kg in wk 2, plateaued to wk 5 and then declined to 3,556 kcal/kg in wk 6. A quadratic (P < 0.001) reduction in the AMEn of barley was observed as birds grew older, with the AMEn decreasing between wk 1 (3,286 kcal/kg) and wk 2 (2,988 kcal/kg), increasing in wk 3 (3,117 kcal/kg) and then plateauing. The AMEn of corn declined quadratically (P < 0.05) with advancing broiler age; the highest AMEn was observed in wk 1 and 5, the lowest AMEn in wk 2, with the other weeks being intermediate. In conclusion, the present results showed that broiler age has a substantial impact on the AME and AMEn of cereal grains and the effect varied depending on the cereal grain. These data suggest that age dependent AME and AMEn values may need to be considered when formulating broiler diets to improve the precision of feed formulation and production efficiency.

Mathematical prediction of ileal energy and protein digestibility in broilers using multivariate data analysis

A proportional mixture design was used to systematically create a total of 56 diets using ten feed ingredients. Diets differed widely with regards to chemical characteristics and ingredient inclusion levels. Apparent ileal digestibility of energy and protein of the diets were determined in broiler growers fed ad libitum from 21 to 24 d post-hatch. The chemical composition and the in vivo digestibility values were used to establish prediction equations for energy and protein digestibility, using multivariate data analysis. Root mean square error as percentage of the observed means (RMSE%) and residual error were used to evaluate the strength and accuracy of the predictions and to compare predictions based on chemical characteristics with estimates based on table values. The estimates of ileal digestibility of energy from table values were relatively accurate (RMSE% = 5.15) and was comparable to those predicted based on the chemical composition of diets. Estimates of ileal digestibility of protein based on table values were less accurate (RMSE% = 8.21); however, the prediction was improved by multivariate regression (RMSE% = 5.46) based on chemical composition of diets. The best predictors for ileal energy digestibility were starch, crude fiber and phytate contents (P < 0.01) and the best predictors for crude protein digestibility were starch, CF and fat contents (P < 0.05). In conclusion, the ileal digestibility of energy can be accurately predicted using table values; however, the accuracy of prediction of the ileal digestibility of protein can be improved when chemical characteristics of the diet are considered.

Investigation of the effects of substitution levels, assay methods and length of adaptation to experimental diets on determined metabolisable energy value of maize, barley and soya bean meal

1. Two experiments were carried out to investigate the influence of substitution levels, assay methods and adaptation length of broilers to experimental diets on metabolisable energy of corn and barley (Experiment 1) and soya bean meal (Experiment 2). In each experiment, the test feedstuffs proportionately replaced the reference diet at the rates of 150, 300 or 450 g/kg. Each treatment had 8 or 7 replicate cages containing three birds per cage. Broiler chickens were adapted to experimental diets for either 7 or 4 d prior to excreta collection on d 20 and 21.2. Metabolisable energy was determined using the difference method at each substitution level and the regression method, using the 4 combinations of the substitution levels.3. In Experiment 1, AME and AMEn were lower (P < 0.01) for barley than for maize, irrespective of the assay method and there was a trend for an adaptation × cereal grains interaction (P < 0.10) for AME determined by the difference regression method. For maize, AME and AMEn calculated using regression or the difference method were not significantly different, whereas barley AME and AMEn values were greater (P < 0.01) when derived using regression analysis.4. In Experiment 2, there was no significant adaptation length × substitution levels interaction. The AME and AMEn values were lowest (P < 0.01) at 150 g/kg SBM inclusion level when calculated using the difference method. On the other hand, AME and AMEn values determined by the regression method were not influenced by substitution levels.5. It was concluded that the influence of substitution levels on assayed metabolisable energy is feedstuff-dependent and that the regression method produced more consistent metabolisable energy values in a feedstuff-independent manner.

Standardized ileal amino acid digestibility of protein sources for broiler chickens is influenced by the feed form

The aim of present study was to determine the influence of the feed form (FF) on standardized ileal digestibility (SID) of nitrogen (N) and amino acids (AA) in 3 protein sources (PS) for broiler chickens. Six diets were tested in a 3 × 2 factorial arrangement of treatments involving 3 PS (meat and bone meal [MBM], soybean meal [SBM], and canola meal [CM]) in mash and pelleted forms. The basal endogenous N and AA losses were determined by offering a N-free diet in the mash form. From day 1 to 18, the birds were offered a broiler starter diet. The diets and the N-free diet were randomly assigned to 6 replicate cages (8 birds per cage) and fed from day 19 to 23. The ileal digesta were collected on day 23. The SID of N was higher (P < 0.05) in SBM followed by MBM and CM. The average SID of AA in SBM and MBM were similar (P > 0.05), and greater (P < 0.05) than that in CM. The FF had no influence (P > 0.05) on the SID of indispensable AA, the only exception being His, which was reduced (P < 0.05) by pelleting. Pelleting, however, resulted in reduction (P < 0.001) in the SID of all dispensable AA and average of AA. The AA most affected by pelleting was Cys, with a 15.4% decrease in the SID. The standardized ileal digestible contents of protein and the average of indispensable AA and dispensable AA were higher in MBM than in SBM, with CM being the lowest. Pelleting decreased (P < 0.05) the digestible protein and total digestible AA contents. These findings reveal that the FF has a substantial impact on AA digestibility estimates of feed ingredients and it must be considered in AA digestibility assays of ingredients with high protein and AA contents.

Sensitivity of in vitro digestible energy determined with computer-controlled simulated digestion system and its accuracy to predict dietary metabolizable energy for roosters

Two experiments were conducted to validate the sensitivity and accuracy of in vitro digestible energy (IVDE) determined with a computer-controlled simulated digestion system (CCSDS) to predict metabolizable energy (ME) of diets for roosters. In experiment 1, soybean hulls were added to a basal diet (calibration diet 1) at 2.06, 4.12, 6.17, 8.23, 10.28, 12.32, or 14.37% of the diets (calibration diets 2–8) to produce an interval of approximately 80 kcal ME/kg. The sensitivity was measured by comparing the determined and actual IVDE of the diets. With these data, a linear model was developed to predict ME from IVDE. In experiment 2, validation diets were identical except they were composed of different cereal ingredients. For each diet, the correlations and ratios between IVDE and ME were analyzed to test the sensitivity of IVDE to predict ME across different ingredients. In experiment 1, a slope of 0.9899 was calculated in a linear regression of determined IVDE on actual IVDE (R² = 0.9998; P < 0.01). The ratio of determined IVDE to actual IVDE was 0.9878. The ratio of IVDE to apparent metabolizable energy (AME) and to nitrogen-corrected AME (AMEn) was 1.03 and 1.05, respectively. The linear models to predict ME from IVDE were AME = 0.8449 × IVDE + 451 (R² = 0.9812, residual standard deviation [RSD] = 28 kcal/kg; P < 0.01) and AMEn = 0.8357 × IVDE + 436 (R² = 0.9821, RSD = 27 kcal/kg; P < 0.01). In experiment 2, a significant simple correlation was observed between the IVDE and AME or AMEn of validation diets (r > 0.97; P < 0.01). The ratio of IVDE to AME and to AMEn was 1.04 and 1.05, respectively. Predicted and determined AME or AMEn of 8 validation diets differed by less than 100 kcal/kg. The regression of determined AME or AMEn against predicted AME or AMEn (R² ≥ 0.9466; P < 0.01) resulted in an overlapped line where Y = X. These results suggest the IVDE determined with CCSDS is highly sensitive and can be used to accurately predict the ME of diets for roosters across a wide range of cereal grains.

Measurement of ileal endogenous energy losses and true ileal digestible energy of cereal grains for broiler chickens

Two experiments were conducted to determine the ileal endogenous energy losses (IEEL) and nitrogen-corrected apparent metabolizable energy (AMEn) and true ileal digestible energy (TIDE) of 4 cereal grains (corn, sorghum, wheat, and barley) for broilers. In experiment 1, a glucose-based purified diet was used to determine the IEEL for correcting the apparent ileal digestible energy (AIDE) values to TIDE. The diet was randomly allocated to 6 replicates (6 birds per replicate) of male broilers and fed from 18 to 21 d after hatch. The jejunal and ileal digesta were collected on day 21. The results showed that glucose absorption continued beyond the jejunum but was complete in the terminal ileum demonstrating that endogenous energy losses can be quantified in the ileal digesta of birds by feeding a glucose-based diet. The IEEL were determined to be 347 ± 29.4 kcal/kg DM intake. In experiment 2, 4 experimental diets with similar inclusion (957 g/kg) of grains were developed to determine the AMEn, AIDE, and TIDE. Titanium dioxide (5.0 g/kg) was added to all diets as an indigestible marker. Each diet was randomly allocated to 6 replicates (8 birds per replicate) and fed from 14 to 21 d after hatch, and the ileal digesta were collected on day 21. The AIDE was corrected to TIDE using the IEEL value determined in experiment 1. The TIDE of corn, sorghum, wheat, and barley were determined to be 3,920, 3,650, 3,138, and 2,885 kcal/kg DM, respectively, and was higher (P < 0.05) than the corresponding AMEn values of 3,439, 3,284, 2,576, and 2,371 kcal/kg DM, respectively. No differences were observed between the AMEn and AIDE. The AMEn:TIDE ratio tended (P = 0.06) to be lower for viscous cereals (wheat and barley) than that for nonviscous cereals (corn and sorghum). The apparent ileal digestibility of DM, nitrogen, and starch was positively correlated (P < 0.001) with TIDE (r = 0.990, 0.703, and 0.705, respectively) and the AMEn (r = 0.873, 0.483, and 0.656, respectively). Further studies are warranted to determine the TIDE of a range of ingredients and to investigate the application of TIDE as a potential available energy system in poultry feed formulations.

Historical flaws in bioassays used to generate metabolizable energy values for poultry feed formulation: a critical review

Dietary energy available to animals is key for formulating feed as it is required for all aspects of the animal's life. In poultry, apparent (AME) and true (TME) metabolizable energy (ME) values have been used for feed formulation with (AMEn or TMEn) or without correction for nitrogen balance. For the past 50 yr, the accuracy of ME has been an ongoing debate, and the comparability of data produced using different bioassay systems is often questionable. Overall, the ingredient matric ME values used in feed formulation are not consistent, and to some extent, confusing. This review was to examine ME data published in the past century to elucidate the accuracy of different bioassay systems and examine the values for accuracy and useability. A variety of flaws are identified in the literature, suggesting a thorough re-thinking of feedstuff ME values currently used in feed formulation and in developing prediction equations. Two protocols, namely multiple linear regression and basal diet substitution methods, are proposed as more accurate bioassays for feedstuff ME values. AME aligns more closely with the actual energy levels of feed ingredients likely available to growing birds, which should be used for poultry feed formulations instead of AMEn. It is suggested that nutritionists need to carefully apply any reported AME values and only use those in formulation practice after careful scrutinizing. Any in vitro, NIR or table values must be calibrated or computed based on the values produced from flawless bioassays so as to apply the derived values accurately. Flaws identified in this literature review can be avoided with care to achieve more accurate AME. However, the assumption that the energy of individual ingredients is additive in a complete diet is still untrue at least under some circumstances. This may require efforts from industry and researchers to investigate relations among the main ingredients in a complete diet so that more accurate formulation can be performed based on the outcomes that may fine-tune the additivity assumption.