Determining the Amino Acid Digestibility of Soybean Meal from Determining the Amino Acid Digestibility of Soybean Meal from Different Midwest Soybean Varieties Fed to Broilers Different Midwest Soybean Varieties Fed to Broilers

Summary At hatch, 240 one-day old Cobb500 male broilers were placed in battery cages to determine soybean meal (SBM) apparent ileal digestibility (AID) of amino acids (AA). There were 6 broilers per cage and 10 replicates per treatment. A common corn-SBM crumble starter diet was fed from d 0 to 10 with experimental mash diets fed from d 10 to 18 with SBM as the only source of AA. Dietary treatments consisted of 1 of 4 soybean sources varying in quality determined by crude protein (CP) content and processed into SBM. Dietary treatments consisted of a commercially processed SBM with 47% CP (CSBM) or experimentally processed SBM with 42% CP (42SBM), 49% (49SBM), or 52% CP (52SBM). Two sources consisted of soybeans from a similar region and were processed either commercially (CSBM) or experimentally (49SBM) solvent extracted at Texas A&M University. Additional sources included a low quality (42SBM) and high-quality (52SBM) soybean, experimentally solvent extracted into SBM at a pilot-scale facility at Texas A&M University. Dietary treatments were dextrose and SBM-based, and consisted of 1 of 4 SBM sources included in diets formulated to 20% CP. On d 18, broilers were euthanized by CO 2 inhalation and ileal samples were collected for determination of AID of AA. Soybean meal processed from low, medium, and high CP soybeans resulted in increased concentrations of crude protein and indispensable AA. Individual SBM samples indicated that SBM with higher CP had lower NDF. Data were analyzed using the GLIMMIX procedure in SAS 9.4, with cage as the experimental unit, cage location as the blocking factor with Tukey-Kramer adjustment for


Summary
At hatch, 240 one-day old Cobb500 male broilers were placed in battery cages to determine soybean meal (SBM) apparent ileal digestibility (AID) of amino acids (AA).There were 6 broilers per cage and 10 replicates per treatment.A common corn-SBM crumble starter diet was fed from d 0 to 10 with experimental mash diets fed from d 10 to 18 with SBM as the only source of AA.Dietary treatments consisted of 1 of 4 soybean sources varying in quality determined by crude protein (CP) content and processed into SBM.Dietary treatments consisted of a commercially processed SBM with 47% CP (CSBM) or experimentally processed SBM with 42% CP (42SBM), 49% (49SBM), or 52% CP (52SBM).Two sources consisted of soybeans from a similar region and were processed either commercially (CSBM) or experimentally (49SBM) solvent extracted at Texas A&M University.Additional sources included a low quality (42SBM) and highquality (52SBM) soybean, experimentally solvent extracted into SBM at a pilot-scale facility at Texas A&M University.Dietary treatments were dextrose and SBM-based, and consisted of 1 of 4 SBM sources included in diets formulated to 20% CP.On d 18, broilers were euthanized by CO 2 inhalation and ileal samples were collected for determination of AID of AA.Soybean meal processed from low, medium, and high CP soybeans resulted in increased concentrations of crude protein and indispensable AA.Individual SBM samples indicated that SBM with higher CP had lower NDF.Data were analyzed using the GLIMMIX procedure in SAS 9.4, with cage as the experimental unit, cage location as the blocking factor with Tukey-Kramer adjustment for multiple comparisons used.For soybeans grown in a similar region, broilers fed CSBM, processed conventionally, had increased (P < 0.05) AID of total AA, Arg, His, Lys, and Thr compared to 49SBM, processed experimentally.Increasing the CP content of SBM from 42SBM, and 49SBM, to 52SBM increased (P < 0.05) AID of total AA, Arg, His, Leu, Lys, Thr, and Val.Broilers fed CSBM, 49SBM, and 52SBM had increased (P < 0.001) Ile, Met, Phe, and Trp compared to broilers fed 42SBM.In conclusion, CSBM and 49SBM were sourced from a similar location but processed either commercially or experimentally, respectively.Commercially processed SBM had improved AID 1 This study was completed in along with the following study; therefore, references are made to the following study:

Introduction
A shift in major issues affecting competition for soybean meal (SBM) usage in swine and poultry diets has occurred in recent years.Traditionally, SBM is added to livestock and poultry diets because it is an economical source of crude protein and essential amino acids (AA).In recent years, ingredient cost and availability has increased utilization of more economical crystalline amino acids and by-product ingredients.Therefore, it is essential to focus on optimizing SBM quality to maintain its competitive edge in livestock and poultry diets, and continue to find ways to reduce diet cost for producers.Selecting for soybean varieties that result in increased AA concentrations in SBM will provide an improvement in the feeding value of SBM.However, it is important to determine if there is a difference in the digestibility of those AA to further influence the feeding value of SBM.Therefore, the objective of this study was to determine the apparent ileal digestibility (AID) of AA for SBM varieties varying in CP content when fed to broilers.

Materials and Methods
The Institutional Animal Care and Use Committee at Kansas State University (Manhattan, KS) reviewed and approved the protocols used in this study.A total of 240 one-day old male broilers (Cobb 500, Cobb-Vantress, Siloam Springs, AR) were obtained and transported to the Kansas State University Poultry Facility (Manhattan, KS) to be used in an 18-d digestibility study.Broilers were placed in 1 of 2 Petersime batteries with 6 broilers per cage (dimensions, 38.0 × 13.0 in.), balanced by BW and provided a common corn, soybean meal crumble diet.On d 10, cages were randomly assigned to 1 of 4 dietary treatments within location block and balanced by BW with 10 replicates per treatment.Illumination was provided by fluorescent bulbs for the duration of the experiment.A HOBOware data logger was used to record temperature, relative humidity, and light intensity of the battery room.For the first 7 d, averages were 87.4°F, 61.3%, and 13.3 lum/ft 2 , followed by 82.4°F, 71.5%, and 13.2 lum/ ft 2 for the remainder of the experiment for temperature, relative humidity, and light intensity, respectively.Feed was provided ad libitum in a single pan feeder (capacity approximately 4.4 lb) per pen.Water was provided ad libitum through water troughs.A validation study was also completed to determine broiler growth performance using the same four SBM sources added to complete diets. 1

Dietary treatments
Assay diets were dextrose and SBM-based and fed in meal form, formulated to supply 20% CP in the diet (Table 2).All diets used titanium dioxide as an indigestible marker.Dietary treatments consisted of 1 of 4 soybean sources varying in quality determined by crude protein (CP) content and processed into SBM.Two sources consisted of soybeans from a similar region and processed either commercially or experimentally solvent extracted at Texas A&M University.Additional sources included a low quality and high-quality soybean, experimentally solvent extracted into SBM at Texas A&M University.Therefore, dietary treatments consisted of a commercially-processed SBM with 47% CP (CSBM), or experimentally processed SBM with 42% CP (42SBM), 49% (49SBM), or 52% CP (52SBM).

Ileal collection
On d 18, broilers were euthanized by CO 2 inhalation and ileal samples were collected for AA analysis.Ileal contents were collected beginning 0.4-in.posterior to the Meckel's diverticulum and ending 0.4-in.prior to the ileocecal junction.Ileal samples were collected and pooled by pen.Composite samples were stored at -4°F prior to lyophilization.Samples were finely ground to pass through a 0.02-in.screen and sent to the University of Missouri Agricultural Experiment Station (Columbia, MO) for analysis.

Chemical analysis
Individual soybean meal and diet samples were analyzed for proximate analysis and complete AA profile, 3 available Lys, 4 protein solubility, 5 and trypsin inhibitor activity 6 (Table 1).Diets and ileal samples were analyzed for titanium dioxide 7 as an indigestible marker.Ileal contents were analyzed for dry matter and complete AA profile 3 for determination of AID of AA.

Calculations
Calculations for AID of AA were calculated using the following equation 8 : where AA digesta and AA diet represent the AA concentrations (g/kg) in digesta and diet DM, respectively, and TiO 2, diet and TiO 2, digesta represent the digestible marker concentrations (g/kg) in diet and digesta DM, respectively (Table 3).

Statistical analysis
Data were analyzed using the GLIMMIX procedure in SAS v. 9.4 (SAS Inst., Cary, NC), with cage as the experimental unit, cage location as the blocking factor and adjusted using Tukey-Kramer multiple comparisons.
There was an overall treatment effect (P < 0001) for AID of total AA and all indispensable AA.For soybeans grown in a similar region, broilers fed CSBM, processed conventionally, had increased (P < 0.05) AID of total AA, Arg, His, Lys, and Thr compared to 49SBM, processed experimentally.There was no evidence of difference in total amino acid, indispensable AA, or dispensable AA digestibility in broilers fed the CSBM and 52SBM (Table 3).The AID of total AA, Arg, His, Lys, and Thr was greater (P < 0.001) in CSBM compared to 49 SBM.Soybean meal with increasing CP content from 42SBM, 49SBM, and 52SBM had increased (P < 0.001) AID of total AA, Arg, His, Leu, Lys, Thr, and Val.The AID of Ile, Met, Phe, and Trp decreased (P < 0.01) in broilers fed 42SBM compared to CSBM, 49SBM, and 52SBM.
In conclusion, soybean meal processed from low, medium, and high CP soybeans resulted in increased concentrations of crude protein and indispensable AA.Individual soybean samples indicated that soybeans with higher CP had lower NDF.Broilers fed conventionally processed soybean meal had improved amino acid digestibility compared to those fed experimentally processed soybean meal from similar sources.Soybean meal from high crude protein soybeans had increased digestibility of Arg, His, Ile, Leu, Lys, Thr, and Val compared to soybean meal from 42SBM and 49SBM when fed to 18-day old broilers.The increased AID of AA and increased AA content of high CP soybean meal resulted in an increase in digestible amino acid content provided by SBM.Dietary treatments consisted of 1 of 4 soybean meal sources included in diets formulated to 20% crude protein (CP).
3 Dietary treatments consisted of one of the following soybean meal (SBM) sources: control (47% CP; CSBM), a low quality SBM (42% CP; 42SBM), a medium quality SBM (49% CP; 49SBM), and a high quality SBM (52% CP; 52SBM) where 42SBM, 49SBM, and 52SBM soybeans were processed into SBM using a pilot scale facility at Texas A&M University and the CSBM was processed at a commercial soybean crush facility.
4 Means within a row followed by a different letter ( a-c ) are significantly different (P ≤ 0.05).
Appreciation is expressed to the Illinois Soybean Association for partial financial support of this study. 2