Skip to main content
NCBI home page
Journal of Animal Science logoLink to Journal of Animal Science
. 2018 Dec 19;97(2):768–778. doi: 10.1093/jas/sky469

Effect of inclusion level of corn germ meal on the digestible and metabolizable energy and evaluation of ileal AA digestibility of corn germ meal fed to growing pigs1

Zeyu Zhang 1, Zhaoyu Liu 1, Shuai Zhang 1, Changhua Lai 1, Dongli Ma 1, Chengfei Huang 1,✉
PMCID: PMC6358221  PMID: 30566595

Abstract

Two experiments were conducted to investigate the effect of inclusion level of corn germ meal (CGM) on the DE and ME values of CGM and to evaluate the ileal AA digestibility of CGM fed to growing pigs. In Exp. 1, 42 barrows (63.8 ± 2.1 kg BW) were allotted to seven diets in a completely randomized design with six replicates per diet. Diets included a corn–soybean meal (SBM) diet and six additional diets containing 4.85%, 9.70%, 19.40%, 29.10%, 38.80%, or 48.50% CGM. Pigs were fed twice daily, at 0730 and 1630 hours, at a level of 4% of BW, and feces and urine were collected for 5 d. The apparent total tract digestibility (ATTD) of DM, OM, CP, acid-hydrolyzed ether extract, and the DE and ME in diets linearly decreased (P < 0.01) as dietary CGM increased. Inclusion level of CGM had no effect on the DE and ME values of CGM. On a DM basis, the concentration of DE and ME varied from 3,396 to 3,747 kcal/kg and 3,107 to 3,502 kcal/kg, respectively. In Exp. 2, 11 crossbred barrows (30.4 ± 2.9 kg BW) with a T-cannula in the distal ileum were allotted to an 11 × 6 Youden square design with 11 diets and 6 period, which included an N-free diet and 10 CGM test diets. Chromic oxide (0.3%) was included in all diets as an indigestible marker. Pigs were fed daily at 4% of BW during each period, which consisted of 5 d of diet adaptation followed by 2 d of digesta collection. The apparent ileal digestibility (AID) of Ile, Thr, and Ala and the standardized ileal digestibility (SID) of CP and Ile varied (P < 0.01) among the 10 CGM. The AID of CP and all AA except Pro and Tyr, and the SID of all AA except Pro were the greatest (P < 0.05) in sample 7. The AID and SID of CP averaged 40.47% and 64.75%, respectively, and varied from 32.30% to 54.87% and from 57.48% to 72.15%, respectively. The average SID of Lys, Met, Thr, and Trp was 65.61%, 76.15%, 65.29%, and 60.17%, respectively, with a SEM of 4.49, 2.40, 5.95, and 6.82, respectively. The average SID of Pro was 101.76%, with an SEM of 17.26. Increasing dietary CGM decreased the ATTD of nutrients, the DE and ME values of diets but CGM. The AID and SID of AA in CGM are low but source dependent, and CGM may be fed to pigs as an protein-rich feedstuff.

Keywords: AA digestibility, apparent total tract digestibility, corn germ meal, digestible energy, growing pigs, inclusion level

INTRODUCTION

Corn germ meal (CGM), one of the coproducts from the corn wet milling industry, contains about 22.6% CP and fiber equivalent to corn distillers dried grains with solubles (NRC, 2012; Stein et al., 2016). The concentrations of Lys and Trp in CGM are low and cannot meet the requirements for pigs when included in a pig diet as the main source of protein. The standardized ileal digestibility (SID) of most AA in CGM is relatively lower than that of corn (Liu et al., 2014). Cellulose and arabinoxylans are two primary fiber components of both corn coproducts and CGM (Jaworski et al., 2015), and the apparent total tract digestibility (ATTD) of dietary fiber is <50% (Urriola et al., 2010). The poor quality of CP and its high fiber means that up to 30% CGM can be used in diets fed to growing and finishing pigs without changing the growth performance of pigs (Lee et al., 2012). Although global production of CGM is relatively small compare with that of other corn-coproducts, CGM is available in many local markets and may be combined with corn, SBM, and crystalline AA to produce a balanced diet that may be more cost effective than a conventional corn–SBM diet. Therefore, evaluating the nutritive value of CGM is important. However, only a limited number of experiments have been conducted with pigs to evaluate CGM and in all experiments, only one inclusion level of CGM in the experimental diet (Almeida et al., 2011; Rojas et al., 2013; Liu et al., 2014). The higher the substitution rate of the evaluated feedstuff, the more accurately DE and ME can be determined in the feedstuff according to the difference method (Kong and Adeola, 2014). However, higher dietary fiber content can affect energy and other nutrient digestibilities in diets and, therefore, for the evaluated feedstuff (Weber et al., 2010; Chen et al., 2014). Therefore, the objective of the current study was to investigate the hypothesis that different inclusion levels of CGM results in different calculated values for DE and ME of CGM. The second hypothesis was that ileal AA digestibility is consistent among different sources of CGM when fed to growing pigs.

MATERIAL AND METHODS

The protocol for all animal procedures was approved by the Institutional Animal Care and Use Committee at China Agricultural University, Beijing, China.

Experiment 1: Effect of Inclusion Level of Corn Germ Meal on Nutrient Digestibility

Experimental design and dietary treatments.

Forty-two crossbred barrows (Duroc × Landrace × Large White) with an initial BW of 63.8 ± 2.1 kg were allotted to seven diets in a completely randomized design according to their initial BW, with six pigs per diet. Diets included a corn–SBM basal diet containing 76.0% corn, 21.0% dehulled SBM, 1.1% dicalcium phosphate, 0.9% limestone, 0.3% sodium chloride, 0.5% vitamin–mineral premix, and 0.2% choline chloride, and the six additional diets were formulated by substituting 5%, 10%, 20%, 30%, 40%, or 50% CGM at the expense of the corn and SBM in the basal diet. The final, complete experimental diets contained 4.85%, 9.70%, 19.40%, 29.10%, 38.80%, and 48.50% CGM (Table 1). Vitamins and minerals were supplemented in all diets to meet or exceed the nutrient requirements of growing pigs according to the NRC (2012). Chemical compositions of corn, dehulled SBM, and CGM are presented in Table 2.

Table 1.

Ingredient and analyzed chemical composition of diets used in Exp. 1 (%, as-fed basis)

Item Inclusion level of corn germ meal in diet
0.00 4.85 9.70 19.40 29.10 38.80 48.50
Corn 76.00 72.20 68.40 60.80 53.20 45.60 38.00
Dehulled soybean meal 21.00 19.95 18.90 16.80 14.70 12.60 10.50
Corn germ meal 0.00 4.85 9.70 19.40 29.10 38.80 48.50
Dicalcium phosphate 1.10 1.10 1.10 1.10 1.10 1.10 1.10
Limestone 0.90 0.90 0.90 0.90 0.90 0.90 0.90
Sodium chloride 0.30 0.30 0.30 0.30 0.30 0.30 0.30
Vitamin–mineral premix1 0.50 0.50 0.50 0.50 0.50 0.50 0.50
Choline chloride 0.20 0.20 0.20 0.20 0.20 0.20 0.20
Analyzed composition
DM 87.40 87.82 88.02 88.28 88.82 89.22 89.56
Ash 4.40 4.39 4.29 4.31 4.25 4.15 4.40
CP 15.93 16.33 16.68 16.33 17.11 17.61 17.85
AEE2 2.98 3.27 3.33 3.69 4.04 4.55 4.86
NDF 11.23 11.78 14.12 17.44 20.80 22.57 28.18
ADF 3.06 3.34 3.86 4.77 5.61 6.48 8.08
Starch 44.71 43.68 42.06 34.58 34.92 30.70 27.48
GE, kcal/kg 3,783 3,824 3,857 3,910 3,965 4,005 4,046
Open in a new tab

1Premix provided the following per kilogram of complete diet for growing pigs: 5,512 IU vitamin A, 2,200 IU vitamin D3, 30 IU vitamin E, 2.2 mg vitamin K3, 27.6 mg vitamin B12, 4.0 mg riboflavin, 14.0 mg pantothenic acid, 30.0 mg niacin, 400.0 mg choline chloride, 0.7 mg folic acid, 1.5 mg thiamine, 3.0 mg pyridoxine, 44.0 µg biotin, 40.0 mg Mn, 75.0 mg Fe, 75.0 mg Zn, 100.0 mg Cu, 0.3 mg I, and 0.3 mg Se.

2AEE = acid-hydrolyzed ether extract.

Table 2.

Analyzed chemical composition of corn, dehulled soybean meal, and corn germ meal used in Exp. 1 (%, as-fed basis)

Item Corn Dehulled soybean meal Corn germ meal
DM 87.62 88.05 92.04
CP 8.32 45.94 21.15
EE1 3.04 2.05 5.56
AEE2 3.29 2.60 7.06
NDF 10.34 11.52 45.03
ADF 2.73 6.26 11.33
TDF3 8.50 16.73 48.52
IDF4 7.90 15.28 37.64
SDF5 0.60 1.45 10.88
Ash 1.13 6.05 2.66
Starch 63.46 2.02 13.31
GE, kcal/kg 3,737 4,139 4,476
Open in a new tab

1EE = ether extract.

2AEE = acid-hydrolyzed ether extract.

3TDF = total dietary fiber.

4IDF = insoluble dietary fiber.

5SDF = soluble dietary fiber.

Animals housing, feeding, and samples collection.

During the experiment, pigs were individually housed in stainless steel metabolism crates (1.7 × 0.9 × 0.7 m). The crates had adjustable sides to accommodate animal welfare and were located in rooms with the temperature controlled at 20 ± 2.2 °C. Humidity varied from 35% to 63% during the experiment, and the light and dark time was automatically controlled at 12 h each. All pigs had ad libitum access to water via a drinking nipple. All pigs were acclimated to the new environment for 7 d and fed a standard corn–SBM diet before the start of the experiment. Pigs were weighed at the beginning of the experiment. Experimental diets were fed in a meal form, offered to pigs at a level of 4% of initial individual BW, and fed in two equal daily meals at 0730 and 1630 hours. Diet refusals were collected and weighed daily.

The experiment lasted a total of 12 d, including 7 d of experimental diet adaptation followed by 5 d of feces and urine collection beginning at 1600 hours on d 7 and ending at 1600 hours on d 12. During the collection period, an adjustable tray was placed under each metabolism crate, which permitted separate collection of feces and urine. Fresh feces were stored at −18 °C immediately after collection. Urine was collected in buckets containing 50 mL of 6 N HCl located under each crate. The volume of collected urine was measured daily, and 20% was stored at −20 °C. At the end of collection, the collected feces of 5 d from each pig were weighed, dissolved, and then thoroughly homogenized. A subsample was dried in a forced-air oven at 65 °C for 72 h. Urine was thawed, mixed, and subsampled. Before chemical analysis, dried feces were ground through a 1-mm screen. Urine samples (4 mL) were dried in the oven at 65 °C for 8 h with quantitative filter paper in crucibles.

Sample analysis and calculations.

Samples were analyzed for GE using an adiabatic oxygen bomb calorimeter (Parr 6300 Calorimeter; Parr Instrument Company, Moline, IL). Other analyses included DM (method 930.15; AOAC, 2006), CP (method 984.13; AOAC, 2006), ether extract (EE; Thiex et al., 2003), acid-hydrolyzed ether extract (AEE; method 954.02; AOAC, 2006), ash (method 942.05; AOAC, 2006), Ca (method 968.08; AOAC, 2006), and P (method 946.06; AOAC, 2006). Total starch was determined using method 7613.01 of the American Association of Cereal Chemists (1976) using a commercial starch assay kit (STA20; Sigma-Aldrich Corporation, St. Louis, MO). Total dietary fiber and insoluble dietary fiber were also determined (method 985.29; AOAC, 2006). The concentration of soluble dietary fiber (SDF) was calculated as the difference between total dietary fiber and insoluble dietary fiber. Neutral detergent fiber and ADF were determined using filter bags and fiber analyzer equipment (ANKOM Technology, Macedon, NY) following a modification of the procedures of Van Soest et al. (1991). The concentration of NDF was analyzed using heat-stable α-amylase and sodium sulfite without correction for insoluble ash. All chemical analyses were conducted in duplicate.

Calculations.

In Exp. 1, the digestibility and metabolizability of diet components were calculated according to the following equations (Kong and Adeola, 2014): digestibility (%) = [(Cinput − Coutput)/Cinput] × 100 and metabolizability (%) = [(Cinput − Coutput − Curine)/Cinput] × 100, in which Cinput, Coutput, and Curine are the amount of component ingested and voided via the feces and the amount of component voided via the urine, respectively.

The digestibility of each component in the test ingredient was determined using the total collection method and was calculated according to the following equation described by Kong and Adeola (2014): Dti = [Dtd − (Dbd × Pbd)]/Pti, in which Dbd, Dtd, and Dti are the digestibility (%) of the component in the basal diet, test diet, and test ingredient, respectively, and Pbd and Pti are the proportional contribution of the component by the basal diet and the test ingredient to the test diet, respectively.

By definition, DE and ME values are calculated by multiplying the concentration of GE in the diet or ingredient and the digestibility (or metabolizability) of GE in the diet or ingredient.

Experiment 2: AA Digestibility

Experimental design and dietary treatments.

This experiment was conducted to evaluate the apparent ileal digestibility (AID) and SID of AA in CGM. Origins of the 10 test CGM samples are presented in Table 3. Eleven crossbred barrows (30.4 ± 2.9 kg BW) fitted with a T-cannula in the distal ileum according to the method of Stein et al. (1998) were individually housed in stainless steel metabolism crates (1.7 × 0.9 × 0.7 m) located in a temperature-controlled room (22.0 ± 2.3 °C) and allotted to 11 × 6 as indicated in abstract. Pigs were weighed at the beginning of each period. All pigs were fed at a daily level of 4% of BW. Equal meals were provided to pigs at 0730 and 1630 hours each day. The 11 experimental diets included an N-free diet and 10 CGM test diets (Table 4). The N-free diet was used to determine the basal ileal endogenous N losses. The test diets contained 40% of 1 of the 10 CGM as the only source of dietary N. Chromic oxide (0.3%) was included in all diets as an indigestible marker. Vitamins and minerals were supplemented in all diets to meet or exceed the estimated nutrient requirements for growing pigs (NRC, 2012). The CP and AA compositions of the experimental diets are shown in Table 5.

Table 3.

Sources of corn germ meal used in Exp. 2

Number Sources in China
1 Xiwang, Shandong
2 Liangyou, Shandong
3 Aobang, Hebei
4 Zhonghe, Henan
5 Zhengwang, Henan
6 Sanxing, Shandong
7 Guangyuan, Shandong
8 Xuxin, Hebei
9 Jindouzi, Hebei
10 Derui, Neimeng
Open in a new tab
Table 4.

The ingredient composition of the experimental diets in Exp. 2 (%, as-fed basis)

Item Corn germ meal diets N-free diet
Corn — —
Dehulled soybean meal — —
Corn germ meal 40.0 —
Corn starch 40.0 73.35
Soybean oil 2.0 3.0
Sucrose 15.0 15.0
Acetate cellulose1 — 4.0
Dicalcium phosphate 1.5 2.5
Limestone 0.4 0.5
Sodium chloride 0.3 0.45
Chromic oxide 0.3 0.3
Potassium carbonate — 0.3
Magnesium oxide — 0.1
Vitamin–mineral premix2 0.5 0.5
Open in a new tab

1Made by Chemical Reagents Company (Beijing, China).

2Premix provided the following per kilogram of complete diet for growing pigs: 5,512 IU vitamin A, 2,200 IU vitamin D3, 30 IU vitamin E, 2.2 mg vitamin K3, 27.6 mg vitamin B12, 4.0 mg riboflavin, 14.0 mg pantothenic acid, 30.0 mg niacin, 400.0 mg choline chloride, 0.7 mg folic acid, 1.5 mg thiamine, 3.0 mg pyridoxine, 44.0 µg biotin, 40.0 mg Mn, 75.0 mg Fe, 75.0 mg Zn, 100.0 mg Cu, 0.3 mg I, and 0.3 mg Se.

Table 5.

Analyzed CP and AA composition of diet in Exp. 2 (%, as-fed basis)

Item Corn germ meal number N-free diet
1 2 3 4 5 6 7 8 9 10
CP 7.66 7.86 7.32 7.97 9.75 7.55 7.38 8.22 7.19 7.91 0.36
Indispensable AA
Arg 0.38 0.49 0.40 0.40 0.45 0.43 0.41 0.47 0.32 0.44 0.01
His 0.23 0.26 0.23 0.22 0.30 0.24 0.23 0.24 0.21 0.25 0.01
Ile 0.27 0.29 0.27 0.27 0.32 0.26 0.26 0.27 0.22 0.26 0.01
Leu 0.71 0.78 0.71 0.72 0.90 0.71 0.71 0.70 0.65 0.69 0.04
Lys 0.32 0.36 0.30 0.29 0.33 0.31 0.30 0.30 0.22 0.33 0.01
Met 0.12 0.11 0.10 0.11 0.14 0.11 0.11 0.12 0.09 0.12 0.00
Phe 0.31 0.36 0.33 0.32 0.35 0.32 0.32 0.33 0.26 0.32 0.03
Thr 0.31 0.33 0.29 0.31 0.38 0.30 0.29 0.30 0.26 0.30 0.01
Trp 0.07 0.06 0.06 0.06 0.05 0.06 0.06 0.06 0.05 0.08 0.00
Val 0.44 0.55 0.49 0.52 0.63 0.51 0.51 0.54 0.47 0.54 0.01
Dispensable AA
Ala 0.51 0.53 0.47 0.51 0.71 0.47 0.48 0.48 0.48 0.47 0.02
Asp 0.52 0.57 0.49 0.50 0.57 0.47 0.48 0.51 0.40 0.51 0.02
Cys 0.23 0.21 0.22 0.21 0.26 0.21 0.21 0.23 0.22 0.22 0.11
Glu 1.19 1.21 1.05 1.06 1.39 1.06 1.04 1.10 0.97 1.11 0.04
Gly 0.39 0.43 0.38 0.39 0.46 0.37 0.37 0.38 0.32 0.38 0.01
Pro 0.51 0.55 0.49 0.52 0.76 0.55 0.52 0.49 0.57 0.52 0.02
Ser 0.34 0.36 0.31 0.32 0.38 0.31 0.31 0.33 0.26 0.33 0.01
Tyr 0.17 0.15 0.11 0.13 0.13 0.15 0.12 0.14 0.13 0.11 0.02
Open in a new tab

Experimental procedures.

After 7 d of recovery from surgery, pigs were fed 1 of the 11 diets for six 7-d periods, which consisted of a 5-d diet acclimation followed by 2 d of digesta collection. The collection lasted for 9 h daily beginning at 0800 hours according to the procedures described by Stein et al. (1998). On days 6 and 7, a plastic bag was attached to the barrel of the cannula, removed whenever it was filled with digesta, and then stored at −20 °C. At the end of the experiment, digesta samples were thawed, mixed by pig and period, subsampled, and lyophilized in a vacuum freeze dryer (Tofflon Freezing Drying Systems, Minhang District, Shanghai, China).

Analytical methods.

Before analysis, samples of CGM, diets, and digesta were ground through a 1-mm screen and thoroughly mixed. Analyses of the AA content of all CGM samples as well as the diets and digesta were conducted according to Li et al. (2015). For all AA but Met, Cys, and Trp, samples were hydrolyzed with 6 N HCl at 110 °C for 24 h and then analyzed using an AA analyzer (Hitachi L-8900; Hitachi Ltd., Tokyo, Japan). The sulfur AA (Met and Cys) were subjected to cold performic acid oxidation overnight and hydrolyzed with 7.5 N HCl at 110 °C for 24 h before being measured using an AA analyzer (Hitachi L-8900). Tryptophan was analyzed by hydrolyzing the sample with LiOH for 22 h at a constant temperature of 110 °C and then analyzing the sample using HPLC (Agilent 1200 Series; Agilent Technologies Inc., Santa Clara, CA). Analysis of Cr in diets and digesta was conducted using a polarized Zeeman Atomic Absorption Spectrometer (Hitachi Z2000; Hitachi Ltd., Tokyo, Japan) after nitric acid–perchloric acid wet ash sample preparation. All analyses were conducted in duplicate.

Calculations.

In Exp. 2, the AID and SID of AA were calculated using the following equation (Stein et al., 2007): AID = [1 − (AAd/AAf) × (Crf/Crd)] × 100%, in which AAd and Crd are the concentrations of AA and Cr in the ileal digesta (g/kg of DM) and AAf and Crf are the concentrations of AA and Cr in the test diets (g/kg of DM). The AID of CP was calculated using the same equation.

The endogenous loss of N for each AA was measured from pigs fed the N-free diet based on the following equation: IAAend = [AAd × (Crf/Crd)], in which IAAend is the basal endogenous loss of an AA (g/kg of DMI) and AAd and Crd represent the concentrations of AA and Cr in the ileal digesta of the pigs fed the N-free diet. The concentration of Cr in the N-free diet is represented by Crf. The basal endogenous loss of CP was determined using the same equation.

The average IAAend of the six pigs fed the N-free diet was used to calculate the SID of AA in all diets. Standardized ileal digestibility was then calculated using the following equation: SID = [AID + (IAAend/AAf) × 100%].

Statistical analyses.

All the data were checked for normality, and outliers were identified using the UNIVARIATE procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). Then, both data sets were analyzed using the GLM procedure of SAS, with pig treated as the experimental unit. In Exp. 1, the statistical model included the inclusion level of CGM as the only fixed effect. Polynomial contrast was also conducted using the CONTRAST statement to determine linear and quadratic effects of inclusion levels, and contrast coefficients were generated using the IML procedure of SAS. In Exp. 2, the statistical model included the CGM sample as the only fixed effect, one-way ANOVA was used to separate treatment means calculated using the LSMEANS statement, and Tukey’s multiple range test was used for post hoc comparison. Statistical significance was assumed at P < 0.05.

RESULTS

Chemical Composition of Corn Germ Meal and Diets in Exps. 1 and 2

Table 2 shows the chemical composition of the corn, dehulled SBM, and CGM, and Table 1 shows the analyzed composition of the experimental diets used in Exp. 1. The concentrations of EE, AEE, SDF, and GE in CGM used in Exp. 1 were higher than the highest concentrations of EE, AEE, SDF (Table 2), and GE in the 10 CGM samples used in Exp. 2 (Table 6), but each of the other chemical components of the CGM used in Exp. 1 was within the range of values observed among the 10 sources of CGM in Exp. 2. On an as-fed basis, the concentration of AEE and EE varied from 1.68% to 3.70% and from 0.32% to 2.62%, respectively, with an average of 3.29% and 1.90%, respectively. The average concentration of NDF in the 10 CGM samples was 50.44%. The concentration of ADF, SDF, starch, ash, Ca, and P averaged 14.28% (10.10% to 17.40%), 7.05% (1.12% to 9.60%), 15.87% (9.88% to 17.43%), 3.10% (1.42% to 4.98%), 0.09% (0.03% to 0.21%), and 0.45% (0.31% to 0.71%), respectively. Table 7 indicates that the concentrations of AA in the 10 CGM samples greatly varied. The CV for each AA ranged from 6.34% to 19.20% and was >10% for the proximate composition of AEE, EE, ADF, SDF, starch, ash, Ca, and P. The least CV was obtained for Phe. In contrast, the greatest CV was obtained for Trp. Concentrations of Lys, Met, Thr, and Trp ranged from 0.65% to 1.01%, from 0.29% to 0.39%, from 0.70% to 0.96%, and from 0.10% to 0.20%, respectively, with averages of 0.87%, 0.36%, 0.82%, and 0.16%, respectively. The analyzed CP and AA compositions of diets in Exp. 2 are presented in Table 5.

Table 6.

Analyzed chemical composition of corn germ meal in Exp. 2 (%, as-fed basis)

Item Corn germ meal number Mean CV
1 2 3 4 5 6 7 8 9 10
DM 91.27 92.46 92.29 92.26 93.09 91.72 90.87 89.94 92.10 91.11 91.92 0.74
CP 18.27 18.77 19.64 19.26 22.73 18.09 17.23 19.35 16.97 18.71 20.75 8.67
EE1 1.35 2.62 0.72 0.59 0.92 1.61 2.15 1.05 0.32 1.60 1.90 87.08
AEE2 2.40 3.70 2.22 1.68 2.00 3.04 3.44 2.52 1.75 2.92 3.29 52.23
NDF 47.29 45.78 44.93 47.98 37.88 50.71 49.69 52.42 43.67 50.48 50.44 8.88
ADF 13.34 12.42 12.64 13.14 10.10 13.41 14.49 15.51 17.40 12.92 14.28 14.96
TDF3 53.36 49.21 43.83 48.47 44.09 53.21 50.00 48.24 50.00 54.31 53.97 7.76
IDF4 44.25 39.61 42.71 44.24 37.33 45.60 44.12 43.42 48.61 46.96 46.91 9.25
SDF5 9.11 9.60 1.12 4.23 6.75 7.61 5.88 4.81 1.39 7.35 7.05 53.12
Ash 1.69 4.35 2.20 2.48 4.98 1.51 2.64 2.30 4.59 1.42 3.10 45.67
Starch 14.42 16.48 16.71 17.43 12.38 13.93 15.35 17.41 9.88 15.95 15.87 15.89
Ca 0.03 0.15 0.04 0.05 0.10 0.04 0.07 0.05 0.21 0.04 0.09 75.48
P 0.33 0.43 0.39 0.42 0.71 0.31 0.31 0.44 0.34 0.33 0.45 30.73
GE, kcal/kg 4,223 4,235 4,149 4,211 4,209 4,295 4,046 4,244 4,158 4,292 4,206 1.75
Open in a new tab

1EE = ether extract.

2AEE = acid-hydrolyzed ether extract.

3TDF = total dietary fiber.

4IDF = insoluble dietary fiber.

5SDF = soluble dietary fiber.

Table 7.

Analyzed AA composition of corn germ meal in Exp. 2 (%, as-fed basis)

Item Corn germ meal number Mean CV
1 2 3 4 5 6 7 8 9 10
Indispensable AA
Arg 1.12 1.17 1.30 1.03 1.21 1.13 1.04 1.22 0.80 1.22 1.12 12.51
His 0.69 0.68 0.73 0.63 0.83 0.71 0.66 0.68 0.63 0.74 0.70 8.37
Ile 0.69 0.68 0.73 0.67 0.81 0.69 0.64 0.81 0.58 0.70 0.70 9.91
Leu 1.78 1.71 1.80 1.71 2.14 1.78 1.69 1.97 1.60 1.73 1.79 8.73
Lys 0.87 0.89 0.87 0.80 0.90 0.88 0.80 1.01 0.65 0.99 0.87 11.78
Met 0.39 0.34 0.36 0.37 0.39 0.37 0.32 0.38 0.29 0.39 0.36 9.16
Phe 0.98 0.99 1.06 0.97 1.03 0.97 0.94 0.90 0.85 1.02 0.97 6.34
Thr 0.81 0.78 0.83 0.80 0.96 0.82 0.77 0.89 0.70 0.81 0.82 8.49
Trp 0.17 0.15 0.19 0.15 0.17 0.17 0.14 0.20 0.10 0.20 0.16 19.20
Val 1.15 1.15 1.23 1.15 1.38 1.15 1.09 1.31 1.00 1.20 1.18 9.16
Dispensable AA
Ala 1.40 1.37 1.47 1.54 1.96 1.36 1.35 1.57 1.43 1.44 1.49 12.02
Asp 1.32 1.33 1.43 1.32 1.47 1.30 1.24 1.54 1.09 1.39 1.34 9.47
Cys 0.41 0.37 0.38 0.39 0.51 0.42 0.38 0.42 0.41 0.40 0.41 9.85
Glu 2.63 2.65 2.87 2.56 3.27 2.64 2.51 3.53 2.42 2.75 2.78 12.66
Gly 1.05 1.03 1.13 1.05 1.23 1.04 0.99 1.19 0.91 1.08 1.07 8.84
Pro 1.30 1.22 1.25 1.23 1.86 1.32 1.21 1.44 1.38 1.26 1.35 14.44
Ser 0.88 0.89 0.96 0.87 0.99 0.87 0.84 1.00 0.74 0.91 0.90 8.70
Tyr 0.41 0.41 0.46 0.36 0.50 0.42 0.38 0.43 0.27 0.38 0.40 14.86
Open in a new tab

Effect of Inclusion Level on the Apparent Total Tract Digestibility of Nutrients and DE or ME Value of Corn Germ Meal

The ATTD of DM, OM, CP, AEE, and the concentration of DE and ME in the diet linearly decreased as dietary CGM increased (P < 0.01; Table 8). The CGM inclusion level had no effect on the DE or ME value of CGM, and the concentration of DE and ME varied from 3,396 to 3,747 kcal/kg and from 3,107 to 3,502 kcal/kg (on a DM basis), respectively (Table 9).

Table 8.

Effect of inclusion level of corn germ meal on the apparent total tract digestibility (%) of nutrients, DE, and ME values in diets in Exp. 1

Item Inclusion level of corn germ meal in diet SEM P-value
0.00 4.85 9.70 19.40 29.10 38.80 48.50 Linear Quadratic
DM 91.08 89.43 89.04 86.70 86.00 83.87 82.10 0.69 <0.01 0.81
OM 92.86 91.19 90.76 88.36 87.66 85.45 83.84 0.64 <0.01 0.66
CP 91.76 89.69 89.41 86.94 84.59 83.29 83.06 0.85 <0.01 0.05
AEE1 61.26 61.41 58.51 54.82 51.87 54.28 49.16 1.63 <0.01 0.34
NDF 72.75 67.83 69.21 69.16 74.50 70.58 73.95 2.09 0.15 0.43
ADF 70.35 66.14 67.57 65.69 70.53 68.72 73.14 2.14 0.11 0.10
As-fed basis, kcal/kg
DE 3,449 3,415 3,422 3,360 3,366 3,308 3,286 30.24 <0.01 0.93
ME 3,393 3,374 3,377 3,313 3,293 3,224 3,195 33.31 <0.01 0.76
DM basis, kcal/kg
DE 3,946 3,889 3,888 3,806 3,789 3,707 3,669 33.99 <0.01 0.82
ME 3,882 3,842 3,737 3,753 3,708 3,613 3,568 37.42 <0.01 0.86
Open in a new tab

1AEE = acid-hydrolyzed ether extract.

Table 9.

Effect of inclusion level of corn germ meal on the DE and ME value in corn germ meal in Exp. 1

Item Inclusion level of corn germ meal in diet SEM P-value
4.85 9.70 19.40 29.10 38.80 48.50 Linear Quadratic
As-fed basis, kcal/kg
DE 3,448 3,361 3,126 3,269 3,190 3,249 145 0.33 0.29
ME 2,860 3,223 3,086 3,155 3,062 3,117 140 0.58 0.44
DM basis, kcal/kg
DE 3,747 3,652 3,396 3,551 3,467 3,531 157 0.33 0.29
ME 3,107 3,502 3,353 3,427 3,327 3,387 152 0.58 0.44
Open in a new tab

Digestibility of CP and AA in Corn Germ Meal

The AID and SID of CP and AA in the 10 tested CGM samples are shown in Tables 10 and11, respectively. The AID of Ile, Thr, and Ala varied (P < 0.01) among the 10 CGM samples. The SID of CP and Ile varied (P < 0.01) among the 10 CGM samples. Overall, the AID of CP and all AA except Pro and Tyr and the SID of all AA except Pro were greatest (P < 0.05) in sample 7. Sample 1 had the least (P < 0.05) AID and SID of Arg, His, Leu, Thr, and Val. The AID and SID of CP averaged 40.47% and 64.75%, respectively, and varied (P < 0.01) from 32.30% to 54.87% and from 57.48% to 72.15%, respectively. An average AID of 57.40%, 72.87%, 41.03%, and 33.77% was observed for Lys, Met, Thr, and Trp, respectively, with an SEM of 4.32%, 2.41%, 5.02%, and 7.21%, respectively. The average SID of Lys, Met, Thr, and Trp was 65.61%, 76.15%, 65.29%, and 60.17%, respectively, with an SEM of 4.49%, 2.40%, 5.95%, and 6.82%, respectively. In addition, the average SID of Arg and Leu in the 10 CGM samples was (P < 0.05) >80%, and the average SID of Pro was 101.76%, with an SEM of 17.26%.

Table 10.

Apparent ileal digestibility (%) of AA in corn germ meal fed to growing pigs in Exp. 2

Item Corn germ meal number Mean SEM P-value
1 2 3 4 5 6 7 8 9 10
CP 33.52b 47.97ab 32.30b 40.49ab 44.96ab 33.37b 54.87a 34.36b 41.91ab 40.95ab 40.47 4.41 0.01
Indispensable AA
Arg 69.56 84.09 73.11 75.95 79.70 75.71 84.42 78.43 73.32 77.02 77.13 3.35 0.07
His 63.81b 77.92ab 67.00ab 66.79ab 69.61ab 66.93ab 78.59a 69.30ab 67.66ab 69.44ab 69.71 3.03 0.02
Ile 54.71ab 66.38ab 59.81ab 59.72ab 69.27a 56.19ab 70.21a 54.96ab 55.56ab 50.03b 59.68 3.58 <0.01
Leu 65.35 77.92 69.95 71.79 79.87 66.78 79.86 69.86 72.18 66.69 72.03 3.11 0.01
Lys 53.55 68.06 57.57 54.69 60.81 53.17 68.12 53.06 51.34 53.48 57.40 4.32 0.04
Met 73.89 75.25 69.72 71.54 76.20 70.97 79.17 72.06 68.58 71.34 72.87 2.41 0.08
Phe 60.20 70.83 63.84 68.68 72.73 62.61 77.20 68.57 64.54 62.84 67.20 3.59 0.08
Thr 29.08b 47.51ab 33.10ab 42.32ab 52.30ab 42.42ab 55.96a 34.23ab 34.84ab 38.51ab 41.03 5.02 <0.01
Trp 27.26 48.02 30.80 26.68 27.54 25.81 51.84 29.30 30.48 40.00 33.77 7.21 0.08
Val 53.66b 69.75ab 57.65b 64.48ab 70.66ab 60.54ab 75.88a 64.24ab 65.81ab 64.06ab 64.67 3.90 0.02
Dispensable AA
Ala 57.16abc 62.38abc 52.55bc 58.65abc 67.38abc 53.94abc 68.29a 50.99c 58.40abc 58.63abc 59.13 3.35 <0.01
Asp 40.13ab 55.98ab 36.87b 43.19ab 52.54ab 39.93ab 58.89a 39.29ab 38.95ab 38.91ab 44.47 4.69 0.01
Cys 47.17 51.61 44.54 49.72 54.71 45.38 62.50 49.58 54.51 51.52 51.12 3.95 0.08
Glu 60.04ab 70.07ab 56.24b 61.43ab 62.35ab 60.33ab 71.82a 57.53ab 58.07ab 55.84b 61.37 3.35 0.01
Gly 10.27 34.04 21.33 20.34 30.57 28.40 37.72 17.44 28.76 26.24 25.51 7.52 0.30
Pro 18.13 36.97 30.29 48.06 47.13 26.79 45.59 13.79 37.79 28.72 33.33 9.19 0.16
Ser 45.05 60.87 44.31 48.20 57.90 45.53 63.49 47.00 45.05 46.60 50.40 4.49 0.01
Tyr 56.33 58.04 38.83 41.19 41.96 48.80 56.68 48.17 48.22 46.46 48.47 4.95 0.05
Open in a new tab

a–cMeans within a row with different superscripts differ (P < 0.05).

Table 11.

Standardized ileal digestibility (%) of AA in corn germ meal fed to growing pigs in Exp. 2

Item Corn germ meal number Mean SEM P-value
1 2 3 4 5 6 7 8 9 10
CP 58.32b 72.15ab 58.26b 64.35ab 64.45ab 58.56b 80.63a 57.48b 68.33ab 64.99ab 64.75 4.41 <0.01
Indispensable AA
Arg 81.20 93.20 84.21 87.08 89.68 86.19 95.32 88.01 87.45 87.09 87.94 3.35 0.20
His 72.87b 85.80ab 75.85ab 76.31ab 79.87ab 75.31ab 87.49a 77.78ab 77.35ab 77.52ab 78.62 2.90 0.02
Ile 66.96ab 77.75ab 72.35ab 72.30ab 79.65a 69.04ab 83.10a 67.48ab 70.54ab 62.86b 72.20 3.58 <0.01
Leu 74.08b 85.91ab 78.74ab 80.44ab 86.81ab 75.54ab 88.63a 78.80ab 81.83ab 75.72ab 80.65 3.11 0.01
Lys 61.72 75.92 66.23 63.55 68.66 61.51 76.89 61.83 58.42 61.38 65.61 4.49 0.06
Met 76.98 78.44 73.45 74.97 78.76 74.32 82.38 74.99 72.78 74.40 76.15 2.40 0.15
Phe 75.10 80.16 74.26 79.26 82.45 73.31 87.87 78.73 77.78 73.34 78.23 3.59 0.13
Thr 51.74b 72.46ab 56.92ab 62.63ab 73.95ab 62.60ab 83.79a 61.83ab 66.53ab 60.40ab 65.29 5.95 0.02
Trp 51.74 76.58 59.13 54.34 49.40 52.32 79.77 52.03 61.48 64.90 60.17 6.82 0.02
Val 66.18b 79.74ab 68.82ab 74.95ab 79.36ab 71.17ab 86.56a 74.39ab 77.45ab 74.15ab 75.28 3.90 0.04
Dispensable AA
Ala 71.24ab 76.06ab 67.76ab 72.89ab 80.40a 69.34ab 83.26a 66.10ab 73.54ab 61.57b 71.92 4.20 0.01
Asp 57.31ab 71.71ab 54.89b 60.96ab 68.13ab 58.76ab 77.53a 56.87ab 61.07ab 56.44ab 62.37 4.69 0.01
Cys 65.55 75.18 67.30 69.75 73.72 69.34 86.64 71.68 77.48 68.72 72.54 4.52 0.07
Glu 69.66ab 79.59ab 67.17b 72.25ab 70.64ab 71.17ab 82.85a 67.99ab 69.96ab 66.16b 71.74 3.35 0.01
Gly 55.70 84.26 63.83 70.00 71.18 52.43 96.40 58.55 75.75 64.02 69.21 11.20 0.18
Pro 107.38 112.04 104.82 105.38 90.36 71.42 111.93 96.37 117.52 100.38 101.76 17.26 0.82
Ser 64.44 78.74 65.36 68.38 75.10 66.60 84.63 66.81 69.75 66.34 70.62 4.49 0.03
Tyr 69.80 73.57 60.46 59.38 59.11 64.28 75.96 58.79 65.68 58.90 64.59 5.36 0.17
Open in a new tab

a,bMeans within a row with different superscripts differ (P < 0.05).

DISCUSSION

Corn germ meal is a coproduct of the wet milling industry, where processed corn grain is cleaned and steeped and then the corn germ is extracted for food-grade corn oil, resulting in CGM for animal feed (Archer Daniels Midland, 2008). Therefore, CGM has a relatively high concentration of fiber and a relatively low concentration of fat. Some studies have evaluated the concentration of DE or ME in CGM (Anderson et al., 2012; Rojas et al., 2013; Liu et al., 2014), but only two studies (Almeida et al., 2011; Liu et al., 2014) and one review (Stein et al., 2016) were performed on the ileal AA digestibility in CGM fed to pigs. The average concentration of CP in the 10 tested CGM samples in Exp. 2 was in agreement with reported values (Weber et al., 2010; Anderson et al., 2012), but less than those values (Almeida et al., 2011; NRC, 2012; Rojas et al., 2013; Jaworski et al., 2015). Other chemical compositions such as AEE, EE, SDF, ash, Ca, P, and AA greatly varied among the 10 CGM samples. The 11 CGM samples used in the current two experiments were obtained from different manufacturing factories with different processing procedures (Shi et al., 2018), which may be the main reason for the chemical variations among the 11 CGM. For example, during processing of the CGM, a liquid corn extract is produced when the soluble portion of the corn kernel is removed during the steeping process (Archer Daniels Midland, 2008) and is sometimes added back to the CGM product, which may have contributed to the large variation among the 11 CGM samples. In addition to the processing procedures, the hybrids, growing region, storage duration, and drying method of the corn grain used for manufacturing CGM are likely related to the differences in proximate and AA compositions among the 11 CGM samples (de Lima et al., 2012; Li et al., 2014a,b; Liu et al., 2014; Zhang et al., 2016).

In general, CGM contains about 22.6% CP (Stein et al., 2016), much greater than corn grain, which makes CGM possible as an alternative to corn in pig diets. However, the high content and low digestibility of fiber in CGM limits its usage in complete diets for pigs. The average concentration of 50.44% NDF in the 10 tested CGM samples was in good agreement with that of 49.3% NDF reported by Stein et al. (2016). Some studies evaluated the concentration of DE or ME in CGM, but to our knowledge, all these studies focused on only one substitution rate of CGM in the evaluation diet (Anderson et al., 2012; Rojas et al., 2013; Liu et al., 2014). The current work was the first research investigating the effect of dietary CGM on nutrient digestibility and the DE or ME values of CGM fed to pigs. The decreasing ATTD of CP in diets as dietary CGM increased was in agreement with several studies reporting that increasing dietary fiber has negative effects on protein digestibility (Dégen et al., 2009; Zhang et al., 2013; Huang et al., 2015). The negative effect of dietary fiber on CP digestibility may be due to increasing endogenous excretion of N and the passage rate of digesta through the entire gastrointestinal tract (Schulze et al., 1994; Le Goff et al., 2002). Part of the reason was that the excretion of NDF-binding N increased in the upper gastrointestinal tract as dietary NDF increased (Schulze et al., 1994; Dégen et al., 2009). The decreased ATTD of AEE observed in this experiment was in agreement with reports that increasing dietary fiber decreased the ATTD of fat because of increased synthesis of microbial fat in diets with high fiber concentration (Dégen et al., 2007; Kil et al., 2010). The inclusion level of CGM did not affect the ATTD of NDF and ADF indicated that the NDF and ADF digestibility of CGM is similar to the digestibility of NDF and ADF in the basal diet, and which was higher than that of 50% for corn coproducts reported by Urriola et al. (2010). Previous reports showed that increasing dietary fiber decreased the ATTD of CP and fat (Dégen et al., 2009; Huang et al., 2015). The combined effects of decreased ATTD of CP and EE (or AEE) contributed to the decreased DE or ME values of the experimental diets. Though affected the ATTD of some nutrients and DE and ME values of diets, the inclusion level of CGM had no effect on the DE or ME value of CGM.

During Exp. 2, all pigs were healthy, so it is likely that the pigs did not affect the results. The average SID of most AA in the 10 CGM samples was less than reported values (Almeida et al., 2011; Stein et al., 2016). The discrepancy in the SID of Trp and Tyr was even >21% and 15%, respectively, between our values and previously published values (Almeida et al., 2011; Stein et al., 2016). Differences are mainly due to differences in processing procedures including addition or not of corn steep liquor back to the CGM product. Although the concentration of AEE in CGM was not very high, it has been reported that addition of fat or oil increased the ileal digestibility of some AA (Li and Sauer, 1994; Albin et al., 2001; Cervantes-Pahm and Stein, 2008) and that low dietary CP led to higher ileal digestibility of AA (He et al., 2016). Therefore, one possible reason for the greatest ileal digestibility of CP and most AA in sample 7 is the combined effect of its relative low concentration of CP and high AEE content compared with the other samples.

The reason for the low AID and SID of CP and AA in the current CGM samples compared with corn grain is most likely because corn germ and corn bran, two main parts of CGM, have less AID and SID of AA than corn grain (Widmer et al., 2007; NRC, 2012). Corn germ and corn bran have greater concentrations of fiber compared with corn grain, which may have decreased the ileal digestibility of AA in these two components of CGM (Chen et al., 2015). Another reason for the low SID of CP and AA in CGM is most likely due to the high concentration of NDF and ADF, because high fiber can increase the specific endogenous losses of AA (Schulze et al., 1994; Nyachoti et al., 1997; Stein et al., 2007). The specific endogenous losses of AA are not included in the basal endogenous losses of AA determined using the N-free diet. Therefore, increased specific endogenous losses of AA are most likely the main reason for the low SID of CP and AA, because the specific endogenous losses are not included in the calculation of SID (Stein et al., 2007).

The AID of Pro in all CGM samples was very low. In contrast, the average SID of Pro in CGM was very high, >100%. The SID of Pro in CGM was far >62.0% reported by Stein et al. (2016). One reason for the variations in the SID of Pro may be that estimates for the basal endogenous losses of AA and digestibility are often inaccurate when pigs are fed diets containing inadequate indispensable AA (Stein et al., 2007). Another possible reason is that restrictively fed animals have greater basal endogenous losses of Pro compared with animals fully provided with feed (Stein et al., 1999), which can lead to greater SID values according to the calculation for SID of AA (Stein et al., 2007).

CONCLUSIONS

Increasing dietary CGM decreased the ATTD of nutrients, the DE and ME values of diets but CGM. The AID and SID of AA in CGM are low but source dependent, and CGM may be fed to pigs as a protein-rich feedstuff.

Conflict of interest statement. None declared.

Footnotes

1

This study was financially supported by the “863” National High-tech R&D Program (2013AA10230602).

LITERATURE CITED

  1. Albin D. M., Smiricky M. R., Wubben J. E., and Gabert V. M.. 2001. The effect of dietary level of soybean oil and palm oil on apparent ileal amino acid digestibility and postprandial flow patterns of chromic oxide and amino acids in pigs. Can. J. Anim. Sci. 81:495–503. doi: 10.5713/ajas.14.0498 [DOI] [Google Scholar]
  2. Almeida F. N., G. I. Petersen, and Stein H. H.. 2011. Digestibility of amino acids in corn, corn coproducts, and bakery meal fed to growing pigs. J. Anim. Sci. 89:4109–4115. doi: 10.2527/jas.2011-4143 [DOI] [PubMed] [Google Scholar]
  3. American Association of Cereal Chemists 1976. Approved methods of analysis.St. Paul, MN:American Association of Cereal Chemists. [Google Scholar]
  4. Anderson P. V., B. J. Kerr T. E. Weber C. J. Ziemer, and Shurson G. C.. 2012. Determination and prediction of digestible and metabolizable energy from chemical analysis of corn coproducts fed to finishing pigs. J. Anim. Sci. 90:1242–1254. doi: 10.2527/jas.2010-3605 [DOI] [PubMed] [Google Scholar]
  5. AOAC 2006. Official methods of analysis. 18th ed. Arlington, VA:AOAC International. [Google Scholar]
  6. Archer Daniels Midland 2008. Feed ingredients catalog – accessed September 11, 2009 http://www.adm.com/en-US/products/Documents/ADM-Feed-Ingredients-Catalog.pdf.
  7. Cervantes-Palm S. K., and Stein H. H.. 2008. Effect of dietary soybean oil and soybean protein concentration on the concentration of digestible amino acids in soybean products fed to growing pigs. J. Anim. Sci. 86:1841–1849. doi: 10.2527/jas.2007-0721 [DOI] [PubMed] [Google Scholar]
  8. Chen L., Gao L. X., Liu L., Ding Z. M., and Zhang H. F.. 2015. Effect of graded levels of fiber from alfalfa meal on apparent and standardized ileal digestibility of amino acids of growing pigs. J. Integr. Agric. 14:2598–2604. doi: 10.1016/S2095-3119(14)60924-2 [DOI] [Google Scholar]
  9. Chen L., Gao L. X., and Zhang H. F.. 2014. Effect of graded levels of fiber from alfalfa meal on nutrient digestibility and flow of fattening pigs. J. Integr. Agric. 13:1746–1752. doi: 10.1016/S2095-3119(13)60571-7 [DOI] [Google Scholar]
  10. Dégen L., Halas V., and Babinszky L.. 2007. Effect of dietary fibre on protein and fat digestibility and its consequences on diet formulation for growing and fattening pigs: a review. Acta Agric. Scand. A Anim. Sci. 57:1–9. doi: 10.1080/09064700701372038 [DOI] [Google Scholar]
  11. Dégen L., Halas V., Tossenberger J., Szabó C., and Babinszky L.. 2009. The impact of dietary fiber and fat levels on total tract digestibility of energy and nutrients in growing-finishing pigs and its consequence for diet formulation. Acta Agric. Scand. A Anim. Sci. 59:150–160. doi: 10.1080/09064700903254281 [DOI] [Google Scholar]
  12. He L., L. Wu Z. Xu T. Li K. Yao Z. Cui Y. Yin, and Wu G.. 2016. Low-protein diets affect ileal amino acid digestibility and gene expression of digestive enzymes in growing and finishing pigs. Amino Acids 48:21–30. doi: 10.1007/s00726-015-2059-1 [DOI] [PubMed] [Google Scholar]
  13. Huang Q., Y. B. Su D. F. Li L. Liu C. F. Huang Z. P. Zhu, and Lai C. H.. 2015. Effects of inclusion levels of wheat bran and body weight on ileal and fecal digestibility in growing pigs. Asian-Australas. J. Anim. Sci. 28:847–854. doi: 10.5713/ajas.14.0769 [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Jaworski N. W., H. N. Lærke K. E. Bach Knudsen, and Stein H. H.. 2015. Carbohydrate composition and in vitro digestibility of dry matter and nonstarch polysaccharides in corn, sorghum, and wheat and coproducts from these grains. J. Anim. Sci. 93:1103–1113. doi: 10.2527/jas.2014-8147 [DOI] [PubMed] [Google Scholar]
  15. Kil D. Y., T. E. Sauber D. B. Jones, and Stein H. H.. 2010. Effect of the form of dietary fat and the concentration of dietary neutral detergent fiber on ileal and total tract endogenous losses and apparent and true digestibility of fat by growing pigs. J. Anim. Sci. 88:2959–2967. doi: 10.2527/jas.2009-2216 [DOI] [PubMed] [Google Scholar]
  16. Kong C., and Adeola O.. 2014. Evaluation of amino acid and energy utilization in feedstuff for swine and poultry diets. Asian-Australas. J. Anim. Sci. 27:917–925. doi: 10.5713/ajas.2014.r.02 [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Le Goff G., van Milgen J., and Noblet J.. 2002. Influence of dietary fibre on digestive utilization and rate of passage in growing pigs, finishing pigs and adult sows. Anim. Sci. 74:503–515. doi: 10.1017/S1357729800052668 [DOI] [Google Scholar]
  18. Lee J. W., F. K. McKeith, and Stein H. H.. 2012. Up to 30% corn germ may be included in diets fed to growing-finishing pigs without affecting pig growth performance, carcass composition, or pork fat quality. J. Anim. Sci. 90:4933–4942. doi: 10.2527/jas.2012-5129 [DOI] [PubMed] [Google Scholar]
  19. Li S. and Sauer W. C.. 1994. The effect of dietary fat content on amino acid digestibility in young pigs. J. Anim. Sci. 72:1737–1743. doi: 10.2527/1994.7271737x [DOI] [PubMed] [Google Scholar]
  20. Li Q., Shi M., Shi C., Liu D., Piao X., Li D., and Lai C.. 2014a. Effect of variety and drying method on the nutritive value of corn for growing pigs. J. Anim. Sci. Biotechnol. 5:18. doi: 10.1186/2049-1891-5-18 [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Li P. L., Wang F. L., Wu F., Wang J. R., Liu L., and Lai C. H.. 2015. Chemical composition, energy and amino acid digestibility in double-low rapeseed meal fed to growing pigs. J. Anim. Sci. Biotechnol. 6:37. doi: 10.1186/s40104-015-0033-0 [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Li Q., J. Zang D. Liu X. Piao C. Lai, and Li D.. 2014b. Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs. J. Anim. Sci. Biotechnol. 5:11. doi: 10.1186/2049-1891-5-11 [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. de Lima M. B., Rabello C. B. V., da Silva E. P., Lima R. B., de Arruda E. M. F., and Albino L. F. T.. 2012. Effect of broiler chicken age on ileal digestibility of corn germ meal. Acta Sci. 34:137–141. doi: 10.4025/actascianimsci.v34i2.11812 [DOI] [Google Scholar]
  24. Liu Y., M. Song F. N. Almeida S. L. Tilton M. J. Cecava, and Stein H. H.. 2014. Energy concentration and amino acid digestibility in corn and corn coproducts from the wet-milling industry fed to growing pigs. J. Anim. Sci. 92:4557–4565. doi: 10.2527/jas.2014-6747. [DOI] [PubMed] [Google Scholar]
  25. NRC 2012. Nutrient requirements of swine. Washington, DC:National Academic Press. [Google Scholar]
  26. Nyachoti C. M., C. F. de Lange, and Schulze H.. 1997. Estimating endogenous amino acid flows at the terminal ileum and true ileal amino acid digestibilities in feedstuffs for growing pigs using the homoarginine method. J. Anim. Sci. 75:3206–3213. doi: 10.2527/1997.75123206x [DOI] [PubMed] [Google Scholar]
  27. Rojas O. J., Y. Liu, and Stein H. H.. 2013. Phosphorus digestibility and concentration of digestible and metabolizable energy in corn, corn coproducts, and bakery meal fed to growing pigs. J. Anim. Sci. 91:5326–5335. doi: 10.2527/jas.2013-6324 [DOI] [PubMed] [Google Scholar]
  28. Schulze H., P. van Leeuwen M. W. Verstegen J. Huisman W. B. Souffrant, and Ahrens F.. 1994. Effect of level of dietary neutral detergent fiber on ileal apparent digestibility and ileal nitrogen losses in pigs. J. Anim. Sci. 72:2362–2368. doi: 10.2527/1994.7292362x [DOI] [PubMed] [Google Scholar]
  29. Shi M., Liu Z., Wang H., Shi C., Liu L., and Wang J.. 2018. Deterimination and prediction of the digestible and metabolizable energy contents of corn germ meal in growing pigs. Asian-Australas. J. Anim. Sci. doi: 10.5713/ajas.17.0891 [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Stein H. H. and Bohlke R. A.. 2007. The effects of thermal treatment of field peas (Pisum sativum L.) On nutrient and energy digestibility by growing pigs. J. Anim. Sci. 85:1424–1431. doi: 10.2527/jas.2006-712 [DOI] [PubMed] [Google Scholar]
  31. Stein H. H., Lagos L. V., and Casas G. A.. 2016. Nutritional value of feed ingredients of plant origin fed to pigs. Anim. Feed Sci. Technol. 218:33–69. doi: 10.1016/j.anifeedsci.2016.05.003 [DOI] [Google Scholar]
  32. Stein H. H., C. F. Shipley, and Easter R. A.. 1998. Technical note: a technique for inserting a T-cannula into the distal ileum of pregnant sows. J. Anim. Sci. 76:1433–1436. doi: 10.2527/1998.7651433x [DOI] [PubMed] [Google Scholar]
  33. Stein H. H., N. L. Trottier C. Bellaver, and Easter R. A.. 1999. The effect of feeding level and physiological status on total flow and amino acid composition of endogenous protein at the distal ileum in swine. J. Anim. Sci. 77:1180–1187. doi: 10.2527/1999.7751180x [DOI] [PubMed] [Google Scholar]
  34. Thiex N. J., S. Anderson, and Gildemeister B.. 2003. Crude fat, diethyl ether extraction, in feed, cereal grain, and forage (randall/soxtec/submersion method): collaborative study. J. AOAC Int. 86:888–898. [PubMed] [Google Scholar]
  35. Urriola P. E., G. C. Shurson, and Stein H. H.. 2010. Digestibility of dietary fiber in distillers coproducts fed to growing pigs. J. Anim. Sci. 88:2373–2381. doi: 10.2527/jas.2009-2227 [DOI] [PubMed] [Google Scholar]
  36. Van Soest P. J., J. B. Robertson, and Lewis B. A.. 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583–3597. doi: 10.3168/jds.S0022-0302(91)78551-2 [DOI] [PubMed] [Google Scholar]
  37. Weber T. E., S. L. Trabue C. J. Ziemer, and Kerr B. J.. 2010. Evaluation of elevated dietary corn fiber from corn germ meal in growing female pigs. J. Anim. Sci. 88:192–201. doi: 10.2527/jas.2009-1896 [DOI] [PubMed] [Google Scholar]
  38. Widmer M. R., L. M. McGinnis, and Stein H. H.. 2007. Energy, phosphorus, and amino acid digestibility of high-protein distillers dried grains and corn germ fed to growing pigs. J. Anim. Sci. 85:2994–3003. doi: 10.2527/jas.2006-840 [DOI] [PubMed] [Google Scholar]
  39. Zhang W. J., Li D., Liu L., Zang J., Duan Q., Yang W., and Zhang L.. 2013. The effects of dietary fiber level on nutrient digestibility in growing pigs. J. Anim. Sci. Biotechnol. 4:17. doi: 10.1186/2049-1891-4-17 [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Zhang L., L. Liu D. Li Q. Li X. Piao P. A. Thacker M. A. Brown, and Lai C.. 2016. Effects of variety and storage duration on the nutrient digestibility and the digestible and metabolisable energy content of maize fed to growing pigs. Arch. Anim. Nutr. 71:67–80. doi: 10.1080/1745039X.2016.1226034 [DOI] [PubMed] [Google Scholar]

Articles from Journal of Animal Science are provided here courtesy of Oxford University Press

RESOURCES