In Vitro Digestible Energy Research Articles

Predicting energetic values of cereal grains and byproducts using a computer-controlled simulated digestion system for growing pigs

The objective of this study was to predict the apparent total tract digestibility (ATTD) of gross energy (GE), digestible energy (DE), and metabolizable energy (ME) of cereals and byproducts using an in vitro digestion procedure automatically progressed in a computer-controlled simulated digestion system (CCSDS) for growing pigs. In in vivo test to determine the ATTD of GE, DE and ME of feed ingredients, 15 barrows (30.2 ± 2.4 kg of initial body weight) were allotted to a 15 × 6 Youden square design with 15 experimental diets in 6 periods to give 6 replicates per diet. Diets included a corn-soybean meal-based basal diet and 14 test diets formulated with 14 samples of cereals and byproducts. The in vitro digestible energy (IVDE) and IVDE/GE were determined using CCSDS with 5 replicates for each sample. Principal components analysis showed that similar positions of samples were observed on a two-dimensional plot of PC1 and PC2 extracted from chemical composition and each of DE, ME, or IVDE. The ratios of IVDE to DE or ME among 14 samples ranged from 87.7–110.4 % and 91.1–112.9 %, but ranged from 97.8–103.5 % or 100.2–105.7 % when both paddy rice and wheat shorts were excluded in consideration of lever effect. Models to predict DE and ME from IVDE were DE = 0.7428 × IVDE + 945 (R² = 0.71, root mean square error (RMSE) = 157 kcal/kg DM, P < 0.01), ME = 0.7465 × IVDE + 839 (R² = 0.76, RMSE=139 kcal/kg DM, P < 0.01) when 14 samples were included, but regression equations were DE = 0.6924 × IVDE + 1173 (R² = 0.91, RMSE = 49 kcal/kg DM, P < 0.01) and ME = 0.6876 × IVDE + 1098 (R² = 0.95, RMSE = 34 kcal/kg DM, P < 0.01) when paddy rice and wheat shorts were excluded. Our results indicate that IVDE determined with a novel CCSDS can precisely predict the DE and ME of cereals and byproducts with lower fiber content (ADF < 6.01 % DM) for growing pigs.

Predicting the metabolizable energy and metabolizability of gross energy of conventional feedstuffs for Muscovy duck using in vitro digestion method.

In total, two experiments were conducted to evaluate the effectiveness of an in vitro digestion method for predicting the metabolizable energy (ME) and metabolizability of gross energy (ME/GE) values using in vitro digestible energy (IVDE) and the digestibility of gross energy (IVDE/GE) content, respectively, of conventional feedstuffs for Muscovy ducks. In experiment 1, the apparent metabolizable energy (AME), true metabolizable energy (TME), AME/GE, and TME/GE of eight-grain feedstuff samples (two corn samples, three sorghum samples, and three barley samples) and eight protein feedstuff samples (two soybean meal samples, three cottonseed meal samples, and three rapeseed meal samples) were determined by the tube-feeding method with six different ducks for each sample. In experiment 2, a computer-controlled simulated digestion system (CCSDS) contain simulated digestive fluid was used to determine the enzymatic hydrolysis energy value of feedstuffs, which was defined as IVDE in our study. The simulated gastric fluid containing pepsin and simulated small intestinal fluid containing amylase, trypsin, and chymotrypsin for the in vitro gastric and intestinal digestion, respectively. The IVDE and in vitro digestibility of GE (IVDE/GE) of 16 feedstuff samples were determined using the CCSDS with five replicates per sample. The results showed that the IVDE and IVDE/GE were positively correlated with ME and ME/GE of feedstuffs, respectively. The coefficient of determination of eight regression models in predicting ME (grain feedstuffs: AME = 1.050 × IVDE- 0.9293, TME = 1.032 × IVDE + 0.6478; protein feedstuffs: AME = 1.331 × IVDE- 6.685, TME = 1.269 × IVDE-3.490) and ME/GE (grain feedstuffs: AME/GE = 1.069 × IVDE/GE- 6.516, TME/GE = 1.068 × IVDE/GE + 0.7764; protein feedstuffs: AME/GE = 1.093 × IVDE/GE -19.21, TME/GE = 1.196 × IVDE/GE - 13.25) of feedstuffs for Muscovy ducks ranged from 0.8610 to 0.9921. The accuracy of the regression model was acceptable as the difference between measured and predicted ME and ME/GE values was less than 0.45 MJ/kg (100 kcal/kg) and 2.62% for 14 of the 16 feed samples, respectively. In conclusion, the in vitro digestion method can be used to predict the ME and ME/GE of conventional feedstuffs for Muscovy ducks with acceptable accuracy.

An automatically progressed computer-controlled simulated digestion system to predict digestible and metabolizable energy of unconventional plant protein meals for growing pigs.

The objective of this experiment was to develop a new computer-controlled simulated digestion system to predict the digestible energy (DE) and metabolizable energy (ME) of unconventional plant protein meals for growing pigs. Nine meals tested included 1 source of rapeseed meal, 4 sources of cottonseed meal, 2 sources of sunflower meal, and 2 sources of peanut meal. Twenty growing pigs (Duroc × [Landrace × Large White]) with an initial body weight (BW) of 41.7 ± 2.6 kg were allotted to a replicated 10 × 3 incomplete Latin square design to determine the DE and ME of 1 basal diet and 9 experimental diets formulated with 9 unconventional plant protein meals. The DE and ME values of unconventional plant protein meals were calculated by the difference method. The in vitro digestible energy (IVDE) of 1 basal diet, 9 experimental diets, and 9 unconventional plant protein meals were determined with 5 replicates of each sample in a complete randomized arrangement. The IVDE/DE or IVDE/ME ranged from 0.96 to 0.98 or 1.00 to 1.01, and the correlation coefficient between IVDE and DE or ME was 0.97 or 0.98 in 10 experimental diets. Accordingly, the IVDE/DE or IVDE/ME ranged from 0.86 to 1.05 or 0.96 to 1.20, and the correlation coefficient between IVDE and DE or ME was 0.92 or 0.91 in 9 unconventional plant protein meals. The coefficient of variation (CV) of IVDE was less than that of DE and ME in the experimental diets (0.43%, 0.80%, and 0.97% for CV of IVDE, DE and ME, respectively) and unconventional plant protein meals (0.92%, 4.84%, and 6.33% for CV of IVDE, DE and ME, respectively). The regression equations to predict DE from IVDE in 10 experimental diets and 9 unconventional plant protein meals were DE = 0.8851 × IVDE +539 (R2 = 0.9411, residual standard deviation [RSD] = 23 kcal/kg DM, P < 0.01) and DE = 0.9880 × IVDE + 166 (R2 = 0.8428, RSD = 182 kcal/kg DM, P < 0.01), respectively. There was no statistical difference in the slopes (P = 0.82) or intercepts (P = 1.00) of these 2 equations. Thus, 10 diets and 9 unconventional plant protein meals were pooled to establish the regression equation of DE on IVDE as: DE = 0.9813 × IVDE +187 (R2 = 0.9120, RSD = 118 kcal/kg DM, P < 0.01). The regression equations to predict ME from IVDE in 10 experimental diets and 9 unconventional plant protein meals were ME = 0.9559 × IVDE +146 (R2 = 0.9697, RSD = 18 kcal/kg DM, P < 0.01) and ME = 0.9388 × IVDE + 3 (R2 = 0.8282, RSD = 182 kcal/kg DM, P < 0.01), respectively. There was no statistical difference in slopes (P = 0.97) but significant difference between the intercepts (P = 0.02) of these 2 equations. Our results indicate IVDE has similar response to the DE but different response to the ME in 10 experimental diets and 9 unconventional plant protein meals. Therefore, IVDE is more suitable to predict DE than ME of diets and unconventional plant protein meals for growing pigs.

Accuracy of predicting metabolizable energy from invitro digestible energy determined with a computer-controlled simulated digestion system in feed ingredients for ducks.

Two experiments were conducted to study the accuracy of predicting true metabolizable energy (TME) of ingredients for ducks from in vitro digestible energy (IVDE) determined with a computer-controlled simulated digestion system. Experiment 1 was to establish TME prediction models from the IVDE of 9 energy feed ingredients and 12 protein feed ingredients using regression analysis. Experiment 2 was to validate the accuracy of the predicted ME of 10 ingredients randomly selected from Exp. 1. Ten diets were formulated with 2 to 6 of 10 ingredients. Dietary in vivo TME values were compared with calculated values based on the TME predicted in Exp. 1. In Exp. 1, the correlation coefficients between TME and IVDE were 0.9339 (P < 0.05) in 9 energy feed ingredients and 0.8332 (P < 0.05) in 12 protein feed ingredients. No significant difference was observed on the slope and intercept of TME regression models between 9 energy feed ingredients and 12 protein feed ingredients. Therefore, the regression model of TME on IVDE for 21 feed ingredients was TME = 0.7169 × IVDE +1,224 (R2 = 0.7542, P < 0.01). Determined and predicted TME differed by less than 100 kcal/kg of DM in 11 ingredients, and the difference ranged from 100 to 200 kcal/kg of DM in 5 ingredients. However, the difference between determined and predicted TME varied from 410 to 625 kcal/kg of DM in rice bran, rapeseed meal, corn gluten meal, and citric acid meal. In Exp. 2, the determined and calculated TME were comparable (3,631 vs. 3,639 kcal/kg of DM) and highly correlated (r = 0.9014; P < 0.05) in 10 diets. Determined and calculated TME differed by less than 100 kcal/kg of DM in 7 diets and by 106 to 133 kcal/kg of DM in 3 diets. These results have demonstrated that TME can be accurately predicted from IVDE in most feed ingredients, but it is less accurate for rice bran, rapeseed meal, corn gluten and citric acid meal.

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.

Effect of Corn Particle Size on the Particle Size of Intestinal Digesta or Feces and Nutrient Digestibility of Corn-Soybean Meal Diets for Growing Pigs.

Simple SummaryDietary particle size can affect the digestible or metabolizable energy values of diet for pig. So, the mean particle size (MPS) of corn-soybean meal diet was recommended to less than 600 µm to improve growth performance and efficiency of dietary nutrients utilization by growing pigs. However, little information is available on whether further reduction of MPS influences the digestion process and increases digestibility of nutrients. This study evaluated the effects of reducing particle size of corn from 682 to 365 µm on the particle size of intestinal digesta or feces and nutrient digestibility of corn-soybean meal diets for growing pigs. The results showed that the MPS of duodenal digesta, ileal digesta and feces was reduced with the reduction of corn particle size. But, the MPS of corn did not affect the activities of amylase, trypsin and chymotrypsin in the duodenal fluid and the apparent total tract digestibility (ATTD) of dry matter, gross energy, crude protein, ether extract, neutral (NDF) and acid detergent fiber (ADF). These results suggest that the MPS less than 511 µm for corn-soybean meal diet does not improve the utilization of nutrients, thus it’s not necessary to further reduce particle size of corn with MPS of 682 µm.This study was conducted to evaluate the effect of corn particle size on the particle size of intestinal digesta or feces and nutrient digestibility of corn–soybean meal diets. Twenty-four growing barrows (initial BW: 21.9 ± 1.62 kg) were randomly divided into 4 groups of 6 pigs. A T-cannula was surgically placed in the anterior duodenum (about 50 cm from pylorus) of pigs in Groups 1 and 2 or in the distal ileum of pigs in Groups 3 and 4. Corn used to formulate diets had mean particle size (MPS) of 365 µm (Corn 1) or 682 µm (Corn 2), resulting in diets with MPS of 390 µm (Diet 1) or 511 μm (Diet 2). Diet 1 or 2 were randomly assigned within pig Groups 1 or 2 and 3 or 4. The digestive enzyme activities of duodenal fluid, particle size of intestinal digesta and feces, as well as nutrient digestibility, were determined for each pig as the experiment unit. The MPS of duodenal digesta (181 vs. 287 µm, p < 0.01), ileal digesta (253 vs. 331 µm, p < 0.01), and feces (195 vs. 293 µm, p < 0.01) was significantly reduced for pigs fed Diet 1 vs. Diet 2, respectively. Compared with Diet 2, Diet 1 significantly reduced the proportion of particles above 0.5 mm, but significantly increased the proportion of particles between 0.072 and 0.5 mm (p < 0.01) in digesta and feces (p < 0.01). Diet 1 significantly increased solubles percentage (<0.072 mm) in duodenal digesta (p < 0.05) but did not affect solubles percentage in ileal digesta and feces. The MPS of diet did not affect the activities of amylase, trypsin, and chymotrypsin in the duodenal fluid and the apparent total tract digestibility (ATTD) of dry matter, gross energy, crude protein, ether extract, neutral detergent fiber (NDF) and acid detergent fiber (ADF) in pigs offered Diet 1 compared to Diet 2. The in vitro digestible energy (IVDE) (3706 vs. 3641 kcal/kg; p = 0.03) was greater for Corn 1 vs. Corn 2. However, no significant difference was observed in IVDE (3574 vs. 3561 kcal/kg; p = 0.47) for Diet 1 vs. Diet 2. In conclusion, the particle size of digesta and feces was dependent on the dietary particle size. However, the digestive enzyme activities of duodenal fluid and ATTD of energy and nutrients were not affected by reducing dietary MPS from 511 to 390 µm.

Validation of in vitro digestion using simulated small intestinal fluid with specific digestive activity to predict the metabolizable energy of feed ingredients for duck

Two experiments were conducted to validate a method to prepare simulated small intestinal fluid (SSIF) for in vitro digestion in ducks. Experiment 1 compared the in vitro digestible energy (IVDE) of SSIF to endogenous small intestinal fluid (ESIF) on four feeds. The ESIF 1 or 2 obtained from two groups of jejunal cannulated ducks offered diet 1 (3,050kcal/kg of ME and 19.95% of CP) or 2 (2,801kcal/kg of ME and 14.90% of CP) was purified into raw enzyme power (REP) 1 or 2. SSIF 1 to 3 or 4 to 6 were prepared to mimic ESIF 1 or 2, respectively. The enzyme sources were REP 1 for SSIF 1 and 4, REP 2 for SSIF 2 and 5 or reagent enzymes for SSIF 3 and 6, respectively. The IVDE of each feed was determined with SSIF or ESIF. Experiment 2 was to validate whether REP 1 was more effective than only reagent enzymes to prepare SSIF. Ten feeds were determined with pepsin following SSIF 1 or 3 for IVDE 1 or 2, respectively. The accuracy of prediction model of true metabolizable energy (TME) from IVDE 1 or 2 was evaluated to validate the efficacy of SSIF. In experiment 1, higher activities of amylase, trypsin and chymotrypsin were observed in ESIF 1 than ESIF 2 (P < 0.05). The IVDE determined with SSIF 1 and 2 or 3 and 4 were more comparable to that of ESIF 1 or 2 than determinations with SSIF 3 or 6. In experiment 2, the mean IVDE 1 or 2 was 97.22% or 96.23% relative to TME, respectively, and both were highly correlated with TME (P < 0.01; R2 ≥ 0.98). However, the residual SD of TME prediction model with IVDE 1 was less than that generated with IVDE 2 (55vs. 71kcal/kg). In conclusion, the IVDE determined with in vitro digestion of pepsin following SSIF prepared with REP can predict accurately TME of feed for ducks.

Digestible energy of sorghum grain for pigs could be predicted using a computer-controlled simulated digestion system

Prediction equations for digestible energy (DE) of sorghum grains fed to pigs have been generated based on chemical composition in our study. However, an in vitro method mimicking gastrointestinal digestion of pigs is more applicable to predict DE of feed ingredients in practice. This study evaluated in vitro DE (IVDE) and digestibility of gross energy (GE) in 28 samples of sorghum grain with a wide range in nutrient profiles using a 3-step computer-controlled simulated digestion system (CCSDS) and generated prediction equations based on IVDE and in vitro GE disappearance (IVGED) for previously determined DE and apparent total tract digestibility (ATTD) of GE. The IVDE (3305–4068 kcal/kg), IVDE/GE (0.72–0.91), IVGED (0.72–0.90), and in vitro dry matter (DM) disappearance (0.73–0.89; IVDMD) were quite variable and had a high negative correlation with tannin content in sorghum grain (r ≤ −0.90, P < 0.01). The IVDE or IVDE/GE was highly positively correlated with determined DE or DE/GE (r = 0.97 or 0.96, both P < 0.01), and linear relationship between DE and IVDE (kcal/kg of DM) or between DE/GE and IVDE/GE was observed in 28 sorghum cultivars: DE = 0.62 × IVDE + 1462 (R2 = 0.93, RMSE = 40.9 kcal/kg, P < 0.001), or DE/GE = 0.626 × IVDE/GE + 0.331 (R2 = 0.92, RMSE = 0.01, P < 0.001). Differences of less than 50 kcal/kg or 0.02 were observed in 23 or 24 of the 28 samples between determined and predicted DE or DE/GE. Similarly, the positive relationship between ATTD of GE or DM and IVGED or IVDMD was high (r = 0.95 and 0.93, respectively, both P < 0.01), and the prediction equations based on in vitro values were 0.595 × IVGED + 0.351 (R2 = 0.90, RMSE = 0.01, P < 0.001) for ATTD of GE and 0.644 × IVDMD + 0.327 (R2 = 0.87, RMSE = 0.01, P < 0.001) for ATTD of DM. Differences between determined and predicted values were smaller than 0.02 in 25 or 24 out of the 28 samples for ATTD of GE or DM. In conclusion, tannin negatively affects the in vitro enzyme digestion of energy content in sorghum grain. The 3-step enzymatic method using CCSDS could be a promising in vitro digestibility technique to predict DE and digestibility of GE in sorghum gain for pigs.

A computer-controlled simulated digestion system is a promising in vitro digestibility technique to predict digestible energy of corn grain for growing pigs

An equation for digestible energy (DE) of corn grain fed to pigs has been established based on chemical composition or near-infrared reflectance spectroscopy in our laboratory. And an in vitro digestibility technique to predict the DE value of feed ingredients is also applicable in practice. This study was conducted to evaluate the in vitro digestible energy (IVDE) and digestibility of gross energy (GE) in 13 selected samples of corn grain with a wide range in nutrient profiles using a computer-controlled simulated digestion system (CCSDS) and to generate prediction equations based on IVDE and IVDE/GE values for previously determined DE and digestibility of GE (DE/GE). Among the 13 samples, starch, DE and DE/GE content (dry matter basis) ranged from 603 to 662g/kg, 3843 to 4068kcal/kg, and 0.89 to 0.94, respectively. The IVDE (3440–3637kcal/kg) or IVDE/GE (0.80–0.84) showed a similar variation tendency with the DE or DE/GE value in the corn grains. There were highly positive correlations between IVDE and determined DE (r=0.99, P<0.01) and between IVDE/GE and determined DE/GE (r=0.98, P<0.01). Linear relationships were observed in the 13 corn samples: DE=1.14×IVDE – 89.56 (R2=0.97, P<0.01) and DE/GE=1.12×IVDE/GE – 0.18 (R2=0.97, P<0.01). All samples showed the differences of less than 25kcal/kg between observed and predicted DE and less than 0.005 between observed and predicted DE/GE. The slopes and R2 for the linear relationship between observed and predicted values were both 1 and 0.97. Overall, CCSDS is a promising in vitro digestibility technique to predict DE and digestibility of GE in corn gain for pigs.

Using a computer-controlled simulated digestion system to predict the energetic value of corn for ducks

Two experiments were conducted to develop a computer-controlled digestion system to simulate the digestion process of duck for predicting the concentration of ME and the metabolizability of gross energy (GE) in corn. In a calibration experiment, 30 corn-based calibration samples with a previously published ME concentration in 2008 were used to develop the prediction models for in vivo energetic values. The linear relationships were established between in vivo ME concentration and in vitro digestible energy (IVDE) concentration, and between in vivo metabolizability of GE (ME/GE) and in vitro digestibility of GE (IVDE/GE), respectively. In a validation experiment, 6 sources of corn with previously published ME concentration in 2008 randomly selected from the primary corn-growing regions of China were used to validate the prediction models established in the calibration experiment. The results showed that in calibration samples, the IVDE concentration was positively correlated with the AME (r = 0.9419), AMEn (r = 0.9480), TME (r = 0.9403), and TMEn concentration (r = 0.9473). Similarly, the IVDE/GE was positively correlated with the AME/GE (r = 0.95987), AMEn/GE (r = 0.9641), TME/GE (r = 0.9588), and TMEn/GE (r = 0.9637). The coefficient of determination greater than 0.88 and 0.91, and residual SD less than 45 kcal/kg of DM and 1.01% were observed in the prediction models for ME concentrations and ME/GE, respectively. Twenty-nine out of 30 calibration samples showed differences less than 100 kcal/kg of DM and 2.4% between determined and predicted values for 4 ME (AME, AMEn, TME, and TMEn) and for 4 ME/GE (AME/GE, AMEn/GE, TME/GE, and TMEn/GE), respectively. Using prediction models developed from 30 calibration samples, 6 validation samples further showed differences less than 100 kcal/kg of DM and 2% between determined and predicted values for ME and ME/GE, respectively. Therefore, the computer-controlled simulated digestion system can be used to predict the ME and ME/GE of corn for ducks with acceptable accuracy.

Developing a computer-controlled simulated digestion system to predict the concentration of metabolizable energy of feedstuffs for rooster1

Four experiments were conducted to evaluate the effectiveness of a computer-controlled simulated digestion system (CCSDS) for predicting apparent metabolizable energy (AME) and true metabolizable energy (TME) using in vitro digestible energy (IVDE) content of feeds for roosters. In Exp. 1, the repeatability of the IVDE assay was tested in corn, wheat, rapeseed meal, and cottonseed meal with 3 assays of each sample and each with 5 replicates of the same sample. In Exp. 2, the additivity of IVDE concentration in corn, soybean meal, and cottonseed meal was tested by comparing determined IVDE values of the complete diet with values predicted from measurements on individual ingredients. In Exp. 3, linear models to predict AME and TME based on IVDE were developed with 16 calibration samples. In Exp. 4, the accuracy of prediction models was tested by the differences between predicted and determined values for AME or TME of 6 ingredients and 4 diets. In Exp. 1, the mean CV of IVDE was 0.88% (range = 0.20 to 2.14%) for corn, wheat, rapeseed meal, and cottonseed meal. No difference in IVDE was observed between 3 assays of an ingredient, indicating that the IVDE assay is repeatable under these conditions. In Exp. 2, minimal differences (<21 kcal/kg) were observed between determined and calculated IVDE of 3 complete diets formulated with corn, soybean meal, and cottonseed meal, demonstrating that the IVDE values are additive in a complete diet. In Exp. 3, linear relationships between AME and IVDE and between TME and IVDE were observed in 16 calibration samples: AME = 1.062 × IVDE - 530 (R(2) = 0.97, residual standard deviation [RSD] = 146 kcal/kg, P < 0.001) and TME = 1.050 × IVDE - 16 (R(2) = 0.97, RSD = 148 kcal/kg, P < 0.001). Differences of less than 100 kcal/kg were observed between determined and predicted values in 10 and 9 of the 16 calibration samples for AME and TME, respectively. In Exp. 4, differences of less than 100 kcal/kg between determined and predicted values were observed in 3 and 4 of the 6 ingredient samples for AME and TME, respectively, and all 4 diets showed the differences of less than 25 kcal/kg between determined and predicted AME or TME. Our results indicate that the CCSDS is repeatable and additive. This system accurately predicted AME or TME on 17 of the 26 samples and may be a promising method to predict the energetic values of feed for poultry.

In vitro digestible energy of some agricultural residues, as influenced by gamma irradiation and sodium hydroxide

Experiments have been carried out to study the changes in the values of in vitro apparent organic matter digestibility (IVOMD) and in vitro digestible energy (IVDE) of wheat straw (WS), cotton seed shell (CSS), peanut shell (PS), soybean shell (SS), extracted olive cake (EOC) and extracted unpeeled sunflower seeds (ESS) after irradiation by various doses of gamma radiation (0, 100, 150, 200 kGy) or after spraying with different amounts of sodium hydroxide (NaOH): 0, 2, 4, and 6 g NaOH/25 ml water/100 g DM. The results indicate that there were significant increases in IVOMD and IVDE values for all irradiated samples and for sodium hydroxide treatments except for SS and ESS. Combined treatment of irradiation and sodium hydroxide resulted in a larger increase in the digestible energy than the individual treatments.

Changes in contents and in vitro digestibility of laying-hens excreta used as feedstuffs due to drying and gamma irradiation

Experiments have been carried out to study the changes in the values of total nitrogen (N), in vitro digestible crude protein (IVDCP), in vitro apparent organic matter digestibility (IVOMD), in vitro digestible energy (IVDE), crude fibre (CF) and cell-wall constituents (NDF, ADF, ADL) for laying-hens excreta under the effects of: (1) two types of drying: (a) drying at 175°C for 10 minutes (D1); (b) drying at 55°C for 5 days (D2). (2) different doses of gamma irradiation [0, 10, 50, 100, 150 kilogray (kGy)]. The results indicated that there was a significant ( P < 0.05) decrease in values of NDF and ADF (by 7%), CF and IVDCP (by 13%), and N (by 16%), and a significant increase in the values of IVOMD (by 12%) and IVDE (by 630 kJ/kg DM) as a result of drying (D1) in comparison with drying (D2). A significant ( P < 0.05) decrease was observed in the values of NDF and ADF (by 6%), CF (by 12%) and a significant increase in the values of IVOMD (by 13%) and IVDE (by 980 kJ/kg DM) as a result of gamma irradiation treatment (100 kGy) in comparison to the control sample. There was no significant difference between doses (100 kGy and 150 kGy). Gamma irradiation had no effect on N, ADL and IVDCP values. Combined treatment (D1 + 100 kGy) resulted in a better effect in reducing the concentrations of CF, NDF and ADF and in increasing the values of IVOMD and IVDE.

Research Note: The Use of Near Infrared Reflectance Spectroscopy to Measure In Vitro Digestible Energy Content in Poultry Feeds

Near infrared reflectance spectroscopy (NIRA) was used to estimate in vitro digestible energy (IVDE) values in complete poultry feeds. Seventy-one feeds were used in the study ranging in IVDE values from 2.370 to 3.505 kcal/g. The NIRA calibrations were developed using filter and scanning spectrophotometers. Different mathematical treatments of the spectra were employed before selecting the NIRA equations. The accuracy of the predictions were assessed by the standard error of the estimate (SEE). The results of applying NIRA to estimate IVDE showed SEE values that ranged from .124 to .138 kcal/g. The best prediction equation was obtained with a filter instrument using two wavelengths. The results of the present study indicated that NIRA can be used to estimate IVDE in poultry feeds.

In Vitro Estimation of Apparent Metabolizable Energy

A number of experiments were carried out to determine if a two stage in vitro method developed for monogastrics could, using in vitro digestible energy (IVDE), estimate the nitrogen-corrected apparent metabolizable energy (AMEn) of poultry diets. For a total of 11 diets assayed with adult roosters the average apparent metabolizable energy was 2.937 kcal/g, while the in vitro determined digestible energy was 2.969 kcal/g of diet.Regression analysis showed a significant (P<.05) correlation (r = .93) between IVDE and AMEn. The prediction equation generated from regression analysis was: Y = 1.0380X − .143 [r = .93, residual standard deviation (rSD) = ± .145 kcal/g], where Y = apparent metabolizable energy in kilocalories per gram and X = in vitro digestible energy in kilocalories per gram. When percent ether extract (EE) was included in the regression model, the accuracy of predicting AMEn was increased, and the prediction equation became: Y = .9169X1 + .0518X2 − .0213, (r = .98, rSD = ± .073 kcal/g), where Y = apparent metabolizable energy in kilocalories per gram, X1= in vitro digestible energy in kilocalories per gram, and X2 = % EE of the diet. Including other parameters of proximate analysis did not significantly (P>.05) increase the correlation nor improve the accuracy of prediction.When actual IVDE values were compared to predicted values generated from regression equations as estimates of AMEn, the IVDE values were more accurate (root-mean-squared-error = ± .119 kcal/g) than predicted values (rSD = ± .145 kcal/g) for the 11 diets assayed.