Publications (7)12.58 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: 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.
- [Show abstract] [Hide abstract] ABSTRACT: 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.
- [Show abstract] [Hide abstract] ABSTRACT: The objective of this experiment was to determine the effects of fiber level from alfalfa meal and collection period on the intestinal nutrient and energy flow and hindgut fermentation in growing pigs. Twenty-four pigs (initial BW = 21.4 ± 1.5 kg) were prepared by T-cannula insertion into the distal ileum and allotted to 4 treatments. The pigs were provided a corn-soybean meal control diet or a diet in which corn and soybean meal were partly replaced by 5, 10, or 20% of alfalfa meal to give the graded levels of dietary fiber during two 10-d collection periods. The BW of pigs at the start of period 1 and 2 were 32.2 ± 2.4 and 37.7 ± 4.2 kg, respectively. The final BW at the end of period 2 was 46.8 ± 4.0 kg. The apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and energy were measured. The VFA concentration was also determined in the ileal and fecal samples. Nutrient digestibility was not affected by inclusion of 5% alfalfa meal in the diet. The AID, ATTD, and hindgut fermentation of DM, carbohydrates (CHO), and GE decreased (linear, P < 0.05) as the level of alfalfa meal in the diet increased. The intestinal flow of DM, CHO, ADF, and GE increased (linear, P < 0.05) by increasing the level of dietary alfalfa. The pH in the ileal digesta and the concentration of acetate, propionate, and total VFA in the feces increased (linear, P < 0.01) as the level of alfalfa meal in the diet increased. From experiment period 1 to 2, the ATTD and hindgut fermentation of CHO decreased (P < 0.01), whereas the concentrations of propionate, valerate, and total VFA in ileal samples increased (P < 0.05). A multiple linear regression analysis, taking into account both the SDF and IDF intake, explained the variation (P < 0.01) in the total tract flow of NDF (93%), ADF (84%), GE (73%), DM (71%), and CHO (62%). In conclusion, the diet containing 5% of alfalfa meal did not affect nutrient and energy digestion. The intestinal flow of CHO decreased over the course of the 10-d collection period. The VFA concentration increased with fiber level and 10-d exposure to the experimental diets. Soluble and insoluble fibers from alfalfa meal have differential roles in nutrient digestion, which may help explain the variation observed in the intestinal flow of nutrients.
- [Show abstract] [Hide abstract] ABSTRACT: An experiment was conducted to investigate the effects of dietary protein source on the digestive enzymes and electrolyte composition of digesta fluid in the duodenum, jejunum, and ileum of chickens. A 2 × 3 factorial and completely randomized design that used 2 types of diets that differed only in their protein source [a corn-soybean meal-miscellaneous meal diet (CSMD) and a corn-miscellaneous meal diet (CMD)] and 3 types of cannulated roosters (duodenal, jejunal, and ileal cannulations) was adopted. The experiments included 5 replicates for each of the 6 treatments, and each replicate involved 3 cannulated chickens. The digesta samples were collected for 1 h every 4 h between 09:30 and 18:30 h on d 31, 33, and 35 of the experiment. The amylase, lipase, trypsin, and chymotrypsin activities and the electrolyte composition in the duodenal, jejunal, and ileal fluid were determined. In general, no significant differences between the 2 dietary groups were observed for the mean of duodenal, jejuna, and ileal amylase, trypsin, chymotrypsin, and lipase, respectively. However, the duodenal amylase activity was lower in the CMD group than the CSMD group (P < 0.05), which was probably related to the lower duodenal pH value that was observed in this group (P < 0.01). A higher jejunal Mg2+ concentration was observed in chickens that were fed the CMD (P < 0.05), whereas the differences in the Na+, K+, Cl−, and Ca2+ concentrations in the small intestine were not significant between the 2 diets (P > 0.05). In conclusion, the digestive enzymes and electrolytes in the small intestinal fluid of chickens adapted to the protein source of the diet, and each segment of the small intestine displayed different modifications.
- [Show abstract] [Hide abstract] ABSTRACT: Two experiments were conducted to investigate the feasibility of using corn starch as the basal diet to determine the ME of protein feedstuffs using the TME assay in Chinese Yellow chickens. In the first experiment, the TME of corn starch were determined by force-feeding 25 or 40 g of feed. To test the repeatability of the bioassay, the same experiment was repeated 4 times. In the second experiment, the TME of soybean meal and cottonseed meal was determined by considering corn starch as the basal diet, while corn was fed alone to the chickens. To test the accuracy of the TME assay for individual ingredients, the additivity was evaluated by determining the TME of 3 mixed diets: corn-soybean meal diet, corn-cottonseed meal diet, and corn-soybean meal-cottonseed meal diet. In experiment 1, the value of endogenous energy loss was 16.76 to 18.46 kcal/48 h, and no significant differences between the 4 assays were noted. The TME and energy metabolizability of the 25-g corn starch treatment (4.06 kcal/g and 98.06%) were higher than those of the 40-g treatment (3.79 kcal/g and 91.45%; P < 0.01); whereas the CV were less than that of the 40-g treatment, indicating that it is reasonable to use the TME value of the 25-g treatment in feed formulation. In experiment 2, the TME values for corn, soybean meal, and cottonseed meal were 4.02, 3.39, and 2.92 kcal/g, respectively. The observed and predicted TME values of the corn-soybean meal, corn-cottonseed meal, and corn-soybean meal-cottonseed meal diets were in high agreement with differences ranging from -0.02 to 0.01 kcal/g. None of the differences was significant, indicating an accurate measure of the TME of the individual ingredients. Thus, using corn starch as the basal diet to determine the TME of protein feedstuffs was validated.
- [Show abstract] [Hide abstract] ABSTRACT: Two experiments were conducted to establish an ME content prediction model for normal corn for ducks based on the grain’s chemical composition. In Experiment 1, observed linear relationships between the determined ME content of 30 corn calibration samples and proximate nutrients, acid detergent fiber (ADF), and neutral detergent fiber (NDF) were used to develop an ME prediction model. In Experiment 2, 6 samples of corn selected at random from the primary corn-growing regions of China were used for testing the accuracy of ME prediction models. The results indicated that the AME, AMEn, TME, and TMEn were negatively correlated with crude fiber (r = −0.905), ADF (r = −0.915), and NDF (r = −0.95) contents, and moderately correlated with gross energy (GE; r = −0.55) content in corn calibration samples. In contrast, no significant correlations were found for CP, ether extract, and ash contents. According to the stepwise regression analysis, both NDF and GE were found to be useful for the ME prediction models. Because the maximum absolute difference between the in vivo ME determinations and the predicted ME values was 61 kcal/kg, it was concluded that, for White Pekin ducks, the latter could be used to predict the ME content of corn with acceptable accuracy.
- [Show abstract] [Hide abstract] ABSTRACT: The response of digestive enzymes activities in the jejunal fluid of Peking ducks to dietary ME and CP content was investigated. In experiment 1, jejunal digesta from 24 cannulated male white Peking ducks of 18 wk of age were collected for 1 h out of every 4 h beginning at 0930 h on d 16, 18, and 20 of the experiment. The activities of amylase, trypsin, and chymotrypsin in jejunal fluid were determined. In experiment 2, 72 male cannulated ducks were randomly sorted into 4 groups. Four treatments consisted of combinations of 3,050 and 2,800 kcal/kg of ME, and 17.50 and 14.40% CP content were available ad libitum. Jejunal digesta samples were collected for 1 h every 4 h from 0930 to 1830 h on d 31, 33, and 35 of the experiment according to the results of experiment 1. The activities of amylase, trypsin, chymotrypsin, lipase, sucrase, and maltase in jejunal fluid were determined. In experiment 1, significant differences were found in the average activities of amylase and chymotrypsin among days. The collection time significantly affected the 3 enzyme activities, and average enzyme activities during the day were higher and more stable than during the night. In experiment 2, the effect of dietary ME content on the 6 digestive enzymes activities was not significant. But the dietary protein content significantly changed amylase, trypsin, and chymotrypsin activities.