True Amino Acid Digestibility Research Articles

The True Amino Acid Digestibility of 15N-Labelled Sunflower Biscuits Determined with Ileal Balance and Dual Isotope Methods in Healthy Humans

BackgroundSunflower is a promising protein source but data on amino acid (AA) digestibility are lacking in humans. Classically, the determination of AA digestibility requires ileal digesta sampling. The dual isotope method is minimally invasive but has not been compared to the conventional approach. ObjectivesThis study aimed to determine the true ileal digestibility of sunflower AAs in healthy volunteers who ate biscuits containing 15nitrogen (N) protein isolate, in comparison with the dual isotope method. MethodsTwelve healthy volunteers (men and women; 40.4 ± 10.5 years old; BMI, 23.7 ± 2.9 kg/m2) were equipped with a naso-ileal tube. For 4 hours, they consumed 9 repeated meals comprising 15N-sunflower protein biscuits together with 13carbon (C)-AAs, carried either in chocolate (SUN + Ch; n= 7) or apple puree (SUN + P; n= 5). Ileal digesta and blood were sampled throughout 8 hours after ingestion of the first meal. The 15N and 13C AA enrichments were measured in digesta to determine ileal digestibility directly and in plasma to determine lysine and threonine digestibility using the dual isotope method. Differences between methods and between vector groups were analyzed using paired and unpaired t-tests, respectively. ResultsThe ileal digestibility of sunflower indispensable AAs (IAA) was 89% ± 5.3%, with threonine and lysine having the lowest digestibility. In the SUN + Ch meal, IAA digestibility was 3% below that of SUN + P (P < 0.05). The mean free 13C-AA ileal digestibility was 98.1% ± 0.9%. No matter which matrix was used to carry 13C-AAs, plasma 15N and 13C-AA kinetics displayed a 1-hour offset. Digestibility obtained with the dual isotope method (70.4% ± 6.0% for threonine and 75.9% ± 22.3% for lysine) was below the target values. ConclusionsThe ileal digestibility of IAAs from a sunflower isolate incorporated in a biscuit was close to 90% in healthy adults. Under our experimental conditions, the dual isotope method provided lower values than the usual method. Further protocol developments are needed to validate the equivalence between both methods. This trial was registered at http://www.clinicaltrials.gov clinicaltrials.gov as NCT04024605.

Nutritional components and protein quality analysis of genetically modified phytase maize

ABSTRACT The nutritional components and protein quality of genetically modified maize expressing phytase gene (GM) were analyzed and evaluated in this study. The nutritional components were analyzed by Chinese national standard methods. The ileostomy Bama miniature pigs were utilized to analyze the true digestibility of protein and amino acids. The digestible indispensable amino acid score (DIAAS) was adopted to evaluate the protein quality of GM, its parental maize (PM) and commercial available maize Zhengdan 958 (ZD). Meanwhile, the widely used protein digestibility corrected amino acid score (PDCAAS) was also calculated and compared with DIAAS. The content of protein, fat, vitamins, and minerals of all the strains of maize are in the normal ranges of OECD and/or ILSI. The DIAAS of GM, PM, and ZD were 54.57, 31.75, and 33.91, respectively, and the first limiting amino acid for GM, PM, and ZD was lysine. In conclusion, the introduction of phyA2 gene in GM maize does not disturb the digestion of protein/amino acid, but has the ability to promote the digestion of amino acids.

True digestibility of the essential amino acids of high-protein sunflower meals by balanced experiments with intact and caecectomized birds from Gallus species

Abstract. Using adapted methods for balanced experiments with poultry, the true digestibility coefficients of the essential amino acids of two high protein sunflower meals – 40+® and 47® have been established. The true digestibility coefficients by using two methods – with intact and randomized (caecectomized) birds have been compared. Six birds were tube fed and six – feed deprived for both of the fodders. The amino acids were established with amino analyzer AAA-881 after preliminary HCl hydrolysis. The mean digestibility of sunflower meal 40+® is higher in intact (88.11 versus 85.73 of sunflower meal 47®) compared to randomized birds (87.20 versus 85.46 of sunflower meal 47®). The differences by lots are statistically significant only in intact birds. The authors recommend for practical needs to use the average true digestibility coefficients between both meals, established with randomized birds (ileal digestibility).

Natural Fermentation of Cowpea (Vigna unguiculata) Flour Improves the Nutritive Utilization of Indispensable Amino Acids and Phosphorus by Growing Rats.

Cowpea (Vigna unguiculata) is among the most cultivated legumes, with interesting agronomic and environmental properties, and great potential as a nutritious food. The nutritional value of cowpea can be improved by technological processing. In this study, we showed that natural fermentation improved bioavailability of protein, amino acids, and dietary essential minerals from cowpea in growing rats, thus strengthening its potential value as functional food or food supplement. Forty Wistar albino rats (48 ± 1.8 g), were fed one of four experimental diets (n = 10 rats per diet): casein, raw cowpea, fermented cowpea or fermented and autoclaved cowpea. Despite lower growth indices of raw and fermented cowpea protein (PER, FTI) than casein, fermentation enhanced apparent digestibility of arginine, leucine, lysine, methionine, phenylalanine, tyrosine, and valine, and true digestibility of essential amino acids, except for tyrosine and valine, compared to raw cowpea. On the other hand, autoclaving of fermented cowpea flour decreased apparent, as did true digestibility of sulfur amino acids. Regarding the nutritive utilization of dietary essential minerals, Vigna unguiculata was a good source of available P, Mg, and K, while fermentation significantly improved the availability of P. Overall, cowpea was a good source of digestible essential amino acids and minerals and fermentation significantly improved its nutritional value that was not further enhanced by autoclaving.

The effect of varying steam conditioning temperature and time on pellet manufacture variables, true amino acid digestibility, and feed enzyme recovery

Summary Increasing conditioning temperature and conditioning time has been considered a feed manufacture strategy to improve feed hygienics that may also affect feed production and nutritional quality. The objective of the study was to assess how varying steam conditioning temperatures and conditioning times interacted to affect pellet manufacture variables, true amino acid digestibility, and exogenous mixer-added enzyme recovery. Corn and SBM diets that included dried distillers' grains with solubles and meat and bone meal were conditioned at either 77°C, or 82°C, or 88°C with conditioning times of either 30 or 60 s. Treatments were arranged in a three (steam conditioning temperature) × 2 (conditioning time) factorial in a randomized complete block design. Digestible amino acid concentration was estimated using cecectomized roosters in a Latin Square with crossover design. Motor load decreased for 30-s conditioning compared to 60-s conditioning when diets were subjected to 77°C and 82°C, but the time effect was lost at 88°C. Pellet quality increased incrementally with increased steam conditioning temperature (P

The 15N-leucine single-injection method allows for determining endogenous losses and true digestibility of amino acids in cecectomized roosters.

This study was conducted to assess the influence of dietary protein content in poultry when using the 15N-leucine single-injection method to determine endogenous amino acid losses (EAALs) in poultry. Forty-eight cecectomized roosters (2.39 ± 0.23 kg) were randomly allocated to eight dietary treatments containing protein levels of 0, 3%, 6%, 9%, 12%, 15%, 18% and 21%. Each bird was precisely fed an experimental diet of 25 g/kg of body weight. After feeding, all roosters were subcutaneously injected with a 15N-leucine solution at a dose of 20 mg/kg of body weight. Blood was sampled 23 h after the injection, and excreta samples were continuously collected during the course of the 48-h experiment. The ratio of 15N-enrichment of leucine in crude mucin to free leucine in plasma ranged from 0.664 to 0.763 and remained relatively consistent (P > 0.05) across all treatments. The amino acid (AA) profiles of total endogenous AAs, except isoleucine, alanine, aspartic acid, cysteine, proline and serine, were not influenced (P > 0.05) by dietary protein contents. The predominant endogenous AAs in the excreta were glutamic acid, aspartic acid, threonine, serine and proline. The order of the relative proportions of these predominant AAs also remained relatively constant (P > 0.05). The endogenous losses of total AAs determined with the 15N-leucine single-injection method increased curvilinearly with the dietary protein contents. The true digestibility of most AAs and total AAs was independent of their respective dietary protein levels. Collectively, the 15N-leucine single-injection method is appropriate for determining EAALs and the true digestibility of AAs in poultry fed varying levels of protein-containing ingredients.

Lignocellulose Improves Protein and Amino Acid Digestibility in Roosters and Egg Hatchability in Broiler Breeders.

The present work assessed the effect of supplementation of 0.8% dietary Arbocel® RC Fine, a readily available commercial lignocellulose, to poultry feed. In a complete randomized design using 36 individually caged mature dubbed Hy-Line roosters (aged 55 weeks) grouped in 4 treatments with 9 birds per treatment, a digestibility trial was performed to determine apparent and true metabolizable energy values along with digestibility coefficients of protein and amino acid in Arbocel® containing diets. Results showed that 0.8% Arbocel® supplemented diets improved protein digestibility by 6% (P<0.05). Additionally, Arbocel® caused an increase in apparent and true amino acid digestibility in roosters when compared to control diets and controls with 0.8% wheat bran (WB) supplementation. In a second experiment, 26,000 layers and 2,600 roosters aged 33 weeks (Ross 308 broiler breeder strain) were maintained in 6 poultry houses at a commercial breeding farm, with an average of 4330 layers and 433 roosters per house. Performance, egg grade, and hatchability rate were assessed over a post peak period of 6 months. Compared to the control group fed the 0.8% WB diet, the 0.8% lignocellulose dietary supplementation resulted in a decrease (P<0.05) in percent infertility leading to an average increase of 4.07% (P<0.05) in egg hatchability. The Arbocel® fed group had 3.8 more eggs per housed hen compared to control birds. Overall, Arbocel® supplementation at 0.8% resulted in the production of 5.7 more saleable chicks per housed hen during the 6 months trial, a sizeable profit to the farmer.

The effects of Spirulina algae inclusion and conditioning temperature on feed manufacture, pellet quality, and true amino acid digestibility

Diet formulation and manufacturing techniques dictate pellet quality and in turn influence broiler chicken performance; however, the degree of improvement may be dependent on potential changes in nutrient digestibility. For example, high steam conditioning temperature has been shown to increase pellet quality but also decrease amino acid digestibility. Therefore anticipated broiler performance improvement due to increased pellet quality would be diminished. Formulating diets with ingredients that contribute to pellet binding may allow for low temperature conditioning and maintenance of pellet quality. The inclusion of Spirulina algae in broiler diet formulations has been shown to improve pellet quality. The objectives of this study were to describe the manufacture, quality, and true amino acid digestibility (TAAD) of pelleted corn and soybean meal based broiler diets produced with different Spirulina algae inclusions and steam conditioning temperatures. Treatments were arranged as a 5×3 factorial that varied in algae inclusion (0, 0.5, 1, 5, and 10%) and steam conditioning temperature (74, 82, and 91°C). The Spirulina algae was analyzed for mineral content, metabolizable energy, and digestible amino acids to balance treatment formulations. The manufacture of each treatment was replicated three times and blocked by time of manufacture. All treatments were steam conditioned for a 10s duration and extruded through a 4.7×38mm pellet die. Hot pellet temperature (HPT) and pellet mill motor amperage increased (P<0.05) with either increased algae inclusion or steam conditioning temperature. However, pellet production rate was not affected by treatment (P>0.05). Algae inclusion and conditioning temperature interacted to affect pellet durability (P<0.05). Algae inclusion and conditioning temperature increased pellet durability, with algae inclusion having a greater influence at low conditioning temperature. Single comb white leghorn cockerels were precision fed each dietary treatment to determine TAAD. Conditioning temperature, in general, affected TAAD of multiple tested amino acids (P<0.02), more specifically leucine, valine, isoleucine, alanine, and aspartic acid decreased in digestibility when conditioned at 91°C (P<0.05). Lysine TAAD tended to be similarly effected by conditioning temperature (P=0.06). Threonine, cystine, proline, and glutamic acid digestibility were affected by the interaction of conditioning temperature and algae inclusion (P<0.05), demonstrating that TAAD was reduced at either 82°C or 91°C depending on the inclusion of algae. The combination of Spirulina algae inclusion and low conditioning temperature may improve pellet quality without detriment to amino acid digestibility.

True digestibility of protein and amino acids in goats using plants naturally enriched in 13C as a label to determine endogenous amino acid excretion

The objective of this study was to determine whether 13C labeling occurs in goats fed diets with different natural levels of 13C enrichment and, if so, to use 13C as a label to determine true amino acid (AA) digestibility. Thirty-six Xiangdong black goats with initial body weights of 7.5±0.5kg were selected as experimental animals and fed dietary treatments consisting of wheat, barley, and soybeans (C3 diet) or corn, sorghum grain, and sugar cane (C4 diet). The 13C abundance of the amino acid fraction (AAF) of the C3 and C4 diets had average delta 13C values of −28.57‰ and −12.93‰, respectively. Three goats/treatment were slaughtered on days 1, 28, 56 and 84 during the labeling phase, and the AAFs of organs were analyzed for 13C abundance. 13C in the blood AAF increased (−21.70‰, −22.65‰, −23.59‰, and −24.43‰, respectively) with increasing feeding durations in goats fed the C3 diet and decreased (−21.13‰, −16.01‰, −13.78‰, and −12.03‰, respectively) in goats fed the C4 diet. Longissimus dorsi, liver and wool AAFs showed similar trends to those observed in the blood. Each tissue showed a significant dietary treatment effect (P<0.05) and a dietary treatment×labeling phase interaction (P<0.01). After the labeling phase (day 85), six goats from each treatment group were placed in metabolism cages and fed at 0700 and 1900. Three of the goats from each treatment group were implanted with the ruminal cannula and duodenal fistulae and given a 14-day recovery period. From days 15 to 21, a total of 4g chromic oxide, used as an indigestible marker, was administered daily via the ruminal fistulae. At 1900 on day 18 of the collection phase, all goats were switched to the opposite diet type. Thereafter, the duodenal fluids and total feces were collected from days 19 to 21. Additionally, one goat that had not been implanted with a ruminal cannula and duodenal fistulae from each treatment group was killed at 0700 (before feeding) on days 19, 20 and 21, and the AAFs of organs were analyzed for 13C abundance. 13C abundance of the blood AAF was used as an index of endogenous protein labeling. Apparent and true protein digestibilities in the forestomach, whole intestine and whole digestive tract were not different (P>0.05) between the diet treatment groups. The levels of true protein digestibility in the forestomach, whole intestine and whole digestive tract in goats fed the C4 diet tended to be higher than for those in goats fed the C3 diet. On average, the true digestibilities of protein, essential AAs and nonessential AAs were 5.30%, 4.28% 3.17% (forestomach), 5.20%, 5.39% 3.75% (whole intestine) and 3.01%, 4.97%, 4.17% (whole digestive tract) higher, respectively, than the apparent digestibilities of these components in goats fed the C3 diet. In summary, goat tissue protein was labeled with 13C using different diets, and the results show that 13C can be used to determine true AA digestibility.

Effects of algae incorporation into broiler starter diet formulations on nutrient digestibility and 3 to 21 d bird performance

Algae, a human supplement and alternative fuel source, has potential as a feed ingredient for poultry. Three studies were conducted with the following objectives: determine digestible nutrient values for a commercially availableSpirulina algae (Study 1), formulate and pellet a practical broiler starter diet using these data (Study 2), and assess feeding diet formulations with varying levels of algae on Hubbard X Cobb 500 broiler performance and apparent ileal amino acid digestibility (AIAAD; Study 3).Spirulina algae TMEn (2,839 kcal/kg) and true amino acid digestibility (TAAD) values (2.10, 1.07, 0.42, and 1.97% lysine, methionine, cysteine, and threonine, respectively) from Study 1 were used to formulate a practical broiler starter diet containing 21% algae. A diet containing 0% algae was also formulated. Both diets were pelleted, ground, and mixed at different ratios to create diets containing 6, 11, and 16% algae. The 21% algae diet resulted in a nominally lower production rate and an increase in hot pellet temperature and pellet durability compared to the 0% algae diet. Diets containing up to 16% algae resulted in statistically similar ending parameter compared birds fed the 0% algae diet: ending bird weight (EBW), live weight gain, and feed intake (P > 0.05). The 16% algae diet resulted in the highest level of digestible cysteine and lysine (P < 0.0001). All diets containing algae resulted in higher digestible methionine values compared to the 0% algae diet (P < 0.0001). Descriptive feed manufacture, performance, and AIAAD data demonstrated value in algae incorporation into practical diet formulations.

Cockatiel Transition From a Seed-based to a Complete Diet.

To determine the effects of diet transition in cockatiels ( Nymphicus hollandicus ), 14 cockatiels were transitioned over a 12-day period from a seed diet to one of 2 commercial diets advertised as nutritionally complete. Before the transition, cockatiels were fed a seed-based diet for 30 days. The transition strategy consisted of gradually increasing the ratio of complete diet : seed-based diet over the 12-day period. True amino acid digestibility determined on each complete diet (diets A and B) demonstrated that both diets contained highly digestible amino acids. Diets differed in ingredient composition and particle size, analyzed nutrients, and method of processing (baked or extruded). Daily feed intake of seed-based and complete diets was measured. Periodically throughout and after transition, body weights were measured, and blood samples were collected for hematologic testing and plasma biochemical analysis. All cockatiels accepted the transition strategy irrespective of complete diet. Cockatiels transitioned to diet A consumed significantly more of the complete diet and less of the seed-based diet during periods of measurement throughout transition. Total feed intake was significantly greater for cockatiels fed diet B for 33% of the measurement periods (P < .05). Body weight was generally not affected during or after transition (P > .05). Hematologic and plasma biochemical values did not differ between cockatiels fed the 2 complete diets (P > .05). It may be speculated that cockatiels were more accepting of diet A during transition, and diet A more efficiently maintained body weight.

Coeficiente de digestibilidade e valores de aminoácidos digestíveis verdadeiros de diferentes cultivares de milho para aves

The digestibility and true digestible amino acid content of eight cultivars of maize was determined using the method of force-feeding roosters cecectomized. The experimental design was completely randomized, represented by eight cultivars, five replicates and a rooster each. Five roosters were kept fasting for corrections corresponding to metabolic and endogenous losses of amino acids. Significant differences (P <0.05) among maize cultivars for the true digestibility of amino acids, methionine, threonine, arginine, cystine and serine were observed. The values of true digestibility coefficients for essential amino acids, for methionine, threonine and arginine ranged from 85.61 to 93.57%, from 66.27 to 84.97% and 83.39 to 93.10% respectively. For the other essential amino acids, the average values were: 72.84% for lysine, 85.64% for methionine+cystine, 87.29% for histidine, 85.33% for valine, 87.11% for isoleucine, 94.04% for leucine and 90.65% for phenylalanine. The true digestibility coefficients of nonessential amino acids cystine and serine that showed significant difference ranged from 73.97 to 89.21% and from 77.31 to 92.68%, respectively. For other non-essential amino acids, average values were 88.28% for alanine, 82.68% for aspartic acid, 92.19% for glutamic acid and 87.84% for tyrosine. Due to the variations observed, it is recommended periodic analyzes of maize cultivars used to formulate diets, to ensure the feed quality and the performance of the animals.

Safety and Nutritional Evaluation of Biogas Residue Left After the Production of Biogas from Wastewater

We investigated the safety and nutritional value of biogas residue left after the production of biogas from wastewater. In Exp. 1, ninety-six female mice were selected for acute oral toxicity testing and randomly allocated to 4 treatment groups, which received distilled water (control) or the biogas residue solution at 1 g/mL, 5 g/mL, or 15 g/mL. Activity levels and serum biochemical parameters were measured after 24 hours. In Exp. 2, eighty mice were divided into 2 treatment groups for sub-acute and sub-chronic toxicity testing, which received either a control group diet or the biogas residue diet (20% biogas residue). In Exp. 3, to test the nutritional value of the biogas residue, four pigs were fed either a low-casein corn starch-based diet or a semi-purified diet with biogas residue as the only source of protein, and the apparent and true digestibility of crude protein and amino acids, apparent metabolic energy, and digestible energy were measured. Group differences in serum parameters and mouse weight gain were not significant 24 hours after biogas residue solution gavage, and the viscera appeared normal. At day 30 of the observation period, changes in serum biochemical parameters were not significant, but the mean spleen index of mice treated with biogas residue was greater (P<0.05) than that of the control group. In this study, biogas residue had no significant adverse effects on the body and it was safe as a feed supplement at a 20% replacement level. The current observations showed that the biogas residue might be considered as a protein feed source for pigs.

Effects of calcium lignosulfonate, mixer-added fat, and feed form on feed manufacture and broiler performance

Pelleting technique can affect feed form and nutrient availability. Increasing mixer-added fat (MAF) decreases frictional heat and pressure within the pellet die, but reduces pellet quality (PQ). The use of calcium lignosulfonate (CaLS) may enable use of moderate inclusions of MAF while maintaining PQ. A series of experiments with treatments consisting of CaLS (0, 0.5, or 1%), MAF (1 or 3%), and feed form (pellet or ground pellet) were performed to explore feed mill efficiency, PQ, broiler performance, digesta viscosity, and true amino acid digestibility (TAAD). Increased MAF and CaLS independently reduced energy use of the pellet mill, pellet temperature postextrusion, and decreased and increased PQ, respectively. A 3-way interaction of main effects for FCR demonstrated that the 0.5% CaLS + 3% MAF treatment improved pelleted treatment FCR. The 0.5% CaLS + 3% MAF treatment combination also increased digesta viscosity, demonstrated by a CaLS by MAF interaction effect. Additionally, a 3-way interaction of main effects demonstrated that the 0.5% CaLS + 3% MAF treatment maintained a high level of TAAD in pelleted treatments. The ratio of CaLS to MAF was found to be important to PQ, as well as broiler performance, digesta viscosity, and TAAD. Adding 0.5% CaLS to treatments containing 3% MAF improved PQ, and feeding these pellets improved FCR and increased TAAD.

Effects of varying conditioning temperature and mixer-added fat on feed manufacturing efficiency, 28- to 42-day broiler performance, early skeletal effect, and true amino acid digestibility

Three experiments (EXP) were conducted with the objective of evaluating the effects of varying steam conditioning temperatures (CT) and mixer-added fat (MAF) on a practical broiler finisher diet on feed manufacture variables (EXP 1), 28- to 42-d broiler performance (EXP 2), and early skeletal effect using 3-to 21-d broiler performance and tibiae ash measurements and true amino acid digestibility using cecectomized roosters (EXP 3). For all EXP, we used a 3 CT (74, 85, or 96°C) by 2 MAF (low or high) factorial arrangement, resulting in 6 experimental diets. Prior to EXP 2 and 3, all diets were ground to a common crumble size. In EXP 1, increasing both CT and MAF decreased relative electrical energy use at the pellet mill. In EXP 2, feeding finisher diets manufactured utilizing increased CT and decreased MAF to broilers from 28 to 42 d resulted in increased FCR. Also, CT by MAF interactions demonstrated the highest BW gain when birds were fed diets with high MAF, conditioned at 85°C. In EXP 3, feeding diets manufactured in EXP 1 to broilers from 3 to 21 d resulted in no significant effects on live performance variables. However, a significant CT by MAF interaction was observed, where chicks fed diets using low MAF conditioned at 85 and 96°C resulted in incrementally increased percent tibia ash over those with high MAF. In addition, based on true amino acid digestibility data, altering MAF and especially CT can affect the digestibility of several amino acids.

Effects of Origins of Soybean Meal on Growth Performance, Nutrient Retention and Excreta Microflora of Broilers

An experiment was conducted to determine the effects of origins of soybean meal (SBM) on growth performance, nutrients and energy retention and fecal microflora in broilers. The SBM originating from Korea, Brazil and India were used. A total of 480 broiler chicks (average initial BW, 41.8 g) were randomly allotted to 6 treatments. Each treatment had 4 replicate pens with 20 chicks per pen. Birds were fed diets containing SBM originated from Korea (domestic SBM), Brazil or India (imported SBM) and the diets were based on the total amino acid (TAA) or true digestible amino acid (TDAA). Experimental diets were fed in two phases, starter (d 0～21) and finisher (d 22～35). The overall weight gain, feed intake and FCR were better (P 0.05) in the excreta microflora and overall feed cost per kg body weight gain in birds fed SBM from different origins; however, diets formulated on TDAA basis had lesser (P<0.05) feed cost per kg body weight gain in birds when compared with diets formulated on TAA basis. These results indicate that Korean SBM has better nutrients digestibility than SMB originated from Brazil and India, which contributes to the improved performance of broilers. In addition, better performance was obtained when diets were formulated on TIDAA basis.

Nitrogen-corrected True Metabolizable Energy and Amino Acid Digestibility of Chinese Corn Distillers Dried Grains with Solubles in Adult Cecectomized Roosters.

This study was conducted to evaluate chemical composition, nitrogen-corrected true metabolizable energy (TMEn) and true amino acids digestibility of corn distillers dried grains with solubles (DDGS) produced in China. Twenty five sources of corn DDGS was collected from 8 provinces of China. A precision-fed rooster assay was used to determine TMEn and amino acids digestibility with 35 adult cecectomized roosters, in which each DDGS sample was tube fed (30 g). The average content of ash, crude protein, total amino acid, ether extract, crude fiber and neutral detergent fiber were 4.81, 27.91, 22.51, 15.22, 6.35 and 37.58%, respectively. TMEn of DDGS ranged from 1,779 to 3,071 kcal/kg and averaged 2,517 kcal/kg. Coefficient of variation for non-amino acid crude protein, ether extract, crude fiber and TMEn were 55.0, 15.7, 15.9 and 17.1%, respectively. The average true amino acid digestibility was 77.32%. Stepwise regression analysis obtained the following equation: TMEn, kcal/kg = −2,995.6+0.88×gross energy+49.63×a* (BIC = 248.8; RMSE = 190.8; p<0.01). Removing gross energy from the model obtained the following equation: TMEn, kcal/kg = 57.88×ether extracts+87.62×a* (BIC = 254.3, RMSE = 223.5; p<0.01). No correlation was found between color scores and lysine true digestibility (p>0.05). These results suggest that corn DDGS produced in China has a large variation in chemical composition, and gross energy and a* value can be used to generate TMEn predict equation.

Determination of true digestible amino acids of feedstuffs utilizing cecectomized roosters

The objective of this study was to estimate the true digestibility coefficients of amino acids and digestible amino acid values of some poultry feedstuffs. The feedstuffs were: babassu meal, sunflower meal, corn gluten meal, babassu starchy meal, meat and bone meal, common beans, pearl millet and residues of cookies, pasta and bread. The precise feeding method of Sibbald was used with adult cecectomized Leghorn roosters distributed in a completely randomized design, consisting of ten treatments and six replications with a rooster in each. The treatments were represented by the feedstuffs evaluated. The roosters were kept in a period of fasting for 36 hours and then fed 30 grams of feed. Samples were collected during 56 hours. Simultaneously, six roosters were kept fasting to make corrections to the metabolic and endogenous losses of amino acids. At the end of collections, the excreta obtained were weighed, freeze-dried and subsequently processed, so laboratory analyses were carried out and the coefficients of true digestibility of amino acids were determined. The mean values of the coefficients of true digestibility of essential and non-essential amino acids in percentage were respectively: 0.702 and 0.652 for the babassu meal; 0.852 and 0.786 for the sunflower meal; 0.928 and 0.887 for the corn gluten meal; 0.797 and 0.720 for the meat and bone meal; 0.364 and 0.339 for ground raw beans; 0.924 and 0.837 for ground pearl millet; 0.839 and 0.810 for cookie residue; 0.929 and 0.914 for pasta residue; and 0.904 and 0.899 for bread residue.

Gut luminal endogenous protein: Implications for the determination of ileal amino acid digestibility in humans

The true ileal digestibility assay provides the most informative measure of digestibility to assess bioavailability of amino acids in foods for humans. To determine 'true' estimates of ileal amino acid digestibility, requires that endogenous amino acids present in digesta at the terminal ileum be quantified. The amounts of endogenous amino acids in ileal digesta can be determined after feeding an animal or human a protein-free diet (traditional approach) or by various methods after giving a protein-containing diet. When the protein-free method has been applied with adult human subjects an overall mean value (three separate studies) for endogenous ileal nitrogen flow of 800 mg N/d has been reported. This value is considerably lower than a comparable value obtained after feeding protein of 1852 mg N/d (mean of four separate studies), and thus endogenous ileal N and amino acids should be measured under conditions of protein alimentation. There is some confusion concerning the terminology used to define digestibility, with the term "true" digestibility having different adopted meanings. Here, true amino acid digestibility is defined as apparent amino acid digestibility corrected for the basal amino acid losses determined after giving either a protein-free or a protein-containing diet. Basal losses should be determined at a defined dry-matter and protein intake. The protein-free diet approach to determining endogenous amino acids is considered unphysiological and basal losses refer to ileal endogenous amino acid flows associated with digesta dry-matter flow, and not including "specific" effects of dietary factors such as non starch polysaccharides and anti nutritional factors. Arguments are advanced that the enzyme hydrolysed protein/ultra filtration method may be suitable for routine application with a cannulated pig model, to obtain physiologically-valid basal estimates of ileal endogenous amino acids to allow calculation of true ileal amino acid digestibility in the pig, and then prediction (via statistical relationships) of true coefficients of amino acid digestibility in humans.

Apparent and true digestibility of protein and amino acid in feedstuffs used in Nile Tilapia feed as determined by the technique of dissection

The objective of this study was to determine the coefficients of apparent and true digestibility of protein and amino acids of five feedstuffs (corn, wheat bran, soybean meal, corn gluten meal and fish meal) in 900 sex-reversed Nile tilapia (Oreochromis niloticus) of the Thai strain during the growth phase, with an initial weight of 315±8.45 g. A total of 750 fish were distributed according to a randomized block design (repetitions in time) into five treatments with six replicates of 25 fish each. The remaining 150 fish were fed a protein-free diet to measure endogenous protein and amino acid losses in order to determine the true digestibility of these components. Each tested diet contained a single protein source, which consisted of one of the evaluated feedstuffs. Digestibility was indirectly estimated using chromic oxide at 0.50% as marker. Digesta was collected from the last 5 cm of the distal intestine (between the ileal-rectal valve and the anus) using the dissection technique. Apparent digestibility coefficients of protein and amino acids were, on average, 74.69 and 73.62% for corn, 73.74 and 72.81% for wheat bran, 86.01 and 84.66% for soybean meal, 85.19 and 84.29% for corn gluten meal, 76.74 and 75.56% for fish meal, respectively. True digestibility coefficients of protein and amino acids were, on average, 85.21 and 83.97% for corn, 84.41 and 83.74% for wheat bran, 87.22 and 87.51% for soybean meal, 87.97 and 87.34% for corn gluten meal, and finally 79.58 and 78.44% for fish meal, respectively.