Apparent Digestibility Coefficients Of Amino Acids Research Articles

The Contribution of Phytate-Degrading Enzymes to Chicken-Meat Production.

The contribution that exogenous phytases have made towards sustainable chicken-meat production over the past two decades has been unequivocally immense. Initially, their acceptance by the global industry was negligible, but today, exogenous phytases are routine additions to broiler diets, very often at elevated inclusion levels. The genesis of this remarkable development is based on the capacity of phytases to enhance phosphorus (P) utilization, thereby reducing P excretion. This was amplified by an expanding appreciation of the powerful anti-nutritive properties of the substrate, phytate (myo-inositol hexaphosphate; IP6), which is invariably present in all plant-sourced feedstuffs and practical broiler diets. The surprisingly broad spectra of anti-nutritive properties harbored by dietary phytate are counteracted by exogenous phytases via the hydrolysis of phytate and the positive consequences of phytate degradation. Phytases enhance the utilization of minerals, including phosphorus, sodium, and calcium, the protein digestion, and the intestinal uptakes of amino acids and glucose to varying extents. The liberation of phytate-bound phosphorus (P) by phytase is fundamental; however, the impacts of phytase on protein digestion, the intestinal uptakes of amino acids, and the apparent amino acid digestibility coefficients are intriguing and important. Numerous factors are involved, but it appears that phytases have positive impacts on the initiation of protein digestion by pepsin. This extends to promoting the intestinal uptakes of amino acids stemming from the enhanced uptakes of monomeric amino acids via Na+-dependent transporters and, arguably more importantly, from the enhanced uptakes of oligopeptides via PepT-1, which is functionally dependent on the Na+/H+ exchanger, NHE. Our comprehension of the phytate-phytase axis in poultry nutrition has expanded over the past 30 years; this has promoted the extraordinary surge in acceptance of exogenous phytases, coupled with the development of more efficacious preparations in combination with the deflating inclusion costs for exogenous phytases. The purpose of this paper is to review the progress that has been made with phytate-degrading enzymes since their introduction in 1991 and the underlying mechanisms driving their positive contribution to chicken-meat production now and into the future.

Dietary crude protein concentrations, feed grains, and whey protein interactively influence apparent digestibility coefficients of amino acids, protein, starch, and performance of broiler chickens

The present study was designed to investigate the impacts of dietary crude protein (CP) concentrations (220 and 180 g/kg) in either maize- or wheat-based diets, without or with 25 g/kg inclusions of whey powder (WP) concentrate on performance parameters and apparent amino acid digestibility coefficients in broiler chickens. The maize and wheat used in this study had CP levels of 84 and 119 g/kg, respectively. The 2 × 2 × 2 factorial array of 8 dietary treatments was offered to a total of 336 off-sex, male Ross 308 chicks from 7 to 35 d post-hatch with 7 replicate cages (6 birds per cage) per treatment. A treatment interaction (P = 0.016) between dietary CP and feed grains was detected for weight gains, where birds offered 180 g/kg maize-based diets displayed a weight gain advantage of 6.74% (2,628 vs. 2,462 g/bird) compared to their wheat-based counterparts. An interaction (P = 0.022) between feed grains and whey protein was observed for FCR as the addition of WP to maize-based diets improved FCR by 3.45% (1.314 vs. 1.361), but compromised FCR in wheat-based diets by 2.98% (1.415 vs. 1.374). A treatment interaction (P = 0.038) between dietary CP and feed grains was recorded for relative abdominal fat-pad weights weight gains as birds offered 180 g/kg CP maize-based diets had 43.4% (11.17 vs. 7.79 g/kg) heavier fat-pads than their wheat-based counterparts. Following the reduction in dietary-CP, apparent amino acid digestibility coefficients were depressed to greater extents in wheat-based diets. However, significant interactions between CP and feed grains were found in 14 of the 16 amino acids assessed and significant interactions between CP and WP were observed for 15 amino acids. Maize was the more suitable feed grain in terms of weight gain and FCR in 180 g/kg CP diets despite causing greater fat deposition. The inclusion of WP in reduced-CP diets did not enhance bird performance. Data generated indicate concentrations of microbial amino acids in distal ileal digesta were depressing apparent amino acid digestibility coefficients, which was more evident in wheat-based diets. Higher gut viscosities in birds offered wheat-based diets may have facilitated the proliferation of microbiota along the small intestine.

Capping dietary starch: Protein ratios enhances performance of broiler chickens offered reduced-crude protein, maize-based diets

The objective of this study was to determine if capping dietary starch:protein ratios in reduced-crude protein diets enhances growth performance of broiler chickens offered maize-based diets. A total of 288 off-sex, male Ross 308 chickens were offered a 2 × 3 factorial array of dietary treatments from 7 to 35 days post-hatch. Dietary starch:protein ratios were either standard (mean: 2.47) or capped (mean: 2.12) with three dietary crude protein concentrations of 195, 185 and 175 g/kg. Dietary starch:protein ratios were capped by substituting soybean meal with full-fat soy; sourced from the same supplier. The parameters assessed included growth performance, relative abdominal fat-pad weights, nutrient utilisation, excreta nitrogen concentrations, distal jejunal and distal ileal digestibility coefficients and disappearance rates of starch and protein, jejunal and ileal starch:protein disappearance rate ratios, distal jejunal and distal ileal apparent amino acid digestibility coefficients, distal ileal amino acid disappearance rates and free amino acid concentrations in systemic plasma. Capping dietary starch:protein ratios significantly reduced ileal starch:protein disappearance rate ratios in birds offered 195, 185 and 175 g/kg crude protein by 14.6% (2.40–2.05), 13.8% (2.61–2.25) and 29.3% (3.75–2.65), respectively. Capping starch:protein ratios in 175 g/kg crude protein diets significantly improved weight gain by 3.45% (2398 versus 2318 g/bird) and feed conversion ratio by 3.75% (1.360 versus 1.413) and relative abdominal fat-pad weights were numerically lighter by 10.3% (11.47 versus 12.78 g/kg). Condensing ileal starch:protein disappearance rate ratios were quadratically related (P < 0.001) to improvements in weight gain (r = 0.740), feed conversion ratio (r = 0.786) and lighter fat-pad weights (r = 0.650). Reducing dietary crude protein concentrations depressed apparent ileal digestibility coefficients of 15 of the 16 amino acids assessed (P = 0.021 to < 0.001); average coefficients were reduced by 6.74% (0.803 versus 0.861). These compromised amino acid digestibilities probably contributed to the 6.43% inferior weight gains (2358 versus 2520 g/bird; P < 0.001) and 3.05% inferior feed conversion ratio (1.387 versus 1.346; P < 0.001) following the dietary crude protein reduction from 195 to 175 g/kg. A better comprehension of the impacts of reduced crude protein diets on endogenous amino acid flows and accumulations of microbial amino acids in distal ileal digesta needs to be achieved as both factors will influence apparent amino acid digestibility coefficients. Finally, capping dietary starch:protein ratios in 175 g/kg crude protein diets showed distinct promise in this study as both weight gain and FCR were significantly enhanced.

The Impact of Digestive Dynamics on the Bioequivalence of Amino Acids in Broiler Chickens.

The purpose of this review is to consider the distinct possibility that dietary non-bound and protein-bound amino acids are not bioequivalent in broiler chickens. Usually, with conservative inclusions of a limited number of non-bound (synthetic, crystalline, feed-grade) amino acids in standard broiler diets, bioequivalency would not be an issue. However, reduced-crude protein (CP) broiler diets demand substantial inclusions of an extended range of non-bound amino acids to meet amino acid requirements. A standard diet may contain 5.0 g/kg non-bound amino acids, but a reduced-CP diet may contain up to 50 g/kg and this relative abundance skews the balance of non-bound to protein-bound amino acids and substantial proportions of certain amino acids are present in diets as non-bound entities. Importantly, tangible reductions in dietary CP, for example from 210 to 160 g/kg, usually both compromise broiler growth performance and increase fat deposition. Compromised growth performance is more evident in wheat- than maize-based diets but, paradoxically, fat deposition is more apparent in maize-based diets. The inability of birds to accommodate tangible dietary CP reductions appears to stem partially from the lack of bioequivalency between non-bound and protein-bound amino acids because of the differentials in intestinal uptake rates. Also, reduced-CP broiler diets generate perturbations in apparent amino acid digestibility coefficients which compound the fact that intestinal uptakes of non-bound acid acids are more rapid, and occur more anteriorly in the small intestine, than protein-bound amino acids. The likelihood is that greater proportions of non-bound amino acids transit the enterocytes of the gut mucosa without entering anabolic and/or catabolic pathways to gain entry to the portal circulation. This culminates in post-enteral amino acid imbalances and postprandial oxidation of surplus amino acids which involves deamination of amino acids and elevations in plasma ammonia (NH3) concentrations, but NH3 is inherently toxic and demands detoxification. Excessive deamination coupled with inadequate detoxification could result in 'ammonia overload' which would be expected to compromise growth performance. Thus, the hypothesis is that non-bound and protein-bound amino acids are not bioequivalent; moreover, it may be argued that this distinction is being overlooked and is thwarting the development and acceptance of reduced-CP broiler diets.

Protein value and health aspects of the seaweeds Saccharina latissima and Palmaria palmata evaluated with mink as model for monogastric animals

The aim of the present work was to evaluate the protein value of products from the two seaweeds Saccharina latissima and Palmaria palmata grown in Norwegian waters and to characterize possible beneficial or detrimental effects in the intestine and other organs. Mink, a well-established model for comparison of nutrient digestibility in monogastric animals was used. Two products from each of the seaweeds, a dried whole biomass and a protein concentrate, were evaluated. Five diets were made; a reference diet based on fish meal, and one for each of the four seaweed products. In the latter four, seaweed supplied 200 g/kg of crude protein. Each diet was fed to four male mink for two weeks. The results showed that diets with seaweed were less palatable than the fish meal diet. The animals fed the whole Saccharina diet had a significantly higher water intake and urine production than the other animals, supposedly due to the very high ash content of this seaweed product. This diet also stood out regarding urine concentration of iodine, which was 300 times higher than for the fishmeal-based diet. Apparent digestibility coefficient (ADC) for total amino acids, estimated by difference, showed low values for all the seaweed products; 0.574 and 0.734 for the whole and protein concentrated Saccharina products, and 0.588 and 0.700 for the two Palmaria products, respectively. The apparent amino acid digestibility coefficients (ADC) showed greater variation and were particularly low for histidine, <0.000 and 0.271 for the whole Saccharina and Palmaria products, respectively. Also, the ADC of methionine was low for these products, and cysteine ADC showed negative values for both Saccharina products. The estimated chemical score of the proteins, based on the digestible amino acids profile, was 0 and 520 g/kg for the whole product and protein concentrate of Saccharina, 260 and 520 g/kg for the whole product and the protein concentrate of Palmaria palmata, respectively. Expression of genes associated with digestive and immune functions showed minor effects in the jejunum, somewhat more pronounced effects in the colon. The latter effects were related to immune functions and lipid metabolism. No diet-related alterations in the histology of the jejunum and colon were observed. The histological investigation of liver and kidney structure showed some alterations in the seaweed fed animals. Regarding microbiota assemblage in mucosa of jejunum and colon, no clear diet effects were observed either in richness or diversity. In conclusion: the biological value of the seaweed proteins was low. Only one of the products, the Palmaria protein concentrate, might be considered of any use as a protein source. No clear beneficial or detrimental effects of the seaweed products were observed on gut health and function. The results regarding kidney structure and function, as well as the high iodine in the urine, indicating that further investigations are required to secure that animal health is not challenged by use of these seaweed ingredients in animal diets.

Antioxidant activity and apparent digestibility of amino acids of three macroalgae meals in the diets of Pacific white shrimp (Litopenaeus vannamei)

The antioxidant activity of meals, growth performance, dry matter, crude protein and amino acid apparent digestibility coefficients (ADC) were determined for three macroalgae in Pacific white shrimp juveniles: Gracilaria vermiculophylla , Dictyota dichotoma and Ulva lactuca . For the digestibility determination, test diets included 15% of the test ingredients and 85% of a control diet supplemented with 1% chromic oxide. The amino acid content in the ingredients, diets and feces were analyzed using HPLC. In general, nutrient digestibility values were far higher in the diets with macroalgae meals than in the control diet. In conclusion, diets with the macroalgae U. lactuca and G. vermiculophylla in particular showed high antioxidant activity, high amino acid digestibility and improved Litopenaeus vannamei growth.

Apparent ileal amino acid digestibility of reduced-oil distillers dried grains with solubles fed to broilers from 23 to 31 days of age

An experiment was conducted using male Ross × Ross 708 broiler chicks to determine the effect of oil extraction from corn distillers dried grains with solubles on apparent ileal amino acid digestibility from 23 to 31 d of age. On an as-fed basis, ether extract concentrations were determined as 5.4% (L-distillers dried grains with solubles), 7.9% (M-distillers dried grains with solubles), and 10.5% (H-distillers dried grains with solubles) for the 3 experimental distillers dried grains with solubles sources. Prior to experimentation, each sample (H-distillers dried grains with solubles (control), M-distillers dried grains with solubles and L-distillers dried grains with solubles) was analyzed on an as-fed basis for crude protein (29.2, 27.6, and 27.9%), starch (4.4, 5.2, and 6.1%), neutral detergent fiber (29.5, 33.2, and 29.9%), and total dietary fiber (31.4, 36.6, and 33.6 %). Four hundred and thirty-two male chicks (12 birds per cage; 0.04 m2 per bird) were randomly assigned to 36 battery grower cages. Broilers were fed one of 3 semi-purified diets, which were comprised of 76% L-distillers dried grains with solubles, M- distillers dried grains with solubles, or H-distillers dried grains with solubles as the sole amino acid source from 23 to 31 d of age. Apparent ileal amino acid digestibility coefficients were negatively affected (P < 0.05) by oil extraction for Met (0.722, 0.788, and 0.791), Lys (0.504, 0.510, and 0.552), Thr (0.563, 0.566, and 0.612), Trp (0.708, 0.733, and 0.767), and Arg (0.762, 0.776, and 0.799) for L-distillers dried grains with solubles, M-distillers dried grains with solubles, and H-distillers dried grains with solubles, respectively. Conversely, no differences in apparent amino acid coefficients were reported for Ile, Leu, and Val. These results indicated that L-distillers dried grains with solubles had lower apparent amino acid digestibility coefficients for Met, Lys, Thr, Trp, and Arg compared with H-distillers dried grains with solubles.

Influence of white- and red-sorghum varieties and hydrothermal component of steam-pelleting on digestibility coefficients of amino acids and kinetics of amino acids, nitrogen and starch digestion in diets for broiler chickens

Two experiments were conducted to examine the influence of sorghum variety and the hydrothermal component of steam-pelleting diets on apparent amino acid digestibility coefficients and digestion kinetics of amino acids, nitrogen and starch in broiler chickens. In experiment one, 84 male Ross 308 chicks were offered steam-pelleted diets based on white (Liberty) and red (Buster) sorghum from 7 to 28 days post-hatch. In experiment two, the same red sorghum-based diets were offered to chicks from 7 to 28 days post-hatch as either unprocessed raw mash or reground mash following steam-pelleting at 95°C. In both experiments, digesta samples from proximal jejunum, distal jejunum, proximal ileum and distal ileum were collected in their entirety at day 28. The samples were then freeze-dried and weighed for determination of mean retention time in each small intestinal segment. The digestion kinetics of amino acids, nitrogen and starch were determined using an exponential mathematical model to relate apparent digestibility coefficients with mean retention times in each small intestinal segment. In experiment one, white sorghum-based diets had significantly higher average amino acid digestibility coefficients than red sorghum in the proximal ileum and distal ileum (P<0.05). Nine from sixteen amino acids in white sorghum-based diets had significantly higher apparent digestibility coefficients in the proximal ileum and distal ileum. The potential digestible fraction of starch and rate of starch digestion in white sorghum-based diet were significantly higher than red sorghum (P<0.05). However, there were no significant differences in digestion rates of nitrogen and amino acids. However, pre-determined feed conversion ratios were strongly correlated with potential digestible starch (r=−0.840, P<0.001). The differences in white and red sorghum-based diets were more pronounced in starch digestion than nitrogen digestion and further research is required to identify the precise causes of deficient starch digestion in red sorghum. In experiment two, the hydrothermal component of the steam-pelleting process had a negligible impact on digestion of amino acids as there were no significant differences in the extent or rate of amino acid digestion in raw mash and reground mash diets. Therefore, the linear increases of amino acid digestibilities with increased conditioning temperatures observed in a previous study may be attributed to the feed form effect of intact pellets generating heavier relative gizzard weights; thereby enhancing the overall protein digestive process.

Protease supplementation of sorghum-based broiler diets enhances amino acid digestibility coefficients in four small intestinal sites and accelerates their rates of digestion

Apparent amino acid digestibility coefficients in the proximal jejunum, distal jejunum, proximal ileum and distal ileum of broilers fed sorghum-based diets without or with exogenous protease were determined at 28 days post-hatch. The digestion kinetics of amino acids were determined using an exponential mathematical model to relate digestion coefficients at four intestinal sites with mean retention times in each small intestinal segment. Protease increased average digestibility coefficients in the distal jejunum by 12.6% (0.681 vs. 0.605; P<0.05), in the proximal ileum by 5.0% (0.783 vs. 0.746; P=0.055) and in the distal ileum by 4.7% (0.822 vs. 0.785; P<0.05). In distal ileum, protease significantly increased the digestibility of thirteen amino acids, which ranged from a 4.5% increase in histidine (0.820 vs. 0.785, P<0.05) to a 7.9% increase in proline (0.779 vs. 0.722, P<0.01). Protease supplementation significantly increased digestion rates of twelve amino acids from 34.2% for histidine (2.57 vs. 3.45×10−2min−1, P<0.05) to 55.7% for proline (2.28 vs. 3.55×10−2min−1, P<0.01). Protease did not significantly influence retention times in each intestinal site. Protease significantly increased predicted glycaemic response by 18.8% (P<0.05). There were no significant correlations between digestion rates of starch and amino acids. The present study indicates that the Bacillus lichenformis-derived protease has the capacity to improve amino acid digestibility coefficients in sorghum-based diets and accelerate the digestion rate of protein and amino acid absorption.

Apparent Digestibility of 12 Protein‐Origin Ingredients for Pacific White Shrimp Litopenaeus vannamei

AbstractUsing 0.5% chromic oxide as an external indicator, apparent digestibility coefficients (ADCs) were determined for 12 protein feed ingredients (fish meal [FM], blood meal [BM], meat‐and‐bone meal [MBM], poultry byproduct meal [PBM], shrimp head meal [SHM], squid visceral meal [SVM], soybean meal [SBM], rapeseed meal [RM], cottonseed meal [CM], peanut meal [PM], corn gluten meal [CGM], and brewer's yeast [BY]) fed to Pacific white shrimp Litopenaeus vannamei (mean initial weight ± SD = 4.45 ± 0.21 g). The shrimp were randomly allocated to thirty‐nine 150‐L tanks (20 shrimp/tank) and were hand‐fed a reference diet or test diet (70% reference diet and 30% test feed by weight) twice daily to satiation. Feces were collected by siphoning. The observed range of ADCs of the 12 ingredients was 48.6–87.0% for dry matter, 55.7–92.3% for crude protein, 2.1–92.5% for crude lipid, 52.1–79.9% for phosphorus, and 51.1–97.2% for gross energy. Relatively high ADCs were observed for dry matter in FM (87.0%) and MBM (76.5%); for crude protein in FM (90.9%), SBM (92.3%), and PM (88.8%); for crude lipid in FM (92.5%) and SVM (88.5%); and for phosphorus (79.9, 72.7, 72.5, and 78.5%) and gross energy (97.2, 82.3, 84.0, and 84.6%) in FM, MBM, PBM, and BY. The ADCs of amino acids for the 12 ingredients were 86.7–97.4% (FM), 58.4–98.8% (BM), 46.9–99.6% (MBM), 54.8–95.4% (PBM), 79.0–100.0% (SHM), 58.3–93.0% (SVM), 60.7–99.4% (SBM), 62.6–99.6% (RM), 52.9–91.4% (CM), 60.1–99.9% (PM), 15.6–97.8% (CGM), and 30.3–98.4% (BY). Fish meal, SBM, and PM showed high average ADCs for total amino acids (&gt;90%). Crude protein ADCs corresponded with amino acid ADCs. Resultant digestibility data may provide more accurate information pertinent to formulating commercial feeds for Pacific white shrimp.

Digestibility of different wheat products in white shrimp Litopenaeus vannamei juveniles

Dry matter, energy, crude protein and amino acid apparent digestibility coefficients (ADCs) were determined in white shrimp juveniles for six wheat products: hard red winter whole grain meal (HWG), Rayon whole grain meal (RWG), Durum whole grain meal (DWG), hard red winter clear flour (HCF), mixed wheat 2nd clear flour (MCF) and semolina (S). The test diets included 30% of the test ingredients and 70% of a ground commercial diet supplemented with 1% chromic oxide and 1% sodium alginate. Amino acid contents in the ingredients, diets and feces were analyzed, and digestibility was determined by difference in order to minimize the impact of endogenous amino acid losses; crude protein and amino acids ADCs were adjusted for dietary preprandial losses in seawater. In general, nutrients digestibility was far higher in the wheat products than in the fish meal-based reference diet. Dry matter and crude protein ADCs were not statistically different among wheat products (from 84 to 96% and from 88 to 107% respectively). Energy ADCs were significantly higher for clear flours (96% for HCF and MCF) than for whole grain meals and S (from 83 to 86%). Total amino acids (TAA) and essential amino acids (EAA) ADCs, once adjusted for preprandial leaching from the experimental diets, ranged from 81 to 89% and from 58 to 81% respectively, and were statistically comparable among wheat products. Low Thr ADCs appear as a common feature of the amino acids digestibility profiles for whole grain meals, clear flours, or semolina.

Apparent dry matter, energy, protein and amino acid digestibility of four soybean ingredients in white shrimp Litopenaeus vannamei juveniles

Dry matter, energy, protein and amino acid apparent digestibility coefficients (ADC) were determined in Pacific white shrimp juveniles (6 g average initial weight) for four soybean products: full fat soybean meal (FFSBM, 38% CP in dry matter), solvent extracted soybean meal (SBM, 52% CP), soybean protein concentrate (SPC, 71% CP) and soybean protein isolate (SPI, 89% CP), obtained from soybeans processed by different manufacturers in USA and México. The test diets included 30% of the test ingredients and 70% of a ground commercial diet supplemented with 1% chromic oxide and 1% sodium alginate. Amino acid contents in the ingredients, diets and feces were analyzed by HPLC at Evonik-Degussa laboratory. Amino acid profiles of the four soybean product samples were quite similar except for a lower content of methionine and cystine in SPI. In general, nutrient digestibility values were far higher in the soy products than in the fish meal-based reference diet. Dry matter and energy ADCs were significantly higher for SPI (92 and 98%, respectively) than for FFSBM, SBM and SPC (83 and 89%, respective averages). Crude protein ADC was not significantly different among FFSBM, SBM and SPI, but SPC had significantly a lower value (93 vs 96%). Total amino acid (92 vs 97%) and essential amino acid (91 vs 96%) digestibility profiles were almost identical for FFSBM, SBM and SPI, while the SPC profile was parallel but 3.5 to 7 percentage units lower. Cys and Thr were the least digestible amino acids in all samples, while Gly and Arg were generally the most digested. Compared to the ADC of crude protein, the ADCs for Thr and Cys were 3–4% lower, while arginine ADC was 2–3% higher. The ADCs for Lys and Met were similar to that of crude protein, although Lys and Met digestibility may be overestimated due to their high solubility in seawater.

Nutrients apparent digestibility coefficients of selected protein sources for juvenile Siberian sturgeon (Acipenser baeriiBrandt), compared by two chromic oxide analyses methods

Apparent digestibility coefficients (ADCs) of dry matter (ADCd), crude protein (ADCp), energy (ADCe) and amino acids in selected feedstuffs were determined for juvenile Siberian sturgeon (8.38 ± 0.20 g). The tested feedstuffs were fishmeal (FM), meat and bone meal (MBM), poultry by-product meal, hydrolysed feather meal, fermented feather meal solvent-extracted cottonseed meal and soybean meal. ADCs were determined using a reference diet and test diets at 7 : 3 ratios with 5 g kg−1 chromic oxide (Cr2O3) as an inert marker. Fish were reared in a recirculating system and fed to apparent satiation five times daily. Cr2O3 in diets and faeces samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and acid-digestion colorimetry (AC) methods, respectively. The results showed that ICP-AES method was more accurate for Cr2O3 determination than AC method, and the results determined by ICP-AES method were used in this study. ADCd and ADCp of seven tested ingredients were lowest for MBM (59.1 and 84.5%) and highest for FM (79.9 and 94.5%); ADCe of tested ingredients were from 71.8% for SECM to 93.2% for FM. ADCs of amino acid in test ingredients followed similar trend to the ADCp. The ADCs of individual amino acids varied from 61.6% (histidine in MBM) to 98.8% (valine in FM).

Endogenous Amino Acid Flow in Broiler Chicks Is Affected by the Age of Birds and Method of Estimation

The determination of ileal endogenous amino acid (IEAA) and total amino acid (TAA) concentrations is critical to standardizing amino acid digestibility coefficients. The IEAA and TAA flow in broiler chicks was measured on d 5, 15, and 21 at 2 geographical locations. Chicks were fed a nitrogen-free diet (NFD) or graded levels of casein (50, 100, or 150 g/kg of diet), which were assumed to be highly digestible. The IEAA and TAA flow (mg/kg of DM intake) on d 5 in chicks fed the NFD was higher (P < 0.05; Met = 154, Thr = 539) than values for d 15 (Met = 51, Thr = 274) and d 21 (Met = 50, Thr = 274). A comparison of the regression and NFD analyses showed higher (P < 0.05) flows on d 5 for those birds fed the NFD diet, with no differences between methods on d 15 and 21, with the exception of Lys, Met, and Glu (d 21). At all 3 ages evaluated, there was a linear increase (P < 0.05) in IEAA and TAA flows with increasing level of dietary casein. There was a decrease in IEAA and TAA flows that stabilized between d 15 and 21. The result suggests that the NFD and the regression method will give similar results on d 15 and 21. These observations also suggest that the relatively low apparent amino acid digestibility coefficients for broiler chicks at a younger age may be the result of a significantly high level of endogenous amino acid flow.

Protein quality of poultry by-product meal manufactured from whole fowl co-extruded with corn or wheat

Three experiments were conducted with turkey poults to characterize the protein quality of a novel poultry by-product meal composed of aged fowl extruded with either corn (CHM) or wheat (WHM). In Experiment 1, a growth assay was conducted to determine a dietary protein response range for semipurified diets containing CHM or WHM as the sole sources of dietary protein. Diets contained 12, 15, and 18% CP, and there was a linear increase in BW with no significant differences between the 2 sources. The same dietary protein levels were used to determine the protein efficiency ratio (PER), net protein ratio (NPR), and apparent amino acid digestibility of CHM and WHM in Experiments 2 and 3. In Experiment 3, WHM and CHM were also compared with soybean meal (SBM) and meat and bone meal (MBM). In Experiment 2, there were no significant differences between CHM and WHM in PER or NPR, but the variability between levels of CP did account for a significant level of CP x source interaction (P < 0.05). In Experiment 3, there were no significant protein level effects on PER or NPR, but the values for MBM were consistently lower than those for CHM, WHM, and SBM. The apparent amino acid digestibility coefficients for MBM were also consistently lower than those for CHM and WHM. In conclusion, the extruded WHM and CHM products have acceptable protein quality and were better than MBM as single sources of dietary protein.