Apparent Amino Acid Availability Research Articles

Combination of three null mutations affecting seed protein accumulation in pea (Pisum sativum L.) impacts positively on digestibility

The presence of so-called anti-nutritional factors can reduce the bioavailability of nutrients following consumption of seeds which are otherwise an excellent source of proteins, carbohydrates and micronutrients. Among the proteins associated with negative effects on quality in pea (Pisum sativum L.) seeds are lectin, pea albumin 2 (PA2) and trypsin inhibitors (TI). Here we have investigated the impact of these proteins on protein digestibility and amino acid availability, using naturally occurring and derived mutant lines of pea lacking these proteins. The mutations were stacked to generate a triple mutant which was compared with a wild-type progenitor and a line lacking the major seed trypsin inhibitors alone. In vitro digestions following the INFOGEST protocol revealed significant differences in the degree of hydrolysis, protein profile and apparent amino acid availability among the pea variants. Proteins resistant to digestion were identified by MALDI-TOF mass spectrometry and amino acid profiles of digested samples determined. The results indicate that pea seeds lacking certain proteins can be used in the development of novel foods which have improved protein digestibility, and without negative impact on seed protein concentration or yield.

Amino acid availability from selected animal- and plant- derived feedstuffs for market-size sunshine bass (Morone chrysops × Morone saxatilis)

A study was conducted with market-size (867 g) hybrid striped bass to determine the nutrient digestibility and apparent amino acid availability of six common feedstuffs. The animal-protein feedstuffs tested were menhaden fish meal (MEN), anchovy fish meal (ANCH), pet-food grade poultry by-product meal (PBM-pet), and feed-grade poultry by-product meal (PBM-feed), while the plant-protein feedstuffs were dehulled solvent extracted soybean meal (SBM) and distiller’s dried grains with solubles (DDGS). Test diets consisted of a 70 : 30 mixture of reference diet to test ingredient with chromic oxide (10 g kg−1%) as the inert marker. Diets were randomly assigned to triplicate tanks of fish that were fed their respective diets for 7 days prior to fecal collection by stripping. Two feeding trials were conducted sequentially to determine the digestibility of the six test ingredients. In trial 1, the three ingredients evaluated were MEN, PBM-feed, and PBM-pet. In trial 2, the three ingredients evaluated were ANCH, SBM, and DDGS. Apparent digestibility coefficients of protein (ADC-CP) were significantly (P < 0.05) different among test ingredients in trial 1 as protein digestibility of MEN (86%) was significantly higher (P < 0.05) than that of PBM-feed (75%), but was not significantly different from that of PBM-pet (78%). Protein digestibilities in trial 2 were not significantly different among test ingredients and averaged 76% for ANCH, SBM, and DDGS. Some apparent amino acid availability coefficients differed among feedstuffs for both trial 1 and trial 2. MEN provided higher amino acid availabilities for alanine, aspartic acid, glutamic acid, lysine, valine, and tryptophan (99%, 98%, 94%, 96%, 99%, and 108%, respectively) when compared to PBM-feed (73%, 50%, 69%, 80%, 77%, and 91%, respectively) and PBM-pet (79%, 66%, 81%, 81%, 78%, and 99% respectively). Glycine, histidine, leucine, and proline availabilities in MEN (95%, 96%, 100%, and 98%, respectively) were significantly (P < 0.05) higher than those of PBM-feed (64%, 82%, 82%, and 57%, respectively), but were not significantly different from PBM-pet (85%, 92%, 89%, and 80%, respectively). For trial 2, apparent amino acid availabilities for cystine, isoleucine, lysine, and tyrosine were significantly higher (P < 0.05) among treatments fed SBM (100%, 87%, 93%, and 97%, respectively) and ANCH (37%, 95%, 92%, and 84%, respectively) compared to treatments fed DDGS (−13%, 52%, 62% and 62%, respectively). Overall, amino acid availability in SBM and the two PBM’s appear comparable to MEN and ANCH and corroborate their high value as potential replacements for fish meal in sunshine bass diets. However, DDGS provided the lowest availabilities for several amino acids and should be used with caution.

Amino Acid Availability of Soybean Meal for Florida Pompano

AbstractAvailability of amino acids in soybean meal was determined in a feeding trial with Florida pompano Trachinotus carolinus by using a standard digestibility marker method. Fecal samples were manually stripped from anesthetized fish to avoid contact with water and resultant leaching losses. Apparent amino acid availability coefficients (mean ± SD) for dehulled, solvent‐extracted soybean meal ranged from 78.4 ± 2.2% to 96.5 ± 1.0%. Apparent energy digestibility was 67.4 ± 0.8%. Apparent crude protein digestibility was 84.3 ± 0.5%.

Apparent amino acid availability from feedstuffs in extruded diets for rainbow trout Oncorhynchus mykiss

Apparent amino acid availability coefficients of several typical and novel feed ingredients were determined in rainbow trout using extruded diets and the faecal stripping technique. The ingredients were tested included five fish meals, three terrestrial animal by-products, five plant protein concentrates, four plant meals, and seven low-protein plant ingredients. Amino acid availability from the fish meals was relatively high ranging from 90 to 101%. Lower coefficients overall were observed for Menhaden fish meal FAQ when compared to the other fish meals. No differences in apparent amino acid availability were detected among the animal by-products. Within the plant concentrate group, rice protein concentrate and barley protein concentrate exhibited generally lower amino acid availabilities compared to other concentrates tested. Among the plant meals, only the availabilities of histidine, valine, isoleucine and lysine in flaxseed meal were lower than those of soybean meal. Apparent amino acid availabilities among the low-protein plant products were variable and significantly different.

Nutrient Digestibility of Cereal Grain Products and By‐products in Extruded Diets for Nile Tilapia

Abstract Apparent digestibility coefficients (ADCs) provide estimates of nutrient availability in feedstuffs and can be used as a tool for selecting ingredients to compound cost‐effective diets for fish. Extrusion process is one factor that could influence ADC values. Thus, a digestibility trial was undertaken to evaluate ADC of protein, energy, and dry matter, and apparent amino acid availability (AAAA) in five cereal grain products/by‐products (corn, wheat middlings, broken rice, rice bran, and sorghum) in compounded diets for Nile tilapia. Chromic oxide was used as an external inert marker. The digestibility values of energy and dry matter in ingredients, in decreasing order, were highest for broken rice (95.34 and 96.45%), sorghum (82.37 and 87.29%), corn (67.34 and 82.21%), rice bran (57.58 and 55.59%), and wheat middlings (48.94 and 45.88%). Protein digestibility value was higher for corn (72.86%) and the lowest value was observed for sorghum (56.77%), while broken rice, wheat middlings, and rice bran presented values ranging from 63.01 to 66.88%. AAAA values were higher for corn (70.05%) and the lowest methionine and cystine availability values were recorded for wheat middlings and broken rice, respectively. Broken rice appears as one of the most indicated ingredient for using in Nile tilapia diets because of its highest values of nutrient digestibility when compared to the other energetic sources. The use of this information should aid more precise and economic diet formulation for Nile tilapia.

The influence of caecectomy on amino acid availability of three feedstuffs for ganders

1. Experiments were conducted to assess the influence of caecectomy on amino acid availability (AAA) of three feedstuffs for goose. 2. Nine caecectomised and 9 intact Yangzhou ganders, 24 weeks old, were used in these experiments. Fish meal, soybean meal and cottonseed meal were used as the sole source of protein. The endogenous amino acid (AA) losses were evaluated by a nitrogen (N)-free diet method. The influence of caecectomy on apparent amino acid availability (AAAA) in fish meal, soybean meal and cottonseed meal was assessed in experiment 1 and true amino acid availability (TAAA) of three protein diets was determined in experiment 2. 3. Results showed that, in the soybean meal and cottonseed meal, the AAAA and TAAA of most AA determined by the intact ganders were higher than in the caecectomised ganders; in the fish meal, the AAAA and TAAA of most AA determined by the intact ganders were lower than in the caecectomised ganders. 4. Results of the present study suggest that the effect of caecectomy on AAA in geese was dependent on the feedstuff assayed, and it was better to use caecectomised poultry for AAA assessment.

Amino acid availability and protein digestibility of several protein sources for Nile tilapia,Oreochromis niloticus

Apparent amino acid availability coefficients and protein digestibility of four animal products [fish meal (FM), meat and bone meal (MBM), poultry by-product and feather meal] and four plant protein-rich products [soybean meal (SBM), cottonseed meal-28, cottonseed meal-38 and corn gluten meal (CGM)] were determined for Nile tilapia, Oreochromis niloticus. Ingredients were incorporated to a practical reference diet at a 7 : 3 ratio (70% of reference diet and 30% of test ingredient). Chromic oxide was used as external digestibility marker. Among animal products poultry by-product meal (PBM; 89.7%) and FM (88.6%) presented the highest apparent protein digestibility (APD) while MBM (78.4%) and feather meal (78.5%) presented the lowest APD. Among plant protein-rich products CGM (91.4%) and SBM (92.4%) presented the highest APD values while cottonseed meal-28 presented the lowest APD (78.6%). Average apparent amino acid availability of feed ingredients was similar to protein digestibility with 92.3%, 89.6%, 73.4%, 80.7%, 88.9%, 84.4%, 91.2% and 79.7% values for SBM, CGM, cottonseed meal-28 and 38, FM, MBM, PBM and feather meal respectively. These results indicate that O. niloticus is able to utilize efficiently different feedstuffs.

Effect of protein source and nutrient density on growth efficiency, histology and plasma amino acid concentration of rainbow trout (Oncorhynchus mykiss Walbaum)

The eiects of protein source and nutrient density on growth e⁄ciency, nutrient digestibility and plasma amino acid concentrations of rainbow trout were evaluated. A 3 by 2 factorial treatment design with three protein sources, ¢sh meal^barley (F^B), plant concentrates (PC) and plant meals (PM), and two nutrient densities were used. A commercial reference diet was also fed. Triplicate tanks of 30 ¢sh (initial wt. 28 g) were fed each diet, and the ¢nal weight averaged 240 g ¢sh � 1 . Protein source and nutrient density aiected feed intake, weight g ain and feed conversion ratio. Weight gain of trout fed the PC and PM diets was approximately 10% less than ¢sh fed the F^B diets. Protein retention was aiected by protein source, but not nutrient density, and was the highest for the ¢sh fed diets containing ¢sh meal and the lowest for the ¢sh fed PM diets. Apparent digestibility coe⁄cients and apparent amino acid availabilities of the diets corresponded with diierences in weight gain. This study provides further evidence that growth rates of trout fed ¢sh meal-free diets, using conventional and concentrated plant protein ingredients, are good but some limitation to growth exists in the ¢sh mealfree diets.

Effects of replacing fish meal with soy protein concentrate on feed intake and growth of juvenile Japanese flounder, Paralichthys olivaceus

A feeding trial was conducted to investigate the effects of partially or totally replacing fish meal (FM) with soy protein concentrate (SPC) on feed intake, growth and nutrient utilization in diets of Japanese flounder. Six isonitrogenous and isoenergetic diets (crude protein 49 %, gross energy 19 kJ/g) were formulated, in which FM protein was replaced by SPC at 0% (S0), 25% (S25), 50% (S50), 75% (S75), 87.5% (S87.5) and 100 % (S100), respectively. To investigate the effects of supplementation with either crystalline amino acid mixture (CAA) or encapsulated CAA by cellulose acetate phthalate (CAP-AA) to balance Diet S75, two other diets were formulated to add 3.09% of either CAA ( l-lysine, dl-methionine, l-leucine, l-valine, and l-threonine) (S75 CAA) or CAP-AA (S75 CAP-AA), respectively. Each diet was randomly assigned to triplicate groups of 45 fish per aquarium (initial weight 2.45 ± 0.01 g). Fish were maintained in flow-through aquaria (320 l/tank) at water temperature ranging from 18.0 to 26.0 °C. Fish were fed twice daily to apparent satiation for 9 weeks. Feed intakes of fish fed Diets S0 or S25 were significantly higher than those in fish fed Diets S50, S75, S87.5 or S100 ( P < 0.05). The specific growth rate of fish significantly decreased with increasing dietary SPC ( P < 0.05). Feed efficiency ratio and protein efficiency ratio of fish fed Diets S0 or S25 were significantly higher than those in fish fed Diets S87.5 or S100 ( P < 0.05). Apparent digestibility coefficients of dry matter, crude protein, and apparent amino acid availability decreased with increasing dietary SPC. Supplementation with CAA or CAP-AA significantly improved feed intake, growth, and apparent digestibility of protein and the supplemented amino acids ( P < 0.05). The retentions of protein and Arg, Ile and Phe + Tyr in fish fed the diet with CAP-AA were generally higher than those in fish fed the diet supplemented with CAA, although no significant differences were observed in growth. These results indicates that protein from SPC could not effectively replace FM protein in diets of Japanese flounder because of lower feed intake, amino acid imbalance and poor utilization of nutrients. However, amino acids supplementation is able to significantly improve feed intake and growth of fish.

Amino acid availability from animal, blended, and plant feedstuffs for hybrid striped bass (Morone chrysops x M. saxatilis)

The refinement of hybrid striped bass feed formulations has been progressing rapidly. There is still, however, limited information available regarding nutrient digestibility and amino acid availability from common feedstuffs. A pair of experiments was conducted to determine the protein digestibility and amino acid availability to sunshine bass from an assortment of commercially available animal protein feedstuffs, blended animal products and plant protein feedstuffs in extruded diets. The feedstuffs tested were blood meal, poultry by-product meal, fish solubles, Pro-Pak 60, Pro-Pak 65, ProCon 65RDB, and 60FMC for the animal protein feedstuffs and brewer's yeast, canola meal, peanut meal, and sunflower meal for the plant protein feedstuffs. Test diets consisted of a mixture of nutritionally complete reference diet and test ingredient. Triplicate tanks of fish were fed their respective diets for 7 days prior to collection of faeces by stripping. Apparent digestibility coefficients of protein (ADC-CP) in the animal products ranged from 47% for 60FMC to a high of 70% for fish solubles. ADC-CPs for animal products were not different across products. Blood meal, poultry by-product meal, Pro-Pak 60, Pro-Pak 65, and ProCon had intermediate ADC-CPs of 63, 55, 63, 57 and 52%, respectively. ADC-CP in plant feedstuffs ranged from 43% for canola meal to 80% for peanut meal. Brewer's yeast, canola meal, and sunflower meal had intermediate ADC-CPs at 54, 43 and 69%, respectively. Apparent amino acid availability coefficients were variable across animal products and did not necessarily correlate to the ADC-CPs for a given feedstuff. Isoleucine availability was low in blood meal at 38% compared with 59% or better for the remaining amino acids. Lysine, tyrosine and phenylalanine availability from fish solubles was low at 31, 35 and 44%, respectively. Amino acid availability from Pro-Pak 60 was consistently higher across all amino acids for the animal products and blends tested. Of the plant products tested, peanut meal was the best performing feedstuff relative to amino acid availability.

Comparisons of amino acid availability by different methods and metabolizable energy determination of a Chinese variety of high oil corn

TME, true amino acid availability (TAAA), AME, and apparent amino acid availability (AAAA) were determined in Chinese high oil corn (CHOC) and conventional corn (CC). The CC and CHOC contained 4.58 and 8.44% ether extract (DM basis), respectively. A precision-fed rooster assay was used in which each corn sample was tube-fed (50 g) to 16 roosters and excreta were collected for 48 h. A N-free diet and fasting methods were used to evaluate endogenous amino acid (AA) losses. Endogenous losses of 10 AA were different (P < 0.05) with the N-free and fasting methods; in most cases the mean value for the N-free treatment was greater (P < 0.05) than for the fasting treatment. The TME value for CHOC was greater than for CC (4,193 vs. 3,961 cal/g DM; P < 0.05). The true availability of aspartic acid, threonine, isoleucine, and leucine of CC and CHOC was higher (P < 0.05) for the N-free method than for the fasting method. When compared within the N-free or within the fasting method, the true availabilities of lysine, methionine, and proline were higher (P < 0.05) in CHOC than in CC, but the true availability of phenylalanine was lower (P < 0.05) in CHOC than in CC. The AAAA values, although lower, followed similar patterns as the TAAA values. The results of this study indicated that availability of AA in CHOC is equal or superior to that in CC and that the available energy for poultry is higher in CHOC than in CC.

Evaluation of different markers to determine apparent nutrient digestibility coefficients of feed ingredients for South African abalone ( Haliotis midae L.)

Chromic oxide (Cr 2O 3), acid-insoluble ash (AIA) and crude fibre were evaluated as inert markers in digestibility studies with Haliotis midae by calculating apparent dry matter, organic matter, energy, protein and amino acid availability for fish meal, soybean meal and cottonseed meal included at 30% into a reference diet. AIA was the only marker that yielded consistent realistic apparent digestibility coefficients (ADCs), which were comparable ( P>0.05) to values derived through total collection. Both Cr 2O 3 and crude fibre in faeces were either lower or similar to their respective levels in feed, resulting in negative ADCs. Leaching of markers from the diets did not have an effect ( P>0.05) on digestibility coefficients. No difference ( P>0.05) was found in apparent dry matter digestibility between faeces voided either during the night or daytime. Washing of faeces with distilled water after collection had no influence ( P>0.05) on AIA content. In all test ingredients, mean apparent amino acid availability reflected apparent protein digestibility. Apparent digestibility of protein in fish meal (76%) by H. midae was within the range of values reported for fish species (62–91%). Soybean meal is a promising feed ingredient in abalone feeds due to the high apparent digestibility of its organic matter (79%), energy (83%), protein (85%) and both essential and non-essential amino acids (mean of 86%).

Metabolizable Energy Values and Amino Acid Availability of Vetch (Vicia sativa) and Ervil (Vicia ervilia) Seeds Soaked in Water and Acetic Acid

In two experiments we evaluated the effect of water and acetic acid soaking on ME, apparent amino acid (AA) availability, and true AA availability of vetch (V) and ervil (E) seeds. In Experiment 1, the feedstuffs were untreated (U) V or coarsely ground V soaked in water (1:10, wt/vol) at 40 C for 72 h with a water change every 12 h (40WV), vetch soaked in 1% acetic acid for 24 h at 40 C (40AAV) or at room temperature (RTAAV), or dehulled soybean meal (SBM). In Experiment 2, E seeds were subjected to the same soaking methods, and the ingredients were UE, 40WE, 40AAE, RTAAE, and SBM. Each feedstuff was precision-fed to five individually caged mature ISA Brown roosters. A group of five roosters was used to correct for metabolic and endogenous energy and amino acid losses. The AME, AMEn, TME, and TMEn of UV and UE (in parentheses) were 2,558 (2,663), 2,840 (3,098), 3,026 (3,154), and 2,934 (3,176) kcal/kg DM, respectively, and were, in general, higher than those of SBM. The TMEn of V increased as a result of soaking in water or acetic acid, whereas that of E decreased in 40WE and RTAAE by 492 and 920 kcal/kg DM, respectively (P < 0.05). The apparent availability of most essential amino acids in UV and UE was lower (P < 0.05) than that of SBM. Acetic acid soaking of V, irrespective of temperature, and E at 40 C resulted in apparent AA availability similar to that of SBM except for Met. The true AA availability of V treated or not, and that of E soaked at 40 C, were similar to that of SBM. Results indicated that UV and UE are energy rich ingredients but detrimental to amino acid availability. Soaking the seeds in acetic acid at room temperature and at 40 C improved the nutritional value of V and E, respectively.

Digestibility, Apparent Amino Acid Availability and Waste Generation Potential of Soybean Flour-Poultry Meat Meal Blend Diets for the Sharp-Toothed Catfish, Clarias gariepinus, Fingerlings

ABSTRACT Nutrient digestibility and amino acid availability were assessed in sharp-toothed catfish, Clarias gariepinus, fingerlings fed diets containing soybean flour (SF): poultry meat meal (PMM) blends (25:75, 50:50, and 75:25) and 0.5 or 1.0% Cr2O3. There was agreement between the pattern of overall protein digestibility and average amino acid availability, despite the variability in individual amino acid availability. The best dry matter, lipid, and protein digestibility coefficients and amino acid availability values were obtained with diets containing 0.5%. Chromic oxide inclusion level appeared to affect nutrient availability. Increased marker level resulted in decreased nutrient digestibility coefficients. Similarly, these diets generated lower fecal crude protein than those with 1.0% 0203. However, the latter group recorded higher protein retention efficiency. Dry matter and lipid of diets containing more soybean flour seemed to be more digestible than those of poultry meat meal. A similar trend was observed for the apparent availability of the amino acids. This investigation has indicated that low level of marker was better in digestibility study. Utilization of more SF than PMM in the diets of this catfish was more beneficial and should be encouraged in the feed industries producing catfish diets.

Availability of amino acids from various fish meals fed to Atlantic salmon ( Salmo solar)

Amino acid availability values for Atlantic salmon were evaluated for two steam- and one flamedried herring meal, menhaden meal, anchovy meal, and a Norwegian capelin meal (Norse-LT94®). Apparent amino acid availabilities were calculated based on feces collected either by manual stripping or sedimentation (Guelph CYAQ-2 digestibility system). Apparent crude protein availability values obtained from manually stripped feces showed that Norse-LT94® (87.0%) was not significantly different from any of the herring meals (82.6 and 85.1 %) tested but was higher ( P < 0.05) than from both the anchovy (76.7%) and menhaden meals (78.2%). Availabilities calculated with values from feces collected by sedimentation were approximately 9% higher than those from manually stripped feces due to leaching of faecal constituents. The amino acid availability values of common feedstuffs should be used for feed formulation as their availability within a feed ingredient is quite variable.

Digestibility, apparent amino acid availability and waste generation potential of soybean flour: poultry meat meal blend based diets for tilapia, Oreochromis niloticus (L.), fingerlings

Nutrient digestibility and amino acid availability were assessed in tilapia, Oreochromis niloticus (L.), fingerlings fed diets containing soybean flour (SF): poultry meat meal (PMM) blends (25:75, 50:50 and 75:25), and 0.5 or 1.0% Cr2O3. Although there was variability in individual amino acid availability, average availability was in agreement with the pattern of overall protein digestibility. The best lipid, protein digestibility and amino acid availability values were obtained in the 75:25 SF:PMM blend and 0.5% Cr2O3 treatment, which corresponded to the lowest level of faecal crude protein while the best ash digestibility was observed with 25:75 SF:PMM blend and 1.0% Cr2O3. Chromic oxide inclusion level appeared to affect nutrient availability. Increased marker level might have resulted in decreased nutrient digestibility coefficients. Protein and lipid of diets containing more soybean flour seemed to be more digestible than those of poultry meat meal while the reverse was the case for ash.

Metabolizable Energy and Amino Acid Availability of Full-Fat Seeds, Meals, and Oils of Flax and Canola

The TME, true amino acid availability (TAAA), AME, and apparent amino acid availability (AAAA) were determined in full-fat seeds, meals, oils, and meal-oil mixtures of flax and canola using Single Comb White Leghorn roosters by the force feeding and total excreta collection assay. The metabolizable energy values were corrected to zero nitrogen balance to obtain AMEn and TMEn.The AMEn and TMEn, contents of canola seed (4.46 and 4.56 kcal/g) were respectively higher (P < .05) than those of flax seed (3.75 and 3.75 kcal/g). Flax meal contains contents of AMEn (2.07 kcal/g) and TMEn (2.07 kcal/g) similar to those (1.98 and 2.09 kcal/g) of canola meal. There were no differences in AMEn and TMEn values between flax oil (8.10 and 8.28 kcal/g) and canola oil (8.25 and 8.46 kcal/g). No differences were observed among AME, AMEn, TME, and TMEn values within each test ingredient except canola meal: its TME value was higher (P < .05) than its AMEn value. The TAAA values were higher for full-fat seeds than for the meals and also higher for canola seed and meal than for flax seed and meal. The AAAA values, although lower than TAAA values, followed similar patterns as TAAA values. Both AAAA and TAAA values were higher when the ingredients were fed with a basal diet than when fed alone.

Protein Digestibility and Amino Acid Availability of Fish Meal Fed to Largemouth Bass Infected with Intestinal Acanthocephalans

Abstract Two groups of young largemouth bass (Micropterus salmoides), one infected with intestinal acanthocephalans (Neoechinorhynchus cylindratus) and the other free of worms, were compared with respect to the apparent protein digestibility and the apparent amino acid availability of herring meal fed to them; analyses were by the indicator (Cr2O3) method. Digesta samples from three intestinal sections and fecal samples revealed that presence of the worms lowered both protein digestibility and amino acid availability. It also increased the variability of those measurements among replicates, particularly in the anterior intestinal section where infections were more pronounced. The specific mode of acanthocephalan influence (e.g., provision by N. cylindratus of nitrogen products or direct competition with the host for amino acids) was not determined. To avoid this source of error, intestinal parasites of test fish should be eliminated by therapeutic treatment before nutritional studies are conducted.

Effect of Overcooked Soybean Meal on Chicken Performance and Amino Acid Availability

Studies were conducted to evaluate the effect of overcooked soybean meals (SBM) on chick growth and amino acid availability. The SBM were custom-prepared at a commercial processing plant by changing the conditions of a desolventizer-toaster (DT) unit. Six progressively overcooked meals (designated SBM1 to 6 with SBM1 as normal, and SBM6 overcooked) were produced by increasing temperature by up to 50% and extending retention time by up to 75% above normal.The meals measured .05, .03, .01, .09, .00, and .00 ΔpH of urease activity; 6.10, 5.01, 4.62, 4.83, 2.32, and 1.78 mg/g SBM of trypsin inhibitor activity; 92, 89, 91, 88, 81, and 81% of protein solubility in .2% KOH; and 46, 43, 41, 40, 23, and 19% of protein solubility in .1M borate at 40 C, respectively. Glucose content in the hydrolysate of the soluble carbohydrate extract did not differ among the meals, indicating no differences in the degradation of sucrose, raffinose, and stachyose with increasing heat treatment.In a chick growth experiment with a methionine-adequate, low-protein diet, chicks fed SBM1 showed significantly greater weight gain than chicks fed SBM3, 5, or 6. The SBM1, 2, 5, and 6 were chosen for a study of amino acid availability. No differences were observed in amino acid content. There were significant differences in apparent amino acid availability to growing chicks, but not in true amino acid availability by adult roosters among the four meals. The results suggest that the temperature or the retention time of a DT unit may be increased by 50% over the usual operating conditions without reducing amino acid availability from SBM.

Assessment of Extruded Grain Amaranth as a Feed Ingredient for Broilers.: 2. Apparent Amino Acid Availability Values

Apparent amino acid availabilities (AAAA) were determined for grain amaranth in two experiments using broilers. Total collection method (TCM) and acid-insoluble ash (AIA), as a marker, were used for these determinations. Individual amino acid availabilities for the extruded grain were calculated both by regression analysis and by difference from the basal diet. From the linear regression equations, TCM produced more accurate results than did the AIA method, based on standard errors of the intercept and coefficient of determination. Predicted AAAA, based on linear regression equations, from the TCM were 92.4, 79.9, and 89.4% for methionine, lysine, and arginine, respectively. Using the TCM and calculation by difference, average AAAA on an as-fed basis were 85.0, 79.1, and 92.9% for methionine, lysine, and arginine, respectively. The AAAA of 11 other amino acids were also determined.