Apparent Amino Acid Digestibility Research Articles

Effects of corn source and exogenous enzymes on growth performance and nutrient digestibility in broiler chickens

This study was conducted to investigate the effects of exogenous enzymes on growth performance, ileal digestible energy (IDE) and apparent ileal digestibility of CP and amino acids (AA) in broiler chickens fed corn-soy diets formulated using 3 different sources of corn (corn 1, corn 2, and corn 3). One-day-old male broiler chicks (n = 3,600) were allocated to 15 dietary treatments as 5 treatments for each corn as follows: positive control (PC) with no exogenous enzymes and adequate in all nutrients; negative control (NC) without exogenous enzymes and a 3% reduction in calculated ME relative to the PC diet; NC plus a commercial xylanase; NC plus a commercial mixture of xylanase, amylase, and protease; and NC plus a commercial mixture of xylanase and β-glucanase. Enzyme products had no effects on performance variables, and in some instances, they had negative impacts. In most cases, there were no effects of enzyme products on IDE and digestibility of CP and AA in the starter and finisher phases. Effects of exogenous enzymes on ileal digestibility were mainly found in the grower phase, and these responses were mostly observed in birds fed corn 2 diets compared with birds receiving corn 1 or corn 3 diets. Although analyzed nutrient contents of 3 corn samples were similar, supplementing corn 2 diets with enzyme products was associated with greater responses on digestibility parameters. Factors related to diets (e.g., availability of substrates) and birds (e.g., enzymatic activities in the digestive tract) may have limited nutrient digestibility, and these limitations may have provided favorable conditions for exogenous enzymes to specifically work on their substrates in corn 2 diets in the grower phase. Effects of enzyme products on IDE and digestibility of CP and AA were not consistent and varied depending on corn sources, enzyme products, and dietary phases.

The Content of Amino Acids in Pasture Vegetation and Their Apparent Digestibility in 2-year-old Horses

Ten samples of plant vegetation and 10 samples of fresh excrement were taken from the same pasture area. The excrement were collected from 10 2-year-old Old Kladruber horses that received the pasture vegetation daily. The apparent digestibility of nitrogen and amino acids in pasture vegetation was determined by using the acid-insoluble ash marker method. In comparison with excrement, the pasture vegetation contained higher levels of Ser, Ala, Leu, and His and higher levels of Pro (P ≤ .01), Met (P ≤ .01), and Arg (P ≤ .05). The mean level of Ile in pasture vegetation was lower than in excrement (P ≤ .05). The apparent digestibility of amino acids from pasture vegetation was high for Pro and Met (86.75 and 89.39%), moderate for Ser, Ala, Leu, His, and Arg (68.61%-76%), and low for Asp, Thr, Glu, Gly, Val, Leu, Tyr, Phe, and Lys (56.15%-66.03%). The digestibility of lysine and Ile was relatively low (56.39% and 56.15%, respectively). The total content of nitrogen per dry matter was 10.98 ± 2.46 g/kg for pasture vegetation and 12.12 ± 2.38 g/kg for excrement, whereas the content of protein nitrogen was 7.20 ± 0.25 g/kg and 6.89 ± 0.21 g/kg of dry matter in pasture vegetation and excrement, respectively. This means that only 65.55% and 56.90% of N is bound in proteins in pasture vegetation and excrement, respectively. Non-protein nitrogen accounts for 34.45% in pasture vegetation and for 43.10% in excrement.

Separate feeding of calcium improves performance and ileal nutrient digestibility in broiler chicks

A total of 144 Cobb 500 broilers were used to investigate if modern commercial broilers could regulate their calcium (Ca) intake using choice feeding and whether separating the delivery of a portion of the Ca from the mixed ration would be advantageous for performance and nutrient recovery. Birds were fed corn+soy-based diets formulated to contain 2.5, 5.0, 7.5 or 10.0 g/kg total Ca and all groups had access to a separate Ca source (CaCO3). The trial was conducted from Day 1 to Day 21 and birds had ad libitum access to both the experimental diets and a separate Ca source throughout. Total feed and separate Ca intake were monitored daily, weight gain and feed intake weekly and on Day 21, the apparent ileal digestibility of DM, nitrogen, selected minerals and amino acids were determined. Consumption of the separate Ca source increased (P < 0.05) with decreasing total Ca concentration of the mixed ration. No differences (P > 0.05) in toe ash were found. Increasing dietary Ca concentration negatively influenced the apparent ileal digestibility of DM, nitrogen, minerals and amino acids. It can be concluded that broilers can select and consume Ca from a separate source to broadly maintain their requirement. Feeding a separate source of Ca in combination with reduced dietary Ca in the mixed ration had beneficial effects on nutrient digestibility, phosphorus excretion and performance.

Impact of systemic immune system stimulation on intestinal integrity and function in pigs

Immune system stimulation (ISS) can cause physiological changes in the intestine and impact nutrient utilization in pigs. Our previous work showed that ISS reduced the apparent ileal digestibility of dietary protein and amino acids, increased ex vivo active nutrient transport, but had no effect on transepithelial resistance. A gene expression study was conducted to further investigate the impact of ISS on small intestinal function and integrity. Sixteen of 28 gilts (BW 63 ±4 kg) were injected (i.m.) every 48 h, for 7 d, with increasing amounts of E.coli lipopolysaccharide. Remaining pigs were injected with saline. Pigs were euthanized to collect ileal tissue. Total RNA was extracted and reverse transcribed, and gene expression was determined by qPCR. Immune system stimulation increased expression of MUC2 and SGLT1 by 1.6 and 2.0 folds, respectively (P < 0.05), but had no effect on MUC5AC and GLUT2 (P >; 0.10). No effect of ISS was observed on the expression of genes that control tight junctions, i.e. claudin‐3 and 4, occludin, ZO‐1 and MLCK (P >; 0.10). Collectively, these results suggest that systemic ISS does not affect intestinal integrity and barrier function, but alters absorptive capacity of the small intestine. Reduced apparent ileal digestibility of protein and amino acids in ISS pigs may be associated with increased gut endogenous protein loss, since mucin is the main component of such loss. USDA 2011–68004‐30336

Comparative effects of dietary carbohydrases without or with protease on the ileal digestibility of energy and amino acids and AMEn in young broilers

Four digestibility trials using broilers from 12 to 21d or 7 to 21d of age were conducted to evaluate the nutrient digestibility responses of two enzyme combinations when supplemented to maize–soybean meal (SBM) based diets without (trials 1 and 3) or with (trials 2 and 4) 70 or 100g/kg maize dried distillers grain with solubles (DDGS). Apparent ileal digestible energy (AIDE), apparent ileal digestibility (AID) of amino acids (AA), total tract apparent retention (TTAR) of nitrogen (N) and N-corrected apparent metabolisable energy (AMEn) were assessed. In each trial, a control diet and the control diet supplemented with an enzyme complex containing xylanase and amylase (XA) or one containing protease, xylanase and amylase (PXA) were tested. Trials 1 and 2 had six replicate cages per treatment, with six birds per cage; and trials 3 and 4 had eight replicate cages per treatment, with five birds per cage. Data were analysed by ANOVA for each trial, as well as a combined dataset, which model included the main effects of maize-DDGS inclusion, dietary enzyme and trial site and all two-way interactions. Across trials, both XA (13.61MJ/kg) and PXA (13.70MJ/kg) increased the AIDE (P<0.05) compared to the control diets (13.29MJ/kg). XA increased (P<0.05) AMEn (12.89MJ/kg) compared to the control diets (12.61MJ/kg), and PXA further increased it (13.00MJ/kg) compared to XA. Supplementation with XA had no effect on the AID of AA, whereas PXA increased the AID of nitrogen and all AA (P<0.05) except methionine. The AA with the greatest response to PXA were cysteine (+5.4%), threonine (+4.4%), glycine (+3.6%) and valine (+3.3%). The least responsive AA to PXA inclusion were methionine (+1.0), glutamine (+2.0), lysine (+1.9%) and arginine (+2.2%). Irrespective of the AA, PXA increased AID of AA as a proportion of the ileal undigested fraction of AA in the control diets by 12–13%. Supplemental xylanase and amylase increased AIDE and AMEn and the addition of protease on top of carbohydrases further increased AID of AA and AMEn in young broilers fed maize–SBM diets without or with maize-DDGS.

Digestibility of dietary components and amino acids in plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings

The apparent digestibility (AD) of dietary components, energy and essential amino acids (EAA) of selected locally available animal and plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings was studied. The AD of the test ingredients (ADi) differed (P < 0.05) and ranged from 81.1% to 90.8%, for ADiDM, from 84.0% to 95.0% for ADiCP, from 78.4% to 86.9% for ADiOM and from 79.0% to 87.8% for ADiGE. The highest ADiDM, ADiCP and ADiOM in the test ingredients were found for shrimp head meal, catfish by-product meal, golden apple snail and groundnut cake, while the lowest values were obtained for earthworm meal and rice bran. The highest ADiGE was found in rice bran, followed by golden apple snail and catfish by-product meal, while there were no differences (P < 0.05) between the other test ingredients, except for earthworm meal. The AD of total and individual EAA was high in catfish by-product meal and shrimp head meal, followed by decreasing AD in golden apple snail, groundnut cake, rice bran and earthworm meal ingredients (P < 0.05). The low AD of earthworm meal may limit its potential to be used as replacement for fish meal in the feed.

Use of a gastrointestinal model to assess potential amino acid bioavailability in diets for rainbow trout (Oncorrhynchus mykiss)

The effect of different factors (protein composition, thermal treatment, presence of an acid-salt) on the potential bioavailability of amino acids (AAs) for intestinal absorption in rainbow trout diets was evaluated with a gastro-intestinal model (GIM). The in vitro assay consisted of a detailed evaluation of the rates of release of individual AAs, as well as of the whole AA profile of the dialysates produced after hydrolysis performed using enzyme extracts obtained from fish stomach and intestine. The results were compared to values of apparent amino acid digestibility measured in vivo. In addition, solubility and buffering capacity (BC) were evaluated, as they are major factors conditioning the potential bioaccessibility of dietary protein during digestion. Both parameters were significantly affected by the presence of a vegetable protein in the diet. As a result of enzyme hydrolysis, clear differences were detected in the release rates of release of different AAs, in particular for those that are targeted by digestive proteases (Arg, Lys, Phe). A significant correlation was obtained between the total mass of AAs dialysed in vitro and their digestibility estimated from digestibility coefficients calculated in vivo, although this was not possible when using values of individual AAs. The concept and framework for future assays involving in vitro-in vivo correlations is discussed.

Content and apparent ileal digestibility of protein and amino acids in diets fed to parent stock of farm-raised polar foxes (Alopex lagopus L.)

This study aimed to compare content and apparent ileal digestibility of protein and amino acids in diets used over 1 year (4 feeding periods) on 2 farms of reproductive polar foxes (A and B). Two diets (1 from farm A, 1 from farm B) from the same feeding period were tested in succession (4 eight-day digestibility experiments) on 5 polar foxes with 'end-to-end' ileorectal anastomosis. The main protein sources were poultry, fish, and beef offal in diets A and beef offal in diets B. In diets A, considerably higher content of protein and total essential and nonessential amino acids was found. In each feeding period, diets B had higher (P < 0.05) digestibility of protein and amino acids including sulfur-containing amino acids. Methionine was the amino acid of the highest digestibility in diets A and arginine in diets B. In the diets from both farms, high digestibility was noted for histidine, lysine, phenylalanine, glutamic acid, and proline. The lowest digestibility was recorded for cystine. Too high a content of ash in diets A reduced (P < 0.05) digestibility of protein and amino acids. Diversified composition of feeds for polar foxes provides a definitely higher supply of digestible protein and amino acids.

Bioefficacy of a mono-component protease in the diets of pigs and poultry: a meta-analysis of effect on ileal amino acid digestibility

SummaryA meta-analysis of the effect of a mono-component bacterial protease (RONOZYME® ProAct) on the apparent ileal digestibility of amino acids in poultry and swine diets was conducted to examine functional patterns, mean effects and variability of response. A total of 25 independently-conducted experiments were included comprising a total of 804 datapoints. The mean response to protease was +3.74% (SE 1.1%, P &lt; 0.001) and this ranged from +5.6% for Thr (SE 1.2%, P &lt; 0.001) to +2.7% for Glu (SE 1.2%, P &lt; 0.05). For the most economically critical amino acids (Lys, Cys, Met and Thr) the mean response was 4.5%. The effect of protease was independent of geography, animal species and diet composition (P &gt; 0.05). However, the inherent digestibility of amino acids in the control diet as a single explanatory term explained around 47% of the variance (P &lt; 0.001) in effect. When the inherent digestibility of amino acids in the control diet was less than 70% protease addition improved amino acid digestibility in 90% of cases with a mean improvement of around 10%. When the inherent digestibility of amino acids in the control diet was more than 90% there was a protease-mediated improvement in digestibility in only 60% of cases with a mean improvement of around 2%. It can be concluded that the inherent digestibility of amino acids in the diet without protease supplementation is the primary explanatory term for the efficacy of this exogenous protease, demonstrating that it is highly effective in improving the digestibility of amino acids across a wide range of feed ingredients. Benchmarking diets or feed ingredients as to their relative nutritional value would enhance the ability of nutritionists to determine the likely return on investment on use of bacterial proteases in their operation.

Ileal digestibility of amino acids in pea protein isolates, wheat-corn distillers dried grains with solubles, and short-season corn fed to broiler chicks

The apparent ileal digestibility (AID) of amino acids (AA) in 4 pea protein isolates [PPI; experiment (Exp.) 1], 5 wheat- and corn-derived distillers grains with solubles (wcDDGS; Exp. 2), and 5 short-season corn (Exp. 3) samples for broiler chickens were determined. In addition, a reference wheat sample was included in each experiment to measure the repeatability of the ileal digestibility assay used. Birds (n = 180 for Exp. 1 and n = 216 for Exp. 2 or 3) were fed test diets from d 15 to 21 of age. Reference wheat and PPI were included in test diets at 91.7 and 25%, respectively, as the sole source of AA, whereas wcDDGS and corn were combined with wheat in test diets at 47.7% test ingredient (wcDDGS or corn) and 51% wheat as the sources of AA. Chromic oxide at 0.3% was added in all diets as the indigestible marker. Each test diet was randomly assigned to 6 cages of 6 male birds each. On d 21, birds were killed and ileal digesta were collected to determine the AID of AA. The mean AID values for indispensable AA ranged from 86.0% (Thr) to 94.7% (Arg) for PPI, 50.7% (Lys) to 79.8% (Leu) for wcDDGS, and 73.9% (Thr) to 95.3% (Arg) for corn. Overall, the CV range for AID of AA was widest for wcDDGS (8.1% for Met to 29.4% for Lys) followed by corn (3.0% for Met to 10.7% for Thr) and then PPI (2.7% for Lys to 6.1% for Thr). For wcDDGS and corn, the within-sample variation (assay condition) was more than between-sample variation (feed differences), whereas the reverse was true for PPI. No differences were detected in the AID of CP and AA for reference wheat among experiments.

Low-Fiber Canola. Part 2. Nutritive Value of the Meal

The nutritive value of meals derived from black- and yellow-seeded Brassica napus and canola-quality Brassica juncea was determined with broiler chickens and young turkeys. A higher apparent ileal digestibility of total amino acids was observed in chickens fed diet containing yellow-seeded B. napus than in those fed conventional black-seeded B. napus or canola-quality B. juncea (88.8 vs 83.4 and 84.2%, P < 0.05). Metabolizable energy (AME(n)) contents for yellow- and black-seeded B. napus and B. juncea as determined with broiler chickens were 2190, 1904, and 1736 kcal/kg DM, respectively. In the turkey assay, the AME(n) values for yellow- and black-seeded B. napus and B. juncea canola averaged 2166, 2007, and 1877 kcal/kg DM, respectively. Multicarbohydrase enzyme addition to broiler chicken diets increased energy utilization (from 1943 to 2249 kcal/kg DM, on average), with the most pronounced effect observed for B. juncea canola (from 1736 to 2356 kcal/kg DM).

Effects of a 6-phytase on the apparent ileal digestibility of minerals and amino acids in ileorectal anastomosed pigs fed on a corn–soybean meal–barley diet

Phosphorus of plant-based feedstuffs for monogastric animals is mainly in the form of phytic P, which has a very low bioavailability. The nondigested phytic P may contribute to P pollution. Furthermore, phytic acid may reduce digestibility of other minerals and protein. This study evaluated effects of the microbial 6-phytase RONOZYME HiPhos on apparent ileal digestibility of P, phytic acid, Ca, CP, energy, and AA in six 60-d-old ileorectal anastomosed pigs. In a duplicated 3 × 3 Latin square design, pigs had free access to alternatively a corn (Zea mays)-soybean (Glycine max) meal-barley (Hordeum vulgare)-based diet or this diet supplemented with RONOZYME HiPhos at either 500 units/kg (RH500) or 1000 units/kg (RH1000). Pigs fed diets supplemented with RH500 or RH1000 increased (P < 0.05) digestibility of P, Ca, and Lys. Pigs fed diet RH1000 increased (P < 0.05) digestibility of CP, total AA, indispensable AA, Glu + Gln, His, Gly, Ala, Tyr, Leu, Phe, and Met. Similar to growth trials with increased total tract digestibility of P and Ca, phytase increased apparent ileal digestibility of these indispensable minerals and phytate. The phytase increased digestibility of CP and indispensable AA indicating a better availability of plant-based proteins.

Lower gut nitrogen supply does not affect apparent ileal digestibility of nitrogen or amino acids in growing pigs1

An implicit assumption in measures of ileal digestibility (ID) to estimate bioavailability of AA and N is that ID is not influenced by lower gut N metabolism. The absorption of nitrogenous compounds from the lower gut, derived from fermentative AA catabolism, may have an impact on N metabolism and microbial AA synthesis in the upper gut as a result of CO(NH(2))(2) recycling. The objective of this trial was to determine the apparent ID of N and AA in growing pigs fed a corn (Zea mays) starch and soybean (Glycine max) meal-based diet and receiving an infusion of N into the caecum at 40% of N intake. Eight pigs (initial BW of 23.3 ± 0.55 kg) were fitted with simple T-cannulas in the ileum and cecum and randomly assigned to 1 of 3 continuous cecal infusion treatments [saline, sodium caseinate, or CO(NH(2))(2)] according to a crossover design with 3 periods. Digesta samples were collected and pooled per pig for each 2-d period, freeze-dried, ground, and analyzed for DM, OM, total N, and AA. Lower gut N supply did not affect apparent ID of DM, OM, total N (85.4, 83.4, and 82.7 ± 1.74%; P = 0.31), or any AA (e.g., 90.1, 89.0, and 89.9 ± 1.08% for Lys; P = 0.70) for saline, casein, and CO(NH(2))(2) treatments, respectively. Apparent ID may be an insufficiently sensitive measure to determine effects of lower gut N metabolism on N absorption from the lower gut and subsequent recycling into the upper gut.

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.

Effect of ileal sub-section and the method of collection of digesta on the determination of apparent ileal digestibility of amino acids in broilers

This study investigated the effect of the site of digestive sampling (terminal ileum vs. entire ileum) and the method of digesta collection (flushing vs. squeezing) on the determination of ileal amino acid (AA) digestibility in broilers. An experimental diet was formulated based on soybean meal and dextrose. The diet was fed to broiler chickens from 14 to 18days of age. Twenty four replicate pens (twelve birds each) were given access to the experimental diet. Ileal contents were collected after euthanizing the birds by cervical dislocation at 18days of age. Digesta were collected from the terminal (last 15cm of the distal ileum) or entire ileum using either by flushing or squeezing with saline solution. The section from which the digesta were collected did not have a significant impact on the AA digestibility coefficients. However, values were higher (P<0.01) when based on digesta samples that were collected via flushing than digesta collected via squeezing. The results suggest that flushing procedure to determine AA digestibility is a more accurate procedure than squeezing the digesta from ileum. However, the digestive section (terminal or entire ileum) of collection of digesta did not affect the CAID of AA in broilers.

Effects of dietary supplementation of antimicrobial peptide-A3 on growth performance, nutrient digestibility, intestinal and fecal microflora and intestinal morphology in weanling pigs

In this study, effects of dietary supplementation of the antimicrobial peptide-A3 (AMP-A3) on growth performance, coefficient of total tract apparent digestibility (CTTAD) of nutrients, serum immunoglobulins, intestinal and fecal microflora and intestinal morphology in weanling piglets were evaluated when used as a substitute to the antibiotics. A total of 240 weanling piglets (Landrace×Yorkshire×Duroc, initial body weight (BW): 5.74±0.38kg) were randomly allotted to 4 treatments on the basis of BW. There were 4 replicate pens in each treatment with 15 pigs per pen. The dietary treatments were: PC (positive control; basal diet+1.5g apramycin/kg diet) and AMP-A3 (basal diet supplemented with 0, 60 and 90mg AMP-A3/kg diets). The experimental diets were fed in a meal form for 2 phases (d 0–14, phase I and d 15–28, phase II post-weaning). Pigs fed the PC diet had greater (P<0.05) overall average daily gain (ADG), average daily feed intake (ADFI) and the CTTAD of crude protein (CP, phase I) and dry matter (DM) and CP (phase II) than pigs fed the AMP-A3 diet. Increasing levels of dietary AMP-A3 linearly improved (P<0.05) overall ADG and CTTAD of DM and CP (phase I and II). Pigs fed the PC diet had lower (P<0.05) coliforms (cecum and feces) and total anaerobic bacteria (TAB, cecum) than pigs fed the AMP-A3 diet. When pigs offered increasing levels of the AMP-A3 diets, there was a linear decline (P<0.05) in TAB, coliforms and Clostridium spp. in the ileum, cecum and feces (d 14 and 28). Pigs fed the PC diet had lower (P<0.05) crypt depth and greater (P<0.05) villus height to crypt depth ratio (VH:CD) of the jejunum than pigs fed the AMP-A3 diets. Increasing levels of AMP-A3 in the diets of pigs increased (linear, P<0.05) villus height and VH:CD and decreased (linear, P<0.05) crypt depth of the duodenum and jejunum. Dietary treatments had no effect (P>0.05) on the coefficient of ileal apparent digestibility of amino acids and serum immunoglobulin concentrations. The results obtained in the present study indicate that the AMP-A3 had beneficial effects on growth performance, CTTAD of nutrients, intestinal morphology and intestinal and fecal microflora and can be used as a potential alternative to antibiotic growth promoters in weanling pigs.

Influence of limestone and phytase on broiler performance, gastrointestinal pH, and apparent ileal nutrient digestibility

An experiment was conducted to determine the influence of 2 levels of dietary Ca from limestone and 3 levels of phytase on broiler performance, bone ash, gastrointestinal pH, and apparent ileal digestibility (AID) of Ca, P, and amino acids. Cobb 500 broilers (n = 576) were allowed access to one of 6 corn-soy diets from 0 to 16 d. Experimental diets contained 1.03% or 0.64% Ca from limestone and 0.61% total P. Each diet was supplemented with 0, 500, or 5,000 FTU/kg of phytase to create a 2 × 3 factorial experiment. Broiler feed intake (FI) and BW gain were not affected by dietary Ca or phytase. Feed conversion ratio was improved (P < 0.05) as dietary phytase increased (1.36, 1.34, and 1.31, respectively). Tibia ash percent was reduced (P < 0.05) from 41.4 to 40.0% as dietary Ca decreased but increased with phytase addition (P < 0.05). Gizzard and ileal pH were reduced (P < 0.05) in broilers fed 0.64% Ca compared with broilers fed 1.03% Ca. Phytase at 5,000 FTU/kg increased (P < 0.05) pH in the gizzard, duodenum, jejunum, and ileum. Apparent ileal P digestibility was increased (P < 0.05) in broilers fed 0.64% Ca compared with broilers fed 1.03% Ca (0.68 vs. 0.73, respectively). Apparent ileal Ca digestibility was increased (P < 0.05) in broilers fed 1.03% Ca compared with broilers fed 0.64% Ca (0.67 vs. 0.53, respectively). Phytase improved AID of CP in broilers fed 1.0% Ca but did not have an effect on AID of CP in broilers fed 0.64% Ca, which resulted in a Ca × phytase interaction (P < 0.05). In conclusion, high dietary Ca increased pH in gizzard and ileum and interfered with the AID of P and CP. The interactions between Ca and phytase in the gastrointestinal tract are complex, and feeding phytase at doses above industry recommendations may allow for reduced-Ca diets while maintaining broiler performance, bone ash, and improving amino acid digestibility.

Digestibility of amino acids in Indian mustard protein concentrate and Indian mustard meal compared to that of a soy protein concentrate in rainbow trout and Atlantic salmon

Digestibility trials were carried out to determine the apparent digestibility of amino acids (AA) of two novel plant protein ingredients, Indian mustard protein concentrate—(IMC, 62% crude protein) and Indian mustard meal (IMM, 42% crude protein) produced through a low temperature process, and a commercially available soy protein concentrate (SPC, 57% crude protein) in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). The apparent digestibility coefficient (ADC) of crude protein (CP) from IMC was 90% and 97% for trout and salmon, respectively. The ADCs of CP from IMM and SPC were also very high (>95%) for both species. The ADCs of lysine (95%), isoleucine (91%), leucine (86%) and phenylalanine (90%) from IMC were slightly lower (P<0.05) than those from IMM and SPC for rainbow trout. Conversely, for Atlantic salmon, ADCs of isoleucine from both IMC (94%) and IMM (92%) were lower than those from SPC (97%). Despite small differences, the ADC of most AA in these novel products were very good (>90%). These results suggest that low glucosinolate Indian mustard protein concentrate and Indian mustard meal are ingredients of high nutritive value. However, it is hypothesized that the high phytic acid level in the Indian mustard protein concentrate may negatively affect the digestibility of CP and certain amino acids when used at high level in the feed of fast growing fish.

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.

The influence of lupin seed germination on the chemical composition and standardized ileal digestibility of protein and amino acids in pigs

The germination process can modify the chemical composition of nutrients in seeds, which can influence the digestibility and utilization of sprouts in animal diets compared to raw seeds. The aims of research were to provide controlled germination process of lupin seeds, monitor the changes in seed composition and determine the influence of the germination on the coefficients of standardized ileal digestibility (SID) of crude protein and amino acids in growing pigs, compared to raw lupin seeds. The seeds of two lupin species were used: yellow (RYL) (Lupinus luteus, cv. Lord) and blue (RBL) (Lupinus angustifolius, cv. Graf). Germination was provided in the dark at 24°C for 4 days. Nutritional and antinutritional compositions of raw and germinated seeds (GYL and GBL, respectively) were analysed. Digestibility study was performed on pigs with an average body weight of 25 kg, and the pigs were surgically fitted with a T-cannula in the distal ileum, with chromic oxide as an indicator. Seed germination increased the crude protein and fibre concentrations, but reduced the levels of the ether extract, nitrogen-free extracts and all amino acids in protein. The content of alkaloids and raffinose family oligosaccharides decreased in both lupin species. Germination had no positive impact (p>0.05) on the SID of crude protein and amino acids. Germination of lupin seeds negatively influenced the SID of lysine and methionine (p<0.05). The results of the research revealed a decrease in the concentrations of antinutritional factors in the sprouts of yellow and blue lupins compared to raw seeds; however, no positive effect was observed on the coefficients of the standardized ileal apparent digestibility of protein and amino acids.