Effect of Natuphos Phytase supplementation to feed on performance and ileal digestibility of protein and amino acids of broilers

Evaluation of exogenous phytase in high-phytate diets for broiler chickens and pigs

There is a gap in the understanding of the relationship between dietary phytate levels and the relative efficacy of phytase to improve amino acid (AA) digestibility in pigs and chickens. Two experiments were conducted to investigate the effect of exogenous phytase on standardized ileal digestibility (SID) of AA and the apparent ileal digestibility (AID) of P in both standard- (SP) and high-phytate (HP) diets for broilers and swine. There were either 40 cages of Cobb 500 male broilers or 10 crossbred barrows (35 kg) fitted with ileal T-cannulas. Both studies were allotted to five dietary treatments (8 replicates). Treatments consisted of four corn-soybean meal-based diets arranged in a 2 × 2 factorial of standard or high phytate and exogenous phytase at 0 or 1 000 phytase units (FYT)/kg; and one N-free diet. Birds were fed a common starter diet from d 0 to 20 and fed experimental diets from d 20 to 25. Birds were euthanized on d 25 via CO2 asphyxiation, and digesta were collected from the terminal ileum. Pigs were fed for a total of four 7-d periods, where digesta were collected on d 6 and 7 of each period. Diet and digesta samples were analyzed for DM, N, Ti, AA, and P to determine AA and P digestibility. The SID of AA was determined by correcting the AID of AA for the basal endogenous losses estimated using the N-free diet. Main effects of the diet type (standard or HP) and phytase (0 or 1 000 FYT/kg), and the interaction of diet type and phytase were evaluated. For both experiments, the HP diets produced lower SID of AA compared to the SP (P < 0.001). For broilers, there was a phytase effect (P < 0.001) for the SID of all AAs evaluated regardless of the diet type. For pigs, phytase improved (P < 0.05) the SID of Met, Lys, Cys, Glu and Ser and tended to improve (P < 0.10) Arg, Leu, Thr, and Tyr. There were no significant interactions for either experiment. For both experiments, AID of P was lower for the HP diets (P < 0.01), and phytase produced greater AID of P for both diet types (P < 0.01). These data indicate that phytase greatly improves the digestibility of P for broilers and pigs and has the ability to significantly increase the digestibility of amino acids for these animals, regardless of the dietary phytate P.

Effects of thermostable phytase supplemented in diets on growth performance and nutrient utilization of broilers

Phytase is an enzyme that has the ability to release phosphorous (P) from phytate by hydrolyzing inositol-phosphate linkages. Recently, thermostable phytases have gained great consideration because the reduction in phytase activity was found when exposed to heat during feed pelleting. In this study, the effects of the granular thermostable phytase (Aspergillus niger) on growth performance and nutrient utilization of broilers were investigated. A total of 96 21-day-old Arbor Acres broilers were randomly distributed into six treatments including basal diet (control) and basal diet supplemented with 500, 1,000, 2,000, 4,000, 8,000 U of phytase/kg. In general, the metabolizable energy (ME) and the apparent and true availability of dry matter (DM), organic matter (OM), ether extract (EE), crude protein (CP), and amino acids (AA) showed both linearly (p < .01) and quadratically (p < .01) increase with increasing levels of phytase in the diet. Additionally, diet supplementation with phytase could improve (p < .05) body weight (BW), average daily gain (ADG), and feed/gain (F/G) on day 42 compared with the control. The results suggested that diet supplementation of the granular thermostable phytase in the crumbled pellets could improve chicken growth performance and nutrient utilization.

Effects of multi-carbohydrase and phytase on standardized ileal digestibility of amino acids and apparent metabolizable energy in canola meal fed to broiler chicks

Two assays were conducted to evaluate nutritive value of canola meal (CM) fed to broiler chicks without or with a multi-carbohydrase (MC) preparation (700 U α-galactosidase, 2,200 U galactomannanase, 30,000 U xylanase, and 22,000 U β-glucanase per kg of diet) and phytase (Phy, 500 FTU per kg of diet). Assay 1 determined apparent total tract digestibility (ATTD) of nutrients and metabolizable energy (AME) by the difference method. Assay 2 determined apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids by the index method. Two reference diets (RD) - an 85% corn based and a 5% casein-cornstarch diet fortified with vitamins and minerals - were made for assays 1 and 2, respectively. For each assay, the test diets were made by mixing RD and CM 7:3 wt/wt basis and fed without or with MC or Phy or combination. A total of 245 day-old male broilers (Cobb 500) was allocated to 5 treatments to give 7 replicates (7 birds/cage). The birds were fed a commercial diet from day zero to 10 followed by assay 1 fed from d 11 to 18 and assay 2 fed from d 19 to 21. Excreta samples were collected on d 15 to18, and all birds were slaughtered on d 21 for ileal digesta. There was an interaction (P < 0.05) between MC and Phy on ATTD of DM, N, and P. There was no interaction (P > 0.05) between MC and Phy on AMEn; however, MC and Phy individually improved AMEn retention. Enzymes interacted (P < 0.05) on SID of Arg, His, Leu, Met, Thr, Ala, Asp, Gln, and Gly. In this context, feeding a combination of MC and Phy resulted in higher (P < 0.05) SID of Arg, His, Met, and Thr relative to single activity or control. Both enzymes improved (P < 0.05) SID of Lys independently. The combination of carbohydrase and Phy may be an effective strategy to improve amino acid utilization in CM for poultry.

Efficacy of New 6-Phytase from Buttiauxella spp. on Growth Performance and Nutrient Retention in Broiler Chickens Fed Corn Soybean Meal-based Diets

A total of 420 day-old male Ross chicks were weighed at d 1 of life and assigned to test diets to assess the efficacy of a new Buttiauxella spp. phytase expressed in Trichoderma reesei. Diets were: positive control (PC) adequate in nutrients and negative control (NC) diet (40% and 17% less available phosphorous (P) and calcium (Ca), respectively) supplemented with 6 levels of phytase 0, 250, 500, 750, 1,000, and 2,000 phytase units (FTU)/kg of diet. All diets had titanium dioxide as digestibility marker and each diet was allocated to ten cages (6 birds/cage). Diets were fed for 3 wk to measure growth performance, apparent retention (AR) on d 17 to 21 and bone ash and ileal digestibility (AID) on d 22. Growth performance and nutrient utilization was lower (p<0.05) for NC vs PC birds. Phytase response in NC birds was linear (p<0.05) with 2,000 FTU showing the greatest improvement on body weight gain (20%), feed conversion (7.4%), tibia ash (18%), AR of Ca (38%), AR of P (51%) and apparent metabolizable energy corrected for nitrogen (5.1%) relative to NC. Furthermore, phytase at ≥750 FTU resulted in AID of total AA commensurate to that of PC fed birds and at ≥1,000 FTU improved (p<0.05) AR of P, dry matter, and N beyond that of the lower doses of phytase and PC diet. In conclusion, the result from this study showed that in addition to increased P and Ca utilization, the new Buttiauxella phytase enhanced growth performance and utilization of other nutrients in broiler chickens in a dose-dependent manner.

Reduction of Phosphorus Pollution from Broilers Waste through Supplementation of Wheat Based Broilers Feed with Phytase

The present study was conducted to reduce phosphorus pollution from broilers waste by supplementing phytase enzyme in broilers fee. Two hundred two-week-old broilers (Hubbard) were selected and randomly allocated to three dietary treatment groups, one control group (without phytase) and two trial groups (group A with 300 U/kg phytase and group B with 600 U/kg phytase). Each group was composed of 5 replicates with 10 chicks. Broilers fed the control diet (without phytase) gained weight slower (P< 0.05) than the other treatment groups. A significant increase in body weight gain of group A (28.00 ± 2.97) and group B (29.75 ± 3.45) was observed as compared to control group (26.75 ± 2.78). The feed intake of the birds fed the diets containing microbial phytase 600 U/kg was the highest. Phytase significantly (P> 0.05) reduces excreta P and Ca level. Phytase addition did not affect excreta pH. The presence of phytase in feed mixtures significantly (P> 0.05) improves the body weight gain and feed intake of broiler chickens.

Evaluation of nutrient equivalency of microbial phytase in hens in late lay given maize-soybean or distiller's dried grains with solubles (DDGS) diets

1. An experiment was conducted with 360 Lohmann LSL-Classic White Leghorn layers (64 weeks old) to evaluate the effects of supplementation of microbial phytase on production, egg quality, bone, selected manure parameters and feed costs. 2. Experimental diets were formulated as follows: (1) maize-soybean (CS), (2) CS+300 units of phytase (FTU)/kg diet which was formulated to recoup only calcium and available phosphorus equivalency for phytase (CS+PHYCa+P), (3) CS+300 FTU/kg diet which was formulated to recoup total nutrient equivalency for phytase (CS+PHYtotal), (4) CS+100 g/kg distiller's dried grains with solubles (DDGS), (5) DDGS+300 FTU/kg diet which was formulated to recoup only calcium and available phosphorus equivalency for phytase (DDGS+PHYCa+P), or (6) DDGS+300 FTU/kg diet which was formulated to recoup total nutrient equivalency for phytase (DDGS+PHYtotal). 3. Each dietary treatment was assigned to 4 replicate groups with 3 cages and 5 hens per cage. The hens were provided with feed and water ad libitum. The experiment lasted for 8 weeks. 4. CS+PHYCa+P, CS+PHYtotal, DDGS+PHYCa+P and DDGS+PHYtotal diets supplemented with phytase provided similar percentage egg production, egg weight, egg mass, exterior egg quality, initial and final body weight compared with phytase-free diets. 5. However, supplementation of phytase to the experimental diets and calculation of the total nutrient equivalency for enzyme caused increased feed intake and decreased feed conversion ratio and Haugh unit. 6. No differences in manure dry matter, crude ash, total nitrogen, tibia crude ash, calcium and phosphorus contents were found among the experimental diets. On the other hand, manure total phosphorus content was significantly decreased in the DDGS diet and diets supplemented with phytase in comparison to the CS diet. 7. It was concluded that the addition of microbial phytase to the CS-based diets or diets with DDGS of hens in late lay and using Ca and available P equivalency of enzyme in feed; formulation may provide an economic benefit and decrease the amount of phytate P excretion in the manure without compromising production and egg quality parameters.

Effect of two microbial phytases on mineral availability and retention and bone mineral density in low-phosphorus diets for broilers

1. The efficacy of supplementation of a low-phosphorus (low-P) maize-soyabean meal diet for broiler chickens with two different microbial (fungal and bacterial) phytases was examined. 2. Broiler chickens received a low-P maize-soyabean meal diet containing either no phytase or one of the two phytases included at one and two times the manufacturer's recommended inclusion level for 21 d. 3. Titanium dioxide was included in the diets as an indigestible marker. Excreta were collected quantitatively from d 18 to 21, and at the end of the study the birds were killed and ileal digesta and leg bone samples collected. 4. No differences were observed for body weight gain and feed intake or apparent metabolisable energy (AME) among all dietary treatment groups. 5. Dietary phytase supplementation improved the apparent retention of Ca, Na and Cu and ileal phytate P absorption from 32% to 44% across inclusion levels. 6. Bone mineral density (BMD) was improved for both phytases across inclusion levels by, on average, 9% for the tibia and 13% for the femur. 7. Dietary phytase supplementation of the low-P diet improved apparent ileal digestibility of serine, glycine, valine, isoleucine, tyrosine, histidine, lysine and arginine. 8. When the results from the present study were combined with the results from other similar published studies and analysed statistically, factors such as dietary P and Ca concentration, as well as bird breed and age, rather than the type or activity of microbial phytase, had the greatest impact on the extent to which dietary supplementation improved P and Ca retention. 9. More work is required to explain the interrelationships between the multiple factors influencing the efficacy of phytase on the availability of dietary minerals.

Extra-phosphoric effects of phytase with and without xylanase in corn-soybean meal-based diets fed to broilers

Two experiments were conducted to evaluate the extra-phosphoric effects of phytase on amino acid (AA) and energy digestibility (experiments 1 and 2) and growth performance (experiment 2) of broilers fed diets adequate in Ca and nonphytate P supplemented with xylanase. Ross × Ross 708 broiler chicks (864 males in experiment 1 and 1,152 females in experiment 2) were randomly distributed into battery cages (6 replicate cages per treatment) with 12 birds per cage at 1 d of age. In both experiments, factorial arrangements of treatments were evaluated consisting of 6 phytase [0, 1,000, 2,000, 4,000, 8,000, or 16,000 phytase units (FTU)/kg] and 2 xylanase [0 or 16,000 birch xylan units (BXU)/kg] concentrations in experiment 1 and 4 phytase (0, 500, 1,000 or 2,000 FTU/kg) and 4 xylanase (0, 8,000, 16,000, or 32,000 BXU/kg) concentrations in experiment 2. Treatments were provided from 27 to 32 d of age in experiment 1 and from 1 to 32 d of age in experiment 2. Digesta contents of the terminal ileum were collected at 32 d of age (experiment 1 and 2), and growth performance was measured at 1, 14, and 25 d of age in experiment 2. There was no interaction of phytase and xylanase; only main effects of phytase were observed. In experiment 1, broilers fed diets supplemented with phytase at 1,000 FTU/kg had increased (P < 0.05) apparent ileal digestibility (AID) of all AA with the exception of Ala and Met. Diets fed to broilers supplemented with higher concentrations of phytase did not further increase AID of any AA (P > 0.05) above the addition of 1,000 FTU/kg of phytase. Phytase supplementation did not affect ileal digestible energy (P > 0.05). For all variables measured, significant log-linear or log-quadratic effects of phytase (P > 0.05) were not observed. In contrast, broilers fed diets supplemented with phytase in experiment 2 exhibited log-linear (P < 0.05) increases in AID of AA but not apparent ileal digestible energy. However, supplementation with 2,000 FTU/kg of phytase increased (P = 0.05) ileal digestible energy by 36 kcal/kg compared with the basal diet. Broilers fed diets with 1,000 FTU/kg of phytase had improved growth performance (P < 0.05) in comparison with broilers fed diets containing 0 or 500 FTU/kg of phytase. The addition of 500 FTU/kg of phytase in diets fed to broilers did not affect ileal digestibility or growth performance (P > 0.05). Data obtained from these experiments demonstrated extra-phosphoric effects in broilers fed diets supplemented with 1,000 FTU/kg of phytase and diminishing returns with higher concentrations.

Evaluation of the compositional and nutritional values of phytase transgenic corn to conventional corn in roosters

Three experiments were conducted to evaluate the compositional and nutritional values of corn grains [phytase transgenic corn (PTC) and isogenic conventional corn (CC)] and compare the efficacy of corn-based phytase and extraneous microbial phytase for enhancing the utilization of phytate phosphorus (P) in single corn or corn-soybean mixed meals (corn:soybean = 2.5:1, wt:wt) fed to roosters. Following a 48-h fasting period, 16 roosters were given 50 g of each sample via crop intubation and excreta were collected for 48 h. Nitrogen-free and phosphorus-free diets were used to evaluate endogenous amino acid and endogenous P losses, respectively. Chemical composition was not different between PTC and CC, whereas the phytase content for PTC was greater than CC (8,047 vs. 37 FTU/kg of corn, DM basis; P < 0.001). No difference was observed in the TME and true amino acid availability values between the PTC and CC in roosters. The true P utilization for PTC was greater than CC (37.92 vs. 55.85%; P < 0.001), and CC and PTC contained 0.13 and 0.19% available P (AP, DM basis; P < 0.001), respectively. There was no difference in P utilization (72.76 vs. 70.23%; P > 0.05) between roosters fed PTC and extraneous microbial phytase in equivalent FTU/kg of diets. The results of this study indicated that the chemical composition, TME, and true amino acid availability in PTC are essentially equivalent to that in CC, and the true P utilization for roosters is higher in PTC than in CC. Corn expressing phytase is as efficacious as equivalent microbial phytase when supplemented in corn-soybean diets for chickens.

Effect of a novel phytase on growth performance, apparent metabolizable energy, and the availability of minerals and amino acids in a low-phosphorus corn-soybean meal diet for broilers

The addition of microbial phytase to diets for broiler chickens has been shown to improve the availability of phytate P, total P, some other minerals, and amino acids. In this study, the effect of a novel microbial phytase expressed by synthetic genes in Aspergillus oryzae on amino acid and mineral availability was assessed. Phytase was incorporated (1,000 and 2,000 U/kg) into low-P corn-soybean meal-based diets for broilers. Broilers received the experimental diets for 3 wk, and excreta were collected from d 18 to 21 for the determination of AME and mineral retention. On the 22nd day, the broilers were killed and the left leg removed and ileal digesta collected. Ileal phytate P and total P absorption, ileal amino acid digestibility, as well as the bone mineral content and bone mineral density were determined. Ileal phytate P absorption and absorbed phytate P content of the low-P corn-soybean meal diet were significantly (P < 0.05) higher after dietary inclusion of the novel phytase (49-60% and 65-77% higher, respectively). Apparent ileal total P absorption and apparent total P retention was 12 to 16% and 14 to 19% higher (P < 0.05), respectively, after dietary inclusion of phytase. The bone mineral content and bone mineral density in the tibia were 32 to 35% and 19 to 21% higher (P < 0.05), respectively, after dietary phytase inclusion. The apparent ileal digestibility of threonine, tyrosine, and histidine increased significantly (P < 0.05) by 14, 9, and 7%, respectively, after dietary inclusion of microbial phytase. Overall, the inclusion of a novel microbial phytase into a low-P corn-soybean meal diet for broiler chickens greatly increased phytate P and total P absorption, bone mineral content and density, as well as the digestibility of some amino acids.

Effects of freeze-dried Mitsuokella jalaludinii culture and Natuphos(®) phytase supplementation on the performance and nutrient utilisation of broiler chickens

BACKGROUND

Phytate-bound phosphorus (P) in poultry diets is poorly available to chickens. Hence exogenous phytase is often added to their diets. Mitsuokella jalaludinii is a rumen bacterial species that produces high phytase activity. In this study the effects of freeze-dried active M. jalaludinii culture (FD-AMJC) and Natuphos(®) phytase (phytase N) supplementations on the growth performance and nutrient utilisation of broiler chickens fed a low-available P (aP) diet were evaluated.

RESULTS

Supplementation of FD-AMJC or phytase N to the low-aP diet improved the feed intake, feed conversion rate, body weight gain, dry matter (DM) digestibility and P, Ca and Mn retention, increased the tibia bone ash content, Ca and P concentrations in tibia DM and P and Zn concentrations in plasma and reduced the P excretion of broiler chickens. However, the feed conversion rate, P and Ca retention, DM digestibility and reduction of P excretion were better with FD-AMJC than phytase N supplementation. Supplementation of FD-AMJC to the low-aP diet also improved the apparent metabolisable energy value of the diet, Cu and Zn retention and crude protein digestibility, but phytase N supplementation did not.

CONCLUSION

FD-AMJC supplementation was more efficient in improving nutrient utilisation and reducing P excretion in chickens than phytase N supplementation.

BOARD-INVITED REVIEW: opportunities and challenges in using exogenous enzymes to improve nonruminant animal production

Diets fed to nonruminant animals are composed mainly of feed ingredients of plant origin. A variety of antinutritional factors such as phytin, nonstarch polysaccharides, and protease inhibitors may be present in these feed ingredients, which could limit nutrients that may be utilized by animals fed such diets. The primary nutrient utilization-limiting effect of phytin arises from the binding of 6 phosphate groups, thus making the P unavailable to the animal. The negative charges allow for formation of insoluble phytin-metal complexes with many divalent cations. Furthermore, phytin and protein can form binary complexes through electrostatic links of its charged phosphate groups with either the free amino group on AA on proteins or via formation of ternary complexes of phytin, Ca(2+), and protein. The form and extent of de novo formation of binary and ternary complexes of phytin and protein are likely to be important variables that influence the effectiveness of nutrient hydrolysis in plant-based diets. Nonstarch polysacharides reduce effective energy and nutrient utilization by nonruminant animals because of a lack of the enzymes needed for breaking down the complex cell wall structure that encapsulate other nutrients. Enzymes are used in nonruminant animal production to promote growth and efficiency of nutrient utilization and reduce nutrient excretion. The enzymes used include those that target phytin and nonstarch polysaccharides. Phytase improves growth and enhances P utilization, but positive effects on other nutrients are not always observed. Nonstarch polysaccharide-hydrolyzing enzymes are less consistent in their effects on growth and nutrient utilization, although they show promise and it is imperative to closely match both types and amounts of nonstarch polysaccharides with appropriate enzyme for beneficial effects. When used together with phytase, nonstarch polysaccharide-hydrolyzing enzymes may increase the accessibility of phytase to phytin encapsulated in cell walls. The future of enzymes in nonruminant animal production is promising and will likely include an understanding of the role of enzyme supplementation in promoting health as well as how enzymes may modulate gene functions. This review is an attempt to summarize current thinking in this area, provide some clarity in nomenclature and mechanisms, and suggest opportunities for expanded exploitation of this unique biotechnology.

Phytate and phytase: consequences for protein utilisation

The excretion of large amounts of P in effluent from intensive pig and poultry units is indicative of the poor availability of phytate-bound P in plant-derived feed ingredients. This environmental problem prompted the development and acceptance of microbial phytase feed enzymes for single-stomached animals. Their introduction led to an increasing recognition that phytate may have adverse effects on protein utilisation in addition to P. Consequently, the nutritional relevance of protein–phytate interactions for pigs and poultry is considered in the present review. Since the current understanding of the effects of protein–phytate interactions comes mainly from responses obtained to added phytase, literature on the influence of microbial phytases on amino acid digestibility and utilisation is summarised, followed by a discussion of possible mechanisms contributing to the negative effects of phytate. However, the rationale for the protein responses to added phytase remains largely speculative, and several modes of action are probably involved. It may be that the release of protein from protein–phytate complexes occurring naturally in feed ingredients, the prevention of formation of binary and ternary protein–phytate complexes within the gut, the alleviation of the negative impact of phytate on digestive enzymes and the reduction in endogenous amino acid losses are all contributing factors. A better understanding of the mechanisms of protein–phytate interactions and the modes of action of exogenous phytase enzymes is clearly desirable. Studies are also needed to identify and quantify the factors that contribute to the variable amino acid responses to added phytase. It appears that the relative solubilities of phytate salts and proteins from different feed ingredients and their effects on the extent of protein–phytate complex formation, coupled with variations in the effectiveness of phytase in different dietary contexts, may be the major factors responsible.

Phytic acid and phytase: implications for protein utilization by poultry

The effect of the ingestion of myo-inositol hexaphosphate (IP6) and phytase (EC 3.1.3.26) on the digestibility of casein was investigated using growing broiler chickens. A total of 64 female Ross broilers were used in a precision feeding study. One group of 8 birds was fed a solution of glucose to estimate endogenous losses. Seven groups, each of 8 birds, were fed either casein, casein + 1,000 units of phytase activity (FTU), casein + 2,000 FTU, casein + 0.5 g of IP6, casein + 0.5 g of IP6 + 1,000 FTU, casein + 1 g of IP6, or casein + 1 g of IP6 + 1,000 FTU. The excretion of DM, amino acids, nitrogen, minerals, and phytate-phosphorus was determined over a 48-h period and nutrient digestibility coefficients were calculated. Casein was found to be highly digestible, with true coefficients of DM, N, and amino acid digestibility of between 0.85 and 1.0. However, the ingestion of IP6 reduced (P < 0.05) the digestibility coefficients of amino acids, N, and DM of casein compared with birds fed casein alone. Supplementation of the mixture of casein and IP6 with phytase improved (P < 0.05) the digestibility coefficients of amino acids compared with birds fed on casein and IP6 with no supplemental phytase. The excretion of endogenous minerals was increased (P < 0.05) by the ingestion of IP6 and reduced (P < 0.05) by the supplementation of IP6 with phytase. In the absence of exogenous phytase, the recovery of phytate-P in excreta was approximately 80%. However, the recovery of phytate-P was significantly reduced by the addition of exogenous phytase to the IP6/casein mixture. It can be concluded that the ingestion of IP6 reduces the digestibility coefficients of amino acids and the metabolizability of nitrogen of casein. This is likely to be mediated partially through increased endogenous losses. However, the addition of phytase can partially ameliorate the detrimental effects of IP6 on protein utilization.

Influence of an Escherichia coli-derived phytase on nutrient utilization in broiler starters fed diets containing varying concentrations of phytic acid

The influence of an Escherichia coli-derived phytase, on nutrient utilization was investigated in broilers fed starter diets containing different concentrations of phytate. The study was conducted as a 3 x 4 factorial arrangement of treatments with 3 concentrations of phytic acid (10.4, 11.8, and 13.6 g/kg; equivalent to 2.8, 3.3, and 3.8 g of phytate P/kg) and phytase (0, 500, 750, and 1,000 FTU/kg). One unit of phytase (FTU) is defined as the quantity of enzyme that releases 1 micromol of inorganic phosphorus/min from 0.00015 mol/L of sodium phytate at pH 5.5 at 37 degrees C. The dietary phytic acid concentrations were manipulated by the inclusion of rice bran. Increasing dietary concentrations of phytic acid resulted in reductions (P < 0.01) in AME. Phytase additions tended to increase AME (P = 0.07), regardless of dietary phytate concentrations. Apparent ileal digestibility coefficients of protein and most amino acids were influenced by phytate (P < 0.05 to 0.001) and phytase (P < 0.001). Phytase improved ileal protein and amino acid digestibility at all phytate concentrations, but the trend in responses to increasing phytase additions was different at different phytate concentrations as shown by significant phytate x phytase interactions (P < 0.01 to 0.001). At the lowest phytate concentration, the ileal digestibility coefficients increased with increasing phytase supplementation. At the medium and high phytate concentrations, the greatest responses were observed at 500 FTU/kg of phytase, with little improvement attributable to further additions. Ileal digestibility of P was lowered (P < 0.01) by increasing phytate concentrations and increased (P < 0.001) with increasing additions of phytase. A significant phytate x phytase interaction (P < 0.05) was also observed, where the improvements in P absorption with added phytase were found to be greater at high phytate concentrations. These data demonstrate the anti-nutritive effects of phytic acid and the potential of microbial phytase to improve energy utilization and the availability of P and amino acids in broilers fed starter diets.

Effect of phytase supplementation to a low- and a high-phytate diet for growing pigs on the digestibilities of crude protein, amino acids, and energy1,2,3

Supplementation of microbial phytase usually improves the digestibility and utilization of phosphorus in feedstuffs of plant origin. The effect of phytase supplementation on the digestibilities of AA also has been examined, but the results have been inconsistent. This study was carried out to determine the effect of phytase (Natuphos) supplementation, at a rate of 2,000 phytase units/kg, to two basal diets on the apparent ileal digestibilities (AID) of GE, CP, and AA, and on the apparent total-tract digestibilities (ATTD) of CP and GE. The basal diets contained 18% CP and were formulated (as-fed basis) to contain either a low (0.22%) or high content (0.48%) of phytate P. The high-phytate diet contained 20% rice bran, which is a rich source of phytate and has low intrinsic phytase activity. Eight barrows (average initial BW = 40.6 kg), fitted with a simple T-cannula at the distal ileum, were fed the four diets according to a replicated 4 x 4 Latin square design. The pigs were fed twice daily at 0800 and 2000, equal amounts each meal, at a rate of 2.4 times the daily maintenance requirement for ME. Each experimental period comprised 14 d. Ileal digesta were collected from 0800 to 2000 on d 12, 13, and 14. Feces were collected from 0800 on d 8 until 0800 on d 12. Chromic oxide was used as the digestibility marker. The AID of GE, CP, and AA and the ATTD of CP and GE were less in the high- than in the low-phytate diet (P < 0.01). With the exception of glutamic acid, phytase supplementation did not affect (P > 0.10) the AID of CP and AA. There was no effect (P > 0.05) of phytase on the ATTD of CP and GE. These results show that if a response occurs to phytase supplementation, it is independent of the dietary phytate content.

Efficacy of an evolved Escherichia coli phytase in diets of broiler chicks

An evolved Escherichia coli-derived phytase was evaluated for its efficacy in improving growth performance and nutrient utilization of broiler chicks. One hundred forty-four 7-d-old male broiler chicks were grouped by weight into 6 blocks of 6 cages with 4 birds per cage. Six corn-soybean meal-based mash diets were randomly assigned to cages within each block. The 6 diets were adequate P (7.7 g of P/kg of diet), low P (3.9 g of P/kg of diet), low P diet plus 0.75 or 1.5 g of inorganic P from monosodium phosphate, and low P diet plus the evolved Escherichia coli phytase at 500 or 1,000 units/kg of diet. The chicks were fed the experimental diets from 8 to 22 d of age. The evolved Escherichia coli phytase improved weight gain (P < 0.05), feed intake (P < 0.01), percentage tibia ash (P < 0.01), and retention of P (P < 0.001), Ca (P < 0.01), N (P < 0.05), and a number of amino acids (P < 0.05). The evolved Escherichia coli phytase was, therefore, efficacious in improving broiler growth performance, bone characteristics, and retention of P, Ca, N, and a number of amino acids.

Effect of microbial phytase on ileal digestibility of phytate phosphorus, total phosphorus, and amino acids in a low-phosphorus diet for broilers

The study aimed to assess the effect of a commercially available microbial phytase added to a corn-soybean meal diet on phytate P and total P in terminal ileal digesta as well as on true ileal amino acid digestibility. Three low-P diets containing 0, 500, or 750 U/kg of microbial phytase were fed to 21-d-old broiler chickens. Titanium dioxide was used as an indigestible marker. Ileal contents were collected from euthanized birds and analyzed, along with the diets, for total P, phytate P, and amino acids. Endogenous P determined at the terminal ileum was 446 +/- 59 mg/kg food dry matter (mean +/- SE). Endogenous ileal amino acids ranged from 219 +/- 33 mg/kg food dry matter for tryptophan to 1,255 +/- 166 mg/kg food dry matter for glutamic acid. Supplementation with microbial phytase resulted in a significantly (P < or = 0.05) greater phytate P disappearance (11% greater disappearance vs. unsupplemented control) from the terminal ileum. Similarly, true ileal total P digestibility was (P < or = 0.05) higher (10 to 12%) when microbial phytase was added. True ileal amino acid digestibility was significantly (P < or = 0.05) greater in the presence of microbial phytase for all the amino acids examined with the exception of methionine, tyrosine, histidine, and tryptophan. The mean increase in true ileal amino acid digestibility was 3.4%. The effect of phytase on true ileal phytate P, total P, and amino acid digestibility was similar for the 2 phytase inclusion levels tested. Microbial phytase improved phytate P and total P digestibility, as well as true ileal amino acid digestibility, for a corn-soybean diet.

Evaluation of Microbial Phytase in Broiler Diets

Two trials were conducted to evaluate the efficacy of a new microbial phytase (Phyzyme XP) for broiler chicks. Trial 1 used 192 8-d-old male broilers in a 14-d trial to assess growth and nutrient utilization. Dietary treatments (221.9 g/kg CP) included a positive control [5.0 g/kg nonphytate P (NPP)], negative control (1.2 g/kg NPP), and negative control plus 500 or 1,000 phytase units/kg of diet. Phytase addition increased weight gain, feed intake, feed efficiency, and tibia and toe ash (linear, P < 0.01) with tibia ash also responding quadratically (P < 0.05). Apparent ileal digestibility of P (linear and quadratic, P < 0.05), tryptophan, and valine (linear, P < 0.05) also increased. Linear and quadratic responses were observed for retention of DM, nitrogen, P, and several amino acids (P < 0.05) with added phytase. Trial 2 utilized 576 1-d-old male broilers over a 42-d period to evaluate growth performance. Diets were formulated for starter (222.7 g/kg CP) and grower (201.5 g/kg CP) phases and included a positive control (starter and grower, 5.0 and 3.8 g/kg NPP, respectively); negative control (starter and grower, 2.4 and 1.8 g/kg NPP, respectively); negative control plus 500, 750, or 1,000 phytase units/kg; and negative control plus 500 phytase units/kg of Natuphos phytase. Phytase increased weight gain and feed intake (starter, grower, overall) as well as feed efficiency during the starter period (linear, P < 0.05). Feed intake was also improved during the grower period and overall (quadratic, P < 0.05). Tibia and toe ash of birds fed for the first 21 d increased (linear, P < 0.05) with tibia ash also increasing quadratically (P < 0.05). Overall, tibia and toe ash were improved due to phytase addition (linear and quadratic, P < 0.05). In conclusion, this microbial phytase, derived from Escherichia coli and expressed in Schizosaccaromyces pombe, elicited improved growth performance, bone mineralization, and P utilization in broiler chicks.

High dietary phytase levels maximize phytate-phosphorus utilization but do not affect protein utilization in chicks fed phosphorus- or amino acid-deficient diets1

Four trials investigated the effect of high levels of three phytase enzymes on P and protein utilization in chicks. The three phytases were derived from Aspergillus (Fungal Phytase 1), Peniophora (Fungal Phytase 2), and E. coli. Within each assay, 8-d-old male chicks were given ad libitum access to their experimental diet for 10 to 14 d. For Trials 1, 2, and 3, the basal diet was a corn-soybean meal diet deficient in P that was analyzed to contain 23% CP and 0.38% total P (0.10% estimated available P, as-fed basis). Phytase supplementation levels were based on the assessment of phytase premix activity (i.e., P release from Na phytate at pH 5.5 and 37 degrees C). In Trial 1, supplementation of inorganic P from KH2PO4 (0 to 0.20%) resulted in a quadratic (P < 0.05) response in weight gain, gain:feed, and tibia ash concentration but a linear (P < 0.01) increase in tibia ash weight. Tibia ash was higher (P < 0.01) for chicks fed E. coli phytase than for those fed Fungal Phytase 1 at 500, 1,000, and 5,000 phytase units (FTU)/kg, but did not differ between these two phytases at 10,000 FTU/kg. In Trial 2, E. coli phytase supplementation at 1,000 FTU/kg maximized growth and bone responses, whereas addition of either of the two fungal phytases resulted in increasing responses up to 5,000 and 10,000 FTU/kg. Dietary addition of Fungal Phytase 2 resulted in the poorest (P < 0.01) responses among the three phytases. Escherichia coli phytase supplementation at 10,000 FTU/kg in Trial 3 resulted in tibia ash (millligrams) responses that were greater (P < 0.05) than those resulting from either 0.35% inorganic P supplementation or 10,000 FTU/kg of Fungal Phytase 1 or 2. Trial 4 showed that E. coli phytase supplementation at either 500 or 10,000 FTU/ kg did not improve protein efficiency ratio (gain per unit of protein intake) of chicks fed low-protein soybean meal or corn gluten meal diets that were first-limiting in either methionine or lysine, respectively. These results demonstrate that high dietary levels of efficacious phytase enzymes can release most of the P from phytate, but they do not improve protein utilization.

The Yeast Production System in Which Escherichia coli Phytase is Expressed May Affect Growth Performance, Bone Ash, and Nutrient Use in Broiler Chicks

The efficacy of three Escherichia coli-derived phytase preparations on the performance and nutrient utilization of broiler chicks was evaluated. Two hundred sixteen 7-d-old male broiler chicks were grouped by weight into 6 blocks of 6 cages with 6 birds per cage. Six corn-soybean meal-based diets were randomly assigned to cages within each block. The 6 diets were adequate P, very low P, and low P and contained (g of P/kg of diet) 7.7, 4.0, and 5.1, respectively; and low-P diet plus phytase preparation A, B, or C at 1,000 units/kg of feed. All 3 phytase preparations were produced in different yeast production systems with slightly different glycosylation patterns. Preparation A was produced in Pichia pastoris, B in Schizosaccharomyces pombe, and C in Saccharomyces cerevisiae. The chicks were fed the experimental diets from 8 to 22 d of age. Excreta samples were collected between 17 and 21 d of age. At the end of the study, blood was collected, chicks were killed, and tibiae were removed from 3 birds per cage. Weight gain, feed intake, and feed efficiency among the 3 phytase preparations did not differ, although only phytase A diet outperformed (P < 0.05) the low-P diet in terms of weight gain and feed efficiency. All 3 phytase diets outperformed (P < 0.05) the low-P diet in bone mineral content, density, strength, percentage ash, P retention, and serum P levels. Phytase B diet outperformed the adequate-P diet in bone strength. All 3 preparations increased (P < 0.05) Ca retention with phytase B or C showing a better retention of Ca than phytase A. All 3 phytase preparations showed similar P use as indicated by BW gain and tibia bone characteristics.

Phytase effects on amino acid digestibility in molted laying hens

Two hundred sixteen previously molted Dekalb Delta Leghorn laying hens (78 wk of age) were utilized to determine the effect of phytase on the ileal digestibility of amino acids. The hens were randomly arranged in a 3 x 2 factorial to evaluate three diet types that were corn-soybean meal (C-SBM), C-SBM-meat and bone meal (C-SBM-MBM), and C-SBM-wheat middlings (C-SBM-WM) and two levels of phytase (0 or 300 U/kg of diet). Each treatment was administered to four replicates of nine hens per replicate. Hens were fed the experimental diets for 21 d, and daily egg production and feed intake were recorded. After 21 d, the hens were euthanized, and ileal contents were collected for amino acid and digestible energy determination. Egg production of the hens did not differ among the treatments (P > 0.05). A significant interaction between diet type and phytase level for Ala, Gly, Leu, and Met was observed. The interaction resulted because phytase numerically increased amino acid digestibilities for the C-SBM-MBM and C-SBM-WM diets, but phytase addition numerically decreased the amino acid digestibilities for the C-SBM diet. Diet type had a significant effect on digesibilites of most amino acids. The latter effect was due primarily to lower amino acid digestibilities for the C-SBM-MBM diet than the C-SBM-WM diet. Phytase had no significant affect on digestibility of any amino acid. Ieal digestible energy was significantly affected by diet type but not by phytase. In conclusion, diet type had a significant effect on apparent ileal amino acid digestibility and digestible energy, but phytase had no consistent effect.

Efficacy of phytase for increasing protein efficiency ratio values of feed ingredients

Data previously reported in several studies have suggested that phytase improves amino acid digestibility in chicks. It was the objective of the current study to determine if phytase would increase the protein efficiency ratio (PER) values (g weight gain per g protein intake) for several feed ingredients fed to chicks. Six experiments were conducted and ingredients evaluated were casein, soybean meal, canola meal, cottonseed meal, peanut meal, wheat middlings, wheat bran, rice bran, defatted rice bran, meat and bone meal, and corn gluten meal. Casein was evaluated to serve as a phytate-free control ingredient. Each feedstuff was analyzed for CP and included in cornstarch:dextrose diets as the only source of protein to provide 10% dietary protein in Experiments 1 to 5 or 18% dietary protein (soybean meal) in Experiment 6. Dietary Ca and nonphytate P levels were varied among experiments and ranged from 0.95 to 1.5% Ca and 0.35 to 0.675% nonphytate P. The test ingredient diets were fed with 0 or 1,200 units of phytase/kg to New Hampshire x Columbian chicks from 8 to 17 or 20 d of age. The PER values varied greatly among ingredients, ranging from 1.4 for corn gluten meal to 4.2 for canola meal. Phytase addition had no significant effect (P > 0.10) on PER values for any of the ingredients evaluated, except for an increase for casein in one experiment. The results indicated that 1,200 U of phytase/kg did not significantly increase protein utilization of several feed ingredients as assessed by a PER chick growth assay.

Microbial phytase does not improve protein-amino acid utilization in soybean meal fed to young chickens

Three growth trials were conducted with young chicks to evaluate crude protein (CP) utilization in soybean meal (SBM) as affected by dietary addition of microbial phytase. In assay 1, chicks were fed two CP-deficient (50 or 150 g CP/kg) levels of dehulled SBM, and each SBM level was then supplemented with equimolar amounts of cystine or methionine (Met) or with 1200 U phytase/kg. At 50 g CP/kg, cystine or Met supplementation improved (P < 0.05) measures of growth performance, but when 150 g CP/kg from SBM was fed, only Met addition improved (P < 0.05) weight gain, food efficiency and protein efficiency ratio (PER). Thus, Cys was more limiting than Met in the diet that contained 50 g CP/kg, but Met was clearly first-limiting in the diet that contained 150 g CP/kg. Phytase supplementation did not improve (P > 0.10) chick performance at either level of CP. Chicks in assay 2 were fed 100 g CP/kg furnished by SBM, casein or corn gluten meal in the absence and presence of 1200 U phytase/kg. Weight gain, gain/food and PER values were greater (P < 0.05) in chicks fed SBM than in those fed casein, and greater (P < 0.05) in chicks fed casein than in those fed corn gluten meal. Phytase supplementation had no effect (P > 0.10) on any measure of chick performance, regardless of the protein source fed. In assay 3, three deficient levels of CP (50, 100 and 150 g/kg) from SBM were fed in the absence and presence of 1200 U dietary phytase/kg. Weight gain, food efficiency and protein accretion increased linearly (P < 0.05) as a function of protein intake, but phytase supplementation had no effect (P > 0.10) on slopes of the body weight and protein accretion curves. Likewise, phytase addition did not affect (P > 0.10) measures of protein utilization, i.e., weight gain/protein intake and protein gain/protein intake at any of the CP levels that were fed. Because sulfur amino acids are the growth-limiting factors when protein-deficient levels of SBM are fed to young chicks, we conclude that dietary addition of phytase does not improve sulfur amino acid utilization in SBM.