Coli-derived Phytase Research Articles

Effect of an Escherichia coli-derived phytase and a carbohydrase-protease cocktail derived from Bacillus spp. on performance, digestibility, bone mineralization and gut morphology in broilers fed different nutrient density diets.

Enzyme combinations, particularly phytase (PHY) with various carbohydrases and proteases, are utilized in commercial broiler production to enhance nutrient and energy bioavailability. A feeding study was undertaken to determine whether the efficiency of an Escherichia coli-derived PHY and a feed enzyme complex (FEC) derived from Bacillus spp. containing carbohydrase and protease as main activities in broiler chickens is dependent on diet quality. A total of 900 male one-day-old broiler chickens (Ross 308) were assigned to a 2×3 factorial arrangement of the treatments with 2 different nutrient density diets, standard nutrient diet (SN diet) and a low-nutrient diet (LN diet; -100kcal/kg for AMEn and -5% for crude protein [CP] and limiting amino acids), and 3 enzyme treatments (control [no enzymes], PHY and PHY+FEC). Each treatment group was composed of 6 replicates of 25 birds each. The LN diet caused a decrease in performance index, tibia length and diameter, tibia calcium content and jejunal villus surface area (VSA). The interaction effects between diet and enzyme supplementation were observed (p<0.05) on overall average daily gain (ADG), performance index, tibia ash content and jejunal villus height (VH) and VSA, with the favourable benefits of PHY+FEC treatment being more pronounced in the LN diets. Regardless of dietary nutrient density, supplementation with PHY alone or combined with FEC enhanced (p<0.05) final body weight, overall ADG and jejunal villus height (VH)/crypt depth, with the highest values observed in the PHY+FEC group. The PHY+FEC treatment also improved (p<0.05) overall feed conversion ratio, apparent ileal digestibility of dry matter, organic matter, CP, and energy, and tibia phosphorus content compared to the control treatment. The results indicate that the simultaneous addition of PHY and FEC to the LN diets improved the growth rate, bone mineralization and gut morphology.

Effect of Graded Levels of an Enhanced E.coli Phytase with Step-Wise Reduction of Supplemental Inorganic Phosphate on Growth Performance of Broilers Fed Corn-Soy Diet

ABSTRACT This study evaluated the potential of incremental doses of an enhanced Escherichia coli-derived phytase to support step-wise reduction of supplemental inorganic phosphate in an all-vegetable broiler diet. Corn-soybean meal-based diets containing 0.40/0.80%, 0.35/0.70%, and 0.30/0.60% avP and Ca, respectively from 0-10, 10-25, and 26-42 days posthatch served as experimental control (PC). Three test diets were formulated with 500, 1000, and 1500 FTU/kg of phytase assigned respectively an avP matrix of 0.15, 0.19, and 0.23% and a fixed Ca matrix of 0.15%. An additional diet (PC++) containing extra avP and Ca (+0.05% avP/+0.1% Ca) to that of PC was included to test if avP and Ca were not limiting in PC. Each diet was offered to 16 replicates of straight-run broilers kept in floor pens (30 birds per pen). PC++ had lower (p<0.05; 10 and 25 d) or similar (42 d) BW and toe ash compared with PC confirming the avP and Ca set in PC were sufficient to support optimal growth and bone mineralization. Compared to the PC, diets containing 1000 and 1500 FTU phytase had higher BW (p<0.05) at 10 and 25 d. For the overall period of 0-42 d, FI, BW and FCR did not differ across treatments. Percentage-, but not the absolute-, toe ash at phytase treated groups was significantly (p<0.05) low compared with the PC. The experiment demonstrated that 1500 FTU/kg of enhance E. coli phytase supports optimal BW and FCR of broilers fed corn-soy diet largely void of supplemental inorganic phosphate.

Efficacy and phosphorus equivalency values of two bacterial phytases (Escherichia coli and Citrobacter braakii) allow the partial reduction of dicalcium phosphate added to the diets of broiler chickens from 1 to 21 days of age

The objective of this study was to determine the efficacy and the phosphorus equivalency of two bacterial phytases (Citrobacter braakii-derived phytase or genetically-modified Escherichia coli phytase) in the diets of broiler chickens from 1 to 21days of age. A total of 2100 male broiler chickens were randomly distributed in 10 treatments with 10 replicates of 21 chicks each. A basal diet was formulated containing 1.8g per kg of non-phytate phosphorus and 9g per kg of total calcium (T1). For treatments 2–4, dicalcium phosphate was added to give 0.9, 1.8, or 2.7g per kg of additional inorganic phosphorus. The treatments from 5 to 7 received 500, 1000, or 2000 phytase units of Citrobacter braakii (FYT) per kg while the treatments from 8 to 10 received 250, 500, or 1000 phytase units of Escherichia coli (FTU) per kg. Increasing levels of inorganic phosphorus from dicalcium phosphate at 0.9, 1.8, and 2.7g per kg improved (P<0.05) feed intake by 52, 71, and 80%; weight gain by 41, 75, and 32%; tibia ash weight by 64, 156, and 185%; and tibia phosphorus by 110, 323, and 378%, respectively. Increasing levels of Citrobacter braakii-derived phytase at 500, 1000, and 2000 FYT per kg contributed to a significant improvement (P<0.05) of 52, 55, and 65% for feed intake; 37, 56, and 65% for weight gain; 52, 87, and 133% for tibia ash weight; and 96, 173, and 273% for tibia phosphorus, respectively. Increasing levels of Escherichia coli-derived phytase at 250 to 500, and 1000 FTU per kg increased (P<0.05) feed intake by 50, 61, and 70%; weight gain by 49, 60, and 76%; tibia ash weight by 80, 103, and 164%; and tibia phosphorus by 128, 198, and 330%. Linear regression equations (P<0.05) were used to estimate phosphorus equivalency values of the two phytases. The Citrobacter braakii- and Escherichia coli-derived phytases can be used in the diets of broiler chickens from 1 to 21days of age to partially reduce the addition of dicalcium phosphate as a phosphorus source. The supplementation of 500, 1000, and 2000 phytase units of Citrobacter braakii per kg were determined to be equivalent to the average addition of 0.625, 1.091, and 2.024g of inorganic phosphorus from dicalcium phosphate per kg in broiler diets, respectively. The supplementation of 250, 500, and 1000 phytase units of Escherichia coli per kg were determined to be equivalent to the average addition of 0.763, 1.307, and 2.395g of inorganic phosphorus from dicalcium phosphate per kg in broiler diets, respectively.

Effect of diets containing enzyme supplements and microwave-treated or untreated wheat on inositol phosphates in the small intestine of broilers

The objective was to study the effect of diets containing microwave-treated wheat and supplemental enzymes on myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) hydrolysis and the presence of inositol phosphate isomers (InsPs) in the small intestine of broilers. We assigned 16-day-old broilers to 48 pens of 15 broilers each (n=8 pens per treatment) in a 2×3 factorial arrangement of treatments. Birds were fed a wheat-soybean meal diet that was low in phosphorus (4.8g/kg dry matter) and that contained either microwave-treated (BDTW) or untreated (BDUTW) ground wheat. Diets were used without an enzyme supplement or after supplementation with an E. coli-derived phytase, alone or in combination with a xylanase. On d 23, samples of digesta from the duodenum/jejunum and lower ileum were pooled per segment on a pen basis, freeze-dried, and analyzed for P, InsPs, and the marker TiO2. Statistical significance was evaluated by a two-way analysis of variance. Microwaving affected dietary intrinsic phytase activity (BDUTW: 623U/kg; BDTW: 121U/kg). Interactions between microwave treatment and enzyme supplementation were found for InsP6 hydrolysis (P=0.048) and P net absorption (P=0.004) in the ileum. In both segments, InsP6 hydrolysis (duodenum/jejunum: P=0.004, ileum: P=0.002) and P net absorption (P≤0.001) were significantly increased by supplementation of phytase, but no further increments were caused by supplemental xylanase. The significant interaction on InsP6 hydrolysis in the ileum was due to a higher InsP6 hydrolysis for BDTW (78%) than for BDUTW (69%) in the absence of supplemental phytase. In birds that were fed the phytase-supplemented diets, microwave treatment of wheat had no effect on InsP6 hydrolysis. The significant interaction on P net absorption in the ileum was due to reduced P net absorption by microwave treatment in the presence but not absence of supplemental phytase. Broilers and their gut microbiota have a high potential to hydrolyze InsP6 in the intestine. Microwaving may have disrupted wheat aleurone structures in ways that increased accessibility of InsP6 and may have encouraged higher levels of activity among specific phytases of microbial or endogenous mucosal origin in the lower small intestine. Accumulation of InsP3 in the duodenum/jejunum for microwave-treated diets suggested that such treatment reduces the effectiveness of the phosphatases that further degrade InsP3 (P=0.004).

Hydrolysis of phytate and formation of inositol phosphate isomers without or with supplemented phytases in different segments of the digestive tract of broilers.

The objective was to characterise degradation of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) and formation of inositol phosphate (InsP) isomers in different segments of the broiler digestive tract. Influence of an Aspergillus niger (PhyA) and two Escherichia coli-derived (PhyE1 and PhyE2) phytases was also investigated. A total of 600 16-d-old broilers were allocated to forty floor pens (ten pens per treatment). Low-P (5·2g/kg DM) maize-soyabean meal-based diets were fed without (basal diet; BD) or with a phytase added. On day 25, digesta from different digestive tract segments were pooled per segment on a pen-basis, freeze-dried and analysed for P, InsP isomers and the marker TiO2. InsP6 degradation until the lower ileum (74 %) in BD-fed birds showed a high potential of broilers and their gut microbiota to hydrolyse InsP6 in low-P diets. Different InsP patterns in different gut segments suggested the involvement of phosphatases of different origin. Supplemented phytases increased InsP6 hydrolysis in the crop (P<0·01) but not in the lower ileum. Measurements in the crop and proventriculus/gizzard confirmed published in vitro degradation pathways of 3- and 6-phytases for the first time. In the intestinal segments, specifically formed InsP4-5 isomers of supplemented phytases were still present, indicating further activity of these enzymes. Myo-inositol tetrakisphosphate (InsP4) accumulation differed between PhyE1 and PhyE2 compared with PhyA in the anterior segments of the gut (P<0·01). Thus, the hydrolytic cleavage of the first phosphate group is not the only limiting step in phytate degradation in broilers.

Influence of phytate level on broiler performance and the efficacy of 2 microbial phytases from 0 to 21 days of age

Phytate is an antinutrient in animal feeds, reducing the availability and increasing the excretion of nutrients. Phytases are widely used to mitigate the negative influences of phytate. This trial was designed to compare the efficacy of 2 Escherichia coli-derived phytases on broiler performance and bone ash as influenced by dietary phytate level. A total of 1,024 Arbor Acres male broilers were used with 8 replicate pens of 16 birds/pen. Experimental diets were based on low available phosphorus (avP; 1.8 g/kg) with low (6.40 g/kg) or high (10.65 g/kg) phytate. The low-avP diets were then supplemented with mono-dicalcium phosphate to increase the avP level to 4.5 g/kg, 500 phytase units/kg of phytase A, or 500 phytase units/kg of phytase B to create 8 experimental diets. Feed intake, BW gain, FCR, and livability were influenced by a P source × phytase interaction. Feed intake, BW gain, and livability were reduced and FCR was higher in broilers fed low-avP diets, particularly in the presence of high phytate. Phytase A or phytase B improved feed intake, BW gain, and FCR, particularly in the high-phytate diet. However, broilers fed phytase A ate more and were heavier than broilers fed phytase B. Tibia ash was lowest in broilers fed the low-avP diet and highest in broilers fed the diet supplemented with mono-dicalcium phosphate. Phytase increased tibia ash, and broilers fed phytase A had an increase in tibia ash compared with broilers fed phytase B. In conclusion, high dietary phytate reduced broiler performance. Phytase A and phytase B improved bone ash and growth performance, especially in the high-phytate diets. However, phytase A was more efficacious than phytase B, regardless of the level of phytate.

Comparative effects of three phytases on the phosphorus and calcium use in the weaned piglet

The addition of phytase to swine diets has generally increased P digestibility and consequently reduced fecal excretion of P. The comparative effects on P and Ca digestibility of dietary inclusion of 5 different phytases were evaluated in the weaned piglet. RONOZYME HiPhos is a microbial 6-phytase produced by synthetic genes, mimicking a gene from Citrobacter braakii, and was compared to the Escherichia coli-derived phytases Phyzyme and OptiPhos. In total, 112 weaned piglets (28 d old) were allocated to 8 equal groups of 14 animals. Pigs were fed for 29 d a vegetable-based diet without addition of mineral P [Co(-)] or this diet supplemented with 12 g/kg feed of CaHPO(4) [Co(+)] or with HiPhos at 1000 units/kg (H1000) or 1500 units/kg (H1500), Phyzyme at 500 units/kg (P500) or 750 units/kg (P750), or OptiPhos at 500 units/kg (O500) or 750 units/kg (O750). All phytases reduced (P < 0.05) fecal P concentration and excretion and increased (P < 0.05) P digestibility and apparent P absorption. The digestible P equivalences of H1000, H1500, P500, P750, O500, and O750 were 0.94, 1.50, 0.67, 0.92, 0.58, and 1.11 g of full available P/kg of feed, respectively. Calcium digestibility was increased (P < 0.05) and Ca excretion reduced (P < 0.05) by the phytases. The 3 phytase preparations increased digestibility and apparent absorption of P and Ca in weaned piglets fed a diet containing P exclusively from plant origin.

Histomorphology and small intestinal sodium-dependent glucose transporter 1 gene expression in piglets fed phytic acid and phytase-supplemented diets1

An experiment was conducted to determine the effect of dietary phytic acid (PA) and phytase supplementation on small intestinal histomorphology and Na-dependent glucose transporter 1 (SGLT1) gene expression in piglets. Twenty-four piglets with an average initial BW of 7.60 ± 0.73 kg were randomly assigned to 3 experimental diets, to give 8 piglets per diet. The diets were a casein-cornstarch-based diet that was supplemented with 0 or 2% PA, or 2% PA (as Na phytate) plus an Escherichia coli-derived phytase at 500 phytase units/kg. The basal diet was formulated to meet the 1998 NRC energy, digestible AA, mineral, and vitamin requirements for piglets. After 10 d of feeding, the piglets were killed to determine small intestinal histomorphology and small intestinal SGLT1 gene expression. Phytic acid supplementation did not affect (P > 0.1) villus height (VH) and the VH-to-crypt depth (CD) ratio, but did decrease (P < 0.05) CD in the jejunum. Phytase supplementation did not affect (P > 0.1) VH, CD, and the VH-to-CD ratio. Phytic acid supplementation reduced SGLT1 gene expression in the duodenum, jejunum, and ileum by 1.1-, 5.4-, and 2.4-fold, respectively. Phytase supplementation increased SGLT1 gene expression in the jejunum by 2.6-fold, but reduced SGLT1 gene expression in the duodenum and ileum by 2.0- and 4.0-fold, respectively. In conclusion, PA reduced CD in the jejunum and SGLT1 gene expression in the duodenum, jejunum, and ileum, whereas phytase supplementation increased the expression of SGLT1 in the jejunum. The reduced SGLT1 gene expression by PA implies that PA reduces nutrient utilization in pigs partly through reduced expression of SGLT1, which is involved in glucose and Na absorption. The increased expression of SGLT1 in the jejunum by phytase supplementation implies that phytase alleviated the negative effects of PA partly through increased expression of SGLT1.

Phytase supplementation improved growth performance and bone characteristics in broilers fed varying levels of dietary calcium

An experiment was conducted to investigate the effect of dietary Ca level on the efficacy of phytase. A total of 288 male Ross × Ross 708 broilers with initial and final BW of 37 and 705 g, respectively, were used in brooder batteries from 0 to 21 d posthatch. Each treatment had 8 replications with 6 broilers/replicate pen. All diets were corn-soybean meal based and formulated to contain 1.26% total Lys. The treatments were positive control with 0.45% nonphytate P and 1% Ca and a negative control with 0.20% nonphytate P with 0.67, 1.00, or 1.33% Ca fed with or without 500 phytase units of Optiphos (Escherichia coli-derived phytase; JBS United Inc., Sheridan, IN). Increasing Ca from 0.67 to 1.33% linearly decreased (P ≤ 0.003) ADG, ADFI, bone breaking strength, bone weight, tibia ash weight, and percentage tibia ash; however, quadratic effects were found for ADFI, G:F, percentage tibia ash, and mortality (P ≤ 0.09). Phytase supplementation increased (P < 0.001) ADG, ADFI, bone breaking strength, bone weight, ash weight, and percentage tibia ash and decreased (P = 0.054) mortality. The increase in ADG, ADFI, bone weight, ash weight, and percentage tibia ash (P ≤ 0.026) and decrease in mortality (phytase × Ca linear; P = 0.058) from phytase supplementation was greater in broilers fed the higher levels of Ca. Calcium utilization was linearly decreased (P < 0.002) with increasing Ca. Phosphorus digestibility and utilization were increased with increasing levels of Ca (P ≤ 0.002); however, P utilization decreased at 1% Ca and increased at 1.33% (quadratic; P < 0.070). Phytase supplementation increased Ca utilization (P < 0.024), P digestibility (P < 0.001), and P utilization (P < 0.029). However, the increase in P digestibility (phytase × Ca; P < 0.021) was greater at the lower levels of Ca whereas P utilization (phytase × Ca; P < 0.001) was greater at 1.33% Ca with phytase supplementation. The results of this research indicate that dietary Ca level, within the ranges used in this experiment, does not negatively affect the efficacy of phytase.

Efficacy of different commercial phytase enzymes and development of an available phosphorus release curve for Escherichia coli-derived phytases in nursery pigs12

In 2 experiments, a total of 184 pigs (PIC, initial BW of 10.3 and 9.7 kg for Exp. 1 and 2, respectively) were used to develop an available P (aP) release curve for commercially available Escherichia coli-derived phytases. In both experiments, pigs were fed a corn-soybean meal basal diet (0.06% aP) and 2 diets with added inorganic P (iP) from monocalcium phosphate (Exp. 1: 0.075 and 0.15% aP; Exp. 2: 0.07 and 0.14% aP) to develop a standard curve. In Exp. 1, 100, 175, 250, or 500 phytase units (FTU)/kg of OptiPhos 2000 or 200, 350, 500, or 1,000 FTU/kg of Phyzyme XP were added to the basal diet. In Exp. 2, 250, 500, 750, or 1,000 FTU/kg of OptiPhos 2000; 500, 1,000, or 1,500 FTU/kg of Phyzyme XP; or 1,850 or 3,700 FTU/kg of Ronozyme P were added to the basal diet. One FTU was defined as the amount of enzyme required to release 1 µmol of iP per minute from sodium phytate at 37°C. For all phytase products, the manufacturer-guaranteed phytase activities were used in diet formulation. All diets were analyzed for phytase activity using both the Phytex and AOAC methods. Pigs were blocked by sex and BW and allotted to individual pens with 8 pens per treatment. Pigs were killed on d 21, and fibulas were collected and analyzed for bone ash. In both experiments, increasing iP improved (linear, P < 0.01) G:F and percentage bone ash. Pigs fed increasing OptiPhos had improved (Exp. 1: linear, P < 0.001; Exp. 2: quadratic, P < 0.001) percentage bone ash, as did pigs fed increasing Phyzyme XP (linear, P < 0.001). In Exp. 2, increasing Ronozyme P improved (quadratic, P < 0.01) percentage bone ash. Using analyzed values from the AOAC method and percentage bone ash as the response variable, an aP release curve was developed for up to 1,000 FTU/kg of E. coli-derived phytases (OptiPhos 2000 and Phyzyme XP) in P-deficient diets. The prediction equation was Y = -0.000000125X(2) + 0.000236X + 0.016, where Y = aP release (%) and X = analyzed phytase (FTU/kg) in the diet.

Influence of an enzyme cocktail and phytase individually or in combination in Ven Cobb broiler chickens

1. An experiment (21 d) was conducted to determine if the response of chicks to a cocktail of xylanase, amylase, and protease (XAP) or Escherichia coli-derived phytase individually or in combination when fed a nutritionally marginal maize–soybean meal diet is age-dependent. 2. A total of 250 one-day-old Ven Cobb broiler chicks were allocated to 5 dietary treatments in a randomised complete block design. The treatments were as follows: (1) positive control with supplemental inorganic P; (2) negative control (NC) marginal in P and ME; (3) NC plus XAP to provide (per kg of diet) 650, 1650 and 4000 U of xylanase, amylase, and protease, respectively; (4) NC plus phytase added to provide 1000 phytase units/kg; and (5) NC plus a combination of XAP and phytase. 3. Low ME and P in the NC diet depressed weight gain and gain:feed. A cocktail of XAP alone did not improve performance, but phytase supplementation improved weight gain. The enzymes were additive in their effects on growth performance. 4. The enzymes had no effect on ileal digestible energy. Ileal N digestibility was higher in diets with XAP or phytase individually compared with NC. Both phytase and XAP individually and in combination improved ileal P digestibility compared with NC. 5. Total tract nutrient retention and ME increased as the birds grew older. There were age × diet interactions in total tract retention of P and Ca; improvement in P retention due to phytase use decreased by 50% as the chicks matured. 6. The current study shows that a combination of XAP and phytase improved performance, but the enhancement in performance appears to be due mainly to phytase. Both XAP and phytase were effective in improving P digestibility and retention of chicks receiving nutritionally marginal maize–soybean meal. 7. The data also showed that the chicks benefited more from the enzyme addition at a younger age and that the contribution of the enzymes to nutrient retention decreased with age in chickens.

An Escherichia coli-derived phytase can fully replace inorganic phosphorus in maize–soybean meal diets for growing-finishing pigs

A total of 396 gilts (PIC 337 × C22 [synthetic white-line dam], 22.4 ± 2.3 kg body weight) was used in a four-treatment trial to investigate the effect of two phytase utilization strategies on growth performance, bone ash and nutrient excretion. Pigs were housed in an environmentally controlled building that contained multiple manure pits. Three contiguous pens housing 11 pigs each were located above each pit. Pens were weighed individually and an average weight for each pit was calculated. Blocks of three pits were then formed based on body weight and randomly allotted to dietary treatments, totaling three pits (nine pens) per treatment. Dietary treatments included (1) a phosphorus (P)-adequate maize–soybean meal control diet (PC), (2) PC less 1.3 g inorganic P (iP)/kg (NC), (3) NC plus 500 FTU phytase (OptiPhos, Phytex LLC)/kg, and (4) a diet devoid of iP with phytase supplemented to meet the P requirements of the pigs. Thus, phytase levels of 1000, 500 and 300 FTU/kg were supplemented from 22 to 49, 49 to 91 and 91 to 130 kg body weight, respectively. The P-releasing values utilized for 300, 500 and 1000 FTU/kg phytase were 1.0, 1.3 and 2.0 g/kg, respectively. Bone ash (metacarpals III and IV; g/100 g and g) was measured on one pig per pen at approximately 74 kg and on three pigs per pen at the end of the trial. Overall, pigs fed the NC diet tended to have lower (P<0.10) weight gains than the other pigs. Additionally, pigs fed the diet devoid of iP with graded phytase supplementation tended to have greater (P<0.10) gain/feed ratios than pigs fed the P-adequate diet. Bone ash (g and g/100 g) was highest (P<0.05) for control and NC + phytase pigs, whereas the NC pigs had the lowest (P<0.05) values, regardless of sampling time. Overall, P excretion was reduced (P<0.01) by 69 g/100 g from pigs fed the diet devoid of iP with graded phytase utilization. Complete replacement of iP with an E. coli-derived phytase maintained growth performance in growing-finishing gilts when diets were formulated to a similar available P concentration using accurate P-releasing efficacy estimates for phytase.

Corn Expressing an Escherichia Coli-Derived Phytase Gene: Comparative Evaluation Study in Broiler Chicks

The efficacy of corn expressing an Escherichia coli- derived gene (corn-based phytase; CBP) and an E. coli-derived microbial phytase (expressed in Pichia pastoris) sprayed onto a wheat carrier (Quantum) was comparatively evaluated in two 14-d broiler chicken studies. In experiment 1, a total of 288 seven-day-old male broiler chicks were grouped by weight into 8 blocks of 6 cages, with 6 birds per cage, and used to measure growth performance, bone mineralization, and nutrient utilization. In experiment 2, a total of 192 seven-day-old male broiler chicks were used, with 4 birds per cage. Six dietary treatment groups were randomly allotted to the cages within each of 8 blocks. The corn-soybean meal-based diets used in each study consisted of a positive control adequate in P and Ca; a negative control (NC) low in P and Ca (no added inorganic P); the NC supplemented with 3,630, 36,300, or 363,000 phytase units (FTU) of CBP/kg; and the NC + 3,630 FTU of Quantum/kg. Growth performance and bone mineralization criteria were reevaluated in the second broiler study. Data from the 2 experiments were combined because there was no diet × experiment interaction and analyzed as a randomized complete block design. Weight gain decreased (P < 0.05) with a reduction in dietary P and Ca in the NC diet. Weight gain, feed efficiency, and percentage of tibia ash of birds fed 3,630 FTU/kg of either CBP or Quantum phytase were not different. There was a quadratic response (P < 0.01) to CBP supplementation of the NC diets in weight gain of the broiler chicks. Feed intake increased quadratically (P < 0.01) with CBP supplementation of the NC diets, but CBP supplementation of the NC diets did not affect feed efficiency. Tibia ash of birds fed the positive control diet was greater (P < 0.01) than that of birds fed the NC diet. There was a quadratic response (P < 0.01) to CBP supplementation of the NC diets in tibia ash of the broiler chicks. Birds fed supplemental phytase had greater (P < 0.01) ileal and total tract P and Ca digestibility than birds fed the NC diet. Data from the study suggest that E. coli phytase expressed in corn is efficacious in P-deficient broiler chick diets for the improvement of growth performance and indices of P utilization, which would minimize the need for supplemental P in broiler diets.

Effects of Phytate and Phytase on the Performance and Immune Function of Broilers Fed Nutritionally Marginal Diets

The effects of phytate and phytase on broiler performance and cellular and humoral immunity was assessed by using 504 Cobb 500 female broilers fed nutritionally marginal diets. At 1 d of age, the chicks were randomly allocated to 6 treatments in a 2 × 3 factorial arrangement including 2 levels of phytate P (0.22 or 0.44%) and 3 dose rates of an Escherichia coli-derived phytase [0, 500, or 1,000 phytase units (FTU)/kg of feed]. Both low- and high-phytate diets were corn and soy based with the same nutritional specifications (AME 2,900 kcal/kg, CP 21.00%, Ca 0.78%, and nonphytate P0.28%), differing only in the concentration of phytate P. The immune status of birds was measured at 14, 21, and 28 d of age. The results revealed that phytase improved feed intake, BW, and feed conversion ratio (P < 0.05), whereas high dietary phytate depressed bird performance (P < 0.05). There was no interaction between phytate and phytase on bird performance. Feeding phytase increased the percentages of erythrocyte rosette-forming cells and erythrocyte-antibody complement cells by 3.03 and 1.83% at d 21, and by 2.76 and 2.20% at d 28, respectively (P < 0.05). The percentages of CD4+ CD8+ T lymphocyte subsets were also increased by phytase (P < 0.05), without affecting the ratio of CD4+ and CD8+. The levels of intestinal secretory IgA were improved with phytase at d 14, 21, and 28 (P < 0.05). Antibodies against Newcastle disease virus vaccine were enhanced at d 21 and 28 in the high-phytate diets with phytase addition (P < 0.05). Increasing the phytase dose to 1,000 FTU/kg did not improve immune function further than 500 FTU/kg. The results suggest that application of phytase in nutritionally marginal diets could enhance lymphocyte numbers and the seral and mucosal antibodies of 1- to 28-d-old broilers, suggesting that both phytate and phytase may have a role in gastrointestinal health and immune competence.

Effects of dietary phytase on performance and nutrient metabolism in chickens

1. A broiler growth study was conducted to compare the effect of different concentrations of an Escherichia coli-derived phytase on performance, apparent metabolisable energy (AME), nitrogen (N), amino acid and mineral metabolisability, sialic acid excretion and villus morphology when fed to broiler chickens. 2. Female Ross 308 broilers (480) were reared in floor pens from 0 to 28 d of age. All birds were fed on nutritionally complete starter (0 to 21 d of age) and grower diets (21 to 28 d of age) with the exception that they were low in P (28 and 23 g/kg available P, respectively). These maize–soy diets were supplemented with 0, 250, 500 or 2500 phytase units (FTU)/kg feed. 3. Between 21 and 28 d of age, two birds from each floor pen were selected, and each pair placed in one of 32 metabolism cages (two birds per cage). Feed intake was recorded and excreta collected for the last 2 d of the feeding period, and AME, N, amino acid and mineral metabolisability coefficients and endogenous losses were determined following a total collection procedure. 4. Feed intake and weight gain increased in a linear manner in response to phytase dose, with an average increase of approximately 11·7 and 13·5%, respectively, compared with chickens fed on the low-P diet. Birds given diets with 2500 FTU weighed 6·6% more and had a 2·4% higher feed conversion efficiency (FCE) than those fed on diets containing 500 FTU. 5. Enzyme supplementation increased the intake of AME and metabolisable N by 10·3 and 3·9%, respectively, principally through increases in feed intake. Birds given enzyme-supplemented diets also improved their intake of metabolisable amino acids and P by approximately 14 and 12·4%, respectively, compared with birds fed on the control diet. Enzyme supplementation did not affect ileal villus morphometry of the birds. †Dr O. Oduguwa is visiting scientist from University of Agriculture, PMB 2240, Abeokuta, Nigeria.

Supplementing corn or corn-barley diets with an E. coli derived phytase decreases total and soluble P output by weanling and growing pigs

The efficacy of an E. coli derived phytase on phosphorus (P) digestibility and excretion, on the form of the P excreted, and the optimal dietary calcium (Ca):P ratio was examined. In exp. 1, 63 barrows (40.4 ± 1.9 kg) were assigned to receive one of 21 treatments arranged as a 3 × 7 factorial. Treatments consisted of three Ca levels (0.50, 0.60 and 0.70%) and seven phytase treatments [0, 250, 500, 1000 and 2000 FTU kg-1 of an E. coli-derived phytase and 500 FTU kg-1 of an A. niger phytase added to a P deficient (0.37% P) diet or 0 FTU phytase kg-1 added to a P adequate (0.53% P) diet]. In exp. 2, 144 pigs (6.52 ± 0.75 kg), received a P adequate (0.60% P) diet or a P deficient (0.44% P) diet supplemented with 0, 250, 500, 1000 or 2000 FTU phytase kg-1 for a 28-d trial. A subset of 36 barrows was then fed the same diets in a balance trial. In exp. 3, 36 barrows (7.1 ± 0.75 kg) were assigned to one of six treatments arranged as a 2 × 3 factorial (0 or 500 FTU of phytase kg-1; 1.0, 1.6 or 2.2 Ca:P ratio). In exp. 1, P digestibility improved from 21 to 54% with increasing phytase (quadratic; P &lt; 0.05). Supplementing the diet with 500 FTU phytase kg-1 decreased the output of total and soluble P by 25% in exp. 2 and to a similar extent in exp. 3 at the lowest Ca:P ratio (P &lt; 0.05). The effect of phytase on total P digestibility was mitigated as the dietary Ca:P ratio increased in exp. 3. Supplementation of swine diets with an E. coli derived phytase decreases output of total and soluble forms of P, but this effect is reduced at high dietary Ca:P ratios. Key words: Swine, E. coli phytase, phosphorus, soluble phosphorus

Corn expressing an Escherichia coli-derived phytase gene: A proof-of-concept nutritional study in pigs1

Two experiments were conducted to investigate the concept that the addition of corn expressing an Escherichia coli-derived gene (corn-based phytase; CBP) to a P-deficient diet would improve growth performance and P utilization in pigs. An E. coli-derived microbial phytase (expressed in Pichia pastoris) sprayed onto a wheat carrier (Quantum) was included for comparison. In Exp. 1, forty-eight 10-kg pigs were blocked by BW into 6 blocks and allotted to 8 dietary treatments such that the BW among dietary treatments was similar and given free access to feed for 28 d. The dietary treatments were a negative control (NC) with no inorganic P supplementation; NC + 2, 4, or 6 g of monosodium phosphate/kg; NC + 16,500, 33,000, or 49,500 phytase units (FTU) of CBP/kg; and NC + 16,500 FTU of Quantum/kg. In Exp. 2, twenty-four 13-kg barrows were assigned to the NC, NC + 16,500 or 33,000 FTU of CBP/kg, or NC + 16,500 FTU of Quantum/kg, in a nutrient- and energy-balance study consisting of 5 d of adjustment and 5-d collection periods. The total collection method was used to determine nutrient and energy balance. Addition of CBP to the low-P NC diet linearly increased (P < 0.01) ADG, G:F, and plasma P concentration of pigs during the 28-d study. There was no difference in ADG, G:F, or plasma P concentration between pigs fed the CBP or Quantum phytase at 16,500 FTU/kg. Weight gain, G:F, and plasma P concentration of pigs increased (P < 0.01) with monosodium phosphate supplementation, confirming P deficiency of the NC diet. Linear improvements (P < 0.05) in DM digestibility and energy retention were observed with CBP supplementation of the NC diet. Although there were linear (P < 0.01) and quadratic (P < 0.05) increases in N digestibility, N retention was unaffected by CBP supplementation of the NC diet in growing pigs. Phosphorus and Ca digestibilities and retentions improved linearly and quadratically (P < 0.01) with the addition of CBP to the NC diet. There was no difference in digestive utilization of P or Ca between pigs fed CBP and Quantum phytase at 16,500 FTU/kg. The data showed that the addition of a corn expressing an E. coli-derived gene to a P-deficient diet improved growth performance and indices of P utilization in pigs, and corn expressing phytase was as efficacious as Quantum phytase when supplemented in P-deficient diets for weanling pigs.

Age-Related Influence of a Cocktail of Xylanase, Amylase, and Protease or Phytase Individually or in Combination in Broilers

This 21-d experiment was conducted to determine if the response of chicks to a cocktail of xylanase, amylase, and protease (XAP) or Escherichia coli-derived phytase individually or in combination when fed a nutritionally marginal corn-soybean meal diet is age-dependent. Six hundred 1-d-old chicks were allocated to 5 dietary treatments in a randomized complete block design. The treatments were as follows: 1) positive control with supplemental inorganic P; 2) negative control (NC) marginal in P and ME; 3) NC plus XAP to provide (per kg of diet) 650, 1,650, and 4,000 U of xylanase, amylase, and protease, respectively; 4) NC plus phytase added to provide 1,000 phytase units/kg; and 5) NC plus a combination of XAP and phytase. Low ME and P in the NC diet depressed weight gain and gain:feed (P < 0.001). A cocktail of XAP alone did not improve performance, but phytase supplementation improved (P < 0.001) weight gain. The enzymes were additive in their effects on growth performance. The enzymes had no effect on ileal digestible energy. Ileal N digestibility was higher (P < 0.05) in diet with XAP or phytase individually compared with NC. Both phytase and XAP individually and in combination improved (P < 0.01) ileal P digestibility compared with NC. Total tract nutrient retention and ME increased (P < 0.01) as the birds grew older. There were age x diet interactions (P < 0.001) on total tract retention of P and Ca; improvement in P retention due to phytase use decreased by 50% as the chicks matured. The current study shows that a combination of XAP and phytase improved performance, but the enhancement in performance appears to be mainly from phytase. Both XAP and phytase were effective in improving P digestibility and retention of chicks receiving nutritionally marginal corn-soybean meal. The data also shows that the chicks benefited more from the enzyme addition at a younger age and that the contribution of the enzymes to nutrient retention decreased with age in chickens.

Efficacy and equivalency of an Escherichia coli-derived phytase for replacing inorganic phosphorus in the diets of broiler chickens and young pigs1

Two studies were conducted to determine the efficacy of an Escherichia coli-derived phytase (ECP) and its equivalency relative to inorganic phosphorus (iP) from monosodium phosphate (MSP). In Exp. 1, one thousand two hundred 1-d-old male broilers were used in a 42-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments were based on corn-soybean meal basal diets (BD) containing 239 and 221 g of CP, 8.2 and 6.6 g of Ca, and 2.4 and 1.5 g of nonphytate P (nPP) per kg for the starter and grower phases, respectively. Treatments consisted of the BD; the BD + 0.6, 1.2, or 1.8 g of iP from MSP per kg; and the BD + 250, 500, 750, or 1,000 phytase units (FTU) of ECP per kg. Increasing levels of MSP improved gain, gain:feed, and tibia ash (linear, P < 0.01). Increasing levels of ECP improved gain, gain:feed, tibia ash (linear, P < 0.01), apparent ileal digestibility of P, N, Arg, His, Phe, and Trp at d 21 (linear, P < 0.05), and apparent retention of P at d 21 (linear, P < 0.05). Increasing levels of ECP decreased apparent retention of energy (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.72, 0.78, and 1.19 g of iP from MSP per kg in broiler diets based on gain, feed intake, and bone ash, respectively. In Exp. 2, forty-eight 10-kg pigs were used in a 28-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments consisted of a positive control containing 6.1 and 3.5 g of Ca and nPP, respectively, per kg; a negative control (NC) containing 4.8 and 1.7 g of Ca and nPP, respectively, per kg; the NC diet plus 0.4, 0.8, or 1.2 g of iP from MSP per kg; and the NC diet plus 500, 750, or 1,000 FTU of ECP per kg. Daily gain improved (linear, P < 0.05) with ECP addition, as did apparent digestibility of Ca and P (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.49 and 1.00 g of iP from MSP per kg in starter pigs diets, based on ADG and bone ash, respectively.

Supplementation of Corn–Soy-Based Diets with an Eschericia coli-Derived Phytase: Effects on Broiler Chick Performance and the Digestibility of Amino Acids and Metabolizability of Minerals and Energy

The effect of the supplementation of diets containing low available P concentrations with low and supra-activities of an Eschericia coli 6-phytase was assessed using growing broiler chicks. A total of 384 female Ross broiler chicks were weighed at d 1 of life and assigned to 1 of 8 experimental treatments. There were 12 replicate cages with 4 chicks per cage, and the diets were fed from d 1 of life for a period of 16 d. A positive control diet (5 g/kg of available P) and a negative control diet (3 g/kg of available P) were used, and 6 more diets were manufactured by supplementing the negative control diet with 150, 300, 600, 1,200, 2,400, and 24,000 U/kg of exogenous phytase. Body weight gain and feed conversion ratios were determined, as were nutrient digestibility coefficients and toe ash values. Birds fed the negative control diet had lower (P < 0.05) weight gains than those fed the positive control diet. The addition of exogenous phytase above 150 U/kg improved (P < 0.05) weight gain, toe ash percentage, and nutrient utilization of the birds fed the negative control diet. Furthermore, the 24,000 U/kg of diet improved (P < 0.05) toe ash percentage and the utilization of several nutrients beyond that of the lower doses of phytase. It can be concluded that the supplementation of diets containing 3 g/kg of available P with exogenous phytase can improve the performance of chicks to that of birds fed a diet containing 5 g/kg of available P. In addition, the use of high doses of phytase (>1,000 U/kg of diet) can improve nutrient availability in poultry diets beyond that of diets containing lower (<1,000 U/kg) phytase activities. These results may be mediated partially by reduced endogenous loss as well as an increase in the availability of dietary nutrients as indicated by improvements in digestibility coefficients.