Effectiveness of an experimental consensus phytase in improving dietary phytate-phosphorus utilization by weanling pigs

Consensus phytase is a new biosynthetic, heat-stable enzyme derived from the sequences of multiple homologous phytases. Two experiments were conducted to determine its effectiveness, relative to inorganic P and a mutant enzyme of Escherichia coli phytase (Mutant-EP), in improving dietary phytate-P availability to pigs. In Exp. 1, 36 pigs (3 wk old, 7.00 +/- 0.24 kg of BW) were fed a low-P corn-soybean meal basal diet plus consensus phytase at 0, 250, 500, 750, 1,000, or 1,250 U/kg of feed for 5 wk. Plasma inorganic P concentration, plasma alkaline phosphatase activity, bone strength, and overall ADG and gain:feed ratio of pigs were improved (P < 0.05) by consensus phytase in both linear (R2 = 0.20 to 0.70) and quadratic (R2 = 0.30 to 0.70) dose-dependent fashions. In Exp. 2, 36 pigs (4 wk old, 9.61 +/- 0.52 kg BW) were fed the basal diet + inorganic P at 0.1 or 0.2%, consensus phytase at 750 or 450 U/kg of feed, Mutant-EP at 450 U/kg of feed, or 225 U consensus + 225 U Mutant-EP/kg of feed. Pigs fed 750 U of consensus phytase or 450 U of Mutant-EP/kg feed had plasma inorganic concentrations and bone strength that fell between those of pigs fed 0.1 or 0.2% inorganic P. These two measures were 16 to 29% lower (P < 0.05) in pigs fed 450 U of consensus phytase/kg of feed than those of pigs fed 0.2% inorganic P. Plasma inorganic P concentrations were 14 to 29% higher (P < 0.05) in pigs fed Mutant-EP vs. consensus phytase at 450 U/kg at wk 2 and 3. In conclusion, the experimental consensus phytase effectively releases phytate P from the corn-soy diet for weanling pigs. The inorganic P equivalent of 750 U of consensus phytase/kg of feed may fall between 0.1 and 0.2%, but this requires further determination.     

Phytase improves iron bioavailability for hemoglobin synthesis in young pigs.

Dietary phytase supplementation improves bioavailabilities of phytate-bound minerals such as P, Ca, and Zn to pigs, but its effect on Fe utilization is not clear. The efficacy of phytase in releasing phytate-bound Fe and P from soybean meal in vitro and in improving dietary Fe bioavailability for hemoglobin repletion in young, anemic pigs was examined. In Exp. 1, soybean meal was incubated at 37 degrees C for 4 h with either 0, 400, 800, or 1,200 units (U) of phytase/kg, and the released Fe and P concentrations were determined. In Exp. 2, 12 anemic, 21-d-old pigs were fed either a strict vegetarian, high-phytate (1.34%) basal diet alone, or the diet supplemented with 50 mg Fe/kg diet (ferrous sulfate) or phytase at 1,200 U/kg diet (Natuphos, BASF, Mt. Olive, NJ) for 4 wk. In Exp. 3, 20 anemic, 28-d-old pigs were fed either a basal diet with a moderately high phytate concentration (1.18%) and some animal protein or the diet supplemented with 70 mg Fe/kg diet, or with one of two types of phytase (Natuphos or a new phytase developed in our laboratory, 1,200 U/kg diet) for 5 wk. In Exp. 2 and 3, diets supplemented with phytase contained no inorganic P. In Exp. 1, free P concentrations in the supernatant increased in a phytase dose-dependent fashion (P<.05), whereas free Fe concentrations only increased at the dose of 1,200 U/kg (P<.10). In Exp. 2 and 3, dietary phytase increased hemoglobin concentrations and packed cell volumes over the unsupplemented group; these two measures, including growth performance, were not significantly different than those obtained with dietary supplemental Fe. In conclusion, both sources of phytase effectively degraded phytate in corn-soy diets and subsequently released phytate-bound Fe from the diets for hemoglobin repletion in young, anemic pigs.     

Comparison of phytase from genetically engineered Aspergillus and canola in weanling pig diets

Ninety-six crossbred pigs with an average weight of 9.0 kg were used in a 5-wk trial to compare the efficacy of genetically engineered Aspergillus ficuum phytase, expressed in Aspergillus niger (Natuphos) or in canola seed (Phytaseed), for enhancing the utilization of phytate P in corn-soybean meal-based diets fed to young pigs and to evaluate the safety of Phytaseed phytase. Three levels of the two sources of phytase (250, 500, or 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing .35% total P, .09% available P, and .50% Ca. There were six pens per treatment (one barrow and one gilt/pen), except that the diet without added phytase was fed to 12 pens of pigs. Pen feed consumption and BW were recorded weekly. During wk 5, pen fecal samples were collected for determination of apparent digestibilities of DM, Ca, and P. At the end of wk 5, all barrows were killed, and the 10th rib on both sides was removed for determination of shear force and energy. Thirty pigs (six from the diet without added phytase and the diets with 500 and 2,500 U/kg phytase from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney, and bone tissues. Both sources of phytase were equally effective in increasing (P < .05) daily gain, gain:feed, apparent digestibilities of DM, P, and Ca, and 10th rib measurements. Fecal P excretion was reduced with phytase addition. Feed intake was increased by phytase levels during wk 4 to 5. No significant abnormalities were seen in any of the 30 pigs necropsied. The fit of a nonlinear function revealed that most measurements were reaching a plateau at 2,500 U/kg phytase. In summary, based on performance, bone measurements, and digestibilities of P, Ca, and DM of young pigs, the efficiency of Phytaseed was similar to that of Natuphos for enhancing the utilization of phytate P in corn-soybean meal-based diets. General necropsy and histologic examination of tissues indicated no toxic effect of phytase.     

The efficacy of an Escherichia coli-derived phytase preparation

Five experiments were conducted to evaluate the effect of an Escherichia coli-derived phytase on phytate-P use and growth performance by young pigs. The first experiment involved time course, pH dependence, and phytase activity studies to investigate the in vitro release of P from corn, soybean meal, and an inorganic P-unsupplemented corn-soybean meal negative control diet. In Exp. 2, which was designed to determine the efficacy of the E. coli-derived vs. fungal phytase-added diets at 0, 250, 500, 750, 1,000, or 1,250 FTU/kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P/min, at pH 5.5, from an excess of 15 microM sodium phytate at 37 approximately C) and a positive control diet, eight individually penned 10-kg pigs per diet (12 diets, 96 pigs) were used in a 28-d growth study. The third experiment was a 10-d nutrient balance study involving six 13-kg pigs per diet (four diets, 24 pigs) in individual metabolism crates. In Exp. 4, eight pens (four pigs per pen) of 19-kg pigs per treatment were used in a 42-d growth performance study to examine the effect of adding the E. coli-derived phytase to corn-soybean diets at 0, 500, or 1,000 FTU/kg (as-fed basis) and a positive control (four diets, 128 pigs). In Exp. 5, six 19-kg pigs per treatment were used in a 10-d nutrient balance study to investigate the effects of the E. coli-derived phytase added to diets at 0, 250, 500, 750, or 1,000 FTU/kg (as-fed basis) and a positive control diet (six diets, 36 pigs). The in vitro study showed that the E. coli-derived phytase has an optimal activity and pH range of 2 to 4.5. Inorganic phosphate release was greatest for soybean meal, least for corn, and intermediate for the negative control diet. Dietary supplementation with graded amounts of E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain, feed efficiency, and plasma Ca and P concentrations in 10-kg pigs in Exp. 2. Phytase also increased P digestibility and retention in the 13-kg pigs in Exp. 3. In Exp. 4, dietary supplementation with E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain and feed efficiency of 19-kg pigs. Supplementation of the diets of 19-kg pigs with the E. coli-derived phytase also improved Ca and P digestibility and retention in Exp. 5. In the current study, the new E. coli-derived phytase was efficacious in hydrolyzing phytate-P, both in vitro and in vivo, in young pigs.     

The effects of citric acid on phytate-phosphorus utilization in young chicks and pigs

Several bioassays were conducted with young chicks and pigs fed phosphorus (P)-deficient corn-soybean meal diets. With diets for chicks containing .62% Ca and .42% P (.10% available P), graded doses of a citric acid + sodium citrate (1:1, wt:wt) mixture (0, 1, 2, 4, or 6% of diet) resulted in linear (P < .01) increases in both weight gain and tibia ash. Relative to chicks fed no citric acid, tibia ash (%) and weight gain (g/d) were increased by 43 and 22%, respectively, in chicks fed 6% citric acid. Additional chick trials showed that 6% citric acid alone or sodium citrate alone was as efficacious as the citric acid + sodium citrate mixture and that 1,450 U/kg of phytase produced a positive response in bone ash and weight gain in chicks fed a diet containing 6% citrate. Varying the Ca:available P ratio with and without citrate supplementation indicated that citric acid primarily affected phytate-P utilization, not Ca, in chicks. Moreover, chicks did not respond to citrate supplementation when fed a P-deficient (.13% available P), phytate-free casein-dextrose diet. Young pigs averaging 10 to 11 kg also were used to evaluate citric acid efficacy in two experiments. A P-deficient corn-soybean meal basal diet was used to construct five treatment diets that contained 1) no additive, 2) 3% citric acid, 3) 6% citric acid, 4) 1,450 U/kg phytase, and 5) 6% citric acid + 1,450 U/kg phytase. Phytase supplementation increased (P < .01) weight gain, gain:feed, and metatarsal ash, whereas citric acid addition increased only gain:feed (P < .05) and metatarsal ash (P < .08). A subsequent 22-d pig experiment was conducted to evaluate the effect of lower levels of citric acid (0, 1, 2, or 3%) or 1,450 U/kg phytase addition to a P-deficient corn-soybean meal diet. Phytase supplementation improved (P < .01) all criteria measured. Weight gain and gain:feed data suggested a response to citric acid addition, but this was not supported by fibula ash results (P > .10). The positive responses to phytase were much greater than those to citric acid in both pig experiments. Thus, dietary citric acid effectively improved phytate P utilization in chicks but had a much smaller effect in pigs.     

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

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.     

Distribution of supplemental Escherichia coli AppA2 phytase activity in digesta of various gastrointestinal segments of young pigs

The objective of this study was to determine the functional location and disappearance of activity of a supplemental Escherichia coli AppA2 phytase and its impact on digesta P and Ca concentrations in the gastrointestinal tract of pigs. In Exp. 1, 18 pigs (8.3 +/- 0.2 kg of BW) were allotted to 3 groups (n = 6 each) and fed a low-P (0.4%) corn-soybean meal, basal diet (BD), BD + phytase [500 units (U)/kg of feed], or BD + inorganic P (iP, 0.1%) for 4 wk. In Exp. 2, 30 pigs (14.5 +/- 0.2 kg of BW) were allotted to 3 groups (n = 10 each) and fed BD, BD + 500 U of phytase/kg of feed, or BD + 2,000 U of phytase/kg of feed for 2 wk. Five or six pigs from each treatment group were killed at the end of both experiments to assay for digesta phytase activity and soluble P concentration in 6 segments of the digestive tract and digesta total P and Ca concentrations in stomach and colon. Compared with pigs fed BD, pigs fed BD + 500 U of phytase/kg of feed in Exp. 1 and BD + 2,000 U of phytase/kg of feed in Exp. 2 had greater (P < 0.05) phytase activities in the digesta of the stomach and upper jejunum (2 m aborally from the duodenum). No phytase activity was detected in the digesta of the lower jejunum (2.12 m cranial to the ileocecal junction) or ileum from any of the treatment groups in either trial. Concentrations of digesta-soluble P peaked in the upper jejunum of pigs fed BD in Exp. 1 and 2, but showed gradual decreases between the stomach and the upper jejunum of pigs fed BD + phytase or BD + iP. In both experiments, pigs fed only BD had greater (P < 0.05) colonic digesta phytase activity and soluble P concentrations than those fed phytase. In Exp. 2, total colonic digesta P or Ca concentrations, or both, of pigs displayed a phytase-dose-dependent reduction (P < 0.05). In conclusion, supplemental dietary AppA2 mainly functioned in the stomach and was associated with a reduced phytase activity in colonic digesta of weanling pigs.     

Escherichia coli phytase improves growth performance of starter, grower, and finisher pigs fed phosphorus-deficient diets

Corn-soybean meal-based diets, consisting of a high-P control (HPC) containing supplemental dicalcium phosphate (DCP), a basal diet containing no DCP, and the basal diet plus Escherichia coli phytase at 500 or 1,000 phytase units per kilogram (FTU/kg; as-fed basis) were fed to evaluate growth performance in starter, grower, and finisher pigs. Pigs were blocked by weight and gender, such that average weight across treatments was similar, with equal numbers of barrows and gilts receiving each treatment in each block. In Exp. 1, 48 pigs with an average initial BW of 11 kg, housed individually, with 12 pens per diet, were used to evaluate growth performance over 3 wk. Overall ADG and G:F were increased linearly (P < 0.05) by dietary phytase addition. Final BW and plasma P concentrations at 3 wk also increased linearly (P < 0.05). In Exp. 2, 128 pigs with an average initial BW of 23 kg, housed four pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase in response to phytase was noted for ADG and G:F in all three 2-wk periods, as well as overall (P < 0.05). Percentage of bone ash also showed a linear increase (P < 0.01). In Exp. 3, 160 pigs (53 kg), housed five pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase was detected for final BW, as well as ADG and G:F in the first and second 2-wk periods, and overall (P < 0.01). Twenty-four 15-kg individually housed pigs were used to evaluate total-tract nutrient digestibility in Exp. 4. Daily absorption of P linearly increased (P < 0.05) with phytase supplementation. Results of this research indicate that E. coli phytase is effective in liberating phytate P for uptake and utilization by starter, grower, and finisher pigs.     

Phosphorus bioavailability, growth performance, and nutrient balance in pigs fed high available phosphorus corn and phytase

Three experiments were conducted to evaluate P bioavailability, growth performance, and nutrient balance in pigs fed high available P (HAP) corn with or without phytase. The bioavailability of P in normal and HAP corn relative to monosodiumphosphate (MSP) for pigs was assessed in Exp. 1. In a randomized complete block design, 96 pigs (average initial BW 9.75 kg) were fed eight diets for 28 d. The reference and test diets were formulated by adding P as MSP, HAP, or normal corn at 0, 0.75, or 1.5 g/kg to a corn-starch-soybean meal basal diet (2.5 g/kg P) at the expense of cornstarch. Plasma inorganic P concentration responded linearly (P < 0.05) to supplemental P intake. Estimates of P bioavailability from HAP andnormal corn when plasma P was regressed on supplemental P intake were 46 and 33%, respectively. In Exp. 2 and 3, pigs were fed corn-soybean meal-based diets containing HAP corn or normal corn and 0 or 600 units of phytase per kilogram in a 2 x 2 factorial arrangement (two corn sources and two levels of phytase). In Exp. 2, 48 crossbred pigs (barrow:gilt, 1:1) averaging 9.25 kg were used to evaluate growth performance. There were no detectable interactions between corn source and phytase for any of the performance criteria measured. Pigs receiving normal corn had the lowest (P < 0.05) BW and rate of gain. Feed efficiency was lower (P < 0.05) in pigs fed normal compared with those fed the HAP corn phytase-supplemented diet. In Exp. 3, 24 crossbred barrows averaging 14.0 kg were used to evaluate nutrient digestibility. There were no detectable interactions between corn and phytase for any of the N and Ca balance criteria. Nitrogen and Ca retention were improved in pigs receiving HAP corn with phytase (P < 0.05). Retention and digestibility of P was lowest (P < 0.01) for pigs on normal corn diet without phytase. The percentage of P digested and retained was improved and fecal P excretion lowered (P < 0.05) by feeding HAP corn.The results of this study indicate that the bioavailability and balance of P in HAP corn is superior to that of normal corn. The addition of 600 phytase units (Natuphos 600, BASF) to HAP corn-based diets further improved P digestibility and reduced P excretion in pigs.     

An Escherichia coli phytase expressed in yeast effectively replaces inorganic phosphorus for finishing pigs and laying hens

Two experiments determined the efficacy of an Escherichia coli phytase (ECP) added to P-deficient, corn-soybean meal diets fed to finishing pigs and second-cycle laying hens. Sixty finishing pigs (49 +/- 0.9 kg) were formed into blocks within sex based on weight and ancestry and allotted to a P-deficient diet unsupplemented or supplemented with 0.10% inorganic P (iP) from KH2PO4 or ECP at 250, 500, 1,000, or 10,000 phytase units (FTU)/kg. Individually fed pigs were allowed ad libitum access to the experimental diets until a BW of 120 +/- 3 kg was achieved, at which time the pigs were euthanized and the left fibula and fourth metatarsal were excised for determination of bone ash. Pigs were fed a 2-phase diet program for early- and late-finishing pigs; available P in the basal diets was set 0.10% below the requirement. Dietary supplementation of iP or ECP increased weight gain (P < 0.10) and G:F (P < 0.01); performance was not different (P > 0.13) among the phytase-supplemented groups. Fibula ash was greatest (P < 0.01) for pigs fed diets containing 10,000 FTU of ECP/kg. Two hundred forty second-cycle hens were allotted to a P-deficient diet or a P-deficient diet supplemented with 0.10% iP or ECP at 150, 300, or 10,000 FTU/kg for a 12-wk experiment. The basal diet was a corn-soybean meal diet with no added iP (17% CP, 3.8% Ca, 0.10% available P). Hens fed the P-deficient diet were removed from the experiment after 4 wk due to poor egg production. Supplementation of iP or ECP resulted in increased (P < 0.01) feed intake, egg weight, and egg production during the first 4 wk. During the entire 12-wk period, there were no differences (P > 0.28) between the iP- and ECP-supplemented groups in feed intake, egg weight, or egg production. These experiments reveal that ECP was as efficacious as supplemental iP and that supplementation of an excess dose of ECP was efficacious and without negative effects in finishing pigs and laying hens.     

Effect of low doses of Aspergillus niger phytase on growth performance, bone strength, and nutrient absorption and excretion by growing and finishing swine fed corn-soybean meal diets deficient in available phosphorus and calcium

Two experiments were conducted to evaluate the efficacy of low doses of Aspergillus niger (AN) phytase for growing and finishing pigs fed corn-soybean meal (SBM) diets with narrow Ca:P ratios that were about 0.9 g/kg deficient in available P and Ca. Experiment 1 utilized 120 pigs with an early finisher period from 51.5 +/- 0.2 to 89.7 +/- 0.9 kg of BW and a late finisher period that ended at 122.5 +/- 2.0 kg of BW. During each period, treatments were the low-P diets with 0, 150, 300, or 450 units (U) of AN phytase added/kg of diet, and a positive control (PC) diet. There were linear increases (P < or = 0.001) in bone strength and ash weight, the absorption of P (g/d and %) and Ca (%), and overall ADG (P = 0.01) with increasing concentration of AN phytase. Pigs fed the diets with 150, 300, or 450 U of AN phytase/kg did not differ from pigs fed the PC diet in growth performance overall, and pigs fed the diets with 300 or 450 U of AN phytase did not differ in P and Ca absorption (g/d) or bone ash weight from pigs fed the PC diet. However, only pigs fed the diet with 450 U of AN phytase/kg had bone strength similar to that of pigs fed the PC diet. Experiment 2 utilized 120 pigs in a grower phase from 25.3 +/- 0.1 to 57.8 +/- 0.8 kg of BW and a finisher phase that ended at 107.6 +/- 1.0 kg of BW. Treatments were the low-P diet with AN phytase added at 300, 500, or 700 U/kg of grower diet, and 150, 250, or 350 U/kg of finisher diet, respectively, resulting in treatments AN300/150, AN500/250, and AN700/350. Growth performance and the absorption (g/d) of P and Ca for the grower and finisher phases were not different for pigs fed the diets containing AN phytase and pigs fed the PC diets. However, pigs fed the PC diets excreted more fecal P (g/d, P < or = 0.01) during the grower and more P and Ca (g/d, P < 0.001) during the finisher phases than the pigs fed the diets with phytase. There were linear increases (P < or = 0.05) in bone strength and bone ash weight with increasing concentration of AN phytase. However, pigs fed the PC diets had a greater bone strength and bone ash weight than pigs fed diets AN300/150, AN500/250 (P < or = 0.02), or AN700/350 (P < or = 0.08). There were no treatment responses for N or DM digestibility in either experiment. Phytase supplementation reduced fecal P excretion from 16 to 38% and fecal Ca excretion from 21 to 42% in these experiments. In conclusion, 450 U of AN phytase/kg was effective in replacing 0.9 g of the inorganic P/kg of corn-SBM diet for finishing swine based on bone strength, whereas 300 or 150 U of AN phytase/kg of diet maintained growth performance of grower or finisher pigs, respectively.     

Effects of combining three fungal phytases with a bacterial phytase on plasma phosphorus status of weanling pigs fed a corn-soy diet

The objective of this study was to determine possible synergistic effects of supplementing one of three fungal phytases: Aspergillus fumitagus PhyA (AFP),A. niger PhyA (ANP), or Peniophora lyci phytase (PLP) with an Escherichia coli AppA phytase (EP) in diets for pigs. Three experiments, each lasting for 4 wk, were conducted with a total of 106 weanling pigs (5 wk old). The corn-soybean meal basal diet (BD) contained no supplemental inorganic P. In Exp. 1, 35 pigs (8.6 +/- 1.0 kg BW) were fed (as-fed basis) BD + AFP at 750 U/ kg of feed, BD + inorganic P (0.2% P), or BD + PLP at 500, 750, or 1,000 U/kg feed. Pigs fed BD + AFP or BD + 0.2% P had higher (P < 0.05) plasma inorganic P concentrations than those fed BD + PLP at the end of the trial (wk 4). In Exp. 2, 35 pigs (8.1 +/- 0.9 kg BW) were fed BD + AFP, EP, PLP, a 1:1 mix of AFP:EP, or a 1:1 mix of PLP:EP at 500 U/kg. Pigs fed the AFP:EP mixture had growth performance and plasma measures similar to those fed either enzyme alone. Pigs fed the PLP:EP mixture had lower (P < 0.05) plasma alkaline phosphatase activity than those fed BD + PLP. Pigs fed BD + PLP had lower (P < 0.05) plasma inorganic P concentrations than pigs fed BD + EP, and higher (P < 0.05) plasma alkaline phosphatase activity than all other groups at wk 4. In Exp. 3, 36 pigs (9.1 +/- 1.2 kg BW) were fed BD + ANP, EP, or a 1:1 mix of ANP:EP at 500 U/kg feed. Pigs fed the two enzymes together had lower (P < 0.05) plasma inorganic P concentration than those fed BD + EP and lower (P < 0.05) plasma alkaline phosphatase activity than pigs fed BD + ANP at wk 4. In conclusion, although the four phytases showed different effects on plasma P status of weanling pigs, there was no synergistic effect between any of the three fungal phytases and the bacterial phytase on the plasma measures or growth performance under the conditions of the present study.     

Supplementation of carbohydrases or phytase individually or in combination to diets for weanling and growing-finishing pigs

The overall objective of the studies reported here was to evaluate the growth and nutrient utilization responses of pigs to dietary supplementation of phytate- or nonstarch polysaccharide-degrading enzymes. In Exp. 1, growth performance and nutrient digestibility responses of forty-eight 10-kg pigs to dietary supplementation of phytase or a cocktail of xylanase, amylase, and protease (XAP) alone or in combination were evaluated. The growth response of one hundred fifty 23-kg pigs to dietary supplementation of phytase or xylanase individually or in combination was studied in Exp. 2 in a 6-wk growth trial, whereas Exp. 3 investigated the nutrient digestibility and nutrient retention responses of thirty 24-kg pigs to dietary supplementation of the same enzymes used in Exp. 2. In Exp. 1, the pigs were used in a 28-d feeding trial. They were blocked by BW and sex and allocated to 6 dietary treatments. The treatments were a positive control (PC) diet; a negative control (NC) diet marginally deficient in P and DE; NC with phytase added at 500 or 1,000 phytase units (FTU)/kg; NC with xylanase at 2,500 units (U)/kg, amylase at 400 U/kg, and protease at 4,000 U/kg; and NC with a combination of phytase added at 500 FTU/kg and XAP as above. In Exp. 2 and 3, the 5 dietary treatments were positive control (PC), negative control (NC), NC plus 500 FTU of phytase/kg, NC plus 4,000 U of xylanase/kg, and NC plus phytase and xylanase. In Exp. 1, low levels of nonphytate P and DE in the NC diet depressed (P < 0.05) ADG of the pigs by 16%, but phytase linearly increased (P < 0.05) ADG by up to 24% compared with NC. The cocktail of XAP alone had no effect on ADG of pigs, but the combination of XAP and phytase increased (P < 0.05) ADG by 17% compared with the NC treatment. There was a linear increase (P < 0.01) in Ca and P digestibility in response to phytase. In Exp. 2, ADG was 7% greater in PC than NC (P < 0.05); there were no effects of enzyme addition on any response. In Exp. 3, addition of phytase alone or in combination with xylanase improved (P < 0.05) P digestibility. Phosphorus excretion was greatest (P < 0.01) in the PC and lowest (P < 0.05) in the diet with the combination of phytase and xylanase. The combination of phytase and xylanase improved P retention (P < 0.01) above the NC diet to a level similar to the PC diet. In conclusion, a combination of phytase and carbohydrases improved ADG in 10-kg but not 23-kg pigs, but was efficient in improving P digestibility in pigs of all ages.     

Effect of microbial phytase addition with or without the trace mineral premix in nursery, growing, and finishing pig diets

Two experiments were conducted to determine the interactive effects of phytase with and without a trace mineral premix (TMP) in diets for nursery, growing, and finishing pigs on growth performance, bone responses, and tissue mineral concentrations. Pigs (initial and final BW of 5.5 and 111.6 kg [Exp. 1] or 5.4 and 22.6 kg [Exp. 2]) were allotted to treatments on the basis of BW with eight (Exp. 1) or six (Exp. 2) replications of six or seven pigs per replicate pen. Pigs were started on the diets the day of weaning (average of 18 d). In both experiments, the treatments were with or without 500 phytase units/kg of diet and with or without the TMP in a 2 x 2 factorial arrangement. The Ca and available P concentrations were decreased by 0.10% in diets with phytase. The nursery phase consisted of Phase I (7 d), Phase II (14 d), and Phase III (13 d) periods. In Exp. 1, 26 of 52 pigs fed the diet without the TMP and without phytase had severe skin lesions and decreased growth performance; therefore, pigs fed this diet were switched to the positive control diet. In Exp. 2, the treatment without the TMP and without phytase had 12 replications instead of six. At the end of Phase III, half these replications were switched to the positive control diet and half were switched to the diet without the TMP but with phytase. In Exp. 1 during Phases II and III and in the overall data, pigs fed the diet without the TMP had decreased ADG and ADFI, but the addition of phytase prevented these responses (phytase x TMP; P < 0.02). Growth performance was not affected by diet during the growing-finishing period. Coccygeal bone Zn and Na concentrations were decreased (P < 0.09) in pigs fed the diet without the TMP, and adding phytase increased (P < 0.03) Zn and Fe concentrations. In Exp. 2 during Phases I and II, pigs fed the diet without the TMP had decreased ADG, but the addition of phytase prevented this response (phytase x TMP; P < 0.10). Pigs fed the diet without the TMP had decreased (P < 0.10) ADG (Phase II and overall), ADFI (Phases II and III and in the overall data), and G:F (Phase III). Coccygeal bone Zn and Cu concentrations were decreased (P < 0.09) in pigs fed the diet without the TMP, and adding phytase increased (P < 0.03) Zn concentration in the bones. These data indicate that removing the TMP in diets for nursery pigs decreases growth performance and bone mineral content, and that phytase addition to the diet without the TMP prevented the decreased growth performance.     

Effect of receiving diets containing alfalfa and certain feed additives on performance of feeder pigs transported long distances

Three experiments were conducted to determine the effect of receiving diets containing alfalfa meal and certain feed additives on performance of comingled feeder pigs transported 900 to 1,100 km. In Exp. 1, the inclusion of 9.4% dehydrated alfalfa meal in receiving diets for 2 wk resulted in no difference (P greater than .1) in gain or feed conversion from purchase to market compared with pigs fed a basal corn-soybean meal (CS) diet or a diet containing 20% ground whole oats (O). In Exp. 2, pigs fed receiving diets containing 10% dehydrated alfalfa meal had no improvement (P greater than .1) in gain (.60 vs .61 kg/d) or conversion (3.25 vs 3.17) compared with CS-fed pigs. In Exp. 3, pigs fed a receiving diet for 2 wk containing 10% mid-bloom alfalfa ate more (P less than .002) feed daily for 2 wk (.82 vs .76 kg) and overall (P less than .04; 1.92 vs 1.85 kg) and had an improved (P less than .03) daily gain from purchase to market (.61 vs .59 kg) compared with CS-fed pigs. In Exp. 2, pigs fed diets containing 44 mg/kg tylosin (T) gained similar to pigs fed no additive (O) and slower (P less than .01) than pigs fed 110 mg/kg chlortetracycline (CTC; .59, .60 and .63 kg/d), with no significant differences in feed to gain conversion (3.12, 3.23 and 3.18).(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of an E. coli phytase expressed in yeast for releasing phytate-bound phosphorus in young chicks and pigs

Four chick trials and one pig trial were conducted to investigate the phosphorus-releasing efficacy oftwo commercial phytase enzymes (Natuphos and Ronozyme) and an experimental E. coli phytase enzyme (ECP) when added to corn-soybean meal diets containing no supplemental inorganic P (iP). In the 13- or 14-d chick trials, three or four graded levels of iP (0, 0.05,0.10,0.15%) from KH2PO4 were added to the basal diet to construct standard curves from which bioavailable P release could be calculated for the phytase treatments. In all cases, phytase supplementation levels were based on an assessment of phytase premix activity (i.e., P release from Na phytate at pH 5.5). Linear (P < 0.01) responses in tibia ash and weight gain resulted from iP supplementation in all assays. In the first chick trial, supplementation of 500 phytase units (FTU)/kg of ECP resulted in superior (P < 0.01) weight gain and tibia ash values compared with 500 FTU/kg of Natuphos. Results of the second chick trial revealed P-release values of 0.032 and 0.028% for 500 FTU/kg Natuphos and Ronozyme, respectively, and these were lower (P < 0.01) than the 0.125% P-release value for 500 FTU/kg of ECP. Tibia ash responded quadratically (P < 0.05) in response to graded levels of ECP up to 1,500 FTU/kg in the third chick trial. Combining Natuphos with either Ronozyme or ECP in Chick Trial 4 revealed no synergism between phytases with different initiation sites of P removal. The pig trial involved 10 individually fed weanling pigs per diet, and and phytase enzymes were supplemented to provide 400 FTU/kg in diets containing 0.60% Ca. Based on the linear regression of fibula ash on supplemental iP intake (r2 = 0.87), P-release values were 0.081% for Natuphos, 0.043% for Ronozyme, and 0.108% for ECP. These trials revealed an advantage of the E. coli phytase over the commercial phytases in young chicks.     

Effect of microbial phytase on energy availability,and lipid and protein deposition in growing swine

Two experiments were conducted to determine the effect of phytase on energy availability in pigs. In Exp. 1, barrows (initial and final BW of 26 and 52 kg) were allotted to four treatments in a 2 x 2 factorial arrangement. Corn-soybean meal (C-SBM) diets were fed at two energy levels (2.9 and 3.2 x maintenance [M]) with and without the addition of 500 phytase units/kg of diet. The diets contained 115% of the requirement for Ca, available P (aP), and total lysine, and Ca and aP were decreased by 0.10% in diets with added phytase. Pigs were penned individually and fed daily at 0600 and 1700, and water was available constantly. Eight pigs were killed and ground to determine initial body composition. At the end of Exp. 1, all 48 pigs were killed for determination of carcass traits and protein and fat content by total-body electrical conductivity (TOBEC) analysis. Six pigs per treatment were ground for chemical composition. In Exp. 2, 64 barrows and gilts (initial and final BW of 23 and 47 kg) were allotted to two treatments (C-SBM with 10% defatted rice bran or that diet with reduced Ca and aP and 500 phytase units/kg of diet), with five replicate pens of barrows and three replicate pens of gilts (four pigs per pen). In Exp. 1, ADG was increased (P < 0.01) in pigs fed at 3.2 x M. Based on chemical analyses, fat deposition, kilograms of fat, retained energy (RE) in the carcass and in the carcass + viscera, fat deposition in the organs, and kilograms of protein in the carcass were increased (P < 0.10) in pigs fed the diets at 3.2 vs. 2.9 x M. Based on TOBEC analysis, fat deposition, percentage of fat increase, and RE were increased (P < 0.09) in pigs fed at 3.2 x M. Plasma urea N concentrations were increased in pigs fed at 3.2 x M with no added phytase but were not affected when phytase was added to the diet (phytase x energy, P < 0.06). Fasting plasma glucose measured on d 28, ultrasound longissimus muscle area (LMA), and 10th-rib fat depth were increased (P < 0.08) in pigs fed phytase, but many other response variables were numerically affected by phytase addition. In Exp. 2, phytase had no effect (P > 0.10) on ADG, ADFI, gain:feed, LMA, or 10th-rib fat depth. These results suggest that phytase had small, mostly nonsignificant effects on energy availability in diets for growing pigs; however, given that phytase increased most of the response variables measured, further research on its possible effects on energy availability seems warranted.     

Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Effects of dietary spray-dried egg on growth performance and health of weaned pigs

Four experiments were conducted to evaluate the nutrient contributions and physiological health benefits of spray-dried egg (SDE) containing only unfertilized eggs as a protein source in nursery pig diets. In all experiments, all diets were formulated to the same ME and Lys content, and each pen within a block (by BW) housed the same number of barrows and gilts. In Exp. 1 and 2 (168 and 140 pigs, respectively; 5 kg BW; 16 d old; 14 replicates/experiment), conducted at a university farm, treatments were with or without 5% SDE in a nursery control diet, which included antibiotics and zinc oxide. Pigs were fed for 10 d after weaning to measure ADG, ADFI, and G:F. The SDE increased (P < 0.05) ADG (Exp. 1: 243 vs. 204 g/d; Exp. 2: 204 vs. 181 g/d) and ADFI (Exp. 1: 236 vs. 204 g/d; Exp. 2: 263 vs. 253 g/d) compared with the control diet but did not affect G:F. In Exp. 3 (1,008 pigs; 5.2 kg BW; 20 d old; 12 replicates/treatment), conducted at a commercial farm, treatments were in a factorial arrangement of with or without SDE and high or low spray-dried plasma (SDP) in nursery diets, which included antibiotics and zinc oxide. Pigs were fed for 6 wk using a 4-phase feeding program (phases of 1, 1, 2, and 2 wk, respectively) with declining diet complexity to measure ADG, ADFI, G:F, removal rate (mortality plus morbidity), and frequency of medical treatments per pen and day (MED). The diets with the SDE increased (P < 0.05) ADFI during phase 1 only (180 vs. 164 g/d) compared with the diets without the SDE but did not affect growth performance during any other phases. The diets with SDE reduced MED during phase 1 (0.75% vs. 1.35%; P < 0.05) and the overall period (0.84% vs. 1.01%; P = 0.062) compared with the diets without the SDE but did not affect removal rate. In Exp. 4 (160 pigs; 6.7 kg BW; 21 d old; 10 replicates/treatment), conducted at a university farm to determine whether SDE can replace SDP, treatments were in a factorial arrangement of with or without SDP or SDE in nursery diets, which excluded antibiotics and zinc oxide. Pigs were fed for 6 wk using the same schedule used in Exp. 3 to measure ADG, ADFI, and G:F. The diets with SDE increased (P < 0.05) ADFI during phase 1 only (195 vs. 161 g/d) compared with the diets without SDE but did not affect growth performance during any other periods. In conclusion, SDE can be an efficacious protein and energy source in nursery pig diets and improves health and, in some instances, increases growth rate.     

Efficacy of yeast phytase in improving phosphorus bioavailability in a corn-soybean meal-based diet for growing pigs

Crossbred barrows (n = 66; 6 wk old) were used in a 6-wk experiment to evaluate the efficacy of phytase from yeast or Aspergillus niger on performance, tibial characteristics, and serum inorganic P concentration. We also investigated the stability of these phytases in acidic solutions with pepsin, which simulated gastric conditions. Pigs were fed a P-adequate diet containing .34% nonphytate-P or a low-P diet containing .20% nonphytate-P. The low-P diet was supplemented with 0, 1,000, 2,000, or 4,000 phytase units (PU; the activity at optimal pH, i.e., pH 4.2 for yeast phytase and pH 5.5 for phytase from Aspergillus niger)/kg of yeast phytase, or 1,000 PU/kg phytase from Aspergillus niger. The graded level of yeast phytase linearly increased ADG (P = .047), tibial weight (P = .091), tibial density (P < .001), and P concentration in tibial cortex (P = .018). Aspergillus niger phytase also increased ADG (P = .022), serum inorganic P concentration (P < .001), tibial density (P = .007), and tibial P concentration (P = .025). The pigs given 1,000 PU/kg Aspergillus niger phytase showed greater ADG (P = .091), tibial density (P= .001), and tibial P concentration (P = .062) than those given 1,000 PU/kg yeast phytase. No measurements differed (P > .31) between the pigs given 1,000 PU/kg Aspergillus niger phytase and those given 4,000 PU/kg yeast phytase. These results suggested that yeast phytase improves bioavailability of P in the diet for growing pigs but the efficacy of yeast phytase is less than that of Aspergillus niger phytase. During incubation in acidic solutions with pepsin, yeast phytase (P < .001) lost more of its activity than Aspergillus niger phytase. This lesser stability of yeast phytase may be responsible for the poorer efficacy of yeast phytase than that of Aspergillus niger. In summary, supplementation of swine diets with yeast phytase is beneficial, but its efficacy is less than that of Aspergillus niger phytase.