Levels Of Nonphytate Phosphorus Research Articles

Performance of Broiler Chickens Fed Low Non Phytate Phosphorus Diets Supplemented with Microbial Phytase

An experiment was conducted with 270 broiler chicks to examine the effect of microbial phytase supplementation to low non-phytate phosphorus (NPP) diets on growth performance, bone mineralisation and nutrients retention during 1 to 21 days of age. Four isonitrogenous and isocaloric diets were formulated to contain 0.30, 0.35, 0.40 and 0.45% NPP with the two lowest NPP levels (0.30 and 0.35%) supplemented with microbial phytase (500FTU per kg diet). Each diet was offered ad libitum to 9 replicates of 5 chicks each throughout the experimental period. The performance in terms of body weight gain, feed intake and feed/gain was significantly depressed in chicks fed lowest level of NPP (0.30%). Supplementation of phytase to either 0.30 or 0.35% NPP diet significantly improved body weight gain and feed conversion, which was comparable with 0.40% NPP diet. The leg abnormality increased and, tibia ash and tibia breaking strength decreased significantly in diets containing 0.30 and 0.35% NPP. Increasing NPP level to 0.40% or supplementing 500FTU phytase/kg diet to 0.30 and 0.35% NPP diets alleviated leg abnormality and enhanced tibia breaking strength and ash content. Serum Ca concentration was not influenced, but serum concentration of P and protein increased significantly either by enhancing NPP content to 0.40% or supplementing microbial phytase to 0.30 and 0.35% NPP diet. The nitrogen retention was significantly higher in 0.40% NPP diet compared with lower levels (0.30 or 0.35% NPP). Supplementation of microbial phytase to low NPP diet (0.30 and 0.35%) significantly increased nitrogen retention. The excretion of nitrogen decreased significantly in phytase-supplemented group compared with that of either 0.40 or 0.45% NPP diet. It is concluded that microbial phytase supplementation (500FTU/kg diet) to low NPP (0.30%) maize-soybean meal based poultry diets enhanced performance, increased retention nutrients (N, Ca and P) and improved bone mineralisation.

Growth, Bone Mineralization and Mineral Excretion in Broiler Starter Chicks Fed Varied Concentrations of Cholecalciferol

An experiment was conducted to study the growth performance, bone mineralization and mineral excretion in broiler starter chicks fed high levels of cholecalciferol (CC) at sub-optimal levels of calcium (Ca) and non-phytate phosphorus (NPP). Five hundred and sixty day-old Vencobb female broiler chicks were housed in raised wire floor stainless steel battery brooder pens (24x30xl8) at the rate of five chicks per pen. A maize-soyabean meal basal diet was supplemented with dicalcium phosphate, oyster shell powder and synthetic CC to arrive at two levels each of Ca (0.50 and 0.60%), and NPP (0.25 and 0.30%) and four levels of CC (200, 1,200, 2,400 and 3,600 ICU/kg) in a 2x2x4 factorial design. Each diet was fed ad libitum to chicks in 7 pens from 2 to 21 days of age. Body weight gain, feed intake and bone weight increased (p<0.05) with increase in level of CC at both the Ca and NPP levels tested. The CC levels required to obtain significant improvement in body weight gain and feed intake reduced (2,400 ICU/kg vs. 1,200 ICU/kg) with increase in levels of P in diet (0.25% vs. 0.3%, respectively). The feed conversion ratio was significantly improved (p<0.05) with increase in level of CC from 200 to 1,200 ICU/kg diet at 0.5% Ca, while at 0.6% Ca, the level of CC in diet did not influence the feed efficiency. Tibia mineralization (density, breaking strength and ash content) and Ca and P contents in serum increased significantly (p<0.05) with increase in levels of CC in diet. The CC effect on these parameters was more pronounced at lower levels of Ca and NPP (0.5 and 0.25%, respectively). The data on body weight gain and feed intake indicated that NPP level in diet can be reduced from 0.30 to 0.25% by increasing CC from 200 to 2,400 ICU/kg. Similarly, the bone mineralization (tibia weight, density and ash content) increased non-linearly (p<0.01) with increase in CC levels in diet. Concentrations of P and Mn in excreta decreased (p<0.01), by increasing CC level from 200 to 2,400 ICU/kg diet. It can be concluded that dietary levels of Ca and NPP could be reduced to 0.50 and 0.25%, respectively by enhancing the levels of cholecalciferol from 200 to 2,400 ICU/kg with out affecting body weight gain, feed efficiency and bone mineralization. Additionally, phosphorus and manganese excretion decreased with increase in levels of CC in broiler diet.

Modified Phosphorus Program for Broilers Based on Commercial Feeding Intervals to Sustain Live Performance and Reduce Total and Water-Soluble Phosphorus in Litter

Two experiments were conducted to adapt the results of previous studies from our laboratory on calcium and nonphytate phosphorus (NPP) requirements to feeding intervals more similar to the commercial broiler industry. Feeding periods of 0 to 14, 14 to 35, 35 to 42, and 42 to 56 d were used. In the first experiment, a positive control diet similar to industry levels (0.45% NPP and 1.0% Ca, 0.40% NPP and 0.9% Ca, 0.35% NPP and 0.8% Ca, and 0.30% NPP and 0.8% Ca for the various feeding periods, respectively) was compared with various combinations of Ca and NPP levels, with phytase supplementation used in some diets with low NPP. It was observed that birds fed starter diets with 0.40% NPP followed by 0.30% during the grower phase grew as well with equivalent feed conversion as those fed the positive control diet. Feeding less than 0.30% during the grower period resulted in excessive mortality over the duration of the study. In the second experiment, consisting of 2 consecutive trials in which birds were housed beginning on new softwood shavings, adjustments were made in the NPP and Ca levels used in the first experiment; diets were fed with or without phytase supplementation. At the conclusion of the second trial, samples of litter were evaluated for total and soluble P contents. All of the modified diets supported BW gain, feed conversion, livability, and bone parameters that did not differ significantly from that of birds fed the positive control diets. Total and soluble P contents of the litter were significantly reduced by the modified diets fed with or without phytase. Use of the modified diets resulted in significant savings in dietary costs associated with reduced levels of P supplementation.

Performance of broiler chicks fed high levels of cholecalciferol in diets containing sub-optimal levels of calcium and non-phytate phosphorus

An experiment was conducted to study the performance, bone mineralization, mineral excretion and retention in female broiler chicks fed high levels of cholecalciferol (CC) in diets containing sub-optimum levels of calcium (Ca) and non-phytate phosphorus (NPP). Four diets were prepared to contain two sub-optimum levels of Ca (5 and 6 g kg −1) and NPP (2.5 and 3 g kg −1) in 2 × 2 factorial manner in maize–soyabean meal basal diet. Each combination of Ca and NPP was supplemented with 200, 1200, 2400 or 3600 ICU of CC kg −1 diet. Five hundred and sixty Vencob broiler female chicks were randomly and evenly distributed into 112 stainless steel raised wire-floor battery brooder pens. Each experimental diet was fed ad libitum to seven replicates from 2 to 42 d of age. Majority of parameters responded non-linearly with increase in levels of CC in diet, except the body weight gain and leg abnormality score at 14 d of age, which linearly increased and decreased, respectively, with CC levels. Body weight gain, feed conversion efficiency (FCE) and leg abnormality score at days 14, 28 and 42 were not affected due to variation in dietary Ca level. At 2.5 g NPP kg −1 diet, weight gain, FCE, tibia length and tibia ash content increased non-linearly with increase in CC. Excretion of Ca and P decreased with the levels of these minerals in diet. Retention of Fe, Zn and Mn in liver increased non-linearly with increase in CC levels in diet. Variation in retention of trace minerals in liver due to CC level was influenced by the ratio between Ca and NPP levels in the diet. Based on the results, it can be concluded that 2.5 g NPP and 5 g Ca kg −1 diet was adequate for broiler chicks weighing 1800 g at 42 d of age when the diet contained higher levels of CC compared to those recommended (200 ICU CC kg −1) for commercial broiler chicks.

Interaction between dietary calcium and non-phytate phosphorus levels on growth, bone mineralization and mineral excretion in commercial broilers

An experiment was conducted to study the interaction between the levels of dietary calcium (Ca) and non-phytate phosphorus (NPP) on growth, bone mineralization and mineral excretion in commercial broilers. Day-old Vencob female broiler chicks ( n = 720) were distributed into 144 stainless steel battery brooders, five birds in each. Four levels each of Ca (6, 7, 8 and 9 g kg −1) and NPP (3, 3.5, 4 and 4.5 g kg −1) were fed in a factorial design through a maize–soya basal diet. Levels of maize, dicalcium phosphate and oyster shell powder were adjusted to obtain the desired levels of Ca and NPP. Each diet was fed ad libitum to chicks in 9 battery brooders from day 1 to 42 days of age. Body weight gain, feed intake and tibia breaking strength were depressed (P≤0.01) and leg abnormality score increased with increase in level of Ca at lower levels of NPP (3 and 3.5 g kg −1 diet) at 14, 28 and 42 days of age. These ill effects were alleviated by reducing the levels of Ca to the minimum levels tested. Tibia breaking strength and tibia ash content in broilers fed the lowest levels of Ca and NPP (6 and 3 g kg −1, respectively) were similar to those fed diets with highest level of these minerals (9 and 4.5 g kg −1, respectively) in diet. Excretion of Ca, P and Fe was lower in broilers fed the lowest levels of minerals (6 g Ca and 3 g NPP kg −1) compared to the higher levels. The requirements of Ca and NPP for performance and bone mineralization were predicted using surface regression analysis. Increase in the level of Ca and NPP above the minimum levels tested did not further improve the variables studied. Based on the data, it could be concluded that levels of 6 g Ca and 3.75 g NPP kg −1 diet would be adequate for commercial broilers from day 1 to 42 days of age.

Responses of Broiler Chicks to Non-Phytate Phosphorous Levels and Phytase Supplementation

Supplementation of broiler diets with phytase has proven to be an effective and realistic method for enhancing the digestibility of phytic acid in monogastric animals. This study was conducted to evaluate the effect of microbial phytase (RonozymeP) supplementation in broiler chicks fed different levels of nonphytate phosphorus (nPP) on performance. Five hundred and seventy six day old mixed sex, Ross broiler chicks were distributed randomly into 6 dietary treatments (three replicate /each 32 chicks). Data were analyzed as a 3×2 factorial arrangement with three levels of nPP (0.45, 0.38, and 0.31 % during starter and 0.43, 0.36, and 0.29 % during grower and finisher periods) and two levels of phytase (0 and 500 F.T.U/kg) in each period. The results showed that chicks fed with lower nPP diets had significantly lower body weight at 40 and 50d; lower daily gain during 20-40d and 0-50 d; and higher feed conversion ratio during 20-40d period. Phytase supplementation to the diets had only significantly increased feed intake during 21-40d period. The interactions between nPP levels and phytase supplementation on body weight at 40d and FCR during 0-20d was significant, in which the BW of the chicks fed lowest nPP diets was improved by phytase, whilst those of chicks fed high nPP diets was adversely affected by phytase supplementation.

The Effect of Phytase and Organic Acid on Growth Performance, Carcass Yield and Tibia Ash in Quails Fed Diets with Low Levels of Non-phytate Phosphorus

An experiment was conducted to investigate the effect of phytase, organic acids and their interaction on body weight gain, feed consumption, feed conversion ratio, carcass yield and tibia ash. A total of 680 three-day old Japanese quail chicks (Coturnix coturnix japonica) were assigned to 20 battery brooders, 34 chicks in each. The experimental period lasted 35 days. The treatment groups employed were: 1) a positive control which included 3.5 g available phosphorus (AP)/kg diet and 10 g Ca/kg diet; 2) a negative control which included 2 g AP/kg diet and 8 g Ca/kg diet, 3) negative control diet supplemented with either 300 FTU phytase/kg diet (phytase) or 4) 2.5 g organic acid (lactic acid+formic acid)/kg diet (organic acid); or 5) 300 FTU phytase/kg diet+2.5 g organic acid/kg diet (phytase+organic acid). All birds were fed with the positive control diet for a week and then transferred to the dietary treatments. At the end of the study, there were no differences (p>0.005) among the groups in body weight, weight gain, feed consumption, feed conversion ratio and carcass yield. Tibia ash, however, was reduced (p<0.001) for quails fed the negative control diet containing a low- level of AP compared to the positive control diet containing adequate AP. The addition of phytase, organic acid or phytase+organic acid to the diets containing the low-level of AP improved (p<0.001) tibia ash. On the other hand, an extra synergistic effect of phytase and organic acid on tibia ash was not determined. This study demonstrated that it may be possible to reduce supplemental level of inorganic P with phytase and/or organic acid supplementation for quail diets without adverse effect on performance and tibia ash. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 2 : 198-202)

Effects of Dietary Non-phytate Phosphorus Levels on Egg Production, Shell Quality and Nutrient Retention in White Leghorn Layers

An experiment was conducted (28 to 44 weeks) to study the laying performance, shell quality, and nutrient retention of White Leghorn layers fed different levels of non-phytate phosphorus (NPP). Six levels of NPP (0.15, 0.18, 0.21, 0.24, 0.27 and 0.30%) at a constant calcium (Ca) level (3.5%) in maize-soya-deoiled rice bran based diets were formulated, and each experimental diet was offered ad libitum for 16 weeks to five replicates with five birds in each replicate. The body weight of WL layers fed diet containing 0.15% NPP was significantly (p<0.05) lower than those fed diet with 0.30% NPP, at 44 weeks of age. However, the hen day egg production, egg weight, daily feed intake and feed consumed per dozen eggs were not influenced by the variation in the NPP levels in the diet. The bone ash content was significantly (p<0.05) higher in the birds fed 0.30% NPP as compared with those fed diets up to 0.24% NPP. Bone ash content was intermediate in the birds fed diet containing 0.27% NPP. The tibia strength followed the same trend as that of bone ash. Dietary NPP content had no influence on serum Ca and protein concentration and activity of alkaline phosphatase. However, serum inorganic P concentration increased linearly with NPP content in the diet. The concentration of P was significantly (p<0.05) higher in the birds fed 0.27% NPP or higher as compared with those fed 0.15% NPP. Levels of dietary NPP had no influence on egg quality parameters like shell wt, shell thickness, shell strength and specific gravity. The retention of nutrients such as DM, N and Ca were comparable among the WL layers fed different levels of NPP. However, the retention of P decreased linearly with increase in the level of NPP in the diet. The retention of P in the birds fed diets up to 0.24% NPP in the diet was comparable, however further increasing the content of NPP (either 0.27% or 0.30%) reduced the retention of P. Based on the results of the present study, 0.15% NPP (180 mg/b/d) in the diets of WL layers is adequate for optimum production performance during 28 to 44 weeks of age, however, WL layers require 0.27% NPP (324 mg /b/d) in the diet for optimum production with better bone mineralization. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 8 : 1171-1175)

Effect of Supplementing Microbial Phytase on Performance of Broiler Breeders Fed Low Non-phytate Phosphorus Diet

An experiment was conducted to study the production performance of broiler breeder females (25 to 40 weeks of age) fed either reference diet or low non-phytate phosphorus (NPP) diet with or without microbial phytase (500 FYT/kg) supplementation. A weighed (160 g/b/d) quantity of feed from each diet was offered daily to 40 replicates of one bird each housed in California type cage having individual feeders. Each cage was considered as a replicate. A continuous 16-h light per day was provided using incandescent bulbs. Body weight, egg production, egg weight, feed per egg mass, egg specific gravity, egg breaking strength, shell thickness, tibia ash and serum Ca and protein concentrations were not affected by reducing the NPP level from 0.30 to 0.18% in the broiler breeder diet. Supplementation of phytase (500 FYT/kg) enzyme to the diet containing 0.18% NPP had no added advantage on any of the above production parameters. The serum inorganic P was increased significantly (p<0.05) by either enhancing the NPP content from 0.18 to 0.30% or supplementing phytase @500 FYT/kg to the diet containing low P which were found comparable. Retention of Ca and P was positive on all the diets. P retention decreased significantly (p<0.05) with either increase in NPP content or phytase supplementation in the diet. Neither NPP nor phytase supplementation influenced bone mineralization in terms of tibia ash and strength. The hatchability was not influenced by either increasing the NPP content or supplementing the enzyme phytase. Similarly, the P concentration in the egg yolk and day old chick, day old and 14 th day body weight and leg score was not altered by increasing the level of NPP or supplementing phytase enzyme. The mortality was within the normal limits in all the three dietary groups. Thus, it can be concluded that 0.18 %N PP (288 mg NPP intake/b/d) in the broiler breeder's diet is adequate in sustaining the optimum performance from 25 to 40 wks of age. Enhancing the NPP content or supplementation of phytase (500 FYT/kg diet) to diet containing 0.18% NPP had no added advantage on performance. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 9 : 1299-1304)

Effects of calcium and nonphytate phosphorus concentrations on phytase efficacy in broiler chicks

Phytase supplementation over a range of different levels of dietary Ca and nonphytate phosphorus (NPP) was investigated by comparing surface response curves from regression equations generated with (experiment 1) and without (experiment 2) phytase using various performance and bone quality parameters. Cobb x Cobb broiler chicks were raised from 0 to 16 d in 2 experiments using corn-soybean meal based diets. Experiment 1 used a 4 x 4 factorial arrangement with diets formulated to contain combinations of 4 levels of Ca: 0.38, 0.58, 0.78, and 0.98% and 4 levels of NPP: 0.2, 0.3, 0.4, and 0.5%. Experiment 2 used a composite rotatable design in which rations were formulated to contain dietary Ca levels of 0.38, 0.47, 0.68, 0.89, and 0.98% and NPP levels of 0.20, 0.24, 0.35, 0.46, and 0.50%. An extra point was included in the design to contain the lowest Ca and lowest NPP levels (0.38% Ca and 0.20% NPP). All combinations of Ca and NPP were fed with 657 phytase units/kg Natuphos 5000 phytase, plus 4 combinations (0.38% Ca and 0.20% NPP, 0.47% Ca and 0.24% NPP, 0.68% Ca and 0.35% NPP, and 0.89% Ca and 0.46% NPP) were fed without phytase to determine the suitability of comparing multiple regression response surfaces for particular variables among experiments. Comparison of surfaces, with and without phytase, showed that growth and bone quality responses to phytase were greatest at low NPP levels and high Ca levels, and these decreased when the Ca level was reduced or when the NPP level was increased. A third experiment confirmed that phytase elicits a greater response at higher Ca levels and lower NPP levels (0.86% Ca and 0.20% NPP) versus low Ca levels and low NPP levels (0.47% Ca and 0.24% NPP). The data demonstrated why it is impossible to determine a single NPP equivalency value for phytase supplements.

Broiler Diet Modification and Litter Storage

Modifying broiler diets to mitigate water quality concerns linked to excess phosphorus (P) in regions of intensive broiler production has recently increased. Our goals were to evaluate the effects of dietary modification, using phytase and reduced non-phytate phosphorus (NPP) supplementation, on P speciation in broiler litters, changes in litter P forms during long-term storage, and subsequent impacts of diets on P in runoff from litter-amended soils. Four diets containing two levels of NPP with and without phytase were fed to broilers in a three-flock floor pen study. After removal of the third flock, litters were stored for 440 d at their initial moisture content (MC; 24%) and at a MC of 40%. Litter P fractions and orthophosphate and phytate P concentrations were determined before and after storage. After storage, litters were incorporated with a sandy and silt loam and simulated rainfall was applied. Phytase and reduced dietary NPP significantly reduced litter total P. Reducing dietary NPP decreased water-extractable inorganic phosphorus (IP) and the addition of dietary phytase reduced NaOH- and HCl-extractable organic P in litter, which correlated well with orthophosphate and phytic acid measured by 31P nuclear magnetic resonance (NMR), respectively. Although dry storage caused little change in P speciation, wet storage increased concentrations of water-soluble IP, which increased reactive P in runoff from litter-amended soils. Therefore, diet modification with phytase and reduced NPP could be effective in reducing P additions on a watershed scale. Moreover, efforts to minimize litter MC during storage may reduce the potential for dissolved P losses in runoff.

Effect of microbial phytase on production performance of White Leghorn layers fed on a diet low in non-phytate phosphorus

1. An experiment with 150 White Leghorn layers was conducted to examine the effect of microbial phytase supplementation of low non-phytate phosphorus (NPP) diets on egg production, eggshell quality, bone mineralisation and retention of nutrients at 32–48 weeks of age. 2. Four isonitrogenous and isocaloric diets were formulated to contain 1·2, 1·8, 2·4 and 3·0 g NPP/kg diet with the two lowest NPP (1·2 and 1·8) supplemented with microbial phytase (Biofeed Phytase, India) at 500 FTU per kg diet. Each diet was offered ad libitum to 5 replicates of 5 layers throughout the experiment. 3. Body weight gain was reduced significantly in the layers fed on the 1·2 g/kg NPP diet as compared to those given diets containing 1·8–3·0 g/kg. Addition of phytase to the 1·2 g/kg diet significantly enhanced the body weight and was comparable with those given diets containing 1·8–3·0 g/kg NPP. 4. No additional advantage resulted from enhancing the NPP levels beyond 1·8 g/kg or adding phytase to a diet containing 1·8 g/kg NPP. 5. Hen d egg production, food intake, food efficiency, shell weight, shell thickness, shell strength and tibia strength followed the same trends as above. However, adding phytase to the 1·8 g/kg NPP diet significantly enhanced tibia ash. Egg weight, specific gravity and Haugh units were influenced by neither NPP concentration nor phytase supplementation. 6. Adding phytase to the 1·2 g/kg NPP diet significantly enhanced nitrogen and phosphorus retention. 7. It was concluded that addition of 500 FTU of microbial phytase/kg diet can allow the reduction of NPP content to 1·2 g/kg in the layer diet, eliminate inorganic phosphorus supplementation and results in significant reduction of nitrogen and phosphorus excretion without affecting the production performance of layers.

Influence of Sodium Source and Level on Performance of Second-Cycle Hens Fed Diets with Different Levels of Nonphytate Phosphorus

Hens of a commercial strain of SCWL hens were subjected to a molt and allowed to resum e production before being placed on test diets consisting of a nutritionally complete basal diet supplemented with three sources of sodium (sodium chloride, sodium bicarbonate, and sodium sulfate) at three levels of added sodium (0.10, 0.20, 0.30%) with three levels of nonphytate phosphorus (0.25, 0.45, and 0.65%) in a complete factorial arrangement. When non-chloride sources of sodium were used the diet was supplemented with 0.12% Cl from calcium chloride. A reference group of hens within each level of nonphytate phosphorus was fed a diet with no supplemental sodium or chloride. Each of the thirty resulting dietary treatments was assigned to eight groups of hens, with a replicate group consisting of five 30.5 x 45.7 cm cages with one hen per cage fed from a common feed container. After allowing the hens to acclimate to the test diets for 28 d data were collected for a second 28 d period on rate of egg production, feed intake, egg weight, shell breaking force, and shell deformation time. Results of the study indicate that no more than 266 mg/d of nonphytate P was adequate for egg production. Increasing the dietary P level greater than 0.45% nonphytate P resulted in a significant reduction in egg shell strength. A dietary sodium intake of 128 mg/d appeared adequate to support optimum performance. Use of sodium bicarbonate or sodium sulfate in place of sodium chloride appeared to have no benefits in regard to egg shell strength in this study.

Phytase Supplementation and Reduced‐Phosphorus Turkey Diets Reduce Phosphorus Loss in Runoff following Litter Application

Concerns about regional surpluses of manure phosphorus (P) leading to increased P losses in runoff have led to interest in diet modification to reduce P concentrations in diets. The objectives of this study were to investigate how dietary P amendment affected P concentrations in litters and P losses in runoff following land application. We grew two flocks of turkeys on the same bed of litter using diets with two levels of non-phytate phosphorus (NPP), with and without phytase. The litters were incorporated into three soils in runoff boxes at a plant-available nitrogen (PAN) rate of 168 kg PAN/ha, with runoff generated on Days 1 and 7 under simulated rainfall and analyzed for dissolved reactive phosphorus (DRP) and total P. Litters were analyzed for water-soluble phosphorus (WSP) and total P, while soils in the runoff boxes were analyzed for WSP and Mehlich-3 phosphorus (M3-P). Formulating diets with lower NPP and phytase both decreased litter total P. Phytase had no significant effect on litter WSP at a 1:200 litter to water extraction ratio, but decreased WSP at a 1:10 extraction ratio. Using a combination of reducing NPP fed and phytase decreased the total P application rate by up to 38% and the P in surplus of crop removal by approximately 48%. Reducing the NPP fed reduced DRP in runoff from litter-amended soils at Day 1, while phytase had no effect on DRP concentrations. Increase in soil M3-P was dependent on total P applied, irrespective of diet. Reducing overfeeding of NPP and utilizing phytase in diets for turkeys should decrease the buildup of P in soils in areas of intensive poultry production, without increasing short-term concerns about dissolved P losses.

Evaluation of Nonuniform Application of Phytase (Simulated) on Growth Performance and Bone Quality in Broiler Chicks

The postpellet application of phytase can be variable and can lead to high coefficients of variation (CV). Two trials were conducted to evaluate the effects of high CV of phytase application (simulated by feeding 2 to 4 times the recommended level of phytase fed every second, third, or fourth day), when added to a standard broiler diet deficient in nonphytate phosphorus (NPP) and fed to 0- to 21-d-old male broilers. A standard curve of graded levels of NPP was included in both trials to determine the NPP requirement. Weight gain, feed efficiency, tibia breaking strength, and percentage tibia ash were assessed in both trials. Trial 1 was designed to evaluate the effect of a high variation (103% CV; 23,000 phytase units (PTU)/kg fed every other day) of added phytase fed on alternate days compared with low variation of added phytase fed daily (0% CV; 11,500 PTU/kg fed daily) and to determine the optimal phytase inclusion level and the NPP requirement. Trial 2 was conducted to determine the maximum variation of phytase addition fed alternate days and reevaluate the NPP requirement. When tibia ash was used as the response criterion, the NPP requirement was determined to be 0.42% in both experiments, and the optimal phytase level was determined to be 14,630 PTU/kg feed. The results of these studies also suggest that feeding a high variation diet of added phytase (103% CV) was not detrimental to the parameters evaluated. Only when the CV exceeded 103% was bone quality negatively affected.

Benefit of feeding dietary calcium and nonphytate phosphorus levels above National Research Council recommendations to tom turkeys in the growing-finishing phases

This experiment evaluated the effects of feeding various dietary Ca and nonphytate P (nPP) levels to Large White male turkeys from 3 to 17 wk of age. After consuming a common prestarter diet, poults were fed approximate NRC (1994) levels of dietary Ca and nPP from 3 to 9 wk of age or levels approximately 25% higher. From 9 to 17 wk of age, each starter group was fed approximately 75 (low P), 100 (medium P), or 145% (high P) of the NRC (1994) requirements for Ca and nPP. Diets were fed as crumbles to 6 wk of age and as pellets from 6 to 17 wk of age. There were no effects on BW or feed efficiency to 9 wk of age. Litter P was increased by 21% when high Ca and nPP were fed from 3 to 9 wk. High dietary Ca and nPP fed during the growing-finishing period generally improved bone strength and ash. Tibia strength and ash were higher in the medium P group compared with in the low P group. Wing bone strength was greater in the high P group than in both the birds fed low or medium P. Litter P was increased by 23% when High P was fed in the growing-finishing period compared to the birds fed the Medium P diet during the same period. The results show there is a benefit to bone strength and mineralization when Ca and nPP are fed at levels higher than NRC (1994) recommendations.

Effects of microbial phytase, produced by solid-state fermentation, on the performance and nutrient utilisation of broilers fed maize- and wheat-based diets

1. The influence of a microbial phytase on the performance, toe ash contents and nutrient utilisation of male broilers fed diets based on maize and wheat was investigated. The experiment was conducted as 2 × 2 × 2 factorial arrangement of treatments. Within the factorial, two diet types (maize–soy or wheat–soy) containing two levels of non-phytate phosphorus (3·0 or 4·5 g/kg) were evaluated and each level of non-phytate phosphorus was supplemented with 0 or 500 PU phytase/kg diet. Each of the 8 dietary treatments were fed to 6 pens of 8 birds from d 1 to 21 post-hatching. 2. Main effects of diet type and phytase were observed for all parameters. Main effect of non-phytate phosphorus was significant only for feed/gain and toe ash contents. Phytase addition improved weight gains irrespective of diet type or non-phytate phosphorus level, but the magnitude of improvement in the phosphorus-deficient wheat–soy diet was greater, resulting in a diet type × non-phytate phosphorus interaction. Responses in toe ash contents were noted only in phosphorus-deficient diets, as indicated by a non-phytate phosphorus × phytase interaction. 3. Phytase addition improved apparent metabolisable energy values of wheat-based diets, but had little effect on the apparent metabolisable energy of maize-based diets as shown by a diet type × phytase interaction. The apparent metabolisable energy was not influenced by dietary non-phytate P. 4. Phytase improved ileal nitrogen digestibility in both diet types, but the responses to added phytase tended to be higher in wheat-based diets, as shown by a diet type × phytase interaction. 5. Increasing the dietary non-phytate phosphorus level reduced phosphorus digestibility and increased excreta phosphorus content. Addition of phytase improved phosphorus digestibility, but the increments were higher in low phosphorus diets resulting in a non-phytate phosphorus × phytase interaction. Phytase addition tended to lower the excreta phosphorus content, but the effects were greater in birds fed low phosphorus diets, as shown by a non-phytate phosphorus × phytase interaction.

Evaluation of Modified Dietary Phosphorus Levels With and Without Phytase Supplementation on Live Performance and Fecal Phosphorus Levels in Broiler Diets. 1. Full-Term Feeding Recommendations

Based on preliminary studies conducted during periods of 0 to 3, 3 to 6, and 6 to 9 wk of age, four different phosphorus regimens were selected for use in long-term feeding trials. Using nonlinear regression, dietary levels of nonphytate phosphorus (NPP) were selected within each age period for 1) maximum body weight without phytase enzyme, 2) maximum body weight with phytase enzyme, 3) maximum tibia ash without phytase enzyme, and 4) maximum tibia ash with phytase enzyme. Two trials of identical design were conducted in which these regimes were compared to NRC recommendations for NPP. To evaluate the sensitivity of the P estimates, diets containing 0.05% above and below the estimates were also fed. Each diet was fed to six pens of 50 male chicks in each of two trials. Body weight, feed conversion, tibia ash, and fecal P content were determined at 21, 42, 53, and 63 d.Feeding levels estimated to maximize body weight, with or without phytase supplementation, supported body weight, feed utilization, and livability that did not differ significantly from birds fed NRC-recommended levels. Tibia ash was reduced in these birds, but no serious leg abnormalities were noted. Birds fed diets with NPP levels chosen to maximize tibia ash without the addition of phytase had tibia ash values that were significantly lower than those of birds fed the diets with NRC levels of NPP; increasing this level by 0.05% resulted in tibia ash content that did not differ significantly from that of birds fed NRC levels. Birds fed diets with NPP levels chosen to maximize tibia ash with the addition of phytase did not differ significantly in tibia ash content from those fed the diets based on NRC levels of NPP. Implementation of the modified levels of NPP could result in marked reductions in fecal P content.

Phosphorus requirements of broiler chicks six to nine weeks of age as influenced by phytase supplementation

Two trials of similar design were conducted to determine the nonphytate phosphorus (NPP) requirements for broilers from 42 to 63 d of age in diets with or without phytase supplementation. Male broilers of a commercial strain were grown to 42 d on nutritionally complete diets with NRC (1994) recommended levels of Ca and NPP. At 42 d, the birds were placed on experimental diets and fed to 63 d. The experimental treatments consisted of a 2 x 6 factorial arrangement with two levels of phytase (0 or 800 U/kg) and six levels of NPP (0.10 to 0.35% in 0.05% increments). Body weight gain, feed conversion, and mortality were determined during the period. At 49, 56, and 63 d, excreta samples were taken, and samples of birds were killed for tibia ash determination. The lowest level of NPP, with or without phytase supplementation, was sufficient for maximum BW gain, feed conversion, and livability. Using nonlinear regression, levels of NPP needed to optimize tibia ash in the absence of phytase were 0.31 +/- 0.004%, 0.23 +/- 0.02%, and 0.22 +/- 0.029% at 49, 56, and 63 d, respectively. When diets were supplemented with 800 U/kg of phytase, the NPP requirement for optimum tibia ash was 0.15 +/- 0.049% at 49 d. At 56 and 63 d, no more than 0.10% NPP (lowest level tested) was sufficient to maximize tibia ash. Compared to current NRC (1994) recommendations, the application of these reduced dietary phosphorus levels could markedly reduce excreta excretion of phosphorus by broilers.

Effects of phytase supplementation on the performance, egg quality, and phosphorous excretion of laying hens fed different levels of dietary calcium and nonphytate phosphorous

An experiment employing a factorial arrangement of two levels (3.0 and 4.0%) of Ca, two levels (0.15 and 0.25%) of nonphytate phosphorus (NPP), and two levels (0 and 300 U/kg diet) of microbial phytase was carried out with 960 ISA-brown layers from 21 to 41 wk of age. There was a significant interaction between NPP level and phytase for egg production. High NPP level and phytase supplementation increased egg production only in the second 10-wk period (31 to 41 wk). High NPP and low Ca increased feed intake, and a significant interaction between levels of NPP and Ca was observed in the first 10 wk. High NPP improved feed efficiency only in the second 10-wk period. Low NPP improved egg specific gravity and eggshell thickness but decreased Haugh units in the first 10-wk period; high NPP decreased the percentage of broken and soft-shell eggs in the second period. Low Ca decreased egg specific gravity, eggshell strength, and eggshell thickness in both periods and increased Haugh units in the second 10-wk period. Phytase supplementation decreased the percentage of broken and soft-shell eggs. High NPP increased fiber availability but decreased Ca availability. High Ca decreased Ca availability, whereas phytase increased availability of dry matter, fiber, and P. High NPP increased retention of P and Fe but also increased excretion of P. High Ca decreased retention of Zn and Fe. Phytase supplementation increased P retention, resulting in decrease of P excretion. In conclusion, supplementation of microbial phytase at a level of 300 U per kg diet of laying hens can improve egg production, decrease broken and soft egg production rate, and P excretion. The effects of phytase supplementation are significantly modified by the level of Ca and NPP.