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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 Recommendations1
2003 Poultry Science Association, Inc.
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 Recommendations1 Poultry Science Department, University of Arkansas, Fayetteville, Arkansas 72701
Primary Audience: Nutritionists, Researchers, Extension Personnel, Broiler Integrators SUMMARY 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. Key words: phosphorus, broilers, phytase, litter, eutrophication 2003 J. Appl. Poult. Res. 12:174–182
DESCRIPTION OF PROBLEM The majority of broilers produced in the United States are grown on litter in areas of high-density bird populations; these areas are usually characterized as being of low agronomic productivity. Therefore, the opportunity to dispose of the litter by land application is often 1 2
limited. There is growing concern in areas of the United States near broiler production units regarding the amount of phosphorus that enters the environment from land application of broiler litter [1, 2]. Therefore, effective and economical means of limiting P excretion by broilers without loss of performance is of vital importance.
Published with approval of the Director, Arkansas Agricultural Experiment Station. To whom correspondence should be addressed: [email protected].
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F. Yan, C. A. Fritts, and P. W. Waldroup2
YAN ET AL.: MODIFIED PHOSPHORUS LEVELS FOR BROILERS
MATERIALS AND METHODS Preliminary Trials A series of preliminary studies was conducted for the periods 0 to 3, 3 to 6, and 6 to 9 wk of age. Details of the studies of the individual feeding periods have been previously reported [17, 18, 21]. During each age period, birds were fed diets ranging from deficit to surfeit levels of nonphytate phosphorus (NPP), either with or without addition of phytase enzyme. Prior to initiation of studies conducted from 3 to 6 or 6 to 9 wk of age the birds were fed nutritionally complete diets with NPP levels considered as adequate for optimum bone development. Using nonlinear regression, levels of NPP were se-
lected within each age period for four different scenarios 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. For 0 to 3, 3 to 6, and 6 to 9 wk of age the NPP estimates were 1) 0.375, 0.20, and 0.15%; 2) 0.30, 0.15, and 0.10%; 3) 0.40, 0.30, and 0.20%; and 4) 0.30, 0.25, and 0.15%, respectively, for the four scenarios listed above. Experimental Treatments Two studies of identical design were conducted to evaluate the application of NPP levels selected within each age interval when fed over an entire growth period to broilers in litter floor pens. To evaluate the sensitivity of these selected levels, additional treatments consisted of diets with NPP levels that were either 0.05% above or below these selected levels. Performance of birds fed the selected levels was compared to that of birds fed NRC [20] recommendations for NPP. Another group of birds was fed commercial diets in which the NPP was 0.05% greater than NRC, more typical of industry levels. This resulted in a total of 14 experimental treatments, each fed to six replicate pens of 50 male broilers in each of two consecutive trials. Diet Formulation Within each age period, a diet was formulated that provided a minimum of 110% of recommended [20] amino acid levels and the appropriate levels of NPP (Table 1). Ingredient composition values (including NPP content) reported by NRC [20] were used in formulating the diets. Calcium levels were set at a minimum of 2:1 Ca:NPP with minimum Ca levels of 0.7, 0.6, and 0.5% for the three age periods, respectively. Calcium levels were not reduced when phytase was added, as previous research from this laboratory indicated that minimal Ca is released by phytase in corn-soybean meal based diets [22]. Aliquots of a common diet, less the dicalcium phosphate and ground limestone supplements, were used to mix the test diets. For each age period, a basal diet (deficit) and a summit diet (highest P level) were prepared, analyzed for Ca and P content to verify proper mixing, and then
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A major portion of the P in poultry diets is in the form of phytate P, an organically bound form of the mineral that is poorly available to monogastric animals. Chickens are lacking or limited in phytase, the enzyme that is necessary to breakdown the phytate molecule and subsequently release P for absorption [3, 4, 5]. The ability of exogenous phytase to improve the availability of phytate-bound P was demonstrated by Nelson et al. [6, 7], but commercial application has been hampered by economics of phytase supplementation versus the cost of providing phosphorus from mineral supplements. Recent commercial development of phytase enzymes offers promise in reducing P excretion by chicks [8, 9]. Although a number of studies have demonstrated that the dietary P needs of broilers may be reduced by phytase supplementation [10, 11, 12, 13, 14, 15, 16, 17, 18], these studies have generally considered only a limited portion of the growing period for broilers. Yan et al. [19] evaluated reduction in P levels over the entire growing period as influenced by phytase supplementation, but the reduction in P level was applied constantly in all feeding periods. It is generally recognized that the P requirement of the chick declines with age [20]. The objectives of this study were to determine the effects of different nutritional strategies on reducing P excretion by broilers and to evaluate the combined effects of these different strategies on their relative contributions to reduced P excretion by broilers.
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176 TABLE 1. Composition (g/kg) and calculated analysis of test diets 0 to 3 wk
3 to 6 wk
6 to 9 wk
Yellow corn Soybean meal (47%) Poultry oil DL-Met (99%) Feed-grade salt BMD-50A Coban-60B Broiler vitamin mixC Lys HCl (98%) Trace mineral mixD Thr Variable ingredientsE Total
602.43 295.42 53.87 3.71 3.50 0.50 0.75 2.00 1.64 1.00 0.83 34.35 1,000.00
681.47 240.64 37.76 2.30 3.41 0.50 0.75 2.00 2.26 1.00 1.00 26.91 1,000.00
751.14 188.23 24.85 1.55 3.32 0.50 0.75 2.00 2.10 1.00 1.16 23.40 1,000.00
Calculated analysis ME, kcal/kg Crude protein, % Met, % Lys, % Thr, % TSAA, % Cl, % Na, %
3,200.00 20.00 0.69 1.20 0.88 1.00 0.28 0.20
3,200.00 18.00 0.53 1.10 0.81 0.80 0.29 0.20
3,200.00 16.00 0.42 0.94 0.75 0.66 0.28 0.20
A
Alpharma, Inc., Ft. Lee, NJ. Elanco Animal Health division of Eli Lilly & Co., Indianapolis, IN. C Provided per kilogram of diet: vitamin A (from vitamin A acetate) 7,714 IU; cholecalciferol, 2,204 IU; vitamin E (from DL-α tocopheryl acetate), 16.53 IU; vitamin B12, 0.013 mg; riboflavin, 6.6 mg; niacin, 39 mg; pantothenic acid, 10 mg; choline, 465 mg; menadione (from menadione dimethylpyrimidinol), 1.5 mg; folic acid, 0.9 mg; thiamin (from thiamine mononitrate), 1.54 mg; pyridoxine (from pyridoxine hydrochloride), 2.76 mg; D-biotin, 0.066 mg; ethoxyquin, 125 mg; Se, 0.1 mg. D Provided per kilogram of diet: Mn (from MnSO4ⴢH2O), 100 mg; Zn (from ZnSO4ⴢ7H2O), 100 mg; Fe (from FeSO4ⴢ7H2O), 50 mg; Cu (from CuSO4ⴢ5H2O) 10 mg; I (from Ca(IO3)2ⴢH2O), 1 mg. E Consisted of dicalcium phosphate, ground limestone, and washed builders sand to provide desired levels of Ca and nonphytate P. B
blended in proportions needed to provide the desired level of NPP. The diets with different phosphorus levels were divided, and one portion was supplemented with phytase. Diets containing phytase were supplemented with 1,000 U/kg of a dry phytase supplement [23] premixed with a portion of the test diet before adding to the mixer. Because phytase is susceptible to heat damage, all diets were fed in mash form. Each treatment diet plus a sample of the common basal diet was analyzed in quadruplicate for crude protein, Ca, total P, Na, and K. Diets treated with phytase were analyzed for phytase activity. Birds and Housing In each of two experiments, male broilers of a commercial strain [24] were obtained from a local hatchery and randomly assigned to pens in a steel-truss poultry house of commercial design.
Used softwood shavings, top-dressed with fresh shavings, served as litter over concrete floors. Fifty birds were placed in each of 84 pens (5.2 m2) for each experiment. Measurements Mean body weights by pens were taken at 21, 42, 53, and 63 d. Feed consumption was determined at the same ages. Mortality was checked twice daily; birds that died were weighed, and the weight used to adjust feed conversion (feed consumed/(weight of live birds + weight of dead birds)). At 20, 41, 52, and 62 d, twelve cohort birds fed the same diets were placed in wire-floored battery pens for 24-h collection of fecal samples. Feces were freeze-dried and analyzed for total P and Ca contents [25]. The 12 cohort birds per treatment were killed by CO2 inhalation followed by cervical disloca-
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Ingredient
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TABLE 2. Calculated and analyzed total P content of diets with different levels of nonphytate phosphorus (NPP)A 0 to 3 wk % NPP 0.50 0.45 0.425 0.40 0.375 0.35 0.325 0.30 0.25
3 to 6 wk
6 to 9 wk
Calculated
Analyzed
% NPP
Calculated
Analyzed
% NPP
Calculated
Analyzed
0.75 0.69 0.67 0.65 0.62 0.60 0.57 0.54 0.49
0.73 0.70 0.66 0.64 0.61 0.59 0.56 0.53 0.50
0.40 0.35 0.30 0.25 0.20 0.15 0.10
0.64 0.59 0.54 0.49 0.44 0.39 0.35
0.65 0.57 0.54 0.47 0.42 0.38 0.36
0.35 0.30 0.25 0.20 0.15 0.10
0.58 0.53 0.48 0.43 0.38 0.33
0.58 0.51 0.47 0.42 0.38 0.33
tion at 21, 42, 53, or 63 d, and the right tibia was removed for ash determination of dry fatfree bone as described by AOAC [26]. Any bird that died was evaluated for leg disorders, and birds were observed for any indication of leg disorders during the study. Statistical Analysis Data were subjected to a one-way ANOVA using the general linear models procedure of SAS software [27], comparing the response of birds fed the various test diets to that of birds fed the diets based upon NRC [20] recommendations in single-degree contrast comparisons. Pen means served as the experimental unit. A preliminary analysis indicated no trial × treatment interaction so data from the two studies were combined for analysis. Mortality data were transformed to √n + 1 prior to analysis; data are presented as natural numbers. Statements of probability are based on P ≤ 0.05.
RESULTS AND DISCUSSION Analytical Results Analysis of the diets for phytase activity indicated an overall average of 1,002 ± 102 U/kg, in comparison to the anticipated 1,000 U/kg [28]. Levels of phosphorus in mixed feeds were in agreement with calculated values (Table 2). Amount of crude protein, Ca, Na, and Cl in the diets was also in good agreement with calculated values (data not shown).
Body Weight The effects of the various treatments on body weight at different ages are shown in Table 3. Birds fed diets with the phosphorus level estimated to maximize body weight, with or without phytase supplementation, and those fed the diets with the phosphorus level estimated to maximize tibia ash, with or without phytase supplementation, did not differ significantly in body weight from those fed the NRC or commercial levels of P. At 42, 53, and 63 d, birds fed the diets with 0.05% less P than estimated for maximum body weight, without phytase supplementation, were significantly lighter than those fed the NRC levels of P. Therefore, it would appear that the P level estimated to maximize body weight in the absence of phytase was adequate but marginal, whereas the levels estimated to maximize body weight in the presence of phytase had an adequate margin of safety. Feed Conversion The effects of the various treatments on feed conversion (g of feed per g of gain) are shown in Table 4. No significant differences were observed among birds fed the various dietary treatments at any age, in agreement with Waldroup et al. [21] who reported that the P required to optimize feed conversion was much lower than that needed to optimize body weight or tibia ash. Mortality The effects of the various treatments on mortality are shown in Table 5. No significant differ-
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A Analyses conducted in quadruplicate by Agricultural Diagnostic Laboratory, University of Arkansas, Fayetteville, AR, using inductively coupled plasma-atomic energy spectroscopy following HNO3 digestion.
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TABLE 3. Effects of dietary treatments on body weight of male broilers (mean of two trials with six pens of 50 birds per trial) NPPA (%) TreatmentB Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
0–3 wk
3–6 wk
6–9 wk
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
21 d 750 755 737 761 741 741 754 752 731 723 735 725 753 758
Probability > F Coefficient of variation
42 d
53 d
63 d
2,216 2,237 2,133* 2,226 2,271 2,241 2,276 2,290 2,224 2,225 2,233 2,254 2,279 2,251
3,036 3,080 2,882* 3,060 3,111 3,116 3,171 3,146 3,054 3,025 3,144 3,132 3,111 3,050
3,525 3,527 3,356* 3,622 3,684 3,722 3,753 3,734 3,586 3,647 3,727 3,718 3,633 3,539
0.53 5.79
0.005 3.78
0.005 5.23
0.05 7.44
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. *Significantly different from those fed NRC [20] recommended levels of NPP (P ≤ 0.05). A
ences were observed among birds fed the various dietary treatments at any age. This result is in agreement with Waldroup et al. [21] who re-
ported that the P required to minimize mortality is much lower than that needed to optimize body weight, tibia ash, or feed conversion.
TABLE 4. Effects of dietary treatments on feed conversion by male broilers (mean of two trials with six pens of 50 birds per trial) NPPA % TreatmentB 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
Probability > F Coefficient of variation
Feed/gram (g/g)
0–3 wk
3–6 wk
6–9 wk
0–21 d
0–42 d
0–53 d
0–63 d
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
1.319 1.324 1.330 1.322 1.317 1.312 1.282 1.325 1.336 1.310 1.317 1.336 1.302 1.294
1.753 1.758 1.759 1.760 1.745 1.739 1.739 1.749 1.762 1.757 1.763 1.744 1.732 1.732
1.938 1.920 1.949 1.953 1.935 1.910 1.909 1.926 1.945 1.941 1.931 1.911 1.910 1.912
2.170 2.161 2.158 2.167 2.148 2.104 2.113 2.137 2.157 2.130 2.140 2.119 2.108 2.117
0.11 3.00
0.79 3.10
0.98 4.26
0.92 4.36
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. A
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Body weight (g)
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TABLE 5. Effects of dietary treatments on mortality of male broilers (Mean of two trials with six pens of 50 birds per trial) Mortality (%)
NPPA (%) TreatmentB Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
3–6 wk
6–9 wk
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
Probability > F Coefficient of variation (natural numbers) Coefficient of variation (transformed numbers)
0–21 d
0–42 d
0–53 d
0–63 d
1.00 0.40 1.00 1.40 1.40 0.60 0.80 2.00 0.80 1.00 0.80 0.80 0.60 0.80
1.40 1.00 1.80 2.00 2.40 1.00 1.80 2.80 1.80 2.20 1.40 2.20 1.60 1.00
3.40 1.20 3.33 3.80 5.40 3.11 3.40 4.60 2.22 4.20 2.60 3.20 2.80 2.00
7.40 3.40 9.80 8.40 7.80 6.22 6.60 5.78 8.80 6.00 5.60 5.80 5.00 4.00
0.66 164.28 0.74
0.66 117.73 0.98
0.40 97.71 1.51
0.66 96.61 2.83
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. A
TABLE 6. Effects of dietary treatments on tibia ash of male broilers (mean of two trials with six pens of 50 birds per trial) NPPA (%) TreatmentB 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
Probability > F Coefficient of variation
Tibia ash (%)
0–3 wk
3–6 wk
6–9 wk
21 d
42 d
53 d
63 d
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.154 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
43.45 44.02 40.69* 2.73* 42.91 41.62* 42.07* 42.51* 41.42* 42.47* 43.57 42.50* 43.19 43.07
44.60 45.11 41.80* 44.37 44.43 42.82* 44.34 44.63 42.95* 43.99* 44.74 44.47 44.54 44.49
46.56 46.90 43.07* 46.08* 46.45 44.15* 46.16* 46.58 44.37* 45.62* 46.58 46.26* 46.57 46.51
48.36 48.82 45.30* 47.72* 48.05* 46.32* 47.79* 48.43 46.11* 47.32* 48.20 48.14* 48.29 48.42
0.0001 3.92
0.0001 2.50
0.0001 1.88
0.0001 1.65
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in bold face type are based on estimates from previous trials over individual age periods. *Significantly different from those fed NRC (1994) recommended levels of nonphytate phosphorus (P ≤ 0.05). A
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
0–3 wk
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0–3 wk 0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
3–6 wk 0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
6–9 wk 1.65 1.41 0.82 0.84 1.01 0.57 0.70 0.88 1.03 1.21 1.29 0.90 1.06 1.25
0.07 0.17 0.13 0.09 0.13 0.13 0.16 0.10 0.06 0.16 0.13 0.05 0.05 0.04
± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.54 1.46 0.74 0.87 1.04 0.74 0.72 0.95 0.86 1.13 1.23 0.64 0.96 1.11
± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.17 0.07 0.08 0.06 0.09 0.04 0.11 0.15 0.07 0.10 0.14 0.05 0.12 0.09
63 d
53 d 1.37 1.28 0.61 0.74 1.05 0.57 0.61 0.87 0.85 0.89 1.16 0.62 0.84 1.00
Fecal P (%)
0.20 0.09 0.10 0.15 0.10 0.14 0.22 0.16 0.17 0.18 0.20 0.11 0.16 0.01
± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.11 0.08 0.05 0.04 0.05 0.04 0.04 0.05 0.05 0.07 0.16 0.10 0.08 0.12
± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.38 1.22 0.84 1.05 1.13 0.72 0.88 0.99 1.04 1.09 1.27 0.73 0.87 1.02
42 d
21 d
B
A
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NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. Treatments in bold face type are based on estimates from previous trials over individual age periods.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Treatment
B
NPPA (%)
TABLE 7. Effects of dietary treatments on excreta P content (mean ± SD) of male broilers (mean of two trials with six pens of 50 birds per trial)
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YAN ET AL.: MODIFIED PHOSPHORUS LEVELS FOR BROILERS Tibia Ash
Fecal Phosphorus The effects of the various treatments on fecal P content are shown in Table 7. The fecal P content of birds fed diets with NPP levels chosen to maximize body weight or tibia ash, with or without phytase supplementation, was lower than that of birds fed diets with NRC or commer-
cial P levels, especially after 21 d of age. Selection of any of the feeding strategies (i.e., maximum body weight or maximum tibia ash, with or without phytase) resulted in a reduction of 40 to 50% in fecal P content, depending upon the age of the chick. The results of this study demonstrate that fecal P excretion by broiler chicks can be markedly reduced while maintaining productivity through the use of reduced dietary P levels, especially after 3 wk of age, combined with the use of phytase supplementation. Feeding to maximize body weight with the use of phytase enzyme resulted in BW and feed conversion that did not differ significantly from that of birds fed diets based on NRC recommendations or diets that contained 0.05% greater P as a margin of safety (commercial levels). Tibia ash of these birds was only slightly less than that of birds fed the NRC or commercial levels, with no indications of increased mortality or leg disorders among the birds. Use of these levels in conjunction with phytase supplementation resulted in more than 50% reduction in fecal P excretion, compared to that of birds fed diets with NRC recommendations. The use of NPP levels fed in combination with phytase supplementation that were estimated to maximize tibia ash resulted in live performance and tibia ash that did not differ significantly from those of birds fed the NRC recommendations and reduced fecal P by 25 to 35%, depending upon the age of the bird.
CONCLUSIONS AND APPLICATIONS 1. All estimates of NPP requirements supported body weight, feed conversion, and livability equivalent to those of birds fed NRC or commercial levels. 2. Estimates of NPP to maximize body weight, with or without phytase, significantly reduced tibia ash as compared to birds fed NRC or commercial levels. 3. Estimates of NPP needed to maximize tibia ash without phytase supplementation resulted in significantly reduced tibia ash compared to birds fed NRC or commercial levels of NPP. Increasing these levels by 0.05% resulted in tibia ash that did not differ from that of birds fed the NRC or commercial levels. 4. Estimates of NPP needed to maximize tibia ash with phytase supplementation resulted in tibia ash that did not differ significantly from that of birds fed NRC or commercial levels. 5. Use of a reduced P scenario that maintained tibia ash resulted in a 25 to 35% reduction in fecal P content, depending upon age of the bird. Acceptance of a slight reduction in tibia ash content allowed for a reduction of up to 50% in fecal P output. 6. Further work is needed to determine if maximum tibia ash is necessary for maintaining live performance and carcass integrity during processing.
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The effects of the various treatments on tibia ash are shown in Table 6. Birds fed diets with P levels chosen to maximize body weight, with or without the addition of phytase, typically had tibia ash values that were significantly less than those of birds fed diets with NRC levels of P; however with 0.05% additional P, tibia ash often did not differ significantly from that of birds fed the NRC diets. Although these birds had lower tibia ash, no indications of leg abnormalities were observed, and mortality was not increased. 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 those 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.
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REFERENCES AND NOTES 1. Edwards, D. R., and T. C. Daniel. 1992. Environmental impacts of on-farm poultry waste disposal—a review. Bioresour. Technol. 41:9–33. 2. Sharpley, A. 1999. Symposium: Reducing the environmental impact of poultry production: Focus on phosphorus. Poult. Sci. 78:660–673. 3. Nelson, T. S. 1967. The utilization of phytate phosphorus by poultry—A review. Poult. Sci. 46:862–871. 4. O’Dell, B. L., A. R. de Boland, and S. R. Koirtyohann. 1972. Distribution of phytate and nutritionally important elements among the morphological components of cereal grains. J. Agric. Food Chem. 20:718–721.
6. Nelson, T. S., T. R. Shieh, R. J. Wodzinski, and J. H. Ware. 1968. The availability of phytate phosphorus in soybean meal before and after treatment with a mold phytase. Poult. Sci. 47:1842–1848. 7. Nelson, T. S., T. R. Shieh, R. J. Wodzinski, and J. H. Ware. 1971. Effect of supplemental phytase on the utilization of phytate phosphorus by chicks. J. Nutr. 101:1289–1294. 8. Ravindran, V., W. L. Bryden, and E. T. Kornegay. 1995. Phytates: Occurrence, bioavailability, and implications in poultry nutrition. Poult. Avian Biol. Rev. 6:125–143. 9. Sebastian, S., S. P. Touchburn, and E. R. Chavez. 1998. Implications of phytic acid and supplemental microbial phytase in poultry nutrition: a review. World’s Poult. Sci. J. 54:27–47. 10. Simons, P. C. M., H. A. J. Versteegh, A. W. Jongbloed, P. A. Kemme, P. Slump, K. D. Bos, M. G. E. Wolters, R. F. Beudeker, and G. J. Verschoor. 1990. Improvement of phosphorus availability by microbial phytase in broilers and pigs. Br. J. Nutr. 64:525–540. 11. Broz, J., P. Oldale, A. H. Perrin-Voltz, G. Thychen, J. Schulze, and C. Simones Nunes. 1994. Effects of supplemental phytase on performance and phosphorus utilization in broiler chickens fed a low phosphorus diet without addition of inorganic phosphorus. Br. Poult. Sci. 35:273–280. 12. Denbow, D. M., V. Ravindran, E. T. Kornegay, Z. Yi, and R. M. Hulet. 1995. Improving phosphorus availability in soybean meal for broilers by supplemental phytase. Poult. Sci. 74:1831–1842. 13. Kornegay, E. T., D. M. Denbow, Z. Yi, and V. Ravindran. 1996. Response of broilers to graded levels of microbial phytase added to maize-soyabean-meal-based diets containing three levels of non-phytate phosphorus. Br. J. Nutr. 75:839–852. 14. Kornegay, E. T., D. M. Denbow, and Z. Zhang. 1997. Phytase supplementation of corn-soybean meal broiler diets from three to seven weeks of age. Keeping Current KC 9702. BASF Corporation, Mount Olive, NJ. 15. Yi, Z., E. T. Kornegay, V. Ravindran, and D. M. Denbow. 1996. Improving phosphorus availability in corn and soybean meal
16. Sohail, S. S., and D. A. Roland, Sr. 1999. Influence of supplemental phytase on performance of broilers four to six weeks of age. Poult. Sci. 78:550–555. 17. Yan, F., J. H. Kersey, and P. W. Waldroup. 2001. Phosphorus requirements of broiler chicks three to six weeks of age as influence by phytase supplementation. Poult. Sci. 80:455–459. 18. Yan, F., J. H. Kersey, C. A. Fritts, and P. W. Waldroup. 2003. Phosphorus requirements of broiler chicks six to nine weeks of age as influenced by phytase supplementation. Poult. Sci. 82:94–300. 19. Yan, F., J. H. Kersey, C. A. Fritts, P. W. Waldroup, H. L. Stilborn, R. C. Crum, Jr., D. W. Rice, and V. Raboy. 2000. Evaluation of normal yellow dent corn and high available phosphorus corn in combination with reduced dietary phosphorus and phytase supplementation for broilers grown to market weights in litter pens. Poult. Sci. 79:1282–1289. 20. National Research Council. 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. 21. Waldroup, P. W., J. H. Kersey, E. A. Saleh, C. A. Fritts, F. Yan, H. L. Stilborn, R. C. Crum, Jr., and V. Raboy. 2000. Nonphytate phosphorus requirement and phosphorus excretion of broiler chicks fed diets composed of normal or high available phosphate corn with and without microbial phytase. Poult. Sci. 79:1451–1459. 22. Yan, F. 2001. Nutritional strategies to reduce phosphorus excretion by broilers. Ph.D. Dissertation. University of Arkansas, Fayetteville, AR. 23. Natuphos, BASF Corporation, Mt. Olive, NJ. One unit of phytase activity is defined as the quantity of enzyme required to produce 1 µmol of inorganic P/min from 5.1 mmol/L of sodium phytate at pH 5.5 in a water bath at 37°C. 24. Cobb 500, Cobb-Vantress Inc., Siloam Springs, AR. 25. Analyses conducted by Agricultural Diagnostic Laboratory, University of Arkansas, Fayetteville, AR, by using inductively coupled plasma-atomic energy spectroscopy following HNO3 digestion. 26. AOAC. 1990. Vitamin D3 in poultry feed supplements. Method 932.16. Pages 1094–1095 in Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists, Arlington, VA. 27. SAS Institute. 1991. SAS User’s Guide: Statistics. Version 6.03 ed. SAS Institute Inc., Cary, NC. 28. Mean ± standard deviation. Phytase analyses were conducted in duplicate on samples of all mixed feed. Assays were kindly conducted by BASF Corporation, Mt. Olive, NJ.
Acknowledgments This research was supported by a grant from U.S. Poultry and Egg Association, Tucker, GA. Contributions of phytase and phytase assays by BASF Corporation, Mt. Olive, NJ, are greatly appreciated.
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5. Raboy, V. 1990. Biochemistry and genetics of phytic acid synthesis. Pages 55–76 in Inositol Metabolism in Plants. D. J. Moore, W. Boas, and F. A. Loewus, ed. Wiley-Liss, New York.
for broilers using microbial phytase and calculation of phosphorus equivalency values for phytase. Poult. Sci. 75:240–249.
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 Recommendations1 Poultry Science Department, University of Arkansas, Fayetteville, Arkansas 72701
Primary Audience: Nutritionists, Researchers, Extension Personnel, Broiler Integrators SUMMARY 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. Key words: phosphorus, broilers, phytase, litter, eutrophication 2003 J. Appl. Poult. Res. 12:174–182
DESCRIPTION OF PROBLEM The majority of broilers produced in the United States are grown on litter in areas of high-density bird populations; these areas are usually characterized as being of low agronomic productivity. Therefore, the opportunity to dispose of the litter by land application is often 1 2
limited. There is growing concern in areas of the United States near broiler production units regarding the amount of phosphorus that enters the environment from land application of broiler litter [1, 2]. Therefore, effective and economical means of limiting P excretion by broilers without loss of performance is of vital importance.
Published with approval of the Director, Arkansas Agricultural Experiment Station. To whom correspondence should be addressed: [email protected].
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F. Yan, C. A. Fritts, and P. W. Waldroup2
YAN ET AL.: MODIFIED PHOSPHORUS LEVELS FOR BROILERS
MATERIALS AND METHODS Preliminary Trials A series of preliminary studies was conducted for the periods 0 to 3, 3 to 6, and 6 to 9 wk of age. Details of the studies of the individual feeding periods have been previously reported [17, 18, 21]. During each age period, birds were fed diets ranging from deficit to surfeit levels of nonphytate phosphorus (NPP), either with or without addition of phytase enzyme. Prior to initiation of studies conducted from 3 to 6 or 6 to 9 wk of age the birds were fed nutritionally complete diets with NPP levels considered as adequate for optimum bone development. Using nonlinear regression, levels of NPP were se-
lected within each age period for four different scenarios 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. For 0 to 3, 3 to 6, and 6 to 9 wk of age the NPP estimates were 1) 0.375, 0.20, and 0.15%; 2) 0.30, 0.15, and 0.10%; 3) 0.40, 0.30, and 0.20%; and 4) 0.30, 0.25, and 0.15%, respectively, for the four scenarios listed above. Experimental Treatments Two studies of identical design were conducted to evaluate the application of NPP levels selected within each age interval when fed over an entire growth period to broilers in litter floor pens. To evaluate the sensitivity of these selected levels, additional treatments consisted of diets with NPP levels that were either 0.05% above or below these selected levels. Performance of birds fed the selected levels was compared to that of birds fed NRC [20] recommendations for NPP. Another group of birds was fed commercial diets in which the NPP was 0.05% greater than NRC, more typical of industry levels. This resulted in a total of 14 experimental treatments, each fed to six replicate pens of 50 male broilers in each of two consecutive trials. Diet Formulation Within each age period, a diet was formulated that provided a minimum of 110% of recommended [20] amino acid levels and the appropriate levels of NPP (Table 1). Ingredient composition values (including NPP content) reported by NRC [20] were used in formulating the diets. Calcium levels were set at a minimum of 2:1 Ca:NPP with minimum Ca levels of 0.7, 0.6, and 0.5% for the three age periods, respectively. Calcium levels were not reduced when phytase was added, as previous research from this laboratory indicated that minimal Ca is released by phytase in corn-soybean meal based diets [22]. Aliquots of a common diet, less the dicalcium phosphate and ground limestone supplements, were used to mix the test diets. For each age period, a basal diet (deficit) and a summit diet (highest P level) were prepared, analyzed for Ca and P content to verify proper mixing, and then
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A major portion of the P in poultry diets is in the form of phytate P, an organically bound form of the mineral that is poorly available to monogastric animals. Chickens are lacking or limited in phytase, the enzyme that is necessary to breakdown the phytate molecule and subsequently release P for absorption [3, 4, 5]. The ability of exogenous phytase to improve the availability of phytate-bound P was demonstrated by Nelson et al. [6, 7], but commercial application has been hampered by economics of phytase supplementation versus the cost of providing phosphorus from mineral supplements. Recent commercial development of phytase enzymes offers promise in reducing P excretion by chicks [8, 9]. Although a number of studies have demonstrated that the dietary P needs of broilers may be reduced by phytase supplementation [10, 11, 12, 13, 14, 15, 16, 17, 18], these studies have generally considered only a limited portion of the growing period for broilers. Yan et al. [19] evaluated reduction in P levels over the entire growing period as influenced by phytase supplementation, but the reduction in P level was applied constantly in all feeding periods. It is generally recognized that the P requirement of the chick declines with age [20]. The objectives of this study were to determine the effects of different nutritional strategies on reducing P excretion by broilers and to evaluate the combined effects of these different strategies on their relative contributions to reduced P excretion by broilers.
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176 TABLE 1. Composition (g/kg) and calculated analysis of test diets 0 to 3 wk
3 to 6 wk
6 to 9 wk
Yellow corn Soybean meal (47%) Poultry oil DL-Met (99%) Feed-grade salt BMD-50A Coban-60B Broiler vitamin mixC Lys HCl (98%) Trace mineral mixD Thr Variable ingredientsE Total
602.43 295.42 53.87 3.71 3.50 0.50 0.75 2.00 1.64 1.00 0.83 34.35 1,000.00
681.47 240.64 37.76 2.30 3.41 0.50 0.75 2.00 2.26 1.00 1.00 26.91 1,000.00
751.14 188.23 24.85 1.55 3.32 0.50 0.75 2.00 2.10 1.00 1.16 23.40 1,000.00
Calculated analysis ME, kcal/kg Crude protein, % Met, % Lys, % Thr, % TSAA, % Cl, % Na, %
3,200.00 20.00 0.69 1.20 0.88 1.00 0.28 0.20
3,200.00 18.00 0.53 1.10 0.81 0.80 0.29 0.20
3,200.00 16.00 0.42 0.94 0.75 0.66 0.28 0.20
A
Alpharma, Inc., Ft. Lee, NJ. Elanco Animal Health division of Eli Lilly & Co., Indianapolis, IN. C Provided per kilogram of diet: vitamin A (from vitamin A acetate) 7,714 IU; cholecalciferol, 2,204 IU; vitamin E (from DL-α tocopheryl acetate), 16.53 IU; vitamin B12, 0.013 mg; riboflavin, 6.6 mg; niacin, 39 mg; pantothenic acid, 10 mg; choline, 465 mg; menadione (from menadione dimethylpyrimidinol), 1.5 mg; folic acid, 0.9 mg; thiamin (from thiamine mononitrate), 1.54 mg; pyridoxine (from pyridoxine hydrochloride), 2.76 mg; D-biotin, 0.066 mg; ethoxyquin, 125 mg; Se, 0.1 mg. D Provided per kilogram of diet: Mn (from MnSO4ⴢH2O), 100 mg; Zn (from ZnSO4ⴢ7H2O), 100 mg; Fe (from FeSO4ⴢ7H2O), 50 mg; Cu (from CuSO4ⴢ5H2O) 10 mg; I (from Ca(IO3)2ⴢH2O), 1 mg. E Consisted of dicalcium phosphate, ground limestone, and washed builders sand to provide desired levels of Ca and nonphytate P. B
blended in proportions needed to provide the desired level of NPP. The diets with different phosphorus levels were divided, and one portion was supplemented with phytase. Diets containing phytase were supplemented with 1,000 U/kg of a dry phytase supplement [23] premixed with a portion of the test diet before adding to the mixer. Because phytase is susceptible to heat damage, all diets were fed in mash form. Each treatment diet plus a sample of the common basal diet was analyzed in quadruplicate for crude protein, Ca, total P, Na, and K. Diets treated with phytase were analyzed for phytase activity. Birds and Housing In each of two experiments, male broilers of a commercial strain [24] were obtained from a local hatchery and randomly assigned to pens in a steel-truss poultry house of commercial design.
Used softwood shavings, top-dressed with fresh shavings, served as litter over concrete floors. Fifty birds were placed in each of 84 pens (5.2 m2) for each experiment. Measurements Mean body weights by pens were taken at 21, 42, 53, and 63 d. Feed consumption was determined at the same ages. Mortality was checked twice daily; birds that died were weighed, and the weight used to adjust feed conversion (feed consumed/(weight of live birds + weight of dead birds)). At 20, 41, 52, and 62 d, twelve cohort birds fed the same diets were placed in wire-floored battery pens for 24-h collection of fecal samples. Feces were freeze-dried and analyzed for total P and Ca contents [25]. The 12 cohort birds per treatment were killed by CO2 inhalation followed by cervical disloca-
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Ingredient
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TABLE 2. Calculated and analyzed total P content of diets with different levels of nonphytate phosphorus (NPP)A 0 to 3 wk % NPP 0.50 0.45 0.425 0.40 0.375 0.35 0.325 0.30 0.25
3 to 6 wk
6 to 9 wk
Calculated
Analyzed
% NPP
Calculated
Analyzed
% NPP
Calculated
Analyzed
0.75 0.69 0.67 0.65 0.62 0.60 0.57 0.54 0.49
0.73 0.70 0.66 0.64 0.61 0.59 0.56 0.53 0.50
0.40 0.35 0.30 0.25 0.20 0.15 0.10
0.64 0.59 0.54 0.49 0.44 0.39 0.35
0.65 0.57 0.54 0.47 0.42 0.38 0.36
0.35 0.30 0.25 0.20 0.15 0.10
0.58 0.53 0.48 0.43 0.38 0.33
0.58 0.51 0.47 0.42 0.38 0.33
tion at 21, 42, 53, or 63 d, and the right tibia was removed for ash determination of dry fatfree bone as described by AOAC [26]. Any bird that died was evaluated for leg disorders, and birds were observed for any indication of leg disorders during the study. Statistical Analysis Data were subjected to a one-way ANOVA using the general linear models procedure of SAS software [27], comparing the response of birds fed the various test diets to that of birds fed the diets based upon NRC [20] recommendations in single-degree contrast comparisons. Pen means served as the experimental unit. A preliminary analysis indicated no trial × treatment interaction so data from the two studies were combined for analysis. Mortality data were transformed to √n + 1 prior to analysis; data are presented as natural numbers. Statements of probability are based on P ≤ 0.05.
RESULTS AND DISCUSSION Analytical Results Analysis of the diets for phytase activity indicated an overall average of 1,002 ± 102 U/kg, in comparison to the anticipated 1,000 U/kg [28]. Levels of phosphorus in mixed feeds were in agreement with calculated values (Table 2). Amount of crude protein, Ca, Na, and Cl in the diets was also in good agreement with calculated values (data not shown).
Body Weight The effects of the various treatments on body weight at different ages are shown in Table 3. Birds fed diets with the phosphorus level estimated to maximize body weight, with or without phytase supplementation, and those fed the diets with the phosphorus level estimated to maximize tibia ash, with or without phytase supplementation, did not differ significantly in body weight from those fed the NRC or commercial levels of P. At 42, 53, and 63 d, birds fed the diets with 0.05% less P than estimated for maximum body weight, without phytase supplementation, were significantly lighter than those fed the NRC levels of P. Therefore, it would appear that the P level estimated to maximize body weight in the absence of phytase was adequate but marginal, whereas the levels estimated to maximize body weight in the presence of phytase had an adequate margin of safety. Feed Conversion The effects of the various treatments on feed conversion (g of feed per g of gain) are shown in Table 4. No significant differences were observed among birds fed the various dietary treatments at any age, in agreement with Waldroup et al. [21] who reported that the P required to optimize feed conversion was much lower than that needed to optimize body weight or tibia ash. Mortality The effects of the various treatments on mortality are shown in Table 5. No significant differ-
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A Analyses conducted in quadruplicate by Agricultural Diagnostic Laboratory, University of Arkansas, Fayetteville, AR, using inductively coupled plasma-atomic energy spectroscopy following HNO3 digestion.
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TABLE 3. Effects of dietary treatments on body weight of male broilers (mean of two trials with six pens of 50 birds per trial) NPPA (%) TreatmentB Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
0–3 wk
3–6 wk
6–9 wk
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
21 d 750 755 737 761 741 741 754 752 731 723 735 725 753 758
Probability > F Coefficient of variation
42 d
53 d
63 d
2,216 2,237 2,133* 2,226 2,271 2,241 2,276 2,290 2,224 2,225 2,233 2,254 2,279 2,251
3,036 3,080 2,882* 3,060 3,111 3,116 3,171 3,146 3,054 3,025 3,144 3,132 3,111 3,050
3,525 3,527 3,356* 3,622 3,684 3,722 3,753 3,734 3,586 3,647 3,727 3,718 3,633 3,539
0.53 5.79
0.005 3.78
0.005 5.23
0.05 7.44
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. *Significantly different from those fed NRC [20] recommended levels of NPP (P ≤ 0.05). A
ences were observed among birds fed the various dietary treatments at any age. This result is in agreement with Waldroup et al. [21] who re-
ported that the P required to minimize mortality is much lower than that needed to optimize body weight, tibia ash, or feed conversion.
TABLE 4. Effects of dietary treatments on feed conversion by male broilers (mean of two trials with six pens of 50 birds per trial) NPPA % TreatmentB 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
Probability > F Coefficient of variation
Feed/gram (g/g)
0–3 wk
3–6 wk
6–9 wk
0–21 d
0–42 d
0–53 d
0–63 d
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
1.319 1.324 1.330 1.322 1.317 1.312 1.282 1.325 1.336 1.310 1.317 1.336 1.302 1.294
1.753 1.758 1.759 1.760 1.745 1.739 1.739 1.749 1.762 1.757 1.763 1.744 1.732 1.732
1.938 1.920 1.949 1.953 1.935 1.910 1.909 1.926 1.945 1.941 1.931 1.911 1.910 1.912
2.170 2.161 2.158 2.167 2.148 2.104 2.113 2.137 2.157 2.130 2.140 2.119 2.108 2.117
0.11 3.00
0.79 3.10
0.98 4.26
0.92 4.36
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. A
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Body weight (g)
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TABLE 5. Effects of dietary treatments on mortality of male broilers (Mean of two trials with six pens of 50 birds per trial) Mortality (%)
NPPA (%) TreatmentB Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
3–6 wk
6–9 wk
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
Probability > F Coefficient of variation (natural numbers) Coefficient of variation (transformed numbers)
0–21 d
0–42 d
0–53 d
0–63 d
1.00 0.40 1.00 1.40 1.40 0.60 0.80 2.00 0.80 1.00 0.80 0.80 0.60 0.80
1.40 1.00 1.80 2.00 2.40 1.00 1.80 2.80 1.80 2.20 1.40 2.20 1.60 1.00
3.40 1.20 3.33 3.80 5.40 3.11 3.40 4.60 2.22 4.20 2.60 3.20 2.80 2.00
7.40 3.40 9.80 8.40 7.80 6.22 6.60 5.78 8.80 6.00 5.60 5.80 5.00 4.00
0.66 164.28 0.74
0.66 117.73 0.98
0.40 97.71 1.51
0.66 96.61 2.83
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in boldface type are based on estimates from previous trials over individual age periods. A
TABLE 6. Effects of dietary treatments on tibia ash of male broilers (mean of two trials with six pens of 50 birds per trial) NPPA (%) TreatmentB 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
Probability > F Coefficient of variation
Tibia ash (%)
0–3 wk
3–6 wk
6–9 wk
21 d
42 d
53 d
63 d
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
0.35 0.30 0.10 0.154 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
43.45 44.02 40.69* 2.73* 42.91 41.62* 42.07* 42.51* 41.42* 42.47* 43.57 42.50* 43.19 43.07
44.60 45.11 41.80* 44.37 44.43 42.82* 44.34 44.63 42.95* 43.99* 44.74 44.47 44.54 44.49
46.56 46.90 43.07* 46.08* 46.45 44.15* 46.16* 46.58 44.37* 45.62* 46.58 46.26* 46.57 46.51
48.36 48.82 45.30* 47.72* 48.05* 46.32* 47.79* 48.43 46.11* 47.32* 48.20 48.14* 48.29 48.42
0.0001 3.92
0.0001 2.50
0.0001 1.88
0.0001 1.65
NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. B Treatments in bold face type are based on estimates from previous trials over individual age periods. *Significantly different from those fed NRC (1994) recommended levels of nonphytate phosphorus (P ≤ 0.05). A
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
0–3 wk
Commercial levels NRC recommended levels 0.05% less than treatment 4 Maximum body weight without phytase 0.05% more than treatment 4 0.05% less than treatment 7 Maximum body weight with phytase 0.05% more than treatment 7 0.05% less than treatment 10 Maximum tibia ash without phytase 0.05% more than treatment 10 0.05% less than treatment 13 Maximum tibia ash with phytase 0.05% more than treatment 13
0.50 0.45 0.325 0.375 0.425 0.25 0.30 0.35 0.35 0.40 0.45 0.25 0.30 0.35
0–3 wk 0.40 0.35 0.15 0.20 0.25 0.10 0.15 0.20 0.25 0.30 0.35 0.20 0.25 0.30
3–6 wk 0.35 0.30 0.10 0.15 0.20 0.10 0.10 0.15 0.15 0.20 0.25 0.10 0.15 0.20
6–9 wk 1.65 1.41 0.82 0.84 1.01 0.57 0.70 0.88 1.03 1.21 1.29 0.90 1.06 1.25
0.07 0.17 0.13 0.09 0.13 0.13 0.16 0.10 0.06 0.16 0.13 0.05 0.05 0.04
± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.54 1.46 0.74 0.87 1.04 0.74 0.72 0.95 0.86 1.13 1.23 0.64 0.96 1.11
± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.17 0.07 0.08 0.06 0.09 0.04 0.11 0.15 0.07 0.10 0.14 0.05 0.12 0.09
63 d
53 d 1.37 1.28 0.61 0.74 1.05 0.57 0.61 0.87 0.85 0.89 1.16 0.62 0.84 1.00
Fecal P (%)
0.20 0.09 0.10 0.15 0.10 0.14 0.22 0.16 0.17 0.18 0.20 0.11 0.16 0.01
± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.11 0.08 0.05 0.04 0.05 0.04 0.04 0.05 0.05 0.07 0.16 0.10 0.08 0.12
± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.38 1.22 0.84 1.05 1.13 0.72 0.88 0.99 1.04 1.09 1.27 0.73 0.87 1.02
42 d
21 d
B
A
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NPP = nonphytate P. Calcium levels were maintained at a minimum 2:1 ratio of Ca:NPP with overall diet minimums of 0.7, 0.6, and 0.5% for 0 to 3, 3 to 6, and 6 to 9 wk, respectively. Treatments in bold face type are based on estimates from previous trials over individual age periods.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Treatment
B
NPPA (%)
TABLE 7. Effects of dietary treatments on excreta P content (mean ± SD) of male broilers (mean of two trials with six pens of 50 birds per trial)
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YAN ET AL.: MODIFIED PHOSPHORUS LEVELS FOR BROILERS Tibia Ash
Fecal Phosphorus The effects of the various treatments on fecal P content are shown in Table 7. The fecal P content of birds fed diets with NPP levels chosen to maximize body weight or tibia ash, with or without phytase supplementation, was lower than that of birds fed diets with NRC or commer-
cial P levels, especially after 21 d of age. Selection of any of the feeding strategies (i.e., maximum body weight or maximum tibia ash, with or without phytase) resulted in a reduction of 40 to 50% in fecal P content, depending upon the age of the chick. The results of this study demonstrate that fecal P excretion by broiler chicks can be markedly reduced while maintaining productivity through the use of reduced dietary P levels, especially after 3 wk of age, combined with the use of phytase supplementation. Feeding to maximize body weight with the use of phytase enzyme resulted in BW and feed conversion that did not differ significantly from that of birds fed diets based on NRC recommendations or diets that contained 0.05% greater P as a margin of safety (commercial levels). Tibia ash of these birds was only slightly less than that of birds fed the NRC or commercial levels, with no indications of increased mortality or leg disorders among the birds. Use of these levels in conjunction with phytase supplementation resulted in more than 50% reduction in fecal P excretion, compared to that of birds fed diets with NRC recommendations. The use of NPP levels fed in combination with phytase supplementation that were estimated to maximize tibia ash resulted in live performance and tibia ash that did not differ significantly from those of birds fed the NRC recommendations and reduced fecal P by 25 to 35%, depending upon the age of the bird.
CONCLUSIONS AND APPLICATIONS 1. All estimates of NPP requirements supported body weight, feed conversion, and livability equivalent to those of birds fed NRC or commercial levels. 2. Estimates of NPP to maximize body weight, with or without phytase, significantly reduced tibia ash as compared to birds fed NRC or commercial levels. 3. Estimates of NPP needed to maximize tibia ash without phytase supplementation resulted in significantly reduced tibia ash compared to birds fed NRC or commercial levels of NPP. Increasing these levels by 0.05% resulted in tibia ash that did not differ from that of birds fed the NRC or commercial levels. 4. Estimates of NPP needed to maximize tibia ash with phytase supplementation resulted in tibia ash that did not differ significantly from that of birds fed NRC or commercial levels. 5. Use of a reduced P scenario that maintained tibia ash resulted in a 25 to 35% reduction in fecal P content, depending upon age of the bird. Acceptance of a slight reduction in tibia ash content allowed for a reduction of up to 50% in fecal P output. 6. Further work is needed to determine if maximum tibia ash is necessary for maintaining live performance and carcass integrity during processing.
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The effects of the various treatments on tibia ash are shown in Table 6. Birds fed diets with P levels chosen to maximize body weight, with or without the addition of phytase, typically had tibia ash values that were significantly less than those of birds fed diets with NRC levels of P; however with 0.05% additional P, tibia ash often did not differ significantly from that of birds fed the NRC diets. Although these birds had lower tibia ash, no indications of leg abnormalities were observed, and mortality was not increased. 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 those 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.
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REFERENCES AND NOTES 1. Edwards, D. R., and T. C. Daniel. 1992. Environmental impacts of on-farm poultry waste disposal—a review. Bioresour. Technol. 41:9–33. 2. Sharpley, A. 1999. Symposium: Reducing the environmental impact of poultry production: Focus on phosphorus. Poult. Sci. 78:660–673. 3. Nelson, T. S. 1967. The utilization of phytate phosphorus by poultry—A review. Poult. Sci. 46:862–871. 4. O’Dell, B. L., A. R. de Boland, and S. R. Koirtyohann. 1972. Distribution of phytate and nutritionally important elements among the morphological components of cereal grains. J. Agric. Food Chem. 20:718–721.
6. Nelson, T. S., T. R. Shieh, R. J. Wodzinski, and J. H. Ware. 1968. The availability of phytate phosphorus in soybean meal before and after treatment with a mold phytase. Poult. Sci. 47:1842–1848. 7. Nelson, T. S., T. R. Shieh, R. J. Wodzinski, and J. H. Ware. 1971. Effect of supplemental phytase on the utilization of phytate phosphorus by chicks. J. Nutr. 101:1289–1294. 8. Ravindran, V., W. L. Bryden, and E. T. Kornegay. 1995. Phytates: Occurrence, bioavailability, and implications in poultry nutrition. Poult. Avian Biol. Rev. 6:125–143. 9. Sebastian, S., S. P. Touchburn, and E. R. Chavez. 1998. Implications of phytic acid and supplemental microbial phytase in poultry nutrition: a review. World’s Poult. Sci. J. 54:27–47. 10. Simons, P. C. M., H. A. J. Versteegh, A. W. Jongbloed, P. A. Kemme, P. Slump, K. D. Bos, M. G. E. Wolters, R. F. Beudeker, and G. J. Verschoor. 1990. Improvement of phosphorus availability by microbial phytase in broilers and pigs. Br. J. Nutr. 64:525–540. 11. Broz, J., P. Oldale, A. H. Perrin-Voltz, G. Thychen, J. Schulze, and C. Simones Nunes. 1994. Effects of supplemental phytase on performance and phosphorus utilization in broiler chickens fed a low phosphorus diet without addition of inorganic phosphorus. Br. Poult. Sci. 35:273–280. 12. Denbow, D. M., V. Ravindran, E. T. Kornegay, Z. Yi, and R. M. Hulet. 1995. Improving phosphorus availability in soybean meal for broilers by supplemental phytase. Poult. Sci. 74:1831–1842. 13. Kornegay, E. T., D. M. Denbow, Z. Yi, and V. Ravindran. 1996. Response of broilers to graded levels of microbial phytase added to maize-soyabean-meal-based diets containing three levels of non-phytate phosphorus. Br. J. Nutr. 75:839–852. 14. Kornegay, E. T., D. M. Denbow, and Z. Zhang. 1997. Phytase supplementation of corn-soybean meal broiler diets from three to seven weeks of age. Keeping Current KC 9702. BASF Corporation, Mount Olive, NJ. 15. Yi, Z., E. T. Kornegay, V. Ravindran, and D. M. Denbow. 1996. Improving phosphorus availability in corn and soybean meal
16. Sohail, S. S., and D. A. Roland, Sr. 1999. Influence of supplemental phytase on performance of broilers four to six weeks of age. Poult. Sci. 78:550–555. 17. Yan, F., J. H. Kersey, and P. W. Waldroup. 2001. Phosphorus requirements of broiler chicks three to six weeks of age as influence by phytase supplementation. Poult. Sci. 80:455–459. 18. Yan, F., J. H. Kersey, C. A. Fritts, and P. W. Waldroup. 2003. Phosphorus requirements of broiler chicks six to nine weeks of age as influenced by phytase supplementation. Poult. Sci. 82:94–300. 19. Yan, F., J. H. Kersey, C. A. Fritts, P. W. Waldroup, H. L. Stilborn, R. C. Crum, Jr., D. W. Rice, and V. Raboy. 2000. Evaluation of normal yellow dent corn and high available phosphorus corn in combination with reduced dietary phosphorus and phytase supplementation for broilers grown to market weights in litter pens. Poult. Sci. 79:1282–1289. 20. National Research Council. 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. 21. Waldroup, P. W., J. H. Kersey, E. A. Saleh, C. A. Fritts, F. Yan, H. L. Stilborn, R. C. Crum, Jr., and V. Raboy. 2000. Nonphytate phosphorus requirement and phosphorus excretion of broiler chicks fed diets composed of normal or high available phosphate corn with and without microbial phytase. Poult. Sci. 79:1451–1459. 22. Yan, F. 2001. Nutritional strategies to reduce phosphorus excretion by broilers. Ph.D. Dissertation. University of Arkansas, Fayetteville, AR. 23. Natuphos, BASF Corporation, Mt. Olive, NJ. One unit of phytase activity is defined as the quantity of enzyme required to produce 1 µmol of inorganic P/min from 5.1 mmol/L of sodium phytate at pH 5.5 in a water bath at 37°C. 24. Cobb 500, Cobb-Vantress Inc., Siloam Springs, AR. 25. Analyses conducted by Agricultural Diagnostic Laboratory, University of Arkansas, Fayetteville, AR, by using inductively coupled plasma-atomic energy spectroscopy following HNO3 digestion. 26. AOAC. 1990. Vitamin D3 in poultry feed supplements. Method 932.16. Pages 1094–1095 in Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists, Arlington, VA. 27. SAS Institute. 1991. SAS User’s Guide: Statistics. Version 6.03 ed. SAS Institute Inc., Cary, NC. 28. Mean ± standard deviation. Phytase analyses were conducted in duplicate on samples of all mixed feed. Assays were kindly conducted by BASF Corporation, Mt. Olive, NJ.
Acknowledgments This research was supported by a grant from U.S. Poultry and Egg Association, Tucker, GA. Contributions of phytase and phytase assays by BASF Corporation, Mt. Olive, NJ, are greatly appreciated.
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5. Raboy, V. 1990. Biochemistry and genetics of phytic acid synthesis. Pages 55–76 in Inositol Metabolism in Plants. D. J. Moore, W. Boas, and F. A. Loewus, ed. Wiley-Liss, New York.
for broilers using microbial phytase and calculation of phosphorus equivalency values for phytase. Poult. Sci. 75:240–249.