Nonphytate P Levels Research Articles

Dietary calcium and nonphosphate phosphorus interaction influences tibiotarsus development and related gene expression of broilers from 1 to 21 days of age

The dietary needs of calcium (Ca) and phosphorus (P) are interdependent, thus accurate evaluation of Ca and P requirements of broilers to support skeleton health and optimal growth is critical. The present study was carried out to investigate the effects of dietary Ca and nonphytate P (NPP) levels and their interactions on growth performance, tibiotarsus characteristics, tibiotarsus metabolism-related enzyme and proteins, and their gene expression of broilers, so as to provide a rational recommendation for Ca and NPP levels in diet. A total of 540 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 15 treatments with 6 replicate cages of 6 birds per cage for each treatment in a completely randomized design involving a 5×3 factorial arrangement of treatments (5 levels of Ca×3 levels of NPP). The birds were fed the corn-soybean meal diet containing 0.60%, 0.70%, 0.80%, 0.90%, or 1.00% Ca and 0.35%, 0.40%, or 0.45% NPP for 21 d. Dietary Ca level affected (P < 0.03) the bone mineral density, bone mineral content (BMC), breaking strength, ash percentage and ash Ca contents in tibia, which showed linear (P < 0.006) responses to dietary Ca levels. Dietary NPP level affected (P < 0.05) tibia BMC, ash percentage, and FGF23 mRNA level. Broilers that received 0.40% and 0.45% NPP had higher (P < 0.04) tibia BMC and ash percentage than those that received 0.35% NPP, but no differences (P > 0.05) were found between 0.40% and 0.45% NPP. Broilers that received 0.40% NPP had higher (P=0.02) tibia FGF23 mRNA level than those that received 0.35% NPP, but no differences (P > 0.05) were detected between 0.40% and 0.45% NPP or 0.45% and 0.35% NPP. The interactions between dietary Ca and NPP affected (P < 0.05) ADG, ALP activity, bone gal protein, FGF23 contents, and the mRNA expression levels ALP and bone gal protein in tibia of broilers. Results from the present study indicate that dietary Ca and NPP interaction influences growth, tibiotarsus development, and related gene expression of broiler chickens. Considering all the criteria, the dietary levels of 0.90% Ca and 0.45% NPP would be optimal for both growth and tibiotarsus development of broilers fed a conventional corn-soybean meal diet from 1 to 21 d of age.

Effects of phytase supplementation on production performance, egg and bone quality, plasma biochemistry and mineral excretion of layers fed varying levels of phosphorus

Excessive fecal excretion of phosphorus (P) has increasingly become an environmental issue due to oversupply of P in layer rations, and thus it is imperative to minimize safety margins for P to ensure the sustainability of the egg industry. In this study, a 12-week feeding trial (22 to 34 weeks of age) was conducted to evaluate the effects of phytase supplementation on production performance, plasma biochemistry, egg and bone quality and P excretion of laying hens fed various levels of non-phytate P (NPP). Forty-eight Lohmann white laying hens were randomly allocated to one of six corn–soybean meal–oat-based diets: diets containing 2.0, 2.5 or 3.0 g/kg NPP without phytase, and diets containing 1.0, 1.5 or 2.0 g/kg NPP with phytase (1 000 U/kg diet) where phytase inclusion was expected to provide 1.0 g/kg NPP to laying hens, thus making the phytase-unsupplemented treatment served as a control for the phytase-supplemented treatment accordingly. Productive performance was recorded during the experimental period. Blood and egg samples were collected, and digestibility studies were conducted at weeks 6 and 12 of the experiment. Bone mineralization was evaluated at the end of the experiment. Egg weight and egg production, feed consumption, BW and feed conversion ratio of laying hens fed lower NPP diets supplemented with phytase were comparable to those of hens fed high NPP phytase-unsupplemented controls. Eggshell thickness, specific gravity, Haugh units, tibia bone mineral density, tibia ash percent, plasma P and other biochemical parameters were not significantly different among dietary treatments. Total P intake, excretion and retention were affected by diet (P < 0.001), but its deposition in eggs was not significantly different. Contrast analysis further showed that total P excretion of phytase present vs phytase absent was averagely reduced by 40.4 mg/hen per day (P < 0.01). Moreover, total P excretion was linearly (P < 0.01) reduced with lowering dietary NPP, and this relationship was similar regardless of whether phytase was supplemented or not. The results from this study indicated that NPP levels in laying hen diets could be reduced to 1.0 g/kg (excluding the portion of NPP released by phytase) with the inclusion of phytase, without negative effects on production performance and health of the hens, thereby diminishing P excretion into environment.

Modelling and optimizing of calcium and non-phytate phosphorus requirements of male broiler chickens from 1 to 21 days of age using response surface methodology

The skeleton is the main site of P and Ca deposition; therefore, accurate estimation of Ca and P requirements is necessary to maintaining health and optimum performance of broiler chickens. A response surface methodology (RSM) using a central composite design (CCD) was used for evaluating and optimizing of Ca and non-phytate P (NPP) requirements of broiler chickens for optimal performance, ileal nutrient digestibility and bone mineralization from 1 to 21 days of age. A total of 750 one-day-old male broiler chickens (Ross 308) were randomly distributed into 50 cages including 9 treatments, each replicated 5 times (except central treatment with 10 replicates) and 15 birds in each cage by CCD. The dietary Ca levels of 4.3, 5.6, 8.6, 11.7 and 13.0 g/kg and NPP of 2.5, 2.9, 4.0, 5.0 and 5.4 g/kg were used for nine treatments of CCD. The results indicated that the linear and quadratic effects of NPP, quadratic effects of Ca and Ca × NPP were significant for average weight gain (AWG, P < 0.05), average feed intake (AFI, P < 0.05), feed conversion ratio (FCR, P < 0.05) and Ca and P apparent ileal digestibility (AID, P < 0.05); however, the linear effect of Ca was significant only for FCR (P < 0.05). On the other hand, tibia and toe ash were affected by NPP (linear and quadratic, P < 0.01) and Ca (quadratic, P < 0.01). The second-order polynomial regression model was significant for AWG (R2 = 0.93, P < 0.001), AFI (R2 = 0.88, P < 0.001), FCR (R2 = 0.78, P < 0.001), AID of Ca (R2 = 0.78, P < 0.001) and P (R2 = 0.88, P < 0.001), tibia ash (R2 = 0.86, P < 0.001) and toe ash (R2 = 0.85, P < 0.001). The multi-objective optimization indicated that broiler chickens from 1 to 21 days of age need 7.03 and 4.47 g/kg of Ca and NPP, respectively, to achieve optimal AWG, FCR, tibia and toe ash. However, the dietary Ca and NPP levels can be reduced to 6.57 and 3.95 g/kg with a slight negative impact on performance and bone mineralization, respectively. In conclusion, the findings indicate that using multi-objective optimization model such as RSM provides more information regarding optimum Ca and NPP requirements of broiler chickens, considering the complex interaction between these two minerals. While the NPP levels are in line with current recommended requirements, Ca levels are considerably lower and suggest that current recommended Ca requirements may be in excess of the needs of the broiler.

Adaptive response of broilers to dietary phosphorus and calcium restrictions

The aim of this study was to evaluate the capacity of chickens to adapt to and compensate for early dietary restriction of non-phytate P (NPP) and/or Ca (10 to 21 d) in a later phase (22 to 35 d), and to determine whether compensatory processes depend on the P and Ca concentrations in the finisher diet. Four diets were formulated and fed to broilers from 10 to 21 d in order to generate birds with different mineral status: L1 (0.6% Ca, 0.30% NPP), L2 (0.6% Ca, 0.45% NPP), H1 (1.0% Ca, 0.30% NPP), and H2 (1.0% Ca, 0.45% NPP). On d 22, each group was divided into three groups which received a low (L, 0.48% Ca, 0.24% NPP), moderate (M, 0.70% Ca, 0.35% NPP), or high (H, 0.90% Ca, 0.35% NPP) finisher diet until 35 d, resulting in a total of 12 treatments. Lowering the Ca level enhanced apparent ileal digestibility of P (P AID) at 21 d especially with the high NPP level (Ca × NPP, P < 0.01). The lower bone mineralization observed at 21 d in broilers fed the L1 diet compared to those fed the H2 diet had disappeared by 35 d with long-term stimulation of the P AID with the low NPP level (P < 0.001). Although P AID and growth performance were improved in birds fed the L1 L compared to the L1 H and H2 H treatments, tibia characteristics tended to be lower in birds fed the L1 L compared to those fed the L1 H treatment. Birds fed the H1 M treatment had higher P AID, growth performance and tibia ash content than those fed the H1 H treatment. A significant increase in the mRNA levels of several genes encoding Ca and P transporters was observed at 35 d in birds fed the L1 followed by the L diet compared to birds fed the L1 followed by the M diet. In conclusion, chickens are able to adapt to early dietary changes in P and Ca through improvement of digestive efficiency in a later phase, and the extent of the compensation in terms of growth performance and bone mineralization depends on the P and Ca levels in the subsequent diet.

A meta-analysis of the effects of nonphytate phosphorus on broiler performance and tibia ash concentration

Decreasing feed costs while maintaining broiler performance at a high level with minimal environmental pollution has become a major challenge for poultry nutritionists in recent years. In this regard, phosphorus (P) is a nutrient that is problematic. To overcome this, a comprehensive knowledge of the responses of broilers to P is needed and the factors that affect its utilization need better understanding. For this purpose, a meta-analysis was conducted using results published in the literature on the responses of broilers to different levels of nonphytate P (NPP), calcium (Ca), microbial phytase (MP), and vitamin D3 or its metabolites (VD). The effects of Ca, MP, and VD on NPP requirements were investigated. Results showed significant (P ≤ 0.0001) linear and quadratic effects of NPP on all the responses, viz. average daily gain (ADG), feed intake (FI), feed efficiency (FE), and tibia ash concentration (TA). Results showed the negative effect of high Ca levels on all investigated responses, although these deleterious effects were alleviated when levels of NPP were increased or MP and/or VD added. Synergistic effects of MP and VD on FI and TA were observed. Best performance for all responses was found when MP and VD were added to low or moderate levels of Ca and NPP. Optimization showed higher levels of NPP are required to maximize TA compared to ADG, FI, and FE. Based on our analysis, requirements for NPP were affected mostly by Ca (increased) and MP (decreased), and, to a lesser extent, VD (inconsistent).

Calcium sources and their interaction with the different levels of non-phytate phosphorus affect performance and bone mineralization in broiler chickens

An experiment was conducted to evaluate the influence of different Ca sources (limestone, Ca chloride, and Lipocal, a fat-encapsulated tricalcium phosphate, TCP) in conjunction with 4 dietary levels of non-phytate P (NPP) on performance, ileal digestibility of Ca and P, and bone mineralization in broiler chickens. Calcium sources were also evaluated in vitro to measure acid-binding capacity (ABC) and Ca solubility at different pH values. Ca chloride showed the highest solubility of Ca, with TCP showing the highest ABC. Ross male broiler-chicks were sorted by BW at 1 d post-hatch and assigned to 5 cages per diet with 5 birds per cage. Twelve diets were arranged in a 3 × 4 factorial of the 3 Ca sources and 4 levels of NPP (0.3%, 0.35%, 0.4% or 0.45%) consisting of 4 added P levels (Ca(H2 PO4)2) with a high dose of phytase (1,150 U/kg) in all diets. On d 14 post-hatch, 3 birds were euthanized, and ileal digesta and the right tibia were collected to determine ileal Ca and P digestibility and bone mineralization, respectively. Feed intake (FI) and weight gain (WG) on d 14 was higher (P < 0.01) with TCP and limestone than with Ca chloride. Added P increased the tibia weight and tibia ash content in chicks fed TCP up to 0.4% NPP and limestone up to 0.35% NPP. Calcium ileal digestibility was higher (P < 0.01) with Ca chloride (73.7%) than with limestone (67.1%) or TCP (66.8%), which increased (P < 0.05) with added levels of P from monocalcium phosphate. Phosphorus ileal digestibility was not affected by the Ca source and increased (P < 0.001) with added levels of NPP. It can be concluded that starting broilers responded better to low-soluble Ca sources compared to high-soluble sources. A level of 0.35%–0.40% NPP with a high dose of phytase (1,150 U/kg) in diets including limestone or TCP is sufficient to guarantee performance and bone formation for broiler chickens from d 0 to d 14.

A meta-analysis of responses to dietary nonphytate phosphorus and phytase in laying hens

Reducing the level of nonphytate P (NPP) in diets for laying hens without negatively affecting their productivity and heath is crucial for sustainable egg production. A meta-analytical approach using a full quadratic model was applied to quantify relationships between dietary NPP and phytase levels and performance of laying hens. Egg production (EP, %), egg mass (EM, g/hen/day), and feed conversion ratio (FCR) were considered as model outputs. A data set containing 168 P or P plus phytase treatments was extracted from 12 published papers. The data were assembled from 14 trials with a total of 8,752 hens in the range of 36 to 76 wk of age. The EP, EM, and FCR were analyzed using a linear mixed model that included the linear and quadratic effects of dietary NPP and phytase levels and their interactions. Except for the quadratic effect of dietary phytase on FCR, all other model components (that is, intercept, linear, quadratic, and interactions) were significant (P<0.05). There was a relatively strong relationship between observed and predicted EP (R2=0.78, RMSE=3.73), EM (R2=0.84, RMSE=2.09), and FCR (R2=0.78, RMSE=0.11), demonstrating that observations within study are practically predictable. Analyses of the model revealed that corn-soybean meal-based diets containing 0.22% of NPP without supplemental phytase resulted in high EP, EM, and feed efficiency in layers. In the presence of 150, 300, and 400 phytase units (FTU)/kg of feed, the dietary NPP level may be decreased and optimal levels were calculated as 0.18, 0.15, and 0.14%, respectively.

Meta-analysis of phosphorus utilization by growing pigs: effect of dietary phosphorus, calcium and exogenous phytase

Optimizing phosphorus (P) utilization in pigs requires improving our capacity to predict the amount of P absorbed and retained, with the main modulating factors taken into account, as well as precisely determining the P requirements of the animals. Given the large amount of published data on P utilization in pigs, a meta-analysis was performed to quantify the impact of the different dietary P forms, calcium (Ca) and exogenous phytases on the digestive and metabolic utilization criteria for dietary P in growing pigs. Accordingly, the amount of phytate P (PP) leading to digestible P (g/kg) was estimated to be 21%, compared with 73% for non-phytate P (NPP) from plant ingredients and 80% for NPP from mineral and animal ingredients (P < 0.001). The increase in total digestible dietary P following the addition of microbial phytase (PhytM) from Aspergillus niger (P < 0.001) was curvilinear and about two times higher than the increase following the addition of plant phytase, which leads to a linear response (P < 0.001). The response of digestible P to PhytM also depends on the amount of substrate, PP (PhytM2 × PP, P < 0.001). The digestibility of dietary P decreased with dietary Ca concentration (P < 0.01) independently of phytase but increased with body weight (BW, P < 0.05). Although total digestible dietary P increased linearly with total NPP concentration (P < 0.001), retained P (g/kg), average daily gain (ADG, g/day) and average daily feed intake (ADFI, g/day) increased curvilinearly (P < 0.001). Interestingly, whereas dietary Ca negatively affected P digestibility, the effect of dietary Ca on retained P, ADG and ADFI depended on total dietary NPP (NPP × Ca, P < 0.01, P < 0.05 and P < 0.01, respectively). Increasing dietary Ca reduced retained P, ADG and ADFI at low NPP levels, but at higher NPP concentrations it had no effect on ADG and ADFI despite a positive effect on retained P. Although the curvilinear effect of PhytM on digestible P increased with PP (P < 0.001), this effect was lessened by total NPP for ADG and ADFI (PhytM × NPP and PhytM2 × NPP, P < 0.05) and depended on both total NPP and Ca for retained P (PhytM2 × NPP × Ca, P < 0.01). This meta-analysis improves our understanding of P utilization, with major modulating factors taken into account. The information generated will be useful for the development of robust models to formulate environmentally friendly diets for growing pigs.

The efficacy of a phytase enzyme fed to Hy-Line W-36 laying hens from 32 to 62 weeks of age

SUMMARY An experiment was conducted to determine the efficacy of a phytase enzyme (Optiphos, JBS United Inc., Sheridan, IN) in corn-soybean meal diets fed to laying hens from 32 to 62 wk of age. Hens were fed diets consisting of a negative control diet containing 0.105% nonphytate P (NPP), a positive control (0.45% NPP), a marginal NPP level (0.20%), or supplemental phytase enzyme at 150, 250, or 15,000 phytase units (FTU)/kg added to the negative control diet. The negative control dietary treatment containing 0.105% NPP was terminated at 39 wk of age because of a severe reduction in egg production compared with all other treatments. No significant differences were observed among the other dietary treatments in BW, egg production, egg weight, egg mass, feed intake, or FE when these parameters were evaluated over the duration of the experiment. No differences in tibia ash were seen at 62 wk of age when compared among the 5 treatments. Excreta P was much higher (P

Effect of Phytase on the Sodium Requirement of Starting Broilers 1. Sodium Bicarbonate as Primary Sodium Source

Recent work has indicated that phytase enzymes may influence Sodium (Na) metabolism in the chick but to date no work has conclusively demonstrated that the Na requirement of the chick for live performance is influenced by phytase supplementation. In this study male broilers were fed diets with Na levels ranging from 0.10-0.28% using sodium bicarbonate as the primary source of supplemental Na. Diets were supplemented with no phytase, 500 FTU/kg (1x) or 2,000 FTU/kg (4x) of phytase. When phytase was added the dietary Ca and Nonphytate P (NPP) were adjusted in accordance with anticipated release of these minerals. For 1x phytase the Ca and NPP were reduced 0.10% each and for 4x phytase were reduced by 0.20% each. The combination of seven Na levels and three phytase treatments resulted in 21 dietary treatments, each of which was fed to six replicate pens of five male chicks housed in electrically heated battery brooders with wire floors. Experimental diets and tap water were provided for ad libitum consumption from day of hatch to 18 d. At 16 d of age excreta from each pen was collected and freeze dried to determine moisture content and the excreta analyzed to determine amounts of Ca, P and Na. There were no significant differences in Body Weight (BW), Feed Conversion (FCR), Feed Intake (FI), fecal moisture (FH2O), or mortality of broilers fed diets with different levels of phytase indicating that the dietary adjustment in NPP and Ca levels for the addition of the phytase did not adversely affect performance of the birds. The dietary Na leve l significantly affected BW, FCR, FI or FH2O. There were no significant interactions of dietary Na and level of phytase supplementation. Regression analysis showed an overall estimate of 0.18±0.01% Na for BW and 0.19±0.01% Na for FCR. There was little indication that the Na requirement was affected by phytase. The level of phytase and Na in the diet had significant effects on excreta levels of P, Ca and Na. The use of lower dietary levels of NPP and Ca in association with the addition of the phytase resulted in significant reduction in excreta levels of these minerals, but had no significant effect on levels of excreted Na. Increasing the dietary Na level significantly affected the levels of all three minerals in the excreta. Although the dietary Na level had significant effects on both excreta P and Ca, these followed no consistent trends with no significant difference in Ca or P excretion between chicks fed diets with the lowest and highest Na levels. There were significant interactions between dietary Na levels and levels of phytase supplementation for all three minerals in the excreta. However, these did not appear to follow any consistent pattern. While it is apparent that phytase influences the metabolism of Na within the body, the data from the present study suggests that this has little impact on the dietary need for Na.

Citric acid improves phytate phosphorus utilization in crossbred and commercial broiler chicks

Previous research in our laboratory has shown that citric acid (CA) improves phytate P utilization in New Hampshire x Columbian (NHC) crossbred chicks fed a P-deficient corn-soybean meal diet. The current study was conducted to determine if CA is also effective in commercial broiler chicks (Ross x Ross). In 3 experiments, 4 replicate groups of 5 male NHC chicks and male commercial chicks were fed corn-soybean meal diets varying in CA and nonphytate P (NPP) from 8 to 22 d of age. In experiment 1, a 2 x 2 x 2 factorial treatment arrangement was used to evaluate the effect of 2 levels of CA (0 and 3%) and NPP (0.13 and 0.28%) in NHC chicks and commercial chicks. The commercial chicks, but not the NHC chicks, fed the 0.13% NPP diet had to be removed from the experiment after 3 to 5 d due to very poor growth and severe leg problems. Chick weight gain and tibia ash were significantly increased (P < 0.05) by CA in both types of chicks. In experiment 2, the same 2 x 2 x 2 factorial treatment arrangement was again used except that the NPP levels were 0.18 and 0.28%. Tibia ash was increased significantly (P < 0.05) with the addition of CA in both breeds of chicks; response was greater at 0.18% NPP than at 0.28% NPP. In experiment 3, graded levels of CA (0, 1, 2, 3, and 4%) were evaluated in commercial chicks fed diets containing 0.18% NPP. Tibia ash increased linearly (P < 0.05) as CA increased from 0 to 4%. The average increase in bone ash resulting from 3% CA supplementation in experiments 2 and 3 was 41%. These results indicate that CA markedly improved phytate P utilization in NHC and Ross x Ross commercial broiler chicks.

Hy-Line W-36 and Hy-Line W-98 laying hens respond similarly to dietary phosphorus levels

Two experiments were conducted to determine if 2 laying hen strains, Hy-Line W-36 and Hy-Line W-98, would respond similarly to being fed corn-soybean meal diets (17% CP and 3.8% Ca) deficient in nonphytate P (NPP). In experiment 1, 3 diets with varying NPP levels (0.10, 0.14, and 0.45%) were fed to 6 replicate groups of 12 hens of each Hy-Line strain from 20 to 50 wk of age. Body weight, egg weight, egg mass, feed intake, and NPP intake were higher for W-98 hens compared with W-36 hens throughout the 30-wk period. The 0.10% NPP dietary treatment was terminated for both strains at 35 wk of age due to similar low egg production. Within each strain, there was no significant difference in egg production performance for hens fed 0.14% NPP compared with hens fed 0.45% NPP. In experiment 2,3 diets with varying levels of NPP (0.10, 0.13, and 0.45%) were fed to 5 replicate groups of 12 hens of each Hy-Line strain from 95 to 112 wk of age. The 0.10% NPP treatment rapidly and severely depressed egg production and was terminated at 99 wk of age for both strains. In addition, egg production and egg mass were depressed similarly in both strains fed 0.13% NPP. In conclusion, this research indicates that Hy-Line W-36 and Hy-Line W-98 hens responded similarly to dietary NPP deficiency, suggesting that both strains have similar NPP requirements.

Confirmation of Phosphorus Availability in Low-Phytate and High-Protein Corn to Growing-Finishing Large White Toms

A 115-d (16.5-wk) experiment was conducted to validate the estimated availability of P in a high nutrient-dense (amino acids and calories), low-phytic acid (NDLP) corn variety as compared with conventional yellow dent (YD) corn when fed to commercial toms. The NDLP corn contained 0.32% P and 90% of this was nonphytate P (NPP) compared with YD corn, which had 0.25% P and 32% of the total P was NPP. Toms consuming NDLP corn were fed diets formulated to have the same dietary NPP level as the control diet with reduced levels of total P. Phosphorus was successfully formulated at 90% availability for NDLP corn with no compromise to growth performance or bone integrity measurements compared with the control diet with YD corn. Ulna breaking strength was the most sensitive measurement of dietary P adequacy under the conditions of the experiment. Excretion of P from toms was decreased by 30% when NDLP corn was fed in place of YD corn during the finishing phase, and litter P was decreased by 19% by replacement of YD corn with NDLP corn.

Growth Performance, Bone Mineralization, and Nutrient Retention Responses of Chicks to Dietary Crude Protein and Non-phytate Phosphorus Concentrations

The objective of this study was to investigate possible interactions between dietary crude protein (CP) and phosphorus (P) in broiler chicks. Two CP levels including an adequate NRC-recommended 230 g/kg or an amino acid-supplemented reduced CP 180 g/kg and 4 level - 4.0, 4.5, 5.0, or 5.5 g of non-phytate P (NPP)/kg in a 2 X 4 factorial arrangement were fed to 6 replicate cages of 6 chicks per cage from 10 to 22 d of age. There were main effects of CP (P < 0.001) and NPP (P < 0.05) concentration on final body weight (FBW), body weight gain (BWG), and gain-to-feed ratio. There was a linear reduction (P < 0.05) in feed intake as dietary NPP level increased. Generally, FBW, BWG and FI were linearly reduced (P < 0.05) with increasing NPP. Gain-to-feed ratio was lower (P < 0.05) for chicks fed the AA-supplemented reduced CP diet than those fed the adequate protein diet. Tibia ash was increased linearly (P < 0.05) with increased dietary NPP, but was not affected by CP. There were both linear and quadratic effects (P < 0.05) of NPP on retention of dry matter and energy. At either CP level, retention of nitrogen and phosphorus was reduced (P < 0.05) with increase in dietary NPP. Retention of P was linearly reduced with increasing NPP concentration and highest in chicks fed the adequate CP diet. These results provide support for an integrated strategy for reducing manure N and P excretion by broiler chickens.

Effects of Corn and Soybean Meal Particle Size on Phosphorus Use in Turkey Poults

Two 28-d experiments were conducted to evaluate the effect of grinding corn or soybean meal (SBM) to various particle sizes on P utilization in turkey poults. Dietary Ca was formulated to be 1.20% in the corn-SBM-based diets of both studies and nonphytate P (NPP) was calculated to be 0.40% in experiment 1 and 0.48% in experiment 2. In experiment 1, corn that had been processed through a roller mill was used or was ground through 3 different screen sizes in a hammer mill to yield 4 corn particle sizes ranging from about 600 to 1,100 μm. Initial (7 d) growth was reduced when the coarsest corn was fed due to lower feed intake. Phosphorus utilization was improved the first 2 wk as corn particle size increased as measured by incidence of rickets, tibia ash, and total P retention. Gizzard weight and phytate P retention were increased at 28 d as corn particle size increased. In experiment 2, corn was ground to approximately 850 μm and commercial SBM (856 μm) was used or ground to 2 finer particle sizes in a hammer mill. Gizzard weight and phytate P retention were increased at 28 d as SBM particle size increased. Other parameters were not affected at least partially due to the higher dietary NPP level fed to prevent severe rickets observed in the first trial. These studies show that young poults can utilize P better from coarser corn and soybean meal, especially when dietary P is low.

A comparison between cholecalciferol and 25-OH-cholecalciferol on performance and eggshell quality of hens fed different levels of calcium and phosphorus

Two experiments were conducted to determine whether the presence of 25-OH-cholecalciferol (25-OH-D3) as compared to vitamin D3 produces any beneficial effect on shell quality of laying hens. Experiment 1 consisted of a 4 × 2 factorial arrangement of the treatments with four determined Ca levels (3.34, 4.3, 4.73, and 4.94%) and two sources of vitamin D (vitamin D3 and 25-OH-D3, which were used at 69 microg/kg diet or 2,760 IU/kg diet). Experiment 2 consisted of a 3 × 2 × 2 factorial arrangement of the treatments with three determined levels of nonphytate P (NPP) (0.11, 0.21, and 0.41%), two levels of phytase (0 and 300 U/kg diet), and two sources of vitamin D (vitamin D3 and 25-OH-D3, which were used at 69 microg/kg diet, the equivalent of 2,760 IU/kg diet). Substitution of vitamin D3 with 25-OH-D3 in neither of the experiments produced any beneficial effect on shell quality. A Ca level of 3.34%, which provided the birds with 3.63 g Ca/hen per d, was adequate for performance and eggshell quality. The NPP level of 0.11% was not sufficient to support performance. However, a NPP level of 0.21% was adequate and resulted in performance that was comparable to that of birds fed the 0.41% NPP diet. The presence of phytase did not have an effect on performance but reduced several indices of the shell quality. In conclusion, under the conditions of the current experiments, the use of 25-OH-D3 did not provide any advantage for shell quality or production performance.

High available phosphorus corn and phytase in layer diets

High available phosphorus corn (HAP) developed using the low phytic acid 1-1 (lpal-1) allele of the corn LPA1 gene containing 0.27% P, with 0.17% nonphytate P (NPP), was compared to near isogenic normal corn (LPA1), which contained 0.23% P and 0.05% NPP. Five levels of NPP from either HAPC or normal corn (0.40, 0.35, 0.30, 0.25 and 0.20% + 300 phytase units (FTU)/kg microbial phytase) were combined in a 2 x 5 factorial experiment for a total of 10 dietary treatments. Each dietary treatment was fed to eight replicate cages with five Hy-Line W-36 hens per replicate cage from 20 to 40 wk of age. Feed consumption and egg production were not significantly affected by dietary NPP level or corn type. Feed conversion ratio (g feed:g egg mass) was improved at the 0.35% NPP level (1.856) compared to the other levels of NPP--0.40, 0.30, 0.25, and 0.20% + phytase having feed conversion ratios of 1.872, 1.905, 1.930, and 1.898, respectively. Egg weight and egg mass decreased significantly as dietary NPP decreased; diets with 0.20% NPP plus phytase had equal egg mass to the 0.35 and 0.40% NPP diets. A significant corn type x NPP interaction effect was observed for egg weight, such that within the HAP corn diets, egg weight decreased more markedly at the 0.25% NPP levels compared to the normal corn 0.25% NPP diets. Specific gravity was not affected by dietary treatment, but percent dry shell was improved at the lower AP levels and with phytase treatment. Dietary NPP level and corn type had no significant effect on bone ash. Excreta levels of total phosphorus decreased significantly as dietary NPP decreased and were lower in the HAP corn excreta compared to normal corn excreta. Total P, Ca, Zn, Cu, and Mn retention were significantly affected by NPP level and corn type. HAP corn reduced Ca, Zn, Cu, and Mn retention compared to normal corn; this negative effect was alleviated by phytase supplementation to HAP corn diets. HAP corn allowed less dicalcium phosphate supplementation in layer diets compared to normal corn while supporting equal egg production. Phytase supplementation of low NPP diets had no significant positive effects on egg production parameters in either corn type diets.

Effects of Added Dietary Fat and Phosphorus on the Performance and Egg Quality of Laying Hens Subjected to a Constant High Environmental Temperature

Two experiments were conducted to study the combined effect of nonphytate P (NPP), fat, and temperature on the performance and egg quality of hens pre- and postpeak. In Experiment 1, 192 Single Comb White Leghorn layers, aged 22 wk, were individually housed in cages under ambient (AT) and constant high temperature (CHT) of 33 ± 1 C. In Experiment 2, 28-wk-old birds were used with a CHT of 35 ± 1 C. Diets contained 0 and 4% added vegetable fat with four dietary NPP levels, ranging from 0.20 to 0.50% in Experiment 1 and from 0.15 to 0.45% in Experiment 2, at increments of 0.1%. These diets were fed to hens for 84 d. Performance and egg quality criteria were measured in both experiments, whereas serum and tibia Ca and P were determined in Experiment 2. Results showed that there was no significant interaction among NPP, fat, and temperature, for any criteria measured. The CHT significantly reduced BW, feed intake, egg production, egg weight, egg mass, and shell thickness. Moreover, it decreased (P < 0.05) serum Ca, P, tibia ash, and tibia P. The lowest NPP levels resulted in the greatest shell thickness (P < 0.05), which decreased with increasing NPP levels in both trials. In the postpeak experiment, the feed intake was significantly reduced by 0.15 and 0.25% NPP. Moreover, 0.15% NPP significantly reduced egg production as compared to 0.35 and 0.45% NPP diets. Levels between 0.25 and 0.45% significantly improved the serum phosphorus content as compared to 0.15%. Added fat improved only serum P level (P < 0.05). The beneficial effect of supplemental fat on hen performance was evident in Experiment 1 but not in Experiment 2, indicating that nutrients were oriented more toward supporting egg production rather than maintaining the BW at the postpeak stage.

Influence of Cage Density and Prior Dietary Phosphorus Level on Phosphorus Requirement of Commercial Leghorns

Two studies were conducted to determine whether cage density and prior dietary nonphytate P (NPP) level affect hens’ P requirements. In Experiment 1, hens were housed at three cage densities (300, 400, and 600 cm2 or 46.5, 62.0, and 93.0 inches2/hen) and fed four levels of NPP (0.15, 0.25, 0.35, and 0.40%) for 6 wk to determine the effect of cage density on the P requirement. Egg production (EP), feed consumption (FC), egg weight (EW), and egg specific gravity (ESG) were measured to evaluate performance. Cage density influenced EP within Week 1 (P < 0.01), and during Weeks 5 and 6, there was a cage density × NPP-level interaction (P < 0.05). At 300 cm2, EP was more severely affected by 0.15 and 0.25% NPP than at 400 and 600 cm2. A linear decrease (P < 0.001) in FC was observed because of decreased NPP. Hens at 300 cm2 consumed 4 g less feed/hen per d than hens at 400 cm2. A linear decrease in EW was observed as the NPP level decreased (P < 0.01) from 0.25 to 0.15%, and there was no effect of cage density. Experiment 2 was conducted to determine the effect of prior dietary P levels on time required to create a P deficiency. Hens fed 0.4% NPP were divided into two groups and fed 0.25 and 0.4% NPP for 4 wk. At the end of 4 wk, hens fed 0.25% NPP were further divided into three groups and were fed diets containing 0.09, 0.25, and 0.30% NPP for an additional 6 wk. Hens fed 0.4% NPP were divided into three groups and fed diets containing 0.09, 0.4, and 0.45% NPP. Reduction of NPP from 0.4 and 0.25% to 0.09% reduced EP by 8.5 and 6.8%, respectively, within 3 wk. Prior NPP levels had no influence on time required to create a P deficiency in terms of EP. Reduction of NPP from 0.4 and 0.25% to 0.09% reduced (P < 0.05) FC. A decline in FC occurred 2 wk earlier in hens previously fed 0.4% than those fed 0.25% NPP. This result indicates that hens fed 0.4% NPP became P deficient more quickly than hens fed 0.25%. We concluded that cage density and prior NPP level affect the hen P requirements or time required to create a P deficiency.

Effect of dietary phosphorus, calcium, and phytase on performance of growing turkeys

Female and male turkeys were fed 110, 73, 52, and 30% of the NRC (1994) nonphytate P (NPP) requirement without and with 500 phytase units (FTU)/kg during 4 to 14 or 16 wk of age, respectively. At 110% P (control; also 110% of NRC Ca), phytase was without effect. At 73% of NPP (100% Ca), without phytase, performance was similar to the control; with phytase, performance was equivalent, and in some stages, superior to the control. At 52% of NPP (90% Ca), performance was inferior without phytase and was variably similar or poorer than the control with phytase. At 30% NPP without phytase, poults gained poorly and showed a high incidence of leg disorder at 8 wk when they were removed from experiment; poults gained better with 80% NRC Ca compared with 110%. At 30% NPP with phytase, turkeys performed remarkably well, although suboptimally, at 80 or 110% NRC Ca. Phytase at 400, 300, and 200 FTU/kg with increasing age periods performed as well as 500 FTU/kg with 73% of NRC NPP (100% Ca) and 52% NRC NPP (90% Ca). These lower phytase levels were not as sufficient as 500 FTU/kg with 30% of NRC NPP; this inadequacy was more severe with higher dietary calcium. Phytase was effective in reducing dietary P requirements of growing turkeys when the NPP levels were below NRC (1994) requirements.