Dietary nPP Research Articles

Effect of phytase supplementation of diets with different levels of rice bran and non-phytate phosphorus on productive performance, egg quality traits, leukocytes profile and serum lipids of laying hens reared indoor under high environmental temperatures

A total of 288 32-wk-old Lohmann Selected Leghorn (LSL-Lite) laying hens were fed on corn-soyabean meal-based diets containing three concentrations of rice bran (RB; 0, 75 and 150 g/kg; equivalent to 1.8, 2.7 and 3.5 g/kg phytate phosphorus), two of non-phytate phosphorus (NPP; 2.5 and 3.5 g/kg) and two of microbial phytase (Phyzyme® XP 5000G; 0 and 150 FTU/kg) in a 10-wk trial under high temperature condition. The average minimum and maximum room temperatures were 26.0 ± 1.9 and 36.0 ± 1.8 °C, respectively, with relative humidity ranging from 42.3 ± 1.8% to 55.1 ± 2.1%. Each dietary treatment was fed to four cages (six birds/cage) from 32 to 42 wk of age. Egg production, egg weight and feed intake were recorded daily. Egg quality traits were recorded every 5 wk. Leukocyte subset counts and blood lipid profile were evaluated at the end of experiment. The results showed that inclusion of 150 g/kg RB negatively influenced (P < 0.05) egg production (EP), feed conversion ratio (FCR), shell weight and shell thickness. Significant reductions (P < 0.05) in the blood triglyceride and total cholesterol were observed with increasing dietary inclusion levels of RB. Although, dietary NPP levels did not influence any of the performance traits, the low-NPP diets caused a decrease (P < 0.05) in shell weight and shell thickness when compared with normal-NPP diets. The H/L ratio, as a stress indicator, was also increased (P < 0.05) by low-NPP diets. These adverse effects were partially overcome by the addition of microbial phytase (PHY). Supplemental PHY improved (P < 0.05) EP, FCR and unmarketable eggs but the magnitude of the responses was greater in low-NPP and high-RB treatments, resulting in significant RB × NPP × PHY interactions. Egg mass, shell weight and shell thickness were also improved (P < 0.05) by PHY addition but the response was greater at the highest concentration of RB, resulting in a significant RB × PHY interaction. Responses were also greater (P < 0.05) in low-NPP diets as indicated by significant NPP × PHY interaction. It can be concluded that the positive effects of PHY supplementation were clearly evident for laying hens reared under the high ambient temperatures pertaining to this study. At high concentration of phytate (high-RB diet) and/or low level of NPP (2.5 g/kg), response to supplemental PHY appears to be increase in terms of performance and egg quality in heat-stressed laying hens.

Effect of dietary nonphytate phosphorus and calcium concentration on calcium appetite of broiler chicks

The effect of dietary nonphytate P (nPP) and Ca concentration on the Ca appetite in broilers was evaluated. A total of 288 one-day-old male Ross 308 broilers were fed a commercial diet for 7 d then randomly allocated to 1 of 8 dietary treatments for a 28-d study. Diets were corn-soybean meal based and formulated to be nutritionally adequate except for nPP and Ca. Two concentrations of Ca (5.0 and 10.0 g/kg) and 4 of nPP (2.5, 3.5, 4.5, and 5.5 g/kg) were used, and all birds had access to a separate Ca source (CaCO3). Bird performance, nutrient digestibility, and tibia ash were determined. Birds fed 5.0 g of Ca/kg diets consumed more (P < 0.01) of the separate Ca source than birds fed diets containing 10.0 g of Ca/kg. Increased consumption (P < 0.01) of the separate Ca source was associated with increasing nPP concentration. Bird performance was not influenced by dietary treatment. Birds fed 5.5 g of nPP/kg diets had lower (P < 0.01) digestibility of DM, CP, and energy than the other groups. Phosphorus digestibility was reduced in birds fed high Ca diets and those fed 2.5 g of nPP/kg diets (P < 0.001). Birds fed 2.5 g of nPP/kg had lower tibia ash values than those fed higher concentrations of nPP while feeding diets containing 10.0 g of Ca/kg led to higher concentrations (P < 0.05) of tibia ash than for birds fed 5.0 g of Ca/kg. This study confirms previous findings that birds are able to meet their Ca requirement when fed Ca separately from the mixed ration. Consumption of the separate Ca source responded to not only Ca concentration but also to the amount of nPP in the diet. These data suggest that dietary nPP concentration influences the Ca specific appetite of broilers, and this may indicate that birds attempt to regulate their intake of Ca relative to nPP. This may be mediated via a physiological mechanism to maintain an appropriate Ca:nPP intake.

Nutritional geometry of calcium and phosphorus nutrition in broiler chicks. Growth performance, skeletal health and intake arrays

The interaction between calcium (Ca) and non-phytate phosphorus (nPP) in broiler nutrition and skeletal health is highly complex with many factors influencing their digestion, absorption and utilisation. The use of an investigative model such as the geometric framework allows a graphical approach to explore these complex interactions. A total of 600 Ross 308-day-old male broiler chicks were allocated to one of 15 dietary treatments with five replicates and eight birds per replicate. Dietary treatments were formulated to one of three total densities of total Ca+nPP; high (15 g/kg), medium (13.5 g/kg) and low (12 g/kg) and at each density there were five different ratios of Ca : nPP (4, 2.75, 2.1, 1.5 and 1.14 : 1). Weekly performance data was collected and at the end of the experiment birds were individually weighed and the right leg removed for tibia ash analysis. Skeletal health was assessed using the latency to lie (LTL) at day 27. At low Ca and high nPP as well as high Ca and low nPP diets, birds had reduced feed intake, BW gain, poorer feed efficiency and lower tibia ash, resulting in a significant interaction between dietary Ca and nPP (P<0.05). LTL times were negatively influenced by diets having either a broad ratio (high Ca, low nPP) or too narrow a ratio (low Ca, high nPP) indicating that shorter LTL times may be influenced by the ratio of Ca : nPP rather than absolute concentrations of either mineral. The calculated intake arrays show that broilers more closely regulate Ca intake than nPP intake. Broilers are willing to over consume nPP to defend a Ca intake target more so than they are willing to over consume Ca to defend an nPP target. Overall dietary nPP was more influential on performance metrics, however, from the data it may appear that birds prioritise Ca intake over nPP and broadly ate to meet this requirement. As broilers are more willing to eat to a Ca intake target rather than an nPP intake target, this emphasises the importance of formulating diets to a accurately balanced density of Ca : nPP considering the biological importance of both minerals.

Nutritional geometry of calcium and phosphorus nutrition in broiler chicks. The effect of different dietary calcium and phosphorus concentrations and ratios on nutrient digestibility

A total of 600 Ross 308-day-old male broiler chicks were used in a 28 day digestibility study to investigate the interaction between dietary calcium (Ca) and non-phytate phosphorus (nPP) on the digestibility of minerals and amino acids. Diets were formulated to be nutritionally adequate except for Ca and nPP. Fifteen mash diets based on corn and soya bean meal with varying concentrations of Ca (6.4 to 12.0 g/kg) and nPP (2.4 to 7.0 g/kg) were used. Diets were clustered around total densities of Ca and nPP of 12, 13.5 or 15.0 (g/kg) and within each density, a range of five Ca : nPP ratios (1.14 : 1, 1.5 : 1, 2.0 : 1, 2.75 : 1 and 4.0 : 1) were fed. Birds had free access to feed and water throughout the study. At day 28, birds were euthanised for the determination of apparent ileal mineral and amino acid digestibility. Data were modelled in R version 2.15 using a linear mixed-effects model and interrogation of the data was performed by fitting a low order polynomial function. At high Ca concentrations, increasing nPP led to an increase in the apparent digestibility of minerals. Apparent ileal digestibility of phosphorus (P) was enhanced with increasing dietary nPP up to 5.5 g/kg beyond which no improvements were found. Maximal Ca digestibility was found in diets with >8.0 g/kg Ca with concomitant low concentrations of nPP. Diets with a broader Ca : nPP ratio improved the digestibility of Ca but were deleterious to the digestibility of P. In this study, apparent digestibility of amino acids was broadly unaffected by dietary Ca and nPP concentrations. However, interactions between Ca and nPP were observed for the digestibility of glutamine, tyrosine and methionine (all P<0.001). Nitrogen digestibility showed discrete optima around 10.0 and 5.0 g/kg nPP and Na digestibility was maximised around 8 to 9.0 g/kg Ca and 4.5 to 5.4 g/kg nPP. These data show that the ratio of Ca : nPP is more influential to mineral digestibility than the absolute dietary concentration of each macro mineral.

Interactions between phytase and xylanase enzymes in male broiler chicks fed phosphorus-deficient diets from 1 to 18 days of age

A total of 735 one-day-old male broiler chicks were used to evaluate the interactions between different levels of phytase and xylanase enzymes on performance and bone mineralization. Basal nonphytate P (nPP)-deficient diets (0.15%) were supplemented with different levels of phytase [0X, 1X, 2X, 3X, and 4X of recommended level (X = 500 phytase units per kg of feed)] alone or in combination with 3 levels of a xylanase preparation [0X, 1X, and 2X of recommended level (X = 0.1 g per kg of feed; a mixture with predominantly xylanase activity)]. A standard curve was developed using different levels of nPP (0.15 to 0.45%) to estimate the P equivalency of each enzyme combination. Treatments were replicated with 7 pens of 5 chicks each. The findings indicated that reducing dietary nPP level had a severely negative influence on bird performance and bone ash content. Results also showed that increasing levels of phytase significantly (P < 0.05) improved BW, feed intake, feed conversion ratio, mortality, and toe and tibia bone ash contents in a dose-dependent fashion. The P equivalency of phytase was also dose dependent, with estimates of 0.08, 0.11, 0.15, and 0.19 for 1X, 2X, 3X, and 4X supplementation levels of phytase, respectively. Xylanase preparation at 1X level failed to influence measured criterion; however, increasing the level of xylanase (2X) resulted in deteriorating BW and feed conversion ratio. The P equivalency of xylanase preparation at 1X and 2X was estimated as 0.010 and 0.014%. There were no interactions between phytase and xylanase preparation (P > 0.05). In conclusion, phytase was effective in improving bird performance and bone mineralization; however, xylanase supplementation failed to enhance phytase efficacy.

Assessment of potential enhancing effects of a carbohydrase mixture on phytase efficacy in male broiler chicks fed phosphorus-deficient diets from 1 to 18 days of age

A total of 540 one-day-old male broiler chicks were used to evaluate the potential enhancing effects of a mixture of 2 commercial carbohydrase preparations on phytase efficacy. A nonphytate phosphorus (nPP) deficient diet (0.15%) was supplemented with different levels of phytase (0X, 1X, 2X, and 3X of recommended level of 500 phytase units per kg of feed), individually or in combination with different levels of a mixture of 2 commercial carbohydrase enzymes [0X, 1X, and 2X of recommended level (X = 0.2 g per kg of feed; a mix with predominantly xylanase and β-glucanase activity)] to determine their effects on performance and bone development. A standard response curve was developed using graded levels of nPP (0.15 to 0.45%) from dicalcium phosphate in a diet with no phytase supplementation to estimate the phosphorus equivalency of the different enzyme combinations. Each diet was fed to 6 replicate pens of 5 male chicks from 1 to 18 d of age. Phytase at normal usage levels of 500 phytase units per kg of feed was effective (P < 0.05) in improving BW, increasing feed intake, reducing mortality rate, and increasing toe and tibia ash without significantly influencing feed conversion. Addition of extra levels of phytase (2X and 3X) significantly (P < 0.05) improved toe and tibia ash without further affecting performance traits. The carbohydrase mixture failed to improve performance or enhance phytase efficacy. The phosphorus equivalency of phytase was dose dependent, with estimates of 0.100, 0.123, and 0.213% for 1X, 2X, and 3X supplementation levels of phytase, respectively, based on tibia ash. In conclusion, results indicate that increasing the level of phytase resulted in significant improvements in utilization of dietary nPP, whereas the carbohydrase preparation had no significant effects on performance or had limited effects in enhancing phytase ability in young broiler chicks.

The effects of feeding high concentrations of cholecalciferol, phytase, or their combination on broiler chicks fed various concentrations of nonphytate phosphorus

SUMMARY Two experiments were conducted to investigate the effects of feeding high concentrations of cholecalciferol (D3), phytase, or their combination on BW gain, FE, tibia ash, and total tract P retention in broiler chicks fed various concentrations of nonphytate P (nPP). In the first experiment, we compared dietary nPP concentrations (0.20, 0.26, 0.33, 0.39, and 0.45%) with supplemental D3 (0, 7,500, and 15,000 IU/kg) for 5- to 23-d-old Ross 308 chicks. In experiment 2, we compared dietary nPP concentrations (0.15, 0.25, 0.35, and 0.45%) with concentrations of D3 (0 or 7,500 IU/kg) and phytase (0 or 1,000 phytase units/kg) for 4- to 18-d-old Ross 308 chicks. The supplementation of D3 resulted in improved FE and total tract P retention in experiment 1, but did not have a positive effect on any of the parameters tested in experiment 2. The addition of higher concentrations of D3 to broiler diets resulted in improved P retention in experiment 1, but did not affect the performance of chicks in either experiment.

The Influence of Dietary Calcium and Phosphorus Imbalance on Intestinal NaPi-IIb and Calbindin mRNA Expression and Tibia Parameters of Broilers.

A 2×2 factorial experiment was conducted to study the effect of dietary calcium and non-phytate phosphorus (nPP) imbalance on calbindin and NaPi-IIb mRNA levels in the small intestine and tibia parameters of broiler chicks. One hundred and forty four 1-d-old Arbor Acres male broiler chicks were divided into four treatments consisted of six replicates with six chicks each. The two dietary calcium levels were 1.10% and 0.60%, and two dietary nPP levels were 0.50% and 0.27%. Results showed that a high Ca/nPP ratio diet (4.07:1) significantly depressed feed intake and weight gain of broilers (p<0.05), but a lower Ca:nPP ratio (1.2:1) had no influence (p>0.05). Low-Ca with low-P diet resulted in low tibia minerals and tibia breaking strength of broilers, and all the tibia parameters were further decreased when the dietary ratio of Ca to P was relative higher. Low dietary Ca or P up-regulated the calbindin and NaPi-IIb mRNA expression levels. Low Ca with normal P diet up-regulated duodenal calbindin mRNA expression level to the greatest extent. Low P with a normal Ca diet significantly enhanced NaPi-IIb mRNA expression level to the highest extent. These results suggest that the calbindin and NaPi-IIb mRNA expression were enhanced by the imbalance between dietary Ca and nPP, and their expression were not only influenced by Ca or nPP level, but also the ratio of Ca:nPP.

Assessment of an experimental phytase enzyme product on live performance, bone mineralization, and phosphorus excretion in broiler chickens

SUMMARY An experiment was conducted to evaluate the effects of a new experimental phytase enzyme product (HiPhos, DSM Nutritional Products Inc.) fed to broilers through 21 d of age. A total of 384 male Ross 708 chicks were placed across 48 grow-out battery pens (8 birds/pen, 8 replications/treatment). All the birds were fed a corn-soybean meal diet (22% CP, 3,087 kcal/kg) adequate in all nutrients except nonphytate P (npP). Dietary treatments were created using 3 npP levels (0.22, 0.30, or 0.38%) and 3 phytase levels [500, 1,000, or 2,000 units of phytase activity (FTY)/kg] in combination with 0.22% npP. On d 21, BW and feed consumption were recorded for each pen, and FCR was corrected for mortality. Twenty-four birds per treatment were euthanized for removal of the left tibia for analysis of breaking strength and ashing. Supplementation of the 0.22% npP diet with 1,000 or 2,000 FTY/kg resulted in BW not different from that of the 0.38% npP treatment (mean of 672 g), an improvement (P

An Examination of the P Requirements of Broiler Breeders for Performance, Progeny Quality and P Balance 2. Ca Particle Size

A 2 x 5 factorial production and balance study with 90 broiler breeders was performed to assess the effects calcium particle size and NPP levels. Cobb 500 broiler breeders, 24 wk of age, were fed 4.68 g Ca intake at peak using 2 particle sizes of dietary calcium carbonate (185.5 microns; 58.8% solubility and 3489.7 microns; 38.5% solubility) and 5 levels of dietary %NPP (0.2% to 0.4% NPP in 0.05% increments; corresponding to a daily intake of 288, 360, 432, 504 and 576 mg at peak intake). Egg production, specific gravity and egg wt were monitored from 24 to 40 wk of age and tibia relative strength at 45 weeks. A retention study was performed at 31 wk of age to determine Ca and P balance. No differences were noted in breeder bone integrity due to NPP intake, though eggs per hen housed and egg shell quality were affected. The breeders fed 288 mg NPP produced the largest number of eggs. The % P retention showed a positive linear response to increasing dietary NPP for breeders fed large particle limestone; but no response in hens fed small particle limestone. The amount of P excreted was increased with P intake but was minimized for hens fed large particle limestone. The amount of Ca excreted was significantly increased with increasing P intake. There was a significant linear increase in excreta Ca and linear decrease in % Ca retention for breeders fed increasing P intake along with small particle calcium but the amount of Ca excreted and % Ca retention was not statistically impacted by particle size. Feeding breeders large particle calcium carbonate increased the egg weight but did not significantly improve shell quality or tibia bone strength. The increased egg weight response for breeders fed large particle calcium carbonate in this short term experiment may have reduced the opportunity for large particle Ca to significantly improve egg shell quality. It can be concluded that particulate Ca sources can improve breeder performance and that dietary levels as low as 0.20% NPP (288 mg/day NPP intake) can be fed without impacting breeder performance; however dietary levels of >0.25%NPP (360 mg/day NPP intake) ensure adequate skeletal integrity.

Influence of dietary non-phytate phosphorous levels and phytase supplementation on the performance and bone characteristics of broilers

Precise phosphorus nutrition is important for significant reductions in both P pollution and ration costs. The influence of different levels (%) of dietary nPP fed from 0 to 20 d (0.45, 0.40, 0.35, 0.30, 0.25, compared with feeding 0.20 nPP with and without 500 F.T.U. of phytase per kg of diet) and from 21 to 36 d of age (0.414, 0.364, 0.314, 0.264, 0.214, compared with 0.164 nPP with and without 500 F.T.U. of phytase per kg of diet) were evaluate using a total of 588 day-old commercial broiler chicks. Each treatment was replicated four times in a completely randomized design. Body weight (BW), daily gain (DG), feed intake (DFI), feed conversion ratio, plasma P level and bone characteristics were determined, and from these data the P equivalency of the phytase was estimated. Feeding diets containing less than 0.40% of nPP to birds between 0 and 20d resulted in inferior BW, DFI, plasma P level and bone characteristics compared with the control. However, optimum FCR and mortality was supported at lower levels of nPP (0.25%). Between 21 and 36 d, 0.364% was enough to optimise BW, DFI, and femur ash (%); whilst only 0.314% or greater was needed to support optimum DG, toe and tibia ash and only 0.214 to 0.264% was required to optimise shank, femur and tibia lengths; FCR and survivability. A broken line analysis also showed that the nPP (%) requirement ranged from 0.267 to 0.410 and 0.272 to 0.380% during 0 to 20 and 21 to 36 d, respectively. Phytase supplementation improved performance and bone criterion and its P equivalency, depending upon the response of interest and birds age, ranged from 0.00 to 0.110%. In conclusion, the results showed that the combination of a lower level of nPP and phytase may be used to increase dietary P utilization, without severe changes in performance and bone quality.

Nonphytate Phosphorus Requirement and Efficacy of a Genetically Engineered Yeast Phytase for Yellow Broilers at 22- to 42-d-Old Age

An experiment was conducted to investigate the requirement of nonphytate phosphorus (nPP) and efficacy of a genetically engineered yeast phytase (PHY A) for Lingnan yellow broilers from 22- to 42-d-old age. A total of 1 320 1-d-old male chicks were randomly divided into 11 dietary treatment groups, which consisted of 4 replicate floor pens with 30 birds per pen. The control group (treatment 1) was fed with basal diet of nPP 0.08% without dicalcium phosphate or phytase supplementation. Dietary levels of nPP were 0.16, 0.24, 0.32, 0.40, 0.48, and 0.56%, respectively, for treatments 2 to 7, through addition of dicalcium phosphate (chemistry grade) to the basal diet. Diets of treatments 8 to 11 were supplemented with PHY A at 200, 400 and 600 U kg −1, a commercial phytase product (PHY B) at 400 U kg −1 level, respectively. The birds in 0.32–0.56% nPP groups gained more than those of the other groups ( P<0.05). The nPP supplementation significantly improved feed intake ( P<0.05). The feed gain ratio was significantly decreased by 0.40% nPP diet compared to the control birds ( P<0.05). The level of 0.48% nPP was required for optimum tibia development. The additions of PHY A at 400 and 600 U kg- 1 level and PHY B all significantly improved ADG ( P<0.05), ADFI ( P<0.05), and dry defatted tibia weight ( P<0.05). Similarly, the percentage of tibia ash was increased by 600 U kg −1 PHY A supplementation ( P<0.05). The requirement of nPP for maximal ADG and highest percentage tibia ash both was 0.40%. The phosphorus equivalency value of PHY A was estimated as 685 U kg- 1 for male yellow broilers of 22- to 42-d-old age.

Evaluation of commercial phytase enzymes on performance and tibia-breaking strength of male broiler chicks

An experiment was conducted to evaluate the effects of 3 commercial phytase enzymes on the performance and bone strength of broilers. All birds were fed a corn-soybean meal diet (22% CP, 3,086 kcal/kg) adequate in all nutrients but nonphytate P (npP) through 28 d of age. Dietary treatments were created using 3 npP levels (0.25, 0.35, and 0.45%, designated low, marginal, and standard, respectively), and 3 commercially available phytase enzymes (A, B, and C) were supplemented in diets containing 0.25% npP. Individual BW and group feed consumption were recorded weekly and feed:gain (corrected for mortality) was calculated weekly. Each week, 24 birds per treatment were slaughtered for tibia collection to evaluate bone strength. Supplementation of the low-npP diet with phytase A or C improved BW, feed consumption, and tibia-breaking strength so that it was similar (P > 0.05) to birds fed the standard-npP diet, whereas supplementing birds with phytase B led to BW, feed consumption, and bone strength closely resembling those of birds fed marginal npP. Feed efficiency was not significantly affected (P > 0.05) by phytase supplementation in comparison with the low-npP or standard-npP treatments. Mortality was significantly decreased with phytase supplementation, regardless of the specific source, in comparison with the low-npP treatment, on conclusion of the experiment. We conclude, given the conditions of this experiment, that broiler performance and bone mineralization are improved when dietary npP is reduced by a minimum of 0.10% and when phytase supplementation is used.

Effects of flesh attachment on bone breaking and of phosphorus concentration on performance of broilers hatched from young and old flocks

Two experiments were conducted to 1) assess any differences on breaking force in bones with or without flesh attachment and 2) determine the effects of dietary nonphytate phosphorus (npP) concentration, maternal flock age, and chick sex on live performance and tibia strength of broilers. For experiment 1, sixty chicks were placed in battery cages and selected weekly for removal of both tibiae (15 chicks/wk). Raw flesh was either completely cut from the bone or left intact and broken using a texture analyzer. For experiment 2, Ross 708 chicks (1,220) were hatched of 25- and 65-wk-old breeder flocks, separated by sex, vaccinated, and placed on used bedding across 64 floor pens (18 males or 17 females/pen, 8 repetitions/treatment). Through 28 d, all birds were fed corn-soybean meal diets (22% CP, 3,086 kcal/kg) adequate in all nutrients but npP, which was included at either 0.35 or 0.50%. Individual BW and pen feed consumption (FC) were recorded weekly and corrected for mortality. Each week, 24 birds/treatment were killed for tibia evaluation. Experiment 1 resulted in no differences in breaking force, whether flesh remained or was removed from the bone. In experiment 2, BW was increased with an increase in npP (P<0.001) at the end of the experiment. Both BW and FC were increased (P<0.001) from 0 to 28 d of age in chicks from the 65-wk-old breeder flock. Males had increased (P<0.001) final BW, FC, and tibia breaking forces. Breaking forces were also improved (P<0.001) when npP was increased or chicks were hatched from older breeder flocks. Interactions were present (P<0.05) for npP concentrationx25-wk breeder flock 7- to 21-d BW gain (BWG) and 0- to 28-d FC, npP x chick sex 7- to 14-d BWG and 21- to 28-d feed conversion ratio, and breeder flock age x chick sex 0 d BW and 7- to 14-d BWG. These results indicate that broiler growth and performance can be affected by maternal flock age, chick sex, and dietary npP.

Growth performance and spontaneous bone fracture incidence of turkey toms fed various levels of calcium and nonphytate phosphorus to heavy market weight

This trial evaluated the effects of various dietary calcium and nonphytate phosphorus (nPP) feeding regimens on the growth and bone integrity of Nicholas 700 toms from 2 to 19 wk of age. After a 2-wk common brooding period, 24 to 25 poults/pen were allocated to 8 pens/treatment. Crumbles were fed from 2 to 5 wk of age and pellets were fed from 5 to 19 wk of age in a 3-wk phase program. Dietary calcium was kept at a 1.8:1 ratio with nPP for all diets. Diet 1 (LOW) was formulated to provide NRC recommendations for each phase change, ending with 0.25% nPP from 17 to 19 wk of age. Diet 2 (MED) nPP levels averaged 0.06 percentage units higher than the LOW diet. Diet 3 (HIGH) averaged 0.10 percentage units higher nPP than the MED diet. Diet 4 (VHIGH) averaged 0.10 percentage units higher nPP than the HIGH diet. Body weight was decreased (P < 0.01) by the LOW diet compared with all other treatments throughout the trial. By 8 wk of age, BW was lower (P < 0.001) when the MED diet was fed compared with the HIGH and VHIGH diets. Feed:gain was worsened (P < 0.02) by the LOW diet, compared with the HIGH and VHIGH diets, throughout the entire trial. The incidences of leg problems and spontaneous bone fractures were increased (P = 0.001) when the LOW diet was fed compared with the other diets. The increase in litter phosphorus (P = 0.001) was directly proportional to increases in dietary nPP. The HIGH and VHIGH diets resulted in the best growth performance and skeletal integrity.

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

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

Effect of Phytase Supplementation on the Calcium Requirement of Broiler Chicks

It has been frequently demonstrated that addition of phytase to corn-soybean meal diets will improve the utilization of the phytate-bound P for the broiler chicken. The effect of phytase on release of other nutrients such as Ca is less clear-cut. A study was conducted to examine the effects of phytase supplementation on diets with various dietary levels of Ca and nonphytate P (nPP). A diet was formulated that provided nutrients in excess of NRC (1994) recommendations with 1.0% Ca and 0.50% nPP. By varying the amounts of dicalcium phosphate, limestone, and sand in aliquots of a common basal diet, diets were prepared with 1) Low-P and Low-Ca, 2) Low-P and High-Ca, 3) High-P and Low-Ca, and 4) High-P and HighCa. The diets were analyzed for Ca and P content and blended as needed to provide test diets in a factorial arrangement of three Ca levels (0.5, 0.7, and 0.9%) with eight levels of nPP (0.15 to 0.50% in increments of 0.05%). These 24 diets were divided and half supplemented with 1000 units/kg of phytase. Each treatment was fed to six pens of six male broilers from one to 21 d of age. Response of both body weight and tibia ash to phytase supplementation in broilers was significantly affected by dietary Ca levels as well as dietary nPP levels. Without phytase supplementation, both body weight and tibia ash were depressed at the lowest level of nPP as dietary Ca level increased. Adding phytase to these diets improved both body weight and tibia ash as a result of increased availability of P. At both 0.5% and 0.7% Ca, the dietary Ca level was a limiting factor in maximizing tibia ash regardless of P level or phytase supplementation. These data indicate that minimal Ca appeared to be released by phytase and that no reduction in Ca level of broiler should be implemented with phytase supplementation.

The effect of virginiamycin in diets with adequate or reduced dietary calcium or nonphytate phosphorus for broilers

Four experiments (EXP) were conducted to evaluate the effects of virginiamycin (Vm) in diets adequate or reduced in Ca or nonphytate P (nPP) levels on growth performance and bone response variables in chicks. All diets were corn-soybean meal (C-SBM) based, and all treatments were replicated 6 or 8 times with 5 or 6 chicks each. In EXP 1 and 2, the dietary treatments were 1) C-SBM with 1.00% Ca and 0.45% nPP (positive control; PC); 2) C-SBM with 0.80% Ca and 0.45% nPP (0.80Ca); 3) C-SBM with 1.00% Ca and 0.35% nPP (0.35nPP); and 4 to 6) Diets 1 to 3 with 11 (EXP 1) or 22 (EXP 2) ppm of Vm. In EXP 1, daily gain (ADG), feed intake (ADFI), bone breaking strength (BBS), milligrams of ash per gram of Ca intake (ASH/Ca), and BBS per gram of Ca (BBS/Ca) or nPP (BBS/nPP) intake were increased in chicks fed Vm (P < 0.04 to 0.07). Chicks fed the 0.35nPP diet with Vm had increased ADG, ADFI, BBS, milligrams of tibia ash (ASH), BBS/Ca, and BBS/nPP (nPP x Vm, P < 0.03 to 0.10). Chicks fed the 0.80Ca diet with Vm had increased ASH, milligrams of ASH per gram of nPP intake (ASH/ nPP), and ASH/Ca (P < 0.01 to 0.09). Tibia ash, BBS, gain:feed (G:F), BBS/nPP, and ASH/nPP were decreased in chicks fed the 0.80Ca diet (P < 0.01 to 0.07). Bone ash percentage (BAP), BBS, BBS/Ca, ASH, and ASH/Ca were decreased in chicks fed the 0.35nPP diets (P < 0.01); ASH/ nPP was increased (P < 0.01). In EXP 2, BAP, ASH, ASH/ Ca, and ASH/nPP were increased in chicks fed Vm (P < 0.02 to 0.07). Chicks fed the 0.80Ca diet had a decreased ASH/nPP (P < 0.04) but an increased BBS/Ca and ASH/ Ca (P < 0.01 to 0.02). Chicks fed the 0.35nPP diet had decreased ADG, ADFI, G:F, BBS, BAP, ASH, ASH/Ca, and BBS/Ca (P < 0.01 to 0.04), but BBS/nPP and ASH/ nPP were increased (P < 0.01 to 0.04). In EXP 3, the dietary treatments were 1) PC; 2) C-SBM with 0.70% Ca and 0.45% nPP (0.70Ca); 3) C-SBM with 1.00% Ca and 0.25% nPP (0.25nPP); 4 to 6) Diets 1 to 3 with 9 ppm of Vm. The addition of Vm to the 0.25nPP diet decreased BBS (nPP x Vm, P < 0.06), but Vm increased BBS in the 0.70Ca and PC diets (P < 0.02). Chicks fed the 0.25nPP diet had decreased ADG, ADFI, and BBS (P < 0.01), and chicks fed the 0.70Ca diets had reduced ADFI, BBS, and G:F (P < 0.03 to 0.10). In EXP 4, 4 levels of nPP (0.15, 0.25, 0.35, or 0.45%) and 3 levels of Vm supplementation (0, 11, or 22 ppm) in a 4 x 3 factorial arrangement were used. The addition of Vm increased ADG, BBS, ASH, ASH/Ca, and ASH/nPP only in chicks fed diets with 0.35 or 0.45% nPP (nPP x Vm, P < 0.05). Daily gain, ADFI, G:F, BBS, BAP, BBS/Ca, and ASH were increased as nPP levels were increased (P < 0.01), but BBS/nPP and ASH/nPP were decreased (P < 0.01) as nPP levels were increased. The results obtained from these EXP indicate that Vm, regardless of supplementation level, can partially overcome an nPP deficiency when nPP levels are = 0.35%.

A comparison of two sources of phytase in liquid and dry forms in broilers

Research with corn-soybean meal diets was conducted to compare phytase sources in commercial broilers. A Ca to nonphytate P (nPP) ratio of 2.5:1 was maintained in all diets. Experiments 1 and 2 were conducted from d 4 to 13 (experiment 1) or d 9 to 23 post-hatching (experiment 2) in batteries. The 10 treatments used in both experiment were: Diets 1 to 4 = 0.20, 0.25, 0.30, or 0.35% nPP; Diets 5 to 7 = diet 1 plus 100, 200, or 300 phytase units/kg of diet from Natuphos (NAT); and Diets 8 to 10 = diet 1 plus 100, 200, or 300 phytase units/ kg of diet from Ronozyme (RON). As nPP levels increased, daily gain (ADG), feed intake (ADFI), gain:feed, and toe and tibia ash percentage were linearly increased (P < 0.06) in experiments 1 and 2. Incremental addition of phytase, regardless of source, linearly increased (P < 0.07) ADG and ADFI in experiment 1. Broilers fed NAT had higher (P < 0.07) toe ash percentage in experiment 1 and 2, and higher (P < 0.02) ADG and ADFI in experiment 2 than those fed RON. In experiment 3, 3,360 broilers were used to test 2 dry phytase products from 0 to 41 d posthatching in a 3-phase feeding program. The treatments were: Diet 1) adequate Ca and nPP; Diet 2) nPP reduced by 0.20%; Diets 3 to 5 = diet 2 plus 300, 500, or 750 phytase units/kg of diet from NAT; and Diets 6 to 8 = Diet 2 plus 300, 500, or 750 phytase units/kg of diet from RON. Broilers fed the adequate Ca and nPP diet had improved ADG and ADFI overall, and tibia ash weight and percentage in all growth phases (P < 0.03) compared with those fed the reduced Ca and nPP diets. Overall, ADG and ADFI were linearly increased (P < 0.05) by incremental phytase addition in experiment 3. Both NAT and RON produce similar growth and bone ash traits in commercial broilers.

Interrelationship between environmental temperature and dietary nonphytate phosphorus in laying hens

Four experiments were conducted to evaluate the effects of phosphorus nutrition on laying hens exposed to heat stress (HS). Hens were fed their respective diet for at least 3 wk prior to initiation of each experiment to allow the hens fed low-P diets to become P deficient. In most experiments, hens housed in non-HS conditions were pair-fed to the HS hens to maintain equal feed intake. In experiments 1 and 2, two levels of nonphytate P (NPP; deficient at 0.10 or 0.16% vs. control at 0.45%) and two temperatures (constant thermoneutral at 21 degrees C or cyclic HS up to 35 degrees C) were evaluated. Low NPP significantly reduced feed intake and hen-day egg production, but the cyclic heat treatment had no effect on hen performance. Experiment 3 was similar to experiments 1 and 2 except that constant HS was implemented. Both constant HS and low dietary NPP reduced feed intake and egg production, and there was no significant interaction between HS and dietary NPP level. In experiment 4, hens were fed 0.10 or 0.45% NPP diets and exposed to a more severe HS (38 degrees C) for 8 h. Hens fed the deficient NPP level showed a 16% incidence of severe heat distress (unable to stand, unresponsive). Our results generally indicated that there was no interaction between dietary NPP level and HS in laying hens. However, subjecting hens that had been fed a P-deficient diet to an acute HS of 38 degrees C did increase the incidence of severe heat distress.