纳米磷酸氢钙中磷在大鼠中的相对效价评定

纳米磷酸氢钙和普通磷酸氢钙分别添加到低磷基础饲粮中,每种磷源的磷添加水平为0·1%,0·2%和0·3%,每处理3重复,每重复4只已断乳的21日龄Wistar雄性大鼠,饲喂4周。结果表明,3个纳米磷酸氢钙处理组与普通磷酸氢钙相同磷添加水平组相比,大鼠胫骨灰分含量和胫骨磷含量显著提高(P<0·05),经斜率比法,以普通磷酸氢钙为参照物、胫骨灰分含量和胫骨磷含量为判据指标计算出纳米磷酸氢钙中磷的相对效价分别为127%和125%。     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to eval- uate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1,150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phos- phorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2,120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemen- ted with 0,250,500 ,or 1,000 P-＇rU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conver- sion as a result of feeding the different sources of in- organic phosphorus. The digestibility of phosphorus was significantly lower （P =0.01 ） for chicks fed di- ets supplemented with tricalcium phosphate than for chicks fed the other two diets. However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feedconversion showed a linear improvement （P = 0.03 ） with increasing levels of phytase inclusion （ days 0 to 33 ）. Phytase supplementation resulted in linear increa- ses in the digestibility of dry matter （P = 0.02 ）, crude protein （ P --- 0.04 ） and energy （ P 〈 0.01 ）. Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium （ P = 0.05 ） and bone breaking strength （P = 0.04 ） than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets sup- plemented with dicalcium phosphate, tricalcium phos- phate or defluorinated phosphate was similar and therefore production costs could be lowered by choo- sing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formu- lated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase sup- plementation. However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be suf- ficient justification for the routine inclusion of phytase in diets fed to broilers.     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to evaluate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1, 150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phosphorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2, 120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemented with 0, 250, 500, or 1,000 FTU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conversion as a result of feeding the different sources of inorganic phosphorus. The digestibility of phosphorus was significantly lower (P = 0.01) for chicks fed diets supplemented with tricalcium phosphate than for chicks fed the other two diets.  However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feed conversion showed a linear improvement (P = 0.03) with increasing levels of phytase inclusion (days 0 to 33).  Phytase supplementation resulted in linear increases in the digestibility of dry matter (P = 0.02), crude protein (P = 0.04) and energy (P < 0.01).  Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium (P = 0.05) and bone breaking strength (P = 0.04) than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets supplemented with dicalcium phosphate, tricalcium phosphate or defluorinated phosphate was similar and therefore production costs could be lowered by choosing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formulated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase supplementation.  However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be sufficient justification for the routine inclusion of phytase in diets fed to broilers.     

Effects of an experimental phytase on performance, egg quality, tibia ash content and phosphorus bioavailability in laying hens fed on maize- or barley-based diets

A 24-week performance trial was conducted to evaluate the efficacy of an experimental phytase on performance, egg quality, tibia ash content and phosphorus excretion in laying hens fed on either a maize- or a barley-based diet. At the end of the trial, an ileal absorption assay was conducted in order to determine the influence of phytase supplementation on the apparent absorption of calcium and total phosphorus (P). Each experimental diet was formulated either as a positive control containing 3.2 g/kg non-phytate phosphorus (NPP), with the addition of dicalcium phosphate (DCP), or as a low P one, without DCP addition. Both low P diets (containing 1.3 or 1.1 g/kg NPP) were supplemented with microbial phytase at 0, 150, 300 and 450 U/kg. The birds were housed in cages, allocating two hens per cage as the experimental unit. Each of 10 dietary treatments was assigned to 16 replicates. Low dietary NPP (below 1.3 g/kg) was not able to support optimum performance of hens during the laying cycle (from 22 to 46 weeks of age), either in maize or barley diets. Rate of lay, daily egg mass output, feed consumption, tibia ash percentage and weight gain were reduced in hens fed low NPP diets. The adverse effects of a low P diet were more severe in hens on a maize diet than in those on a barley diet. Low dietary NPP reduced egg production, weight gain, feed consumption and tibia ash content and microbial phytase supplementation improved these parameters. Hens given low NPP diets supplemented with phytase performed as well as the hens on positive control diets containing 3.2 g/kg of NPP. A 49% reduction of excreta P content was achieved by feeding hens on low NPP diets supplemented with phytase, without compromising performance. Phytase addition to low NPP diets increased total phosphorus absorption at the ileal level, from 0.25 to 0.51 in the maize diet and from 0.34 to 0.58 in the barley diet. Phosphorus absorption increased linearly with increasing levels of dietary phytase. Mean phosphorus absorption was higher in barley diets than in maize diets (0.49 vs 0.39).     

Effects of feeding raw or reconstituted high tannin red sorghum on nutrient utilisation and certain welfare parameters of broiler chickens

1. A feeding trial was conducted on 360 1-d-old chicks from 0 to 6 weeks of age to assess the effect of processed high tannin red sorghum in the diet of broiler chickens on nutrient utilisation and certain welfare parameters. 2. Each of 9 dietary treatments was allotted to 4 groups (replicates) of chicks in a completely randomised design. The treatments were a maize-soy based standard broiler diet (control, RS(0)) and eight test diets formulated by incorporating either raw red sorghum (RS(25), RS(50), RS(75), RS(100)) or reconstituted red sorghum (RS(25)(R), RS(50)(R), RS(75)(R), RS(100)(R)) replacing 25, 50, 75 or 100% of maize from the control diet. 3. The tannin content was reduced from 23 to 16 g/kg in reconstituted red sorghum. 4. Utilisations of nitrogen, calcium and phosphorus retention were similar in all the dietary groups. 5. The cell-mediated immune response measured as footpad index (FPI) value of birds given raw red sorghum was significantly higher than in control and reconstituted red sorghum groups. Similarly, comparatively better humoral response measured as HA titre value was observed in raw red sorghum based groups than in reconstituted ones. 6. Plasma albumin, globulin, protein, glucose, calcium, phosphorus, SGOT, SGPT and uric acid levels did not differ significantly due to dietary treatments. 7. Mild histopathological changes were observed in liver and kidney tissues of birds given raw red sorghum. 8. From the present study, it is concluded that (1) the reconstitution of high tannin red sorghum resulted in about 30% reduction in its tannin concentration; (2) the feeding of reconstituted sorghum based diets to broiler chickens did not exert any appreciable influence on nutrient utilisation, blood biochemicals and enzymes and gross pathological changes; and (3) the birds fed on raw red sorghum exhibited higher immuno-responsiveness in comparison to their reconstituted counterparts.     

耐盐牧草对南疆地区盐渍土的适应和改良研究

以4种耐盐碱牧草(紫花苜蓿、苏丹草、美国饲用甜高粱和墨西哥玉米)为研究对象,采用生物防治盐碱化方法来分析其对南疆地区盐碱化土壤改良的可行性,以期为改良利用盐渍土壤提供理论基础。结果表明,墨西哥玉米对南疆盐渍土的改良最为显著(P<0.05),其农艺性状和产草量也最佳;其次是紫花苜蓿,其抗逆性强、生产性能较好、营养丰富、经济价值高以及兼有固氮和提高土壤肥力等优点,使其成为改良南疆盐渍土合适的选择。在南疆盐渍区形成以墨西哥玉米和紫花苜蓿为主,美国饲用甜高粱和苏丹草为辅的种植模式,可有效地降低土壤盐分。     

玉米-豆粕型肉鸡日粮中添加重组植酸酶效果研究

选用400只7日龄艾维茵雏鸡,研究玉米-豆粕型日粮中添加0,300,600,900IU/kg重组植酸酶和标准水平磷酸氢钙对肉鸡生长性能和磷利用的效果.结果表明,肉鸡体增重和胫骨磷沉积随植酸酶添加剂量而提高,但添加植酸酶不能完全取代无机磷.添加植酸酶可减少肉鸡粪便氮磷排泄量,减轻环境污染.     

磷酸一二钙在产蛋鸡配合饲料中的应用研究

选择210日龄伊莎产蛋高峰期鸡1 755只,随机分为1个对照组和12个试验组.12个试验组分别饲喂对照组日粮基础上(0.14%非植酸磷)添加不同水平(0.06%、0.12%和0.18%非植酸磷)无机磷源(磷酸二氢钾(MPP)、磷酸二氢钙(MCP)、磷酸氢钙(DCP)、磷酸一二钙(MDCP))的日粮.通过测定相对生物学效价(RBV),比较4种无机磷对产蛋鸡生产性能的影响.试验结果表明:在不同磷添加水平下MPP、MCP、DCP、TCP的RBV值,以产蛋率为指标,各组分别为100、101、107和110;以平均蛋重为指标,各组RBV值分别为100、106、124和126;以平均日产蛋量为指标,各组RBV值分别为100、103、114和116.综合各指标的平均生物学效价,各组分别为100、103、115和117.表明以磷酸一二钙作为蛋鸡日粮的无机磷源利用效率最佳,磷酸氢钙是蛋鸡日粮较好的磷源.     

Effect of source of calcium and phosphate,autoclaving, vitamin D3 level and strain of turkey poults on the rachitogenic activity of isolated soybean protein 1

This study was conducted to ascertain the effect of autoclaving, source of calcium and phosphate, vitamin D₃ level and strain of turkey poults on the rachitogenic activity of isolated soybean protein (C‐1 protein‐Skidmore). One‐day‐old poults were fed purified diets of the glucose—C‐1 protein type. The diets contained calcium, phosphorus and vitamin D₃ at levels equal to or greater than the National Research Council's (1960) recommendations. The findings demonstrate that USP hydrated dicalcium phosphate was more effective than food‐grade dicalcium phosphate in overcoming the rachitogenic activity of the C‐1 protein. Autoclaving the C‐1 protein for 80 min destroyed its rachitogenic activity: Vitamin D₃ was also effective in reducing the rachitogenic effect of C‐1 protein. The Broad Breasted White strain proved to be more susceptible to the rachitogenic property of C‐1 protein than the Wrolstad Small White strain. Substituting USP hydrated dicalcium phosphate for food‐grade dicalcium phosphate, autoclaving the C‐1 protein or increasing the vitamin D₃ level increased body weight gains and tibia ash values. The interactions which were shown to exist between source of calcium and phosphate × autoclaving, strain × autoclaving, and vitamin D₃ level × strain demonstrate an interrelationship between these factors.     

Non‐phytate phosphorus requirements and efficacy of a genetically engineered yeast phytase in male lingnan yellow broilers from 1 to 21 days of age

This experiment was conducted to investigate the requirement of non‐phytate phosphorus (nPP) and efficacy of a genetically engineered yeast phytase in performance and tibia characteristics by male Lingnan Yellow broilers from 1 to 21 days of age. A total of 2640 1‐day‐old male chicks were randomly allotted to one of 11 dietary treatments, which consisted of six replicate floor pens with 40 birds per pen. All treatments had the same levels of all nutrients except for phosphorus and phytase. The control group (treatment 1) was fed the basal diet without dicalcium phosphate or phytase supplementation. Dietary concentrations of nPP were 0.11%, 0.19%, 0.27%, 0.35%, 0.43%, 0.51% and 0.59% respectively for treatments 1, 2, 3, 4, 5, 6 and 7, through addition of dicalcium phosphate (chemistry grade) to the basal diet. Diets 8–11 were supplemented with a genetically engineered yeast phytase 250, 500, 750 U/kg and a commercial phytase product 500 U/kg in basal diet respectively. The results showed that 0.46% and 0.51% nPP were required for maximum body‐weight gain and optimum tibia development indicators respectively. However, 0.59% nPP had a negative effect on bird growth. The equivalency value of the genetically engineered yeast phytase was estimated to be 874 U/kg to liberate 0.1% nPP.     

The response of broilers to the feeding of mash or pelleted diets containing maize of varying particle sizes

1. The effects of maize particle size and steam pelleting on growth and nutrient utilisation were studied with broiler chicks. 2. The presence or absence of 10 microg/kg of 1,25 dihydroxycholecalciferol in diets adequate or deficient in phosphorus was also investigated. Food efficiency was superior with the fine maize diets but calcium retention and phytate phosphorus retention were greatest with the coarse maize diets. Pelleting improved food efficiency and growth in both experiments while phytate phosphorus utilisation was decreased. 3. Addition of 1,25-dihydroxycholecalciferol to the diet increased 16-d body weight, bone ash, plasma dialysable phosphorus and retentions of total phosphorus and phytate phosphorus while decreasing phosphorus deficiency rickets and tibial dyschondroplasia. 4. There were significant interactions between maize particle size and food form. The improvement in calcium retention observed with the coarse maize diets was reduced when the diets were pelleted. When fed as a mash, coarse maize diets resulted in increased plasma dialysable phosphorus levels but when the diet was pelleted this response was eliminated. 5. There was also a significant interaction between particle size and phosphorus concentration in that chicks given diets deficient in phosphorus had improved bone ash when fed coarse maize as compared to fine maize. However, this response was eliminated when the diets were adequate in phosphorus. 6. In one experiment, fine maize diets had higher metabolisable energy values and there was a significant interaction between maize particle size and food form as pelleting improved the metabolisable energy value of coarse maize diets but not fine maize diets. In another experiment only pelleting of the factors studied improved the metabolisable energy value of the diets.     

Supplementation of broiler drinking water with liquid ammonium polyphosphate

1. In each of two experiments lasting 21 days a commercially available ammonium polyphosphate solution was provided in the drinking water as the sole source of supplemental phosphorus for day-old chicks housed in batteries. 2. In both experiments, similar daily phosphorus intakes either from dicalcium phosphate in the food or from ammonium polyphosphate in the drinking water supported equivalent responses in body weight gains. The same was true for the tibia ash results in experiment 2. 3. Liquid ammonium polyphosphate, while marketed for addition to diets, appears to be also very effective as a waterborne source of phosphorus for broilers.     

Phosphorus supplementation of lactating dairy cattle on a Northland farm

Forty-eight Friesian or Friesian-X factory supply dairy cows were divided into two groups. Group 1 received a supplement of sodiumtripolyphosphate (TPP, 25g P, 25g Na/cow/day), and group 2 a supplement of sodium chloride (25g Na/cow/day). Supplementation began at peak lactation, when the mean serum inorganic phosphorus (Pi) of all cows was 1.13 mmol/l. After four weeks, group 2 changed from NaCl to dicalcium phosphate supplementation (25g P/cow/day). Serum Pi and yields of milk, butterfat and protein were measured before, during and after supplementation. Pasture availability was assessed and P and Ca contents in pasture and the Pi content in milk were also determined. Supplementation raised serum Pi from 1.30 mmol/l (NaCI) to 1.42 mmol/l (TPP, P<0.05) but when dicalcium phosphate replaced NaCl the difference between groups disappeared (P>0.05). P supplementation had no effect on any milk parameter. Pre-grazing pasture mass above estimated grazing height averaged 2260 kg DM and contained >or=0.39 per cent P. It is concluded that a herd mean serum Pi concentration of around 1.2-1.3 mmol/l imposes no limitation to dairy production around the period of peak lactation of grazing dairy cattle.     

磷酸氢钙品质综合评价在饲料添加剂生产中的重要性

本文对某饲料添加剂厂几批购进的磷酸氢钙原料进行了钙磷常规检测,同时采用目测、简单试剂检测进行了比较测定,阐明了对磷酸氢钙进行综合评价的重要性。并总结出检测劣质磷酸氢钙的简易、快捷的方法。     

降低生长肥育猪饲料中磷酸氢钙水平的研究

分30~60kg BW、60~100kg BW和30~100kg BW三个阶段研究了降低饲料中磷酸氢钙水平及降低磷酸氢钙的同时添加植酸酶对猪生长性能的影响。结果表明:磷酸氢钙添加水平在生长猪(30~60kg BW)饲料中由对照组的0.920%降低到0.552%、肥育猪(60~100kg BW)饲料中由对照组的0.760%降低到0.380%时都没有显著降低猪的生长性能(P>0.05),降低磷酸氢钙的同时添加植酸酶虽没有显著提高猪的生长速度(P>0.05),但能降低料肉比,其中在全阶段(30~100kg BW)的作用显著(P<0.05)。     

Comparative study on yield and chemical composition of maize (Zea mays L.) and sorghum (Sorghum bicolor Moench) using different levels of manure application

The effects of three levels of manure application (0, 4 and 8 ton/10 a) with basic fertilizer (N : P : K = 10:10:10 kg/10 a) on the yield and chemical composition of maize (Pioneer 32K61) and sorghum (FS501) forages were examined in 2 successive years, 2001–2002. Maize was harvested at yellow ripe stage, while sorghum at dough stage. Dry matter yield (DMY) of sorghum was significantly higher than that of maize in both 2001 and 2002. Although, DMY of both sorghum and maize were not significantly affected by manure levels in 2001, they increased with the level of manure in 2002. Maize had higher levels of crude protein (CP) and lower crude fiber concentration than those of sorghum in both 2001 and 2002. Manure application had no effect on chemical compositions of both maize and sorghum except for CP in both years and organic a fraction (Oa) concentration in 2002. The higher manure application might have greater effects on sorghum and maize production because of higher DMY in the second year without any increase in fiber fraction.     

Efficacy of different phosphorus supplements for sows during gestation and lactation

This study was undertaken to compare dicalcium, Curacao, and soft ph sophates as supplemental feeding during gestation and lactation. In Exp eriment 1, 37 crossbred sows at 11 months of age were mated and each of 4 groups given an experimental diet. The basal diet was a 16% crude pro tein-fortified corn-soybean meal containing .34% of phosphorus and .72% of calcium. The test diets were fortified with either dicalcium, Curaca o, or soft phosphate to provide .52% of phosphorus. Limestone was given to maintain .72% of calcium. Animals were confined in a concrete feedin g area and fed 1.8 kg of diet per head per day until Day 94 of gestation . At that time the diet was increased to 2.3 kg/day. On Day 109 of gestation animals were moved to farrowing crates until 10 days postpartu m and then to wooden units until weening at 8 weeks. Sows were sacrific ed after 8 weeks lactation, or if they developed posterior paralysis. In this experiment, the different phosphate sources were without observed influence on the livability or performance of pigs up to 8 weeks of age (p less than .05). Gilts receiving no supplemental phosphorus had significantly lower bone ash and phosphorus than did those receiving either of the supplements. Posterior paralysis was observed in 5 of 9 sows fed the unsupplemented diet, in 3 of 9 fed the soft supplemented diet, and in 2 of 10 fed the Curacao phosphate supplement. None fed dicalcium phosphate developed paralysis. The paralysis usually occurred after 6 weeks of lactation and was often accompanied by a fractured femur. In Experiment 2, 70 sows were bred at 10 months of age and fed 1.8 kg of the experimental diets. During 36 days of lactation, phosphorus digestibility, retention, and balance were shown to be lower for those fed only the basal diet. Bone ash, bone phosphorus, and bone strength were lower in those fed the unsupplemented diet. Results of these studies indicate the need for supplemental phosphorus in sow feeding. When feeding dicalcium phosphate or Curacao phosphate the use of over .5% phosphorus in the sow's diet is unnecessary during gestation and lactation.     

The replacement of some of the soybean meal by the first limiting amino acids in practical broiler diets. I. The value of special supplementation of chick diets with methionine and lysine.

1. Three trials were carried out in order to determine the amount by which dietary protein concentration can be reduced while maintaining the dietary concentrations of the first two limiting amino acids, methionine and lysine. 2. In all trials growth rate and food utilisation declined as the protein concentration of a well-balanced standard chick diet was lowered by replacing soybean meal with sorghum grain (milo), but this trend could be partly or completely prevented when methionine or methionine and lysine levels were restored. 3. Addition of 0-06 to 0-07% methionine, above that considered to be normal, is sufficient to replace approximately 0.9% soybean protein. 4. In diets containing approximately 3 percentage units less soybean protein than required, a supplementation of about 0.15% each of methionine and lysine can replace nearly 2-0% soybean protein, but cannot bring about chick performance equal to that obtained on the control ration, indicating an insufficiency of a third, or third and fourth, limiting amino acid in such low-protein diets.     

Phosphorus utilization in chicks fed hydrated sodium calcium aluminosilicate

Two experiments were conducted to evaluate the effects of hydrated Na Ca aluminosilicate (HSCAS) on P utilization of young broiler chicks. Phosphorus-deficient corn-soybean meal diets containing .36% (.134% available) P and 1% Ca were fortified with 0, .05 and .10% P provided as KH2PO4 (22.8% P) or feed-grade dicalcium phosphate (18.9% P). Diets were available ad libitum to chicks receiving 0, .50 or 1.0% HSCAS during the period 8 to 22 d posthatching. Weight of tibia ash, percentage of tibia ash and bone-breaking force were regressed on supplemental P intake to assess P utilization in the absence or presence of HSCAS. Tibia parameters (ash weight, percentage of ash and bone-breaking force) responded linearly (P less than .01) to P supplementation. Regardless of P source (KH2PO4 or dicalcium phosphate), .5% or 1.0% HSCAS had no effect (P greater than .1) on P utilization. With no supplemental P, tibia parameters also were not affected (P greater than .05) by HSCAS. Phosphorus utilization from dicalcium phosphate was estimated to be 87% as efficient as that observed for KH2PO4. The results suggest that dietary HSCAS does not impair utilization of either phytate or inorganic P.     

Water-soluble phosphorus excretion in pigs fed diets supplemented with microbial phytase

Three experiments were conducted to compare the excretion of water-soluble phosphorus (P) of starter, grower, and finisher pigs fed corn-soybean meal-based P-deficient basal diet containing no added inorganic P (B), P-adequate diet (the basal diet with added dicalcium phosphate; B + P), the basal diet plus 500 units of microbial phytase/kg (B + 500), or the basal diet plus 1000 units of microbial phytase/kg (B + 1000). There were 6 barrows per diet, in a randomized complete block design, with an average initial body weight of 10.4, 20.0, or 51.1 kg for each of starter, grower, and finisher pigs in the three phosphorus balance experiments, respectively. In the experiments, the addition of dicalcium phosphate or phytase to the basal diet increased ( P  < 0.05) the digestibility and retention of P, and there were linear reductions ( P  < 0.05) in water-soluble P excretion as a result of supplementing the basal diet with phytase. In the starter pig experiment, phytase addition at 500 or 1000 units/kg reduced ( P  < 0.05) water-soluble P excretion by 28 or 42%, respectively when compared with the B + P diet. In the grower pig experiment, adding phytase at 500 or 1000 units/kg reduced ( P  < 0.05) water-soluble P excretion by 24 or 34%, respectively when compared with the B + P diet. The use of phytase at 500 or 1000 units/kg reduced ( P  < 0.05) water-soluble P excretion by 11 or 30%, respectively in the finisher pig experiment. The proportion of water-soluble phosphorus in total phosphorus was not affected by dietary treatment in any of the three experiments. In conclusion, adding phytase at 1000 units/kg to a corn-soybean meal-based P-deficient diet basal diet containing no added inorganic P compared with B + P diet reduced the daily excretion of water-soluble P in starter, grower, and finisher pigs by 42, 34, and 30%, respectively.