植酸酶和柠檬酸对肉鸡生产性能及钙、磷利用率的影响

试验以正常营养水平饲粮为对照 ,研究在低营养水平饲粮中添加植酸酶 (0、 30 0g/t)、柠檬酸 (0、 0 5% )对肉鸡生产性能和钙、磷利用率的影响。试验用 2 2 5羽 1日龄黄羽肉鸡随机分为 5个处理 ,每处理 3个重复 ,每重复 1 5只鸡进行 6周试验。结果饲粮营养水平降低 6 %可导致肉鸡日增重 (ADG)和饲料利用率下降 (P <0 0 5) ;在低营养水平日粮中 ,添加 30 0g/t植酸酶、 0 5 %柠檬酸 ,ADG和料肉比 (F/G)与正常营养水平饲粮组差异不显著 (P >0 0 5) ;各处理组的血清Ca、P、AKP活性及胫骨Ca、P差异不显著 (P >0 0 5) ;腿病发生率各处理组差异不显著 (P >0 0 5)。添加 30 0g/t植酸酶、 0 5 %柠檬酸的处理组P排泄量显著低于对照组 (P <0 0 5)。植酸酶与柠檬酸合用能进一步提高生产性能和钙、磷利用率 ,能达到正常营养水平饲粮的效果。植酸酶与柠檬酸合用存在协同效应     

不同钙磷比例的日粮中添加植酸酶对肉鸡养分利用的影响

试验选用20只岭南黄公鸡,随机分成5组,研究在不同钙、磷比例的日粮中添加不同水平的植酸酶对钙、磷和干物质表观消化率以及总磷排出量的影响。第1组到第5组日粮中磷含量均为0.49%,Ca/P比依次为1:1.3、1:1.4、1:1.5、1:1.6和1:1.7,每组内4只鸡随机分成两组,交叉使用基础日粮和加酶日粮,加酶日粮是在基础日粮中添加500pu/kg的植酸酶。结果表明:(1)500pu/kg的植酸酶对钙、磷和干物质表观消化率以及总磷排出量的影响效果不明显;(2)不同Ca/P比对钙、磷的表观消化率有一定的影响,Ca/P比为1.6:1时,基础料钙的表观消化率显著高于其他组(P0.05),当Ca/P比为1.5:1时,基础料磷的表观消化率显著高于其他组(P0.05),但各组间干物质的表观消化率差异不显著(P0.05);(3)不同Ca/P比对总磷排泄量的影响差异极显著(P0.01)。     

低水平钙磷日粮添加植酸酶对肉鸡生长性能和养分消化的影响

文章旨在探讨植酸酶对饲喂低水平钙磷日粮肉鸡生长性能和养分表观消化率的影响.试验将平均初始体重为(61.56±0.66)g的1日龄肉鸡随机分为4组,每组4个重复,每个重复38只.对照组饲喂正常钙磷水平的玉米豆粕型日粮,T1～T3组饲喂低钙磷水平的玉米豆粕型日粮+0、1000和1500?FIU/kg植酸酶,试验分为1～21...     

Effects of microbial phytase on growth and mineral utilisation in broilers fed on maize soyabean-based diets.

1. A 3-week feeding trial with 96 sexed d-old broiler chickens was conducted to examine the effects of microbial phytase supplementation (Natuphos 5000) at 2 dietary energy concentrations on their performance, and the utilisation of nitrogen (N), phosphorus (P), calcium (Ca) and zinc (Zn) and on tibiae ash, Ca, P and Zn concentrations. Four replicate pens (6 birds per pen) of a completely randomised design were used in a 2x2 factorial arrangement of treatments with 2 contents of metabolisable energy (11.72 and 12.55 MJ ME/kg) and 2 additions of phytase (0 and 500 U of microbial phytase/kg). 2. Phytase supplementation significantly improved the utilisation of N, P, Ca and Zn (as a percentage of intake) and increased the concentration of Ca and Zn in the tibiae (P<0.05) because of higher intakes of dry matter, N, P, Ca and Zn. Phytase also significantly reduced the amount of P in the excreta (P<0.05). 3. The AME content of the diet influenced significantly (P<0.05) the excretion of N, P, Ca and Zn and the concentration of P and Ca in tibiae with the birds fed on the high AME diet excreting more minerals and having a smaller percentage of these minerals in their tibiae. However, there were strong interactions between phytase addition and AME in tibia ash and P, with the phytase supplementation producing a higher ash content at the higher AME a and a lower P content at the lower AME.     

植酸酶和柠檬酸对肉鸡生产性能及钙、磷利用率的影响

植物籽实及谷物中60%～80%的磷以植酸磷的形式存在。家禽消化道缺乏水解植酸的酶对植酸磷的利用率很低。业已证明,添加植酸酶可提高植酸磷、Ca、蛋白质等养分的利用,减少粪磷对环境的污染。肉鸡日粮中添加450U/kg的植酸酶,可将日粮的CP水平降低一个百分点而不影响生长性能、胴体品质和AA的消化率,同时可使氮排出量减少10%(Kemme等,1995)。磷消化试验和长期饲养试验的结果表明,300FTU/kg的植酸酶相当于磷酸一钙中的1.0g磷。肉鸡日粮中添加300FTU/kg植酸酶,日粮磷(无论是TP或AP)含量应降低0.1%,Ca水平应减低0.1个百分点。近年来的研究…     

低钙磷饲粮中添加耐热植酸酶对黄羽肉鸡生产性能和养分利用率的影响

为确认经基因工程改造而以酵母发酵生产的植酸酶添加在饲粮中对肉鸡生产性能和养分利用率的影响,本文试验开展了黄羽肉仔鸡的饲养试验和代谢试验.配制3种等蛋白质等能量等钙磷比的玉米-豆粕型试验饲粮(20.5%、12.15 MJ/kg和1.25),其中正对照饲粮含钙0.95%和磷0.76%,负对照饲粮含钙0.61%和磷0.50%,植酸酶组饲粮为在负对照饲粮基础上添加植酸酶(5000 U/g)的饲粮(添加量100 g/t).在饲养试验中,540只2日龄粤黄雏鸡随机分为3个处理(每个处理3个重复,每个重复60只),分别饲喂3种试验饲粮,为期4周.在饲养试验结束时分别从每组每个重复栏中选择2只接近其组平均体重的仔鸡进行屠宰,取出其胫骨测定相关指标.在代谢试验中,从饲养试验结束后的正对照组中选取45只仔鸡随机分成3组(每组3个重复,每重复5只),饥饿48 h后的3组分别自由采食3种试验料5 d,连续收集各重复鸡的排泄物7 d.分别测定试验饲粮和各排泄物烘干样的概略营养成分.试验结果表明:(1)3组间的软脚病率和死亡率差异不显著(P＞0.05),植酸酶组和正对照组的耗料量分别较负对照组提高了2%(P＜0.05)和12%(P＜0.05),增重分别较负对照组提高了5%和13%(P＜0.05),植酸酶组的耗料增重较正和负对照的均降低了3%(P＜0.05);(2)植酸酶组的脱脂胫骨灰分率、含钙率和含磷率均与正对照组的差异不显著(P＞0.05),但都显著高于负对照(P＜0.05),分剐提高了19%、23%和27%;(3)植酸酶饲粮的表观代谢能、氮存留率、钙表观消化率和磷表现消化率均与正对照组差异不显著(P＞0.05),但分别比负对照组提高了1%、5%、29%(P＜0.05)和12%.这表明,耐热植酸酶在低钙磷饲粮中添加可提高饲粮钙、磷、氮的利用率、耗料量和饲料转化率.从而提高黄羽肉鸡的生产性能.     

Effects of dietary boron and phytase supplementation on growth performance and mineral profile of broiler chickens fed on diets adequate or deficient in calcium and phosphorus

1. Two experiments were designed to determine the effect of dietary boron (B) in broiler chickens. In Experiment 1, a 2 × 4 factorial arrangement of treatments was used to investigate the effect of dietary calcium (Ca) and available phosphorus (aP) (adequate or deficient) and supplemental B (0, 20, 40, and 60 mg/kg diet). In Experiment 2, B, at 20 mg/kg, and phytase (PHY) (500 FTU/kg diet) were incorporated into a basal diet deficient in Ca and aP, either alone or in combination.

2. The parameters that were measured were growth performance indices, serum biochemical activity as well as ash and mineral (i.e. Ca, P, Mg, Fe, Cu and Zn) content of tibia, breast muscle and liver.

3. Results indicated that both supplemental B and dietary Ca and aP had marginal effects on performance indices of chickens grown for 42 d.

4. There were positive correlations (linear effect) between B concentrations of serum, bone, breast muscle and liver and the amount of B consumed.

5. Serum T₃ and T₄ activities increased linearly with higher B supplementation.

6. Increasing supplemental B had significant implications on breast muscle and liver mineral composition. Lowering dietary Ca and aP level increased Cu content in liver and both Fe and Zn retention in breast muscle. Tibia ash content and mineral composition did not respond to dietary modifications with either Ca–aP or B.

7. The results also suggested that dietary contents of Ca and aP do not affect the response to B regarding tissue mineral profile. Dietary combination with B and PHY did not create a synergism with regard to growth performance and bioavailability of the minerals.     

低钙磷日粮中添加耐热植酸酶对仔猪钙磷利用的影响

60头杜长大仔猪(9.8±0.1)kg随机分为2个处理,每个处理3个重复.每个重复10头,对照组饲喂含钙0.62%、磷0.49%的基础日粮,试验组饲喂在基础日粮中添加500 U/g植酸酶的日粮.试验期为4周,进行饲养试验.在饲养试验结束时分别从各组每个重复栏中选择1头接近其组平均体重的仔猪进行屠宰,取出其掌骨测定相关指标.另外,选取4头体重相似的生长猪(31±0.6)kg按2×2交叉设计进行消化代谢试验,测定两种试验日粮的相关养分利用率.结果表明:(1)植酸酶组仔猪的鲜掌骨重、脱脂干骨重、脱脂干骨灰分含量、脱脂干骨钙含量和脱脂干骨磷含量分别较对照组提高了9%(P＜0.05)、7%、2%、7%(P＜0.05)和6%(P＜0.05);(2)植酸酶日粮的粗蛋白质表现消化率和表观消化能与对照组差异均不显著(P＞0.05),但其钙和磷的表现消化率、钙和磷的存留率均显著高于对照组(P＜0.05),分别提高了20%、11%、12%和12%.耐热植酸酶在低钙磷日粮中的添加可促进仔猪对钙磷的利用,从而促进仔猪骨骼发育.     

Effect of dietary calcium level and source on mineral utilisation by piglets fed diets containing exogenous phytase

Calcium and phosphorus are essential minerals, closely linked in digestive processes and metabolism. With widespread use of low P diets containing exogenous phytase, the optimal dietary Ca level was verified. The 40‐day study evaluated the effects of Ca level (4, 7 and 10 g/kg diet) and Ca source (Ca from CaCO₃ and from Lithothamnium calcareum) on mineral utilisation in 72 piglets (7.9 ± 1.0 kg BW) fed an exogenous phytase containing diet with 2.9 g digestible P/kg. Measured parameters were growth performance, stomach mineral solubility, bone breaking strength and urinary, serum and bone mineral concentration. The apparent total tract digestibility of minerals was also assessed in the two diets with 7 g Ca/kg, using 12 additional pigs. Regardless of Ca source, increasing dietary Ca impaired feed conversion ratio, increased urinary pH, increased serum and urinary Ca, decreased serum and urinary P, decreased serum Mg and increased urinary Mg, increased serum AP activity, decreased bone Mg increased bone Zn. Bone breaking strength was improved with 7 compared to 4 g Ca/kg. Compared to CaCO₃, Ca from Lithothamnium calcareum increased serum Mg and with, 10 g Ca/kg, it limited body weight gain. The dose response of Ca in a diet with 2.9 g digestible P/kg and including exogenous phytase indicated that: (i) a low dietary Ca was beneficial for piglet growth, but was limiting the metabolic use of P; (ii) a high dietary Ca level impaired P utilisation; (iii) the optimal P utilisation and bone breaking strength was obtained with a dietary Ca‐to‐digestible P ratio of 2.1 to 2.4:1; (iv). Increasing dietary Ca reduced Mg utilisation, but not Zn status, when fed at adequate level. Finally, Ca from Lithothamnium calcareum had similar effects on Ca and P metabolism as CaCO₃, but impaired growth when fed at the highest inclusion level.     

耐高温植酸酶用于颗粒饲料对肉鸡生产性能及钙、磷利用率的影响

试验旨在研究肉仔鸡低磷日粮颗粒饲料中添加耐高温植酸酶对肉鸡生产性能及钙、磷利用率的影响。选取1日龄AA+肉仔鸡,随机分为6个处理,分别饲喂处理1(正对照,正常磷水平)、处理2(负对照,低于正常磷水平)、处理3(负对照+500U植酸酶)、处理4(高磷替代+500U植酸酶)、处理5(负对照+1000U植酸酶)和处理6(高磷替代+1000U植酸酶)试验日粮。试验结果表明:在制粒饲料中添加耐高温植酸酶是可行的。在相同有效磷水平下,随着植酸酶添加水平的提高,出栏体重有增加的趋势;在相同植酸酶添加量的条件下,随着有效磷替代水平的提高,出栏体重有降低的趋势。添加植酸酶有增加胫骨灰分和磷含量的趋势。在正常替代水平下,植酸酶的添加量以500～1000U/kg为宜。在本试验条件下,日粮添加500～1000U/kg植酸酶的情况下,进行磷酸氢钙的高水平替代也是可行的。     

小麦型日粮添加木聚糖酶和植酸酶对肉鸡生长性能、回肠氨基酸表观消化率及常量元素沉积的影响

本文旨在研究小麦型日粮中添加木聚糖酶和植酸酶对肉鸡生长性能、回肠氨基酸表观消化率及矿物元素沉积的影响。试验选择1日龄科宝白羽肉仔鸡850只,随机分成5组,每组5个重复,每个重复34只鸡。一共有5种日粮,即低磷日粮、高磷日粮、低磷日粮+2000 IU/kg木聚糖酶、低磷日粮+500 FTU/kg植酸酶,低磷日粮+2000 IU/kg木聚糖酶+500 FTU/kg植酸酶,试验进行21 d。低磷组较高磷组显著降低了肉鸡的日增重、日采食量及趾骨灰分含量(P <0.05),与低磷组相比,木聚糖酶组显著降低了肉鸡的料比(P <0.05),而植酸酶组显著提高了肉鸡日增重、日采食量、趾骨灰分及饲料利用率(P <0.05)。复合酶组显著提高了15种氨基酸回肠表观消化率(P <0.05)。与低磷组相比,木聚糖酶组显著提高了表观消化能和可消化代谢能及回肠氮消化率(P <0.05),而植酸酶显著提高了氮沉积及回肠氮消化率(P <0.05),复合酶组显著提高了代谢能、可消化代谢能及氮沉积量(P <0.05)。植酸酶和复合酶组较高磷组显著提高了磷表观消化率和沉积量(P <0.05),但低磷组较高磷组显著提高了钙的表观消化率(P <0.05),植酸酶酶和复合酶组较其他3组显著提高了钾的沉积量(P <0.05)。结论 :小麦型日粮同时添加植酸酶和木聚糖酶对肉鸡生长和消化的影响要优于单独添加这两种酶。     

植酸酶对提高肉仔鸡日粮中钙、磷利用率的研究

将试验肉仔鸡随机分成4组,每组设3个重复,每个重复20只。Ⅰ组为不添加植酸酶的基础日粮对照组;Ⅱ组为每千克日粮添加500U植酸酶替代基础日粮中0.09%的无机磷试验组;Ⅲ组为每千克日粮添加500U植酸酶替代基础日粮中0.11%的无机磷试验组;Ⅳ组为每千克日粮添加500U植酸酶替代基础日粮中0.13%的无机磷试验组。试验按0～3周龄和4～6周龄两个阶段进行。试验结果表明:在肉仔鸡玉米-豆粕型日粮中添加0.01%的植酸酶(活性为5000U/g)替代日粮中0.12%的钙和0.11%的无机磷可显著提高肉仔鸡的生长性能,并能取得最佳的经济效益,为最适替代比例。     

Effects of dietary mineral supplementation on the performance and mineral retentions of broilers at high ambient temperatures

1. The relationship between broiler performance and two dietary mineral balance equations was investigated at a high constant ambient temperature (30°C) using a range of 11 salt supplements given to male broiler chicks from 21 to 42 d of age.

2. No relationship was found between broiler performance and either of the two balance equations.

3. Re‐evaluating these equations using retained, rather than dietary, mineral concentrations did not improve the relationship although changes in mineral retentions associated with the supplements indicated that dietary concentrations were not a good indicator of the impact of the diet on the bird's acid‐base homoeostasis.

4. Evidence was found that metabolisable anions supplemented in association with mineral cations may have a significant effect on broiler performance.     

植酸酶对肉鸡生长性能及饲粮养分利用率的影响

饲养试验选用1日龄的良凤花鸡600羽,随机分为4组(每组设3个重复,每个重复50羽),A组为对照组,饲喂玉米-豆粕型基础饲粮,B、C、D组的饲粮为分别以300、500、700 U/kg的植酸酶取代基础饲粮中的30%、50%、70%的磷酸氢钙。结果表明:0～4周龄,与对照组相比,C和D组平均日增重(ADG)分别极显著提高6.29%(P<0.01)和8.27%(P<0.01);平均料重比(F/G),组间差异不显著(P>0.05)。5～8周龄,与对照组相比,B、C和D组的ADG分别有所提高,F/G有所下降,但组间差异不显著(P>0.05)。B、C、D组鸡血清钙、磷、白蛋白、总蛋白、球蛋白含量随着植酸酶添加量的增加呈上升趋势,但差异不显著(P>0.05);血清碱性磷酸酶活性随着植酸酶的添加而呈降低趋势,但差异不显著(P>0.05)。消化代谢试验结果表明,添加不同水平的植酸酶替代饲粮不同比例的磷酸氢钙,肉鸡饲粮干物质、粗蛋白、粗脂肪、粗纤维、粗灰分、钙和能量的表观代谢率虽然比对照组有所改善,但差异不显著(P>0.05);而磷的表观吸收率分别比对照组显著提高了25.39%～32.48%(P<0.01)。     

饲粮中植酸酶、钙、磷不同水平组合对肉仔鸡生长和屠宰性能的影响

利用正交实验[L(934)]把270只艾维茵肉仔鸡随机分为9组,研究植酸酶、非植酸磷和钙水平的不同组合对艾维茵肉仔鸡生长性能、死淘率、屠宰性能及肉品质的影响。结果表明,添加非植酸磷0.18%+钙0.8%组肉仔鸡生长最差,全部发生腿病,并于试验中期死亡或被淘汰;在非植酸磷0.18%+钙0.65%组的饲粮中添加植酸酶600FTU/kg,一定程度上改善了肉仔鸡的生长发育,但日增重仍较差,且死淘率较高;而添加植酸酶1200FTU/kg+非植酸酶0.18%+钙1.00%的组合显著降低了肉仔鸡的食欲与生长发育速度,腿病发生率和死淘率仍较高。饲粮中添加非植酸磷0.28%+不添加植酸酶+钙1.00%组仔鸡生长很差、死淘率较高;添加植酸酶600FTU/kg+非植酸磷0.28%+钙0.80%的组生长效果良好,而非植酸磷0.28%+钙0.65%+植酸酶1200FTU/kg组并未进一步提高生长效果。饲粮非植酸磷为0.38%时的3个组合都表现出较佳的日增重,说明非植酸磷0.38%能满足仔鸡需要。试验处理对仔鸡屠宰性能与肉品质未产生明显影响。饲粮中添加非植酸磷0.28%+钙0.80%+植酸酶600FTU/kg时,肉仔鸡的综合效益较佳。     

耐热植酸酶对肉鸡生产性能、血液及骨骼钙磷含量的影响

选取192羽1日龄艾维茵肉仔鸡,随机分为4组,研究在低磷肉鸡颗粒日粮中分别添加耐热植酸酶(100g/t)和普通植酸酶(200g/t)对肉鸡生产性能及血液和骨骼中相关指标的影响。结果表明:低磷日粮显著降低了肉鸡的生产性能,植酸酶的添加均提高了肉鸡的采食量及日增重,降低了料重比,且耐热植酸酶较普通植酸酶获得了更好的生产性能;低磷日粮降低血清及骨骼中钙、磷含量,提高血清碱性磷酸酶活性,而植酸酶的添加提高了血清及骨骼中钙、磷含量,降低碱性磷酸酶活性。结果提示:耐热植酸酶应用于低磷肉仔鸡颗粒日粮中能提高肉鸡的生产性能和机体对钙、磷的储存。     

日粮钙磷比对肉鸭耐热植酸酶效力的影响

本试验以等能量(11.29 MJ/kg)、等蛋白质(19.40%)和等磷水平(0.46%)的低磷日粮对肉鸭进行代谢试验,研究不同肉鸭日粮钙磷比对耐热植酸酶应用效力的影响.试验共设8种试验饲粮:4种为不含植酸酶的基础日粮.钙磷比分别为1.0、1.2、1.4和1.6(BD1.0、BD1.2、BD1.4和BD1.6);4种为分别在上述4种基础日粮的基础上添加100 g/t植酸酶(即500 U/kg)的试验日粮(PD1.0、PD1.2、PD1.4和PD1.6).在代谢试验结束后,分别测定各试验日粮和粪样的干物质、有机物和总磷的含量.结果表明:(1)4种基础日粮的干物质和有机物的表观消化率以及磷的存留率的差异均不显著(JP＞0.05);(2)PD1.0、PD1.2组和PD1.4组日粮的干物质表观消化率较PD1.6组分别提高了24.6%(P＜0.05)、21.3%(JP＜0.05)和17.6%(P＞0.05),有机物表观消化率分别提高了20.1%(P＜0.05)、16.2%(P＜0.05)和13.6%(P＞0.05),总磷存留率分别提高了3.83%(P＞0.05)、17.6%(P＞0.05)和13.2%(P＞0.05);(3)PD1.0、PD1.2、PD1.4组和PD1.6组的表观可利用磷当量分别为0.10%、0.11%、0.10%和0.06%.综合本试验结果表明,肉鸭日粮钙磷比约为1.2时最有利于耐热植酸酶效力发挥.     

Effect of dietary antioxidant supplementation on the oxidative status of plasma in broilers

In this study, the effect of dietary antioxidants on the plasma oxidative status of growing birds fed a diet rich in polyunsaturated fatty acids was investigated. One‐day‐old broilers were fed for 42 days a diet containing 4% linseed oil and supplemented with single plant extracts rich in antioxidants (natural tocopherols, rosemary, grape seed, green tea, tomato) or a combination of some of these plant extracts, in two different total doses (100 and 200 mg product/kg feed). A diet with synthetic antioxidants with and without α‐tocopheryl acetate (200 mg/kg feed) were also included. The plasma oxidative status was evaluated measuring the ferric reducing ability of plasma (FRAP), the superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) activity. Lipid peroxidation was measured by thiobarbituric acid‐reactive substances (TBARS). No significant effect of the dietary treatments was observed for FRAP as well as for TBARS. However, diet affected GSH‐Px activity (p = 0.002) and a trend for an effect on SOD activity was observed (p = 0.084). A higher GSH‐Px activity was found for 200 mg/kg tomato extract and natural α‐tocopherol in relation to the corresponding 100 mg/kg treatment, and the lowest GSH‐Px activity was measured for the synthetic antioxidants treatment. The lowest and highest SOD activity were found for the 200. and 100 mg/kg treatment with tomato extract respectively. In conclusion, the oxidative status and lipid oxidation of plasma in broilers was not affected by feeding natural antioxidant extracts at the doses in the present study, but some changes in antioxidant enzyme activities were observed, of which the implication remains to be elucidated.     

The effect of dietary calcium and phosphorus supplementation in zeolite a treated dry cows on periparturient calcium and phosphorus homeostasis

Previous studies have proved the possibility of preventing parturient hypocalcaemia by zeolite A supplementation during the dry period, and a recent in vitro study has indicated a marked calcium (Ca) as well as phosphorus (P) binding effect of zeolite A in rumen fluid solutions. Because of the connection between the Ca and P homeostatic systems, the preventive effect against parturient hypocalcaemia may arise from zeolite induced decreased availability of dietary Ca as well as P. In the present study, the expected Ca and P binding capacity was challenged by feeding high and low levels of dietary Ca and/or P to zeolite A treated dry cows. Twenty-one pregnant dry cows were assigned to four experimental groups receiving a dry cow ration unsupplemented or supplemented with extra Ca and/or P. During the last 2 weeks of the dry period all cows additionally received 600 g of zeolite A per day. A high level of dietary P prepartum significantly decreased the plasma Ca concentration before as well as immediately after calving (day 0-3). Conversely, the plasma inorganic phosphate concentration was higher among these cows than among cows receiving no supplemental P. The prepartum dietary Ca level significantly affected the serum 1,25-dihydroxyvitamin D concentration during zeolite supplementation, whereas the periparturient plasma Ca concentration was apparently not affected by the dietary Ca level. During zeolite A supplementation plasma parathyroid hormone was significantly higher among cows receiving additional P. The urinary deoxypyridinoline/creatinine ratio was not affected by the prepartal dietary Ca or P level. Serum aluminium (Al) was significantly higher during zeolite A supplementation than during the preceding period, indicating partial destruction of the zeolite in the intestinal tract with subsequent release and absorption of Al. It is suggested that the effect of prepartum zeolite supplementation on the periparturient Ca homeostasis depends on the level of Ca as well as P in the dry cow ration.