微生物植酸酶可改善11 ~ 130 kg豬只因低鈣日糧導致的骨吸收
本試驗旨在驗證在11 ~ 130 kg豬只階段，短期試驗中以標準化全腸道可消化（STTD）Ca和STTD P比值來表示鈣的需求量在添加或不添加微生物植酸酶的飼糧中是適用的。
試驗分5個階段，選用160頭豬（體重：11.2±1.8kg）被隨機分配給32欄和4個日糧組中，采用2 × 2因子設計，2種日糧配方本質（總Ca和STTD Ca）和2種植酸酶水平（0或500單位/kg飼料），假設植酸酶釋放0.11% STTD P 和0.16% 總Ca。5個階段中STTD Ca：STTD P分別為1.40：1、1.35：1、1.25：1、1.18：1、1.10：1， STTD P滿足需要量；每階段結束時，記錄豬只的體重和剩余飼料量。在第1階段（24天）結束時，每欄1頭豬被實施安樂死，采集血液和右股骨樣本。在第2～5階段結束時，從每個豬圈的同一頭豬身上采集血液樣本。試驗結束時（126天），每欄采集1頭豬右股骨，測定其胴體性狀。
試驗數據顯示，在任何階段，飼糧配方本質和植酸酶添加量對生長性能均未發現相互作用，各處理對整體生長性能也未發現差異。第一階段結束時血漿鈣、磷和骨灰分也不受飼糧處理的影響。試驗第126天，以總鈣為基礎的非植酸酶飼糧的骨灰分高于以STTD Ca為基礎的飼糧；但在植酸酶飼糧中，兩種鈣基礎飼糧的骨灰分沒有差異（交互作用，P < 0.05）。在第2和3階段末，不添加植酸酶的飼糧血漿P顯著高于添加植酸酶的飼糧（P < 0.05），但在第4和5階段末無顯著差異。在2 ~ 5階段血漿鈣濃度呈負的二次效應（P < 0.05），血漿磷濃度在2～5階段顯著增加（二次方程式關系，P < 0.05）。然而，飼糧配方本質和植酸酶含量對胴體特征無交互作用或影響。
由此可見，STTD Ca：STTD P值可用于生長肥育豬飼糧配方，且不影響生長性能和胴體性狀，植酸酶添加可改善低鈣、低磷日糧導致的骨吸收。
Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics, but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg
An experiment was conducted to test the hypothesis that the requirement for Ca expressed as a ratio between standardized total tract digestible (STTD) Ca and STTD P obtained in short-term experiments may be applied to pigs fed diets without or with microbial phytase from 11 to 130 kg. In a 5-phase program, 160 pigs (body weight: 11.2 ± 1.8 kg) were randomly allotted to 32 pens and 4 corn–soybean meal-based diets in a 2 × 2 factorial design with 2 diet formulation principles (total Ca or STTD Ca), and 2 phytase inclusion levels (0 or 500 units/kg of feed) assuming phytase released 0.11% STTD P and 0.16% total Ca. The STTD Ca:STTD P ratios were 1.40:1, 1.35:1, 1.25:1, 1.18:1, and 1.10:1 for phases 1 to 5, and STTD P was at the requirement. Weights of pigs and feed left in feeders were recorded at the end of each phase. At the conclusion of phase 1 (day 24), 1 pig per pen was euthanized and a blood sample and the right femur were collected. At the end of phases 2 to 5, a blood sample was collected from the same pig in each pen. At the conclusion of the experiment (day 126), the right femur of 1 pig per pen was collected and carcass characteristics from this pig were measured. No interactions were observed between diet formulation principle and phytase inclusion for growth performance in any phase and no differences among treatments were observed for overall growth performance. Plasma Ca and P and bone ash at the end of phase 1 were also not influenced by dietary treatments. However, on day 126, pigs fed nonphytase diets formulated based on total Ca had greater bone ash than pigs fed STTD Ca-based diets, but if phytase was used, no differences were observed between the 2 formulation principles (interaction P < 0.05). At the end of phases 2 and 3, pigs fed diets without phytase had greater (P < 0.05) plasma P than pigs fed diets with phytase, but no differences were observed at the end of phases 4 and 5. A negative quadratic effect (P < 0.05) of phase (2 to 5) on the concentration of plasma Ca was observed, whereas plasma P increased (quadratic; P < 0.05) from phases 2 to 5. However, there was no interaction or effect of diet formulation principle or phytase inclusion on any carcass characteristics measured. In conclusion, STTD Ca to STTD P ratios can be used in diet formulation for growing-finishing pigs without affecting growth performance or carcass characteristics and phytase inclusion ameliorates bone resorption caused by low dietary Ca and P.