ABSTRACT

1. Published data on the ileal Ca digestibility in soybean meal (SBM) and canola meal (CM), and the effect of microbial phytase on the Ca digestibility of these ingredients are limited. Therefore, two experiments were conducted, with the primary objective of determining the true ileal digestibility of calcium (Ca) in SBM and CM, without and with microbial phytase, during broiler grower (Experiment 1) and finisher (Experiment 2) periods. A secondary objective was to investigate the influence of microbial phytase on the true ileal digestibility of phosphorus (P), apparent digestibility of nitrogen (N) and minerals, and phytate disappearance in maize-SBM and maize-CM diets. Six experimental diets based on SBM and CM, with three phytase doses (0, 500 and 2000 FTU/kg), were fed to broilers from day 18 to 21 (Experiment 1) or 39 to 42 (Experiment 2) post-hatch. A Ca- and P-free diet, with no added phytase, was also developed to determine the endogenous Ca and P losses. Titanium dioxide was incorporated in all diets as an indigestible indicator. Each experimental diet was randomly allocated to six replicate cages (eight birds per cage). Apparent ileal digestibility was calculated using the indicator method and the true ileal digestibility was calculated by correcting for endogenous losses. Apparent total tract retention (ATTR) of Ca and P was also measured.

2. Ileal endogenous losses of Ca and P were determined to be 236 and 310 mg/kg of dry matter intake (DMI), respectively, in broiler growers and 29 and 130 mg/kg of DMI, respectively, in broiler finishers. True ileal Ca digestibility coefficients of SBM and CM, without added phytase, were determined to be 0.51 and 0.53, respectively, in broiler growers and 0.33 and 0.22, respectively, in broiler finishers. Increasing phytase doses increased (P < 0.05) the true ileal Ca digestibility of CM in both broiler growers and finishers, but Ca digestibility of SBM increased (P < 0.05) only at the superdose (2000 FTU/kg) in broiler finishers. The ATTR of Ca (P < 0.001) in growers was higher in CM than in SBM and was increased in both ingredients by increasing phytase doses. In finishers, the ATTR of Ca was increased (P < 0.001) by both phytase doses in CM, but only by the superdose in SBM, resulting in an ingredient × phytase interaction (P < 0.001).

3. True ileal P digestibility coefficients of maize-SBM and maize-CM diets, without added phytase, were determined to be 0.89 and 0.66, respectively, in broiler growers and 0.82 and 0.57, respectively, in broiler finishers. Supplemental phytase increased (P < 0.05) the true ileal P digestibility of the maize-CM diet in both broiler growers and finishers. However, the P digestibility of the maize-SBM diet was increased (P < 0.05) in broiler finishers only at the superdose (2000 FTU/kg). The ATTR of P was higher (P < 0.001) in the maize-SBM diet during both periods.

4. The apparent ileal digestibility of N, Mg, K and Mn was higher (P < 0.001) in the maize-SBM diet for broiler growers and finishers. Phytase addition had no effect (P > 0.05) on the apparent digestibility of N and minerals in growers and finishers.

5. Increasing phytase doses increased IP6 disappearance in the maize-CM diet, but not in the maize-SBM diet, resulting in an ingredient × phytase interaction (P < 0.001) for growers and finishers.

6. In conclusion, true ileal Ca digestibility coefficients of SBM and CM for broilers were determined in this study. The findings confirmed the influence of broiler age of Ca digestibility. Superdosing of phytase increased the digestibility and ATTR of Ca in CM and SBM by two-fold compared to the normal phytase dose.

抽象的

1.有关豆粕（SBM）和低芥酸菜粕（CM）中回肠钙消化率的公开数据，以及微生物植酸酶对这些成分的钙消化率的影响是有限的。因此，进行了两个实验，其主要目的是确定在肉鸡生长阶段（实验1）和育肥阶段（实验2）期间，在不添加和添加微生物植酸酶的情况下，SBM和CM中钙（Ca）的真实回肠消化率。第二个目的是研究微生物植酸酶对玉米-SBM和玉米-CM日粮中回肠磷的真实回肠消化率，氮和矿物质的表观消化率以及植酸盐消失的影响。六种基于SBM和CM的实验饮食，三种植酸酶剂量（0、500和2000 FTU / kg），孵化后从第18天到21天（实验1）或从39天到42天（实验2）喂饲肉鸡。还开发了无钙和磷的饮食，不添加植酸酶，以确定内源性钙和磷的损失。二氧化钛是所有饮食中不可消化的指标。每个实验饮食被随机分配到六个重复的笼子中（每个笼子八只鸟）。使用指示剂方法计算表观回肠消化率，并通过校正内源性损失计算出真正的回肠消化率。还测量了Ca和P的表观总道保留率（ATTR）。每个实验饮食被随机分配到六个重复的笼子中（每个笼子八只鸟）。使用指示剂方法计算表观回肠消化率，并通过校正内源性损失计算出真正的回肠消化率。还测量了Ca和P的表观总道保留率（ATTR）。每个实验饮食被随机分配到六个重复的笼子中（每个笼子八只鸟）。使用指示剂方法计算表观回肠消化率，并通过校正内源性损失计算出真正的回肠消化率。还测量了Ca和P的表观总道保留率（ATTR）。

2.在肉鸡种植者中，回肠内源性Ca和P的损失分别为236和310 mg / kg干物质摄入量（DMI），在肉鸡育成者中分别为29和130 mg / kg DMI。不添加肌醇六磷酸酶的SBM和CM的真实回肠Ca消化率系数在肉鸡种植者中分别为0.51和0.53，在肉鸡育肥者中分别为0.33和0.22。增加植酸酶剂量增加（P <0.05）CM在两个肉鸡种植者和修整，但SBM的钙消化率真回肠消化率钙增加（P仅在肉鸡修整机的superdose（2000 FTU / kg）的<0.05）。Ca的ATTR（P<0.001）在种植者中CM高于SBM，并且两种成分均通过增加肌醇六磷酸酶剂量而增加。在育肥猪中，两种植酸酶剂量的CM的Ca的ATTR均增加（P <0.001），但只有SBM的过量使Ca的ATTR升高，从而导致成分×植酸酶的相互作用（P <0.001）。

3.在不添加肌醇六磷酸酶的玉米-SBM和玉米-CM日粮中，回肠P的真实回肠磷消化率系数在肉鸡种植者中分别为0.89和0.66，在肉鸡育肥者中分别为0.82和0.57。补充植酸酶提高了肉鸡和育肥猪玉米-CM日粮的回肠磷消化率（P <0.05）。然而，仅在超剂量（2000 FTU / kg）下，肉鸡肥育中玉米-SBM日粮的P消化率增加（P <0.05）。在两个时期中，玉米-SBM日粮中的P的ATTR均较高（P <0.001）。

4.在玉米-SBM日粮中，肉鸡种植者和育肥者的N，Mg，K和Mn的表观回肠消化率更高（P <0.001）。添加植酸酶对种植者和肥育者中氮和矿物质的表观消化率没有影响（P> 0.05）。

5.增加植酸酶剂量在玉米-CM日粮中增加了IP6的消失，但在玉米-SBM日粮中却没有，从而导致了种植者和育肥者的成分×植酸酶相互作用（P <0.001）。

6.总之，本研究确定了肉鸡SBM和CM的真实回肠Ca消化系数。这些发现证实了肉鸡年龄对钙消化率的影响。与正常肌醇六磷酸酶剂量相比，肌醇六磷酸酶的超剂量使CM和SBM中Ca的消化率和ATTR增加了两倍。