Manangi M K, Coon C N
Center of Excellence for Poultry Science, University of Arkansas, Fayetteville 72701, USA.
Poult Sci. 2008 Aug;87(8):1577-86. doi: 10.3382/ps.2007-00336.
Three 5-d bioassays were conducted to investigate the microbial phytase effect on apparent phytate phosphorus (PP) hydrolysis by 21-d-old broilers using corn-soybean meal basal diets. In Experiment 1, broilers fed corn-soy basal diet [0.7% Ca, 0.4% total P (TP), and 0.12% nonphytate P (NPP)] with 0, 250, 500, 750, 1,000, 1,500, 2,000, and 5,000 FTU of phytase/kg diet produced PP hydrolysis (%) of 43.12, 68.12, 74.7, 85.02, 85.25 92.77, 96.91, and 99.45, respectively. In Experiment 2, broilers fed corn-soy basal (0.5% Ca and 0.17% PP) without added phytase and 0.08, 0.13, 0.18, 0.23, 0.28, 0.33, 0.38, and 0.45% NPP had PP hydrolysis (%) of 8.5, 27.6, 26.4, 28.9, 26.3, 17.1, 21.0, and 27.7, respectively. Broilers fed the same 0.5% Ca basal and NPP concentrations with 1,000 FTU of phytase/kg of diet increased (P < 0.05) PP hydrolysis (%) to 80.9, 75.9, 73.5, 72.2, 68.4, 71.6, 58.3, and 62.5, respectively. Experiment 3 was conducted in the same way as Experiment 2 but Ca was maintained at 0.9% for all diets. Phytate P hydrolysis (%) without addition of phytase in 0.08, 0.13, 0.18, 0.23, 0.28, 0.33, 0.38, and 0.45% NPP-fed groups was 49.2, 19.6, 16.0, 8.0, 9.4, 2.1, 4.0, and 4.2, respectively. The addition of phytase increased (P < 0.05) PP hydrolysis (%) to 85.3, 76.1, 70.0, 76.1, 62.6, 68.6, 67.4, and 63.7, respectively. In conclusion, these studies indicated near-complete hydrolysis (99.45%) of PP at greater dietary phytase (5,000 FTU/kg) supplementation, but maximum TP retention was obtained with only 1,000 FTU of added phytase. Maximum PP hydrolysis occurred for broilers fed diets with 1,000 FTU added phytase when the diets contained the lowest concentration (0.08%) of dietary NPP with either 0.5 or 0.9% dietary Ca concentrations. These data also suggest that broilers fed 0.9% dietary Ca have a greater P physiological threshold before a loss in retention compared with broilers fed lower (0.5%) dietary Ca concentrations with no dietary phytase supplementation.
进行了三项为期5天的生物测定，以研究微生物植酸酶对21日龄肉鸡利用玉米-豆粕基础日粮时植酸磷（PP）表观水解的影响。在实验1中，饲喂玉米-豆粕基础日粮[0.7%钙、0.4%总磷（TP）和0.12%非植酸磷（NPP）]且每千克日粮添加0、250、500、750、1000、1500、2000和5000 FTU植酸酶的肉鸡，其PP水解率（%）分别为43.12、68.12、74.7、85.02、85.25、92.77、96.91和99.45。在实验2中，饲喂未添加植酸酶的玉米-豆粕基础日粮（0.5%钙和0.17%PP）以及0.08、0.13、0.18、0.23、0.28、0.33、0.38和0.45% NPP的肉鸡，其PP水解率（%）分别为8.5、27.6、26.4、28.9、26.3、17.1、21.0和27.7。饲喂相同的0.5%钙基础日粮和NPP浓度且每千克日粮添加1000 FTU植酸酶的肉鸡，其PP水解率（%）分别提高（P<0.05）至80.9、75.9、73.5、72.2、68.4、71.6、58.3和62.5。实验3的进行方式与实验2相同，但所有日粮的钙含量均维持在0.9%。在饲喂0.08、0.13、0.18、0.23、0.28、0.33、0.38和0.45% NPP且未添加植酸酶的组中，植酸磷水解率（%）分别为49.2、19.6、16.0、8.0、9.4、2.1、4.0和4.2。添加植酸酶后，PP水解率（%）分别提高（P<0.05）至85.3、76.1、70.0、76.1、62.6、68.6、67.4和63.7。总之，这些研究表明，日粮中添加较高剂量的植酸酶（5000 FTU/kg）时，PP的水解接近完全（99.45%），但仅添加1000 FTU植酸酶时总磷保留量最高。当肉鸡饲喂添加1000 FTU植酸酶且日粮中NPP浓度最低（0.08%）、钙浓度为0.5%或0.9%的日粮时，PP水解率最高。这些数据还表明，与饲喂较低钙浓度（0.5%）且未添加日粮植酸酶的肉鸡相比，饲喂0.9%日粮钙的肉鸡在保留量损失之前具有更高的磷生理阈值。
