Yi Z, Kornegay E T, Denbow D M
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Poult Sci. 1996 Apr;75(4):540-6. doi: 10.3382/ps.0750540.
Day-old male broilers (n = 384) were used in a 21-d trial to investigate the effect of microbial phytase on the retention and utilization of Zn. A corn-soybean isolate basal diet containing 20 ppm Zn was fed alone and supplemented with 5, 10, or 20 ppm Zn as ZnSO4.7H2O or with 150, 300, 450, or 600 U of phytase/kg of diet. Total excreta were collected during Days 18 to 20. Toe, tibia, and liver samples were taken at the end of the experiment. Adding Zn and phytase to the low Zn basal diet linearly increased BW gain and feed intake of broilers (P < 0.01). The gain to feed ratio was not changed by adding Zn but was decreased by adding phytase (P < 0.01). The amount of DM retained was linearly increased by adding Zn and phytase (P < 0.10), but DM retained as a percentage of intake was only increased by adding Zn (P < 0.05). The amount of Zn retained per bird was linearly improved by adding Zn and phytase (P < 0.01). Zinc retained as a percentage of intake was linearly decreased by adding Zn but was linearly increased by adding phytase (P < 0.10). Ash percentage of toe and tibia were not affected by adding Zn but were linearly improved by adding phytase (P < 0.10); however, the amount of ash in toe or tibia was increased by Zn (P < 0.05) and phytase (P < 0.01 for toe; not significant for tibia). The concentration and amount of Zn in toe and tibia were linearly increased by adding Zn and phytase (P < 0.001). The concentration of Zn in liver increased by adding Zn (P < 0.10) but was not significantly improved by adding phytase. The amount of Zn retained in liver was linearly improved by adding Zn and phytase (P < 0.05). Nonlinear or linear response equations of the effects of Zn and phytase levels were generated and used to calculate the Zn equivalency values. The average function of Zn equivalency values (Y, milligrams per kilogram) of microbial phytase (X, units per kilogram of diet) was developed: Y = 0.20 + 0.0082X. The results indicate that approximately 0.9 mg of Zn was released per 100 U of phytase over the range of 150 to 600 U of phytase.
选用1日龄雄性肉鸡（n = 384）进行为期21天的试验，以研究微生物植酸酶对锌保留和利用的影响。单独饲喂含20 ppm锌的玉米 - 大豆分离物基础日粮，并添加5、10或20 ppm硫酸锌（ZnSO4·7H2O）形式的锌，或每千克日粮添加150、300、450或600 U植酸酶。在第18至20天收集总排泄物。实验结束时采集脚趾、胫骨和肝脏样本。向低锌基础日粮中添加锌和植酸酶可使肉鸡的体重增加和采食量呈线性增加（P < 0.01）。添加锌未改变料重比，但添加植酸酶使其降低（P < 0.01）。添加锌和植酸酶可使干物质保留量呈线性增加（P < 0.10），但干物质保留量占摄入量的百分比仅在添加锌时增加（P < 0.05）。每只鸡的锌保留量通过添加锌和植酸酶呈线性改善（P < 0.01）。锌保留量占摄入量的百分比在添加锌时呈线性降低，但在添加植酸酶时呈线性增加（P < 0.10）。添加锌对脚趾和胫骨的灰分百分比无影响，但添加植酸酶可使其呈线性改善（P < 0.10）；然而，脚趾或胫骨中的灰分含量因锌（P < 0.05）和植酸酶（脚趾P < 0.01；胫骨不显著）而增加。添加锌和植酸酶可使脚趾和胫骨中锌的浓度和含量呈线性增加（P < 0.001）。添加锌可使肝脏中锌的浓度增加（P < 0.10），但添加植酸酶未显著改善。添加锌和植酸酶可使肝脏中锌的保留量呈线性改善（P < 0.05）。生成了锌和植酸酶水平效应的非线性或线性响应方程，并用于计算锌当量值。得出微生物植酸酶（X，每千克日粮单位）的锌当量值（Y，毫克/千克）的平均函数：Y = 0.20 + 0.0082X。结果表明，在150至600 U植酸酶范围内，每100 U植酸酶约释放0.9 mg锌。
