USDA-ARS-Laboratory for Agriculture and the Environment, Ames, IA 50011;
J Anim Sci. 2010 Jan;88(1):238-47. doi: 10.2527/jas.2009-2146. Epub 2009 Sep 25.
Five experiments were conducted to investigate the ability of different phytase products to improve P digestibility in finishing pigs. A corn-soybean meal basal diet containing 0.50% Ca, 0.32% P, and 0.40% Cr(2)O(3) was used to calculate apparent P and GE digestibility. Pigs were individually penned and fed their respective diet for ad libitum intake for 12 d before fecal sampling on d 13 and 14 and blood collection on d 14 for plasma P determination. Experiments 1 through 4 used gilts with across-trial average initial and final BW of 84 and 97 kg, respectively. Pigs were fed Natuphos (Exp. 1), OptiPhos (Exp. 2), Phyzyme (Exp. 3), or RonozymeP (Exp. 4) at 0, 200, 400, 600, 800, or 1,000 phytase units (FTU)/kg (where 1 FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P per min, at pH 5.5, from an excess of 15 micromol/L of sodium phytate at 37 degrees C). Experiment 5 used barrows with initial and final BW of 98 and 111 kg, respectively, and were fed diets containing 0, 500, or 1,000 FTU/kg of Natuphos, OptiPhos, Phyzyme, or RonozymeP. Pigs fed Natuphos (Exp. 1) and OptiPhos (Exp. 2) exhibited a linear and quadratic (P < 0.01) improvement in P digestibility with increasing levels of dietary phytase, whereas pigs fed Phyzyme (Exp. 3) and RonozymeP (Exp. 4) exhibited a linear (P < 0.01) improvement in apparent P digestibility with increasing levels of dietary phytase. In Exp. 5, the improvement in apparent P digestibility with increasing levels of dietary phytase was linear (P < 0.01) for Natuphos, Phyzyme, and RonozymeP, but was linear and quadratic (P < 0.01) for OptiPhos. Based on regression analysis, inorganic P release at 500 FTU/kg was predicted to be 0.070, 0.099, 0.038, and 0.030% for Natuphos, OptiPhos, Phyzyme, and RonozymeP, respectively. These estimates are comparable with those of pigs in Exp. 5, for which the estimated inorganic P release at 500 FTU/kg was 0.102, 0.039, and 0.028% for OptiPhos, Phyzyme, and RonozymeP, respectively, but not for the 0.034% value determined for Natuphos. The effect of dietary phytase on GE digestibility was inconsistent with a linear (P < 0.01) improvement in GE digestibility noted for OptiPhos (Exp. 2 and 5) and RonozymeP (Exp. 4), but the quadratic (P < 0.01) improvement for Natuphos. There was no effect of dietary phytase on plasma inorganic P. The data presented show clear improvements in P digestibility, with the estimated level of inorganic P release being dependent on phytase source and level.
进行了五项实验来研究不同植酸酶产品在育肥猪中提高磷消化率的能力。使用含有 0.50%钙、0.32%磷和 0.40%三氧化二铬的玉米-豆粕基础日粮来计算表观磷和总能量消化率。在第 13 天和第 14 天采集粪便样本，并在第 14 天采集血液用于测定血浆磷之前，猪被单独饲养并自由采食其各自的日粮 12 天。实验 1 至 4 使用平均初始和最终体重分别为 84 和 97 公斤的母猪。猪分别饲喂 Natuphos（实验 1）、OptiPhos（实验 2）、Phyzyme（实验 3）或 RonozymeP（实验 4），酶用量分别为 0、200、400、600、800 或 1000 植酸酶单位（FTU）/kg（其中 1 FTU 定义为在 pH 5.5 下，37°C 时从过量的 15 微摩尔/升植酸钠中每分钟释放 1 微摩尔无机磷所需的酶量）。实验 5 使用初始和最终体重分别为 98 和 111 公斤的公猪，并饲喂含有 0、500 或 1000 FTU/kg 的 Natuphos、OptiPhos、Phyzyme 或 RonozymeP 的日粮。饲喂 Natuphos（实验 1）和 OptiPhos（实验 2）的猪表现出磷消化率随着日粮植酸酶水平的线性和二次（P < 0.01）提高，而饲喂 Phyzyme（实验 3）和 RonozymeP（实验 4）的猪表现出随着日粮植酸酶水平的线性（P < 0.01）提高表观磷消化率。在实验 5 中，随着日粮植酸酶水平的提高，表观磷消化率的提高呈线性（P < 0.01），但 OptiPhos 呈线性和二次（P < 0.01）。基于回归分析，预测 Natuphos、OptiPhos、Phyzyme 和 RonozymeP 的 500 FTU/kg 无机磷释放量分别为 0.070、0.099、0.038 和 0.030%。这些估计值与实验 5 中猪的估计值相当，其中 OptiPhos、Phyzyme 和 RonozymeP 的 500 FTU/kg 无机磷释放量分别为 0.102、0.039 和 0.028%，但与 Natuphos 的 0.034%值不一致。日粮植酸酶对总能量消化率的影响与 OptiPhos（实验 2 和 5）和 RonozymeP（实验 4）中观察到的总能量消化率线性（P < 0.01）提高不一致，但与 Natuphos 的二次（P < 0.01）提高一致。日粮植酸酶对血浆无机磷没有影响。所呈现的数据表明磷消化率有明显提高，估计的无机磷释放量取决于植酸酶的来源和水平。
