Two experiments were carried out to determine a time-series effect of phytase on phosphorus (P) utilization in growing and finishing pigs using growth performance, apparent total tract digestibility (ATTD) of nutrients, P excretion, and plasma concentrations of minerals as the response criteria for evaluation. In both experiments, treatments were arranged as a 3 × 4 factorial in a randomized complete block design with 3 corn–soybean meal-based diets including a P-adequate positive control (PC), a low-P negative control (NC; no inorganic P), and NC supplemented with phytase at 1,000 FYT/kg (NC + 1,000); and 4 sampling time points at days 7, 14, 21, and 28 in experiment 1, and days 14, 26, 42, and 55 in experiment 2. In both trials, 96 growing pigs with average body weight (BW) of 19.8 ± 1.16 and 49.8 ± 3.21 kg, respectively, were allocated to the 3 diets with 8 replicates pens (4 barrows and 4 gilts) and 4 pigs per pen. In experiment 1, pigs fed the PC had higher (P < 0.01) BW, average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) when compared with pigs fed the NC. There was an interaction (P < 0.01) between time and diet on the BW and ADG of pigs while a linear and quadratic increase (P < 0.01) was observed with the ADFI and G:F, respectively, over time. Phytase supplementation improved (P < 0.01) all growth performance responses. Pigs fed the PC had greater (P < 0.01) ATTD of P and Ca than pigs fed the NC. There was no interaction effect on the ATTD of nutrients. Phytase addition improved the ATTD of P and Ca over pigs fed the NC. There was an interaction (P < 0.01) between diet and time on the total and water-soluble P (WSP) excreted. There was a quadratic decrease (P < 0.01) in plasma concentration of Ca in pigs over time. In experiment 2, there was a quadratic increase (P < 0.01) in BW, ADG, and G:F of pigs over time. Similarly, the inclusion of phytase improved (P < 0.05) all growth performance parameters except ADFI. A linear increase (P < 0.05) in the ATTD of DM, P, and Ca occurred over time. Phytase inclusion improved (P < 0.01) the ATTD of P and Ca. Plasma concentrations of P were improved by phytase addition. Phytase supplementation of the NC reduced WSP excretion by 45%, 32%, and 35% over the growing, finishing, and entire grow-finish period, respectively. In conclusion, phytase improves the utilization of P in growing and finishing pigs; however, the magnitude of effect on responses may vary over time.

中文翻译：

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添加植酸酶对低磷日粮喂养的生长和肥育猪磷利用的时间序列影响

进行了两个实验来确定植酸酶对生长和肥育猪磷 (P) 利用的时间序列影响，使用生长性能、营养物质的表观全消化道消化率 (ATTD)、磷排泄和矿物质的血浆浓度作为响应评价标准。在这两个实验中，处理被安排为随机完整区组设计中的 3 × 4 阶乘，包含 3 种基于玉米-大豆粉的饮食，包括 P 充足的阳性对照 (PC)、低 P 阴性对照（NC；无无机P), 和添加植酸酶的 NC，浓度为 1,000 FYT/kg (NC + 1,000)；以及实验 1 的第 7、14、21 和 28 天以及实验 2 的第 14、26、42 和 55 天的 4 个采样时间点。在这两个试验中，96 头生长猪平均体重 (BW) 为 19.8 ±分别为 1.16 和 49.8 ± 3.21 kg，被分配到具有 8 个重复栏（4 头公猪和 4 头后备母猪）和每栏 4 头猪的 3 种饮食。在实验 1 中，与饲喂 PC 的猪相比，饲喂 PC 的猪具有更高的 (P < 0.01) BW、平均日增重 (ADG)、平均日采食量 (ADFI) 和增重饲料比 (G:F)数控。时间和饮食对猪的 BW 和 ADG 之间存在交互作用 (P < 0.01)，而随着时间的推移，观察到 ADFI 和 G:F 分别呈线性和二次增长 (P < 0.01)。添加植酸酶改善了 (P < 0.01) 所有的生长性能反应。饲喂 PC 的猪比饲喂 NC 的猪具有更高的 (P < 0.01) P 和 Ca ATTD。对营养素的 ATTD 没有交互作用。与饲喂 NC 的猪相比，添加植酸酶可改善 P 和 Ca 的 ATTD。存在交互作用（P < 0. 01) 饮食和时间之间对总量和水溶性磷（WSP）的排泄。随着时间的推移，猪的血浆钙浓度呈​​二次方下降 (P < 0.01)。在实验 2 中，随着时间的推移，猪的 BW、ADG 和 G:F 呈二次方增长 (P < 0.01)。类似地，植酸酶的加入改善了除 ADFI 之外的所有生长性能参数 (P < 0.05)。DM、P 和 Ca 的 ATTD 随时间呈线性增加 (P < 0.05)。植酸酶的加入提高了 (P < 0.01) P 和 Ca 的 ATTD。添加植酸酶可提高 P 的血浆浓度。在生长期、育肥期和整个生长期，NC 的植酸酶补充剂分别使 WSP 排泄减少了 45%、32% 和 35%。总之，植酸酶提高了磷在生长和肥育猪中的利用率；然而，