Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
J Anim Sci. 2022 Jan 1;100(1). doi: 10.1093/jas/skab350.
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.
进行了两项实验，以确定植酸酶对生长和育肥猪磷（P）利用的时间序列效应，使用生长性能、养分全肠道表观消化率（ATTD）、P 排泄和矿物质的血浆浓度作为评估的反应标准。在两项实验中，处理均采用 3×4 析因设计，在随机完全区组设计中进行，包括 3 种基于玉米-豆粕的日粮，分别为磷充足的正对照（PC）、低磷负对照（NC；无无机磷）和 NC 补充植酸酶 1000 FYT/kg（NC+1000）；以及 4 个采样时间点，分别在第 7、14、21 和 28 天进行实验 1，在第 14、26、42 和 55 天进行实验 2。在两项试验中，分别将平均体重（BW）为 19.8±1.16 和 49.8±3.21kg 的 96 头生长猪分配到 3 种日粮中，每组 8 个重复栏（4 头公猪和 4 头母猪），每个栏 4 头猪。在实验 1 中，与 NC 组相比，饲喂 PC 的猪具有更高的 BW、平均日增重（ADG）、平均日采食量（ADFI）和增重-采食量比（G:F）（P<0.01）。猪的 BW 和 ADG 存在时间和日粮的互作效应（P<0.01），而 ADFI 和 G:F 随时间呈线性和二次增加（P<0.01）。植酸酶补充提高了所有生长性能指标。饲喂 PC 的猪的 P 和 Ca 的 ATTD 高于饲喂 NC 的猪。养分 ATTD 不存在互作效应。与饲喂 NC 的猪相比，添加植酸酶提高了 P 和 Ca 的 ATTD。日粮和时间对总磷（TP）和水溶性磷（WSP）排泄量存在互作效应（P<0.01）。随着时间的推移，猪血浆 Ca 浓度呈二次下降（P<0.01）。在实验 2 中，猪的 BW、ADG 和 G:F 随时间呈二次增加（P<0.01）。同样，植酸酶的添加提高了除 ADFI 以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）。添加植酸酶提高了 P 和 Ca 的 ATTD。添加植酸酶提高了血浆 P 浓度。与 NC 相比，植酸酶补充剂使 WSP 排泄量在生长、育肥和整个生长-育肥期间分别减少了 45%、32%和 35%。总之，植酸酶提高了生长育肥猪对 P 的利用率；然而，其对反应的影响程度可能随时间而变化。
