An experiment was conducted to test two hypotheses: 1) reducing dietary Ca and P reduces gastric pH and diarrhea in weanling pigs; 2) negative effects of low Ca and P on pig growth performance may be overcome if phytase is added to the diets. A total of 320 weanling pigs (6.35 ± 0.87 kg) were allotted to eight corn-soybean meal-based diets in a randomized complete block design with five pigs per pen. Two phase 1 (days 1 to 14) control diets containing 100 or 50% of total Ca and digestible P relative to the requirement, and six diets in which 500, 2,000, or 16,000 units of phytase/kg feed (FTU) were added to each control diet were formulated. Phytase was assumed to release 0.16% total Ca and 0.11% digestible P. Common diets were fed in phases 2 (days 15 to 27) and 3 (days 28 to 42). Growth performance data were recorded within each phase. Data for fecal scores and gastrointestinal pH were recorded for phase 1. Colon content (day 14), the right femur (days 14 and 42), and blood samples (days −1, 14, 27, and 42) were collected from one pig per pen. In phase 1, reducing Ca and P did not reduce gastric pH or fecal score, but pigs fed the 50% diets had reduced (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) compared with pigs fed the 100% diets. In both 50% and 100% diets, phytase above 500 FTU increased (P < 0.05) gain:feed ratio (G:F) and tended (P < 0.10) to reduce gastric pH of pigs. From days 1 to 42, pigs fed the 50% diets tended (P < 0.10) to have reduced ADG and ADFI compared with pigs fed the 100% diets, but among the 100% diets, pigs tended (P < 0.10) to have a linear increase in G:F as phytase level increased. Pigs fed the 50% diets had reduced (P < 0.05) concentrations of inositol phosphate esters (IP) in the colon and reduced bone ash (days 14 and 42) compared with pigs fed the 100% diets. Phytase did not affect bone ash or most blood metabolites. Concentrations of IP in the colon decreased, whereas plasma inositol increased (d 14; P < 0.05) in pigs fed diets with phytase (≥ 500 FTU). In pigs fed the 100% diets, IP in the colon linearly decreased (P < 0.05), but plasma inositol linearly increased (P < 0.05) with increasing levels of phytase. In conclusion, reducing Ca and P in diets for weanling pigs did not influence gastric pH or fecal score, but compromised growth performance and bone ash. However, regardless of dietary Ca and P, high doses of phytase increased phytate degradation and inositol absorption, which consequently increased G:F of pigs.

中文翻译：

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增加的微生物植酸酶增加了断奶猪的植酸盐破坏、血浆肌醇和饲料效率，但日粮钙和磷的降低不影响胃酸碱度或粪便评分，并降低生长性能和骨灰分

进行了一项实验来检验两个假设：1) 减少日粮 Ca 和 P 会降低断奶猪的胃 pH 值和腹泻；2) 如果在日粮中添加植酸酶，可以克服低钙和磷对猪生长性能的负面影响。总共 320 头断奶猪 (6.35 ± 0.87 kg) 被分配到 8 种基于玉米-豆粕的日粮中，采用随机完整区组设计，每栏 5 头猪。两个阶段 1（第 1 至第 14 天）对照日粮含有 100% 或 50% 的总钙和可消化磷（相对于需求），以及 6 种日粮中添加了 500、2,000 或 16,000 单位植酸酶/kg 饲料 (FTU)配制每种对照饮食。假设植酸酶释放 0.16% 的总钙和 0.11% 的可消化磷。普通日粮在第 2 阶段（第 15 至 27 天）和第 3 阶段（第 28 至 42 天）饲喂。在每个阶段内记录生长性能数据。记录第一阶段的粪便评分和胃肠道 pH 值数据。从一头猪收集结肠内容物（第 14 天）、右股骨（第 14 天和第 42 天）和血液样本（第 -1、14、27 和 42 天）每笔。在第 1 阶段，降低 Ca 和 P 并不会降低胃 pH 值或粪便评分，但与饲喂的猪相比，饲喂 50% 日粮的猪的平均日增重 (ADG) 和平均日采食量 (ADFI) 降低了 (P < 0.05) 100% 的饮食。在 50% 和 100% 的日粮中，高于 500 FTU 的植酸酶增加（P < 0.05）增重：饲料比（G：F）并趋于（P < 0.10）降低猪的胃 pH 值。从第 1 天到第 42 天，与饲喂 100% 日粮的猪相比，饲喂 50% 日粮的猪倾向于（P < 0.10）降低 ADG 和 ADFI，但在 100% 日粮中，猪倾向于（P < 0.10）随着植酸酶水平的增加，G:F 呈线性增加。与饲喂 100% 日粮的猪相比，饲喂 50% 日粮的猪的结肠中肌醇磷酸酯 (IP) 浓度降低（P < 0.05），骨灰减少（第 14 天和第 42 天）。植酸酶不影响骨灰或大多数血液代谢物。在饲喂植酸酶（≥ 500 FTU）日粮的猪中，结肠中 IP 浓度降低，而血浆肌醇增加（d 14；P < 0.05）。在饲喂 100% 日粮的猪中，随着植酸酶水平的增加，结肠中的 IP 线性下降（P < 0.05），但血浆肌醇线性增加（P < 0.05）。总之，减少断奶仔猪日粮中的钙和磷不会影响胃液 pH 值或粪便评分，但会影响生长性能和骨灰分。然而，无论膳食钙和磷如何，高剂量的植酸酶都会增加植酸降解和肌醇吸收，