玉米表达的植酸酶对保育猪生长性能、骨骼特征和磷消化率的影响
Jonathan N Broomhead，Philip A Lessard，R Michael Raab，Mike B Lanahan
翻译：朱滔 校对：上海亘泰实业集团
本试验研究了玉米表达的植酸酶（GraINzyme, Agrivida Inc., Woburn, MA）对保育仔猪饲喂低磷日粮下生长性能、骨骼特征和磷消化率的影响。
试验为期41天，选用324头断奶仔猪（21±3d），饲喂同一种日粮适应7天（阶段一），然后随机分至54个圈。每个圈6头仔猪（6.6±1.2kg），均为同一性别猪只，每个处理包括5个母猪圈和4个去势公猪圈。试验共6个处理：正对照（阶段2、3、4有效磷分别为0.4%、0.32%0.32%）、负对照（分别为0.25%、0.17%、0.17%），以及负对照基础上添加500、1000、2000、4000FTU植酸酶。猪在第1、14、28、41天称重，并同时记录采食量。通过在第28至35天日粮中添加三氧化二铬作为标记物，第35天收集粪便，测定磷的全肠道表观消化率。第41天，每圈屠宰4头仔猪，收集掌骨，检测断裂强度和灰分。试验数据通过SAS的RPOC GLM模型进行分析。通过最小二乘法进行分析，检验处理的一次线性和二次线性显著性。
除饲料效率好和15-28天采食量外，正对照组仔猪其它指标明显优于负对照组（P＜0.05）。试验第0-41天，与负对照相比，日粮中添加500FTU植酸酶可以显著提高日增重和采食量（P＜0.05），并与正对照组相似（P＞0.05）。植酸酶添加量超过500FTU后，仔猪对磷的全肠道表观消化率显著高于正对照组和负对照组，并且掌骨断裂强度和骨灰分重量显著高于负对照组。1000和2000FTU植酸酶组掌骨断裂强度和灰分重量与正对照组无显著差异（P＞0.05）。与植酸酶添加量低于1000FTU组和正对照组相比，4000FTU组仔猪第1-41天日增重、磷表观全肠道消化率和骨灰分显著提高（P < 0.05）。随着植酸酶添加量的提高，仔猪日增重、采食量、磷全肠道表观消化率、掌骨断裂强度、骨灰分有线性提高（P＜0.05）。
总之，低磷日粮中添加≥500FTU/kg植酸酶可以改善增重、磷消化率、掌骨断裂强度和骨灰分，且5000FTU组生长速度高于正对照组。
Effects of feeding corn-expressed phytase on the live performance, bone characteristics, and phosphorus digestibility of nursery pigs
Jonathan N Broomhead Philip A Lessard R Michael Raab Mike B Lanaha
A 41-d feeding trial was conducted to determine the efficacy of a corn-expressed phytase (GZ; GraINzyme, Agrivida Inc., Woburn, MA) on the live performance, bone characteristics, and P digestibility of nursery pigs fed a reduced P diet. Weaned piglets (21 ± 3 d; n = 324) were acclimated on a common diet for 7 d (phase 1) before randomization into 54 single-sex pens (5 gilt and 4 barrow pens per treatment) containing 6 pigs (6.6 ± 1.2 kg) per pen. Six treatments were fed: positive control (PC; 0.4% or 0.32% aP for phase 2 or 3 and 4, respectively), negative control (NC; 0.15% reduction in aP), and 500, 1,000, 2,000, or 4,000 FTU per kg phytase from GZ added to NC in a 3-phase feeding program. Pigs were weighed on day 1, 14, 28, and 41, and feed disappearance recorded per phase. Apparent total tract digestibility (ATTD) of P was determined by feeding chromic oxide marker (day 28 to 35) and collecting fecal samples on day 35. On day 41, 4 pigs per pen were euthanized and metacarpal bones were collected to evaluate bone breaking strength (BBS) and ash. Data were analyzed using PROC GLM of SAS (block, sex, and treatment). Treatment least squares means were separated and linear and quadratic treatment effects evaluated. Other than feed efficiency (G:F) and day 15 to 28 ADFI, the pigs fed PC were superior (P < 0.05) to NC-fed pigs in all other variables. Pigs fed ≥500 FTU per kg phytase had increased (P < 0.05) ADG and ADFI compared to NC pigs and equivalent (P > 0.05) ADG and ADFI as PC pigs from day 0 to 41. Feeding ≥500 FTU per kg phytase resulted in higher (P < 0.05) ATTD of P than both NC and PC pigs and higher (P < 0.05) BBS and bone ash weight than NC. Pigs fed 1,000 or 2,000 FTU per kg phytase had equivalent (P > 0.05) BBS and bone ash weight compared to pigs fed PC diets. Feeding 4,000 FTU per kg phytase resulted in higher (P < 0.05) day 1 to 41 ADG, ATTD of P, and bone ash weight compared to feeding ≤1,000 FTU per kg phytase or PC diets. There were linear (P < 0.05) increases in ADG, ADFI, ATTD of P, BBS, and bone ash characteristics as GZ inclusion increased. In conclusion, ≥500 FTU per kg phytase from GZ improved growth, ATTD of P, BBS, and bone ash when added to a reduced P diet and 4,000 FTU per kg phytase increased growth greater than the PC treatment.
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