玉米表達的植酸酶對保育豬生長性能、骨骼特征和磷消化率的影響
Jonathan N Broomhead，Philip A Lessard，R Michael Raab，Mike B Lanahan
翻譯：朱滔 校對：上海亙泰實業集團
本試驗研究了玉米表達的植酸酶（GraINzyme, Agrivida Inc., Woburn, MA）對保育仔豬飼喂低磷日糧下生長性能、骨骼特征和磷消化率的影響。
試驗為期41天，選用324頭斷奶仔豬（21±3d），飼喂同一種日糧適應7天（階段一），然后隨機分至54個圈。每個圈6頭仔豬（6.6±1.2kg），均為同一性別豬只，每個處理包括5個母豬圈和4個去勢公豬圈。試驗共6個處理：正對照（階段2、3、4有效磷分別為0.4%、0.32%0.32%）、負對照（分別為0.25%、0.17%、0.17%），以及負對照基礎上添加500、1000、2000、4000FTU植酸酶。豬在第1、14、28、41天稱重，并同時記錄采食量。通過在第28至35天日糧中添加三氧化二鉻作為標記物，第35天收集糞便，測定磷的全腸道表觀消化率。第41天，每圈屠宰4頭仔豬，收集掌骨，檢測斷裂強度和灰分。試驗數據通過SAS的RPOC GLM模型進行分析。通過最小二乘法進行分析，檢驗處理的一次線性和二次線性顯著性。
除飼料效率好和15-28天采食量外，正對照組仔豬其它指標明顯優于負對照組（P＜0.05）。試驗第0-41天，與負對照相比，日糧中添加500FTU植酸酶可以顯著提高日增重和采食量（P＜0.05），并與正對照組相似（P＞0.05）。植酸酶添加量超過500FTU后，仔豬對磷的全腸道表觀消化率顯著高于正對照組和負對照組，并且掌骨斷裂強度和骨灰分重量顯著高于負對照組。1000和2000FTU植酸酶組掌骨斷裂強度和灰分重量與正對照組無顯著差異（P＞0.05）。與植酸酶添加量低于1000FTU組和正對照組相比，4000FTU組仔豬第1-41天日增重、磷表觀全腸道消化率和骨灰分顯著提高（P < 0.05）。隨著植酸酶添加量的提高，仔豬日增重、采食量、磷全腸道表觀消化率、掌骨斷裂強度、骨灰分有線性提高（P＜0.05）。
總之，低磷日糧中添加≥500FTU/kg植酸酶可以改善增重、磷消化率、掌骨斷裂強度和骨灰分，且5000FTU組生長速度高于正對照組。
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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