Williams S B, Southern L L, Bidner T D
Department of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
J Anim Sci. 2005 Feb;83(2):386-92. doi: 10.2527/2005.832386x.
Three experiments were conducted to determine the effects of phytase, excess Zn, or their combination in diets for nursery pigs. In all experiments, treatments were replicated with five to seven pens of six to seven pigs per pen, dietary Ca and available P (aP) levels were decreased by 0.1% when phytase was added to the diets, excess Zn was added as ZnO, a basal level of 127 mg/kg of Zn (Zn sulfate) was present in all diets, and the experimental periods were 19 to 21 d. In Exp. 1, pigs (5.7 kg and 18 d of age) were fed two levels of phytase (0 or 500 phytase units/kg) and three levels of excess Zn (0, 1,000, or 2,000 ppm) in a 2 x 3 factorial arrangement. Added Zn linearly increased ADG and ADFI during Phase 1 (P = 0.01 to 0.06), Phase 2 (P = 0.02 to 0.09), and overall (P = 0.01 to 0.02). Gain:feed was linearly increased by Zn during Phase 1 (P = 0.01) but not at other times. Dietary phytase decreased ADG in pigs fed 1,000 or 2,000 ppm Zn during Phase 2 (Zn linear x phytase interaction; P = 0.10), did not affect (P = 0.27 to 0.62) ADFI during any period, and decreased G:F during Phase 2 (P = 0.01) and for the overall (P = 0.07) period. Plasma Zn was increased by supplemental Zn (Zn quadratic, P = 0.01) but not affected (P = 0.70) by phytase addition. In Exp. 2, pigs (5.2 kg and 18 d of age) were fed two levels of phytase (0 or 500 phytase units/kg) and two levels of Zn (0 or 2,000 ppm) in a 2 x 2 factorial arrangement. Supplemental Zn increased ADG and G:F during Phase 2 (P = 0.02 to 0.09) and overall (P = 0.07 to 0.08), but it had no effect (P = 0.11 to 0.89) on ADG during Phase 1 or ADFI during any period. Phytase supplementation increased ADG (P = 0.06) and G:F (P = 0.01) during Phase 2. Gain:feed was greatest for pigs fed 2,000 ppm Zn and phytase (Zn x phytase interaction; P = 0.01). Bone (d 20) and plasma Zn (d 7 and 20) were increased (P = 0.01) by added Zn but not affected (P = 0.51 to 0.90) by phytase. In Exp. 3, pigs (5.7 kg and 19 d of age) were fed a basal diet or the basal diet with Ca and aP levels decreased by 0.10% and these two diets with or without 500 phytase units/kg. Supplemental phytase had no effect (P = 0.21 to 0.81) on growth performance. Reduction of dietary Ca and aP decreased (P = 0.02 to 0.08) ADG, ADFI, and G:F for the overall data. These results indicate that excess dietary supplemental Zn increases ADG and plasma and bone Zn concentrations. Dietary phytase did not affect plasma or bone Zn concentrations.
进行了三项试验以确定植酸酶、过量锌或它们的组合对保育猪日粮的影响。在所有试验中，处理方式以每栏6至7头猪、5至7个重复栏进行，当在日粮中添加植酸酶时，日粮中的钙和有效磷（aP）水平降低0.1%，过量锌以氧化锌形式添加，所有日粮中锌（硫酸锌）的基础水平为127mg/kg，试验期为19至21天。在试验1中，仔猪（5.7kg，18日龄）采用2×3析因设计，饲喂两种水平的植酸酶（0或500植酸酶单位/kg）和三种水平的过量锌（0、1000或2000ppm）。添加锌在第1阶段（P = 0.01至0.06）、第2阶段（P = 0.02至0.09）以及整个试验期（P = 0.01至0.02）使平均日增重（ADG）和平均日采食量（ADFI）呈线性增加。在第1阶段，锌使料重比呈线性增加（P = 0.01），但在其他时期无此作用。日粮植酸酶在第2阶段使饲喂1000或2000ppm锌的仔猪的ADG降低（锌线性×植酸酶互作；P = 0.10），在任何时期均不影响（P = 0.27至0.62）ADFI，在第2阶段和整个试验期使料重比降低（P = 0.01和P = 0.07）。补充锌使血浆锌增加（锌二次效应，P = 0.01），但添加植酸酶对其无影响（P = 0.70）。在试验2中，仔猪（5.2kg，18日龄）采用2×2析因设计，饲喂两种水平的植酸酶（0或500植酸酶单位/kg）和两种水平的锌（0或2000ppm）。补充锌在第2阶段和整个试验期增加了ADG和料重比（P = 0.02至0.09和P = 0.07至0.08），但在第1阶段对ADG和在任何时期对ADFI均无影响（P = 0.11至0.89）。补充植酸酶在第2阶段增加了ADG（P = 0.06）和料重比（P = 0.01）。饲喂2000ppm锌和植酸酶的仔猪料重比最高（锌×植酸酶互作；P = 0.01）。添加锌使骨骼（第20天）和血浆锌（第7天和第20天）增加（P = 0.01），但植酸酶对其无影响（P = 0.51至0.90）。在试验3中，仔猪（5.7kg，19日龄）饲喂基础日粮或钙和aP水平降低0.10%的基础日粮，这两种日粮添加或不添加500植酸酶单位/kg。补充植酸酶对生长性能无影响（P = 0.21至0.81）。日粮钙和aP水平降低使整个试验期的ADG、ADFI和料重比降低（P = 0.02至0.08）。这些结果表明，日粮中过量补充锌可增加ADG以及血浆和骨骼中的锌浓度。日粮植酸酶不影响血浆或骨骼中的锌浓度。
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