Shelton J L, Southern L L, Bidner T D, Persica M A, Braun J, Cousins B, McKnight F
Department of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803-4210, USA.
J Anim Sci. 2003 Aug;81(8):2053-62. doi: 10.2527/2003.8182053x.
Two experiments were conducted to determine the effect of phytase on energy availability in pigs. In Exp. 1, barrows (initial and final BW of 26 and 52 kg) were allotted to four treatments in a 2 x 2 factorial arrangement. Corn-soybean meal (C-SBM) diets were fed at two energy levels (2.9 and 3.2 x maintenance [M]) with and without the addition of 500 phytase units/kg of diet. The diets contained 115% of the requirement for Ca, available P (aP), and total lysine, and Ca and aP were decreased by 0.10% in diets with added phytase. Pigs were penned individually and fed daily at 0600 and 1700, and water was available constantly. Eight pigs were killed and ground to determine initial body composition. At the end of Exp. 1, all 48 pigs were killed for determination of carcass traits and protein and fat content by total-body electrical conductivity (TOBEC) analysis. Six pigs per treatment were ground for chemical composition. In Exp. 2, 64 barrows and gilts (initial and final BW of 23 and 47 kg) were allotted to two treatments (C-SBM with 10% defatted rice bran or that diet with reduced Ca and aP and 500 phytase units/kg of diet), with five replicate pens of barrows and three replicate pens of gilts (four pigs per pen). In Exp. 1, ADG was increased (P < 0.01) in pigs fed at 3.2 x M. Based on chemical analyses, fat deposition, kilograms of fat, retained energy (RE) in the carcass and in the carcass + viscera, fat deposition in the organs, and kilograms of protein in the carcass were increased (P < 0.10) in pigs fed the diets at 3.2 vs. 2.9 x M. Based on TOBEC analysis, fat deposition, percentage of fat increase, and RE were increased (P < 0.09) in pigs fed at 3.2 x M. Plasma urea N concentrations were increased in pigs fed at 3.2 x M with no added phytase but were not affected when phytase was added to the diet (phytase x energy, P < 0.06). Fasting plasma glucose measured on d 28, ultrasound longissimus muscle area (LMA), and 10th-rib fat depth were increased (P < 0.08) in pigs fed phytase, but many other response variables were numerically affected by phytase addition. In Exp. 2, phytase had no effect (P > 0.10) on ADG, ADFI, gain:feed, LMA, or 10th-rib fat depth. These results suggest that phytase had small, mostly nonsignificant effects on energy availability in diets for growing pigs; however, given that phytase increased most of the response variables measured, further research on its possible effects on energy availability seems warranted.
进行了两项试验以确定植酸酶对猪能量利用率的影响。在试验1中，将体重初始和终末分别为26和52千克的公猪按2×2析因设计分配到四种处理中。玉米-豆粕（C-SBM）日粮以两种能量水平（2.9和3.2倍维持需要量[M]）饲喂，添加或不添加500单位/千克日粮的植酸酶。日粮中钙、有效磷（aP）和总赖氨酸含量为需要量的115%，添加植酸酶的日粮中钙和aP含量降低0.10%。猪单独饲养，每天06:00和17:00饲喂，自由饮水。处死8头猪并进行研磨以测定初始体组成。在试验1结束时，处死所有48头猪，通过全身电阻抗（TOBEC）分析测定胴体性状以及蛋白质和脂肪含量。每个处理取6头猪进行研磨以测定化学成分。在试验2中，将64头体重初始和终末分别为23和47千克的公猪和小母猪分配到两种处理中（含10%脱脂米糠的C-SBM日粮或钙和aP含量降低且添加500单位/千克日粮植酸酶的该日粮），公猪设5个重复栏，小母猪设3个重复栏（每栏4头猪）。在试验1中，采食3.2倍M能量水平日粮的猪平均日增重（ADG）增加（P<0.01）。基于化学分析，采食3.2倍M日粮的猪与采食2.9倍M日粮的猪相比，胴体脂肪沉积、脂肪千克数、胴体及胴体+内脏的保留能量（RE）、器官脂肪沉积以及胴体蛋白质千克数增加（P<0.10）。基于TOBEC分析，采食3.2倍M日粮的猪脂肪沉积、脂肪增加百分比和RE增加（P<0.09）。采食3.2倍M且未添加植酸酶日粮的猪血浆尿素氮浓度升高，但日粮中添加植酸酶时不受影响（植酸酶×能量，P<0.06）。饲喂植酸酶的猪在第28天测定的空腹血糖、超声背最长肌面积（LMA）和第10肋处脂肪厚度增加（P<0.08），但许多其他反应变量在数值上受植酸酶添加的影响。在试验2中，植酸酶对ADG、平均日采食量（ADFI）、料重比、LMA或第10肋处脂肪厚度无影响（P>0.10）。这些结果表明，植酸酶对生长猪日粮能量利用率的影响较小，大多不显著；然而，鉴于植酸酶使大多数测定的反应变量增加，对其对能量利用率可能产生的影响进行进一步研究似乎是有必要的。
