Denbow D M, Grabau E A, Lacy G H, Kornegay E T, Russell D R, Umbeck P F
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Poult Sci. 1998 Jun;77(6):878-81. doi: 10.1093/ps/77.6.878.
Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.
选用雄性肉鸡（n = 416）来比较在日粮中添加市售植酸酶补充剂或转基因大豆中表达的重组蛋白形式的植酸酶的效果。在7至21日龄期间，肉鸡饲喂含0.20%非植酸磷（nP）的基础日粮，并分别额外添加真菌植酸酶（商品名为Natuphos）或表达重组植酸酶的转基因大豆，添加量分别为400、800或1200 U/kg。作为对照，肉鸡还分别饲喂添加了0.08%、0.16%或0.24% nP的基础日粮。基础日粮作为阴性对照。日粮制成粉料，自由采食。在18至20日龄期间收集每栏鸡的所有排泄物，并在21日龄时宰杀鸡只。在基础日粮中添加nP可使体重增加、饲料效率、采食量、趾骨灰重量和百分比、胫骨剪切力和能量呈线性增加。随着nP水平的增加，磷消化率呈线性下降，但磷排泄量增加。日粮中添加植酸酶可使生长速度、采食量、趾骨灰重量和百分比、胫骨剪切力和能量呈线性增加，磷消化率提高，而磷排泄量减少。除磷消化率外，两种植酸酶来源在生长性能、骨骼矿化和磷排泄方面的反应效果没有差异。从本研究看来，当以市售补充剂形式或转基因种子形式提供植酸酶时，可提高饲喂低nP日粮肉鸡的生长性能。
