Ravindran V, Kornegay E T, Denbow D M, Yi Z, Hulet R M
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Poult Sci. 1995 Nov;74(11):1843-54. doi: 10.3382/ps.0741843.
A 3-wk feeding trial using 920 day-old turkey poults was conducted to evaluate the addition of seven levels of phytase (Natuphos; 0, 200, 400, 600, 800, 1,000, and 1,200 U/kg of diet) to diets containing three levels of nonphytate P (nP) (.27, .36, and .45%). A positive control diet contained .60% nP. Semi-purified basal diets contained soybean meal as the only protein source. The increase in BW gain from added phytase was greatest for the lowest nP diet (nP by phytase interaction, P < .001). At .27% nP, gains improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. At .36 and .45% nP, increases in gains were observed only for 200 U of phytase/kg of diet. The highest phytase addition to.36 and .45% nP diets produced gains equal to those of the positive control diet. Feed intake increases paralleled those of BW gains. Gain:feed was lowest for the .27% nP diets without phytase, but improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. The high incidence of leg disorders and high mortality (40%) observed for the poults fed the .27% nP diet without added phytase declined with the addition of 200 to 400 U of phytase/kg of diet. Ash percentage of toes and tibias increased as the levels of nP (P < .001) and phytase (P < .01) increased; the magnitude of the response to phytase decreased as nP in the diet increased, resulting in an nP by phytase interaction (P < .001). Tibial shear force and stress responded in a similar manner to increasing levels of nP and added phytase. Results show that 652 U of microbial phytase is equivalent to 1 g of P from defluorinated phosphate in turkey starter diets using soybean meal as the only source of phytate P. The response per 100 U of phytase decreased as the total amount of phytase added was increased.
使用920只1日龄火鸡雏进行了一项为期3周的饲养试验，以评估在含有三种非植酸磷（nP）水平（0.27%、0.36%和0.45%）的日粮中添加七个水平的植酸酶（耐酶磷；0、200、400、600、800、1000和1200 U/kg日粮）的效果。阳性对照日粮含有0.60%的nP。半纯化基础日粮以豆粕作为唯一蛋白质来源。添加植酸酶后体重增加的幅度在最低nP日粮中最大（nP与植酸酶的交互作用，P < 0.001）。在nP为0.27%时，日粮中添加800 U/kg的植酸酶体重增加有所改善（P < 0.001），之后达到平台期。在nP为0.36%和0.45%时，仅在日粮中添加200 U/kg的植酸酶时体重增加有所增加。在nP为0.36%和0.45%的日粮中添加最高水平的植酸酶后体重增加与阳性对照日粮相当。采食量的增加与体重增加平行。在不含植酸酶的0.27% nP日粮中，料重比最低，但在日粮中添加800 U/kg的植酸酶后有所改善（P < 0.001），之后达到平台期。在不添加植酸酶的0.27% nP日粮中饲养的雏鸡出现腿部疾病的发生率高且死亡率高（40%），在日粮中添加200至400 U/kg的植酸酶后有所下降。随着nP水平（P < 0.001）和植酸酶水平（P < 0.01）的增加，脚趾和胫骨的灰分百分比增加；随着日粮中nP的增加，对植酸酶反应的幅度减小，导致nP与植酸酶的交互作用（P < 0.001）。胫骨剪切力和应力对nP水平和添加植酸酶水平增加的反应方式相似。结果表明，在以豆粕作为植酸磷唯一来源的火鸡育雏日粮中，652 U的微生物植酸酶相当于1 g脱氟磷酸盐中的磷。随着添加植酸酶总量的增加，每100 U植酸酶的反应下降。
