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试验旨在研究饲料中添加植酸酶对斑点叉尾[初始平均体重(1.70±0.04)g]生长性能及植酸磷利用的影响,确定植酸酶的磷当量。试验采用单因素试验设计,以Ca(H2PO4)2提供外源无机磷,同时添加不同浓度植酸酶,试验设计为10个处理组,分别为1个对照试验组、4个无机磷试验组(0.3%、0.5%、0.8%、1.2%)和5个植酸酶试验组(300、500、1000、1500、2000 U/kg),每个处理3个重复,每个重复30尾鱼。通过折线模型确定植酸酶的最佳添加量;通过回归分析,建立响应指标(特定生长率、椎骨磷)与外源磷添加量之间的线性关系,进而确定植酸酶的磷当量值。结果表明:(1)添加植酸酶的处理组与对照组相比,增重率、特定生长率、蛋白质效率、肥满度均有显著提高(P<0.05),饲料系数、肝体比、脏体比均有下降(P<0.05),成活率各处理组没有显著差别(P>0.05);鱼体粗蛋白、粗灰分、钙、磷及椎骨粗灰分、钙、磷均有显著提高(P<0.05),鱼体粗脂肪含量有所下降。(2)无机磷添加水平与响应指标之间线性关系如下:Y1=0.2714X+2.294(X-无机磷,Y1-特定生长率,R2=0.9238),300、500、1000、1500和2000 U/kg植酸酶分别可替代1 kg饲料中0.13%、0.57%、0.76%、1.46%和1.35%的磷酸二氢钙,等效于添加了0.03%、0.14%、0.19%、0.36%和0.33%的有效磷;Y2=0.8737X+5.1028(X-无机磷,Y2-椎骨磷,R2=0.9638),300、500、1000、1500和2000 U/kg植酸酶分别可替代1 kg饲料中0.47%、1.11%、1.18%、1.38%和1.41%的磷酸二氢钙,等效于添加了0.12%、0.27%、0.29%、0.34%和0.35%的有效磷。在试验条件下,添加1000―2000 U/kg植酸酶能有效改善斑点叉尾生长性能,有利于营养物质在鱼体中的沉积,促进骨骼矿化。以特定生长率为响应指标,植酸酶最佳添加量为1435 U/kg等效于添加了0.37%的有效磷;以椎骨磷为响应指标,植酸酶最佳添加量为1226 U/kg等效于添加了0.33%的有效磷。
The aim of this experiment was to investigate the effect of dietary phytase supplementation on the growth performance and the use of phytate by [initial mean body weight (1.70 ± 0.04) g] of Ictalurus punctatus and determine the phytase P equivalent. The experiments were designed by single factor experiment, exogenous inorganic phosphorus was provided by Ca (H2PO4) 2, and different concentrations of phytase were added at the same time. The experiment was designed as 10 treatment groups, one control group, four inorganic phosphorus test groups 0.3, 0.5, 0.8, 1.2%) and 5 phytase test groups (300, 500, 1000, 1500, 2000 U / kg) with 3 replicates per treatment, Through the regression analysis, the linear relationship between response index (specific growth rate, vertebral phosphorus) and the amount of exogenous phosphorus was established to determine the phytase’s phosphorus equivalent . The results showed that: (1) Compared with control group, phytase-treated group had significantly increased weight gain rate, specific growth rate, protein efficiency and fatness ratio (P <0.05) (P <0.05). There was no significant difference in the survival rate among all treatment groups (P> 0.05). The crude protein, crude ash, calcium, phosphorus and vertebral crude ash, calcium and phosphorus were significantly increased P <0.05), the crude fat content of fish decreased. (2) The linear relationship between the inorganic phosphorus addition level and the response index is as follows: Y1 = 0.2714X + 2.294 (X-inorganic phosphorous, Y1- specific growth rate, R2 = 0.9238), 300,500,1000,1500 and 2000 U / kg phytase could replace 0.13%, 0.57%, 0.76%, 1.46% and 1.35% of monocalcium phosphate in 1 kg of feed respectively, equivalent to adding 0.03%, 0.14%, 0.19%, 0.36% and 0.33% Of available phosphorus; Y2 = 0.8737X + 5.1028 (X-inorganic phosphorus, Y2-vertebral phosphorus, R2 = 0.9638), and phytase of 300, 500, 1000, 1500 and 2000 U / , 1.11%, 1.18%, 1.38% and 1.41% of monocalcium phosphate, which is equivalent to adding 0.12%, 0.27%, 0.29%, 0.34% and 0.35% of available phosphorus. Under the experimental conditions, adding 1000-2000 U / kg phytase can effectively improve the growth performance of channel catfish, is conducive to the deposition of nutrients in the fish to promote bone mineralization. With the specific growth rate as the response index, phytase optimum dosage of 1435 U / kg is equivalent to adding 0.37% available phosphorus; vertebral phosphorus as the response index, phytase optimum dosage of 1226 U / kg Equivalent to the addition of 0.33% available phosphorus.