植酸酶对斑点叉尾鲴生长性能及磷当量的研究

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。

STUDY ON GROWTH PERFORMANCE AND PHOSPHORUS EQUIVALENT OF PHYTASE IN CHANNEL CATFISH (ICTALURUS PUNCTATUS)

The trial was conducted to study the effects of phytase on growth performance and determine the phosphorus equivalent of phytase in channel catfish(initial average weight about 1.70 g).Single factor design was used for the trial,Ca(H2PO4)2 was provided in four inorganic phosphorus diets(0.3%,0.5%,0.8% and 1.2%),and different levels of phytase were sprayed on basal diet(300,500,1000,1500 and 2000 U/kg).To determine the optimum additive amount of phytase by line model,fish of homogeneous sizes were randomly allotted to 10 dietary treatments with triplicates of 30 fish in each tank.The linear relationships were established between supplemented P and response parameters(specific growth rate and vertebra bone phosphorus) to evaluate phytase phosphorus equivalent.The results showed that:(1) Compared with the basal group,growth rate,specific growth rate,protein efficiency ratio and condition fatness were increased significantly(P<0.05);feed coefficient,hepatopancreas somatic indices and viscera somatic indices were decreased significantly(P<0.05);major nutrients(crude protein,ash,phosphorus and cacium) of body and vertebra were increased significantly(P<0.05),but crude fat decreased.(2) The gradual supplemental P and response index fitted well with linear model: Y1=135.94X+7.8316(X-inorganic p,Y1 SGR,R2=0.9453),the phosphorus equivalency Ca(H2PO4)2] of 300,500,1000,1500 and 2000 U/kg diet phytase was 0.13%,0.57%,0.76%,1.46% and 1.35% respectively,and equal to 0.03%,0.14%,0.19%,0.36% and 0.33% available phosphorus added to basal diet;Y2=0.8737X+5.1028(X-inorganic p,Y2-vertebra phosphorus,R2=0.9638),the phosphorus equivalency Ca(H2PO4)2] of 300,500,1000,1500 and 2000 U/kg diet phytase was 0.47%,1.11%,1.18%,1.38% and 1.41% respectively,and equal to 0.12%,0.27%,0.29%,0.34% and 0.35% available phosphorus added to basal diet.In conclusion,1000 U/kg–2000 U/kg phytase supplemented in diet significantly improved growth performance,conduced to the deposition of nutriment in body and bone mineralization.The phosphorus equivalency of 1435 U/kg diet phytase was the optimum and equal to 0.37% available phosphorus added to basal diet if mean specific growth rate was as reference index,then the phosphorus equivalency of 1226 U/kg diet phytase was the optimum and equal to 0.33% available phosphorus added to basal diet if mean specific growth rate was as reference index.