不同添加方式植酸酶处理豆粕对牙鲆生长和饲料利用率的影响

以初始平均体重(2.02±0.02)g的牙鲆(Paralichthys olivaceus)为实验对象,进行为期70d的摄食生长实验,研究不同添加方式的植酸酶对牙鲆生长和饲料利用的影响。在5000.0g豆粕中添加2.5g植酸酶,然后用产朊假丝酵母(Candidautilis)进行发酵预处理,得到植酸酶预处理豆粕。共制作4种等氮等能(粗蛋白49.7%、总能20.9kJ/g)饲料,对照饲料主要以鱼粉为蛋白源;在对照饲料的基础上,用豆粕蛋白替代45%的鱼粉蛋白配制成豆粕组饲料;在每千克豆粕组饲料中添加1000IU植酸酶,配制成植酸酶组饲料;用植酸酶预处理豆粕蛋白替代45%的鱼粉蛋白配制成植酸酶预处理豆粕组饲料。结果表明,与对照组相比较,用豆粕蛋白替代饲料中45%的鱼粉蛋白,若不添加植酸酶则显著降低牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05);直接添加植酸酶组、植酸酶预处理豆粕组牙鲆的特定生长率、饲料效率、蛋白质效率和氮贮积率与鱼粉对照组相比较没有出现显著差异(P0.05);与不添加植酸酶的豆粕组相比较,在含豆粕饲料中添加1000IU/kg饲料的植酸酶显著提高牙鲆的特定生长率(P0.01)、氮贮积率(P0.05)和磷贮积率(P0.01),显著降低氮排放率(P0.05)和磷排放率(P0.01),但饲料效率和蛋白质效率没有显著变化(P0.05);在豆粕中添加植酸酶进行发酵预处理,降低了豆粕中植酸含量,在饲料中添加植酸酶预处理豆粕显著提高牙鲆的特定生长率(P0.01)、饲料效率、蛋白质效率和氮贮积率(P0.05),显著降低氮(P0.05)、磷和钙的排放率(P0.01)。  

EFFECTS OF DIFFERENT SUPPLEMENTAL METHODS OF PHYTASE TO SOYBEAN MAIL ON GROWTH AND FEED UTILIZATION OF JAPANESE FLOUNDER (PARALICHTHYS OLIVACEUS)

A study was conducted to evaluate the effects of different supplemental methods of phytase on growth and feed utilization of Japanese flounder (Paralichthys olivaceus). The phytase-pretreated soybean meal (PP-SBM) was obtained by fermentation with Candida utilis. Four isonitrogenous (49.7% crude protein) and isocaloric (20.9 kJ/g) diets were formulated. The control diet contained 68.0% fish meal (FM) as the main protein source. In soybean meal (SBM) diets with 0 and 1000 IU/kg phytase, 45% of FM protein was replaced by SBM protein. The PP-SBM diet was formu-lated in which phytase-pretreated soybean meal protein replaced 45% of FM protein. Each diet was randomly fed to triplicate groups of Japanese flounder with initial weight (2.02 ± 0.02) g/fish. Fish were fed to apparent satiation twice daily (08:00 and 16:00). During the experiment, water temperature fluctuated from 22.5 to 25.5℃, salinity from 29.5 to 32.0 and dissolved oxygen was not less than 7.0 mg/L. At the end of the 10-week feeding trial, survival and feed intake showed no significant difference among dietary treatments (P>0.05). The specific growth rate (SGR), feed efficiency ratio (FER), protein efficiency ratio (PER), nitrogen retention (P<0.05), phosphorus load and calcium load (P<0.01) of fish fed the SBM diet without phytase were significantly lower than those in control (P>0.05). The SGR, FER, PER and nitrogen retention showed no significant difference among fish fed the SBM diet supplemented phytase, PP-SBM diet and control diet (P>0.05). Comparing with the SBM diet without phytase, the fish fed the SBM diet supplemented phy-tase showed significantly higher SGR (P<0.01), nitrogen retention (P<0.05) and phosphorus retention (P<0.01), and significantly lower nitrogen load (P<0.05) and phosphorus load (P<0.01). The FER and PER showed no significant difference between the treatments of SBM diets with and without phytase (P>0.05). The content of phytate in phy-tase-pretreated SBM was lower than that in SBM. The fish fed the diet contained phytase-pretreated SBM exhibited significantly higher SGR (P<0.01), FER, PER and nitrogen retention (P<0.05), and significantly lower nitrogen load (P<0.05), phosphorus load and calcium load (P<0.01) than the fish fed the SBM diet without phytase. The whole-body moisture and energy were not affected significantly by different supplemental methods of phytase (P>0.05). The whole-body crude protein (P<0.05) and crude lipid (P<0.01) in group of the SBM diet without phytase were signifi- cantly lower than those in control. The whole-body crude protein and crude lipid showed no significant difference among fish fed the SBM diet with phytase, PP-SBM diet and control diet (P>0.05). The ash in fish fed the SBM diet without phytase, SBM diet supplemented phytase and PP-SBM diet was significantly higher than that in fish fed FM diet (P<0.05). The results indicate that supplementation of phytase to the SBM diet can improve growth response and utili-zation of nitrogen and phosphorus, and the pretreatment of soybean meal with 1000 IU/kg diet phytase can improve the growth responses and feed utilization of Japanese flounder (Paralichthys olivaceus).