| In this study, aiming at judging the feasibility of phytase and non-starch polysaccharidesupplementation in turbot(Scophthalmus maximus) feed, a series of experiments wereconducted to investigate the influence of the exogenous enzymes on growth performance,digestibility, digestive enzyme activities, energy budget, budget and excretion of nitrogen andphosphorus, which would provide theoretical bases for the development of high efficiency andenvironment-friendly feed production of turbot(Scophthalmus maximus).1. Effects of phytase on growth and digestive enzymes activities in juvenile turbot(Scophthalmus maximus)The experiment selected juvenile turbot which the initial average body weight was(20.53±0.10)g. The fish were fed the basal diet supplemented with0U/kg,500U/kg,1000U/kgand2000U/kg phytase(D1-D4). Results showed that:(1) Compared with the control group,phytase supplementation significantly improved specific growth rate, and D3was the highest,which increased13.04%(P＜0.05). But feed intake, feed coefficient, protein efficiency ratioand survival rate were not affected significantly (P＞0.05).(2) Compared with the controlgroup, phytase was not affected significantly apparent digestibility of feed dry matter (P＞0.05),but improved apparent digestibility of crude protein, phosphorus and energy of juvenile turbot.And dietary D3of the crude protein and energy increased respectively3.94%and2.96%(P＜0.05). D4of the protein and phosphorus improved respectively2.69%and15.07%(P＜0.05).(3) Phytase was not affected significantly in moisture, crude fat, ash and energy of juvenileturbot (P＞0.05). But crude protein of D3and D4was increased3.29%and3.84%respectively(P＜0.05).(4) Dietary D3and D4increased significantly protease activities of stomach andintestine (P＜0.05), but phytase was not affected the amylase and lipase activities of thestomach and intestine significantly (P＞0.05).(5) In summary, the appropriate level of dietaryphytase was between1000-2000U/kg.2. Effects of phytase on budgets of energy, nitrogen and phosphorus, excretion rate ofnitrogen and phosphorus in juvenile turbot(Scophthalmus maximus)The experiment selected juvenile turbot. The fish were fed the basal diet supplementedwith0U/kg,500U/kg,1000U/kg and2000U/kg phytase (D1-D4). Results showed that:(1)Metabolism energy of fish had the tendency to rise which fed the dietary phytase, with theenergy proportion of growth, defecation and urine had the downward trend (P＞0.05).(2)Compared with D1, growth of nitrogen had increased, and nitrogen excretion and defecationproportion had decreased of fish with fed dietary phytase.(3) Dietary phytase was not affectedthe growth and excretion proportion of phosphorus significantly (P＞0.05), but the defecationhad decreased significantly (P＜0.05).(4) The addition of phytase increased retention ofphosphorus and nitrogen, but the load had the downward trend.(5) When the fish in hungry condition, excretion rate of nitrogen and phosphorus had not affected significantly with phytase(P＞0.05). However, in the full condition, release rate of nitrogen and phosphorus haddecreased, and the D4was the lowest, which decreased31.81%and55.88%respectively (P <0.05).3. Effects of exogenous enzymes on growth, digestibility and digestive enzymes activities injuvenile turbot(Scophthalmus maximus)The experiment selected juvenile turbot which the initial average body weight was (20.53±0.10)g. The fish in control group was fed a basal diet (S1), and the fish in experimentalgroups were fed the basal diet supplemented with200mg/kg phytase,100mg/kg non-starchpolysaccharide and the mixture of the two enzymes (S2-S4). Results showed that:(1)Exogenous enzymes supplementation significantly improved specific growth rate(P＜0.05),and S4was the highest, which increased16.30%. But feed intake, feed coefficient, proteinefficiency ratio and survival rate were not affected significantly (P＞0.05).(2) Dietaryexogenous enzymes improved apparent digestibility of feed dry matter, crude protein,phosphorus and energy of turbot. And dietary S3and S4increased significantly (P＜0.05).(3)Dietary exogenous enzymes were not affected significantly in moisture, crude fat, ash andenergy of juvenile turbot (P＞0.05). But crude protein was increased.(4) Dietary S2and S4increased significantly protease activities of stomach and intestine (P＜0.05), and the S4wasthe highest. But dietary exogenous enzymes was not affected significantly the amylase andlipase activities of the stomach and intestine (P＞0.05).(5) Analysis showed that the manykinds of exogenous enzymes could improve the growth of juvenile turbot.4. Effects of exogenous enzymes on budgets of energy, nitrogen and phosphorus, excretion rateof nitrogen and phosphorus in juvenile turbot(Scophthalmus maximus)The experiment selected juvenile turbot. The fish in control group was fed a basal diet (S1),and the fish in experimental groups were fed the basal diet supplemented with200mg/kgphytase,100mg/kg non-starch polysaccharide and the mixture of the two enzymes (S2-S4).Results showed that:(1) Metabolism energy of fish had the tendency to rise which fed thedietary exogenous enzymes, with the energy proportion of growth, defecation and urine had thedownward trend (P＞0.05), and the defecation proportion of S4decreased25.54%significantly(P＜0.05).(2) Compared with S1, growth proportion of nitrogen had increased, and nitrogenexcretion proportion had decreased of fish with fed dietary exogenous enzymes (P＞0.05). Theproportion of defecation decreased significantly (P＜0.05), and the S4was the lowest, whichdecreased34.33%.(3) Dietary exogenous enzymes was not affected the growth and excretionproportion of phosphorus significantly (P＞0.05), but the defecation had downward trend (P＜0.05), with S4decreased20.68%.(4) The addition of exogenous enzymes improved nitrogen retention, but the load had the downward trend (P＜0.05). Phosphorus retention increased (P＜0.05), with the S2and S4higher than S3significantly. Phosphorus load had the downward trend(P＜0.05), and the S4lower than S1significantly.(5) When the fish in hungry condition,release ratio of nitrogen and phosphorus had not affected significantly with dietary exogenousenzymes (P＞0.05). However, in the full condition, nitrogen excretion rate of S2and S4lowerthan S1significantly (P＜0.05), and the S4was the lowest, which decreased30.00%. Reactivephosphorus of S4lower than S1, with decreased42.65%(P＜0.05).(6) To sum up, the dietaryphytase was more conducive to the phosphorus utilization. Phytase and non-starchpolysaccharide has synergies between each other. |
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