Abstract
This study was aimed to investigate the effect of phytase as a feed additive on growth performance and survival rate against Saprolegnia spp.in common carp, Cyprinus carpio L. A total of 120 C. Carpio (initial mass 20.05-20.35g) were randomly stocked into six treatments in duplicate (10 fish/tank) as follows: T1, T2, and T3 were fed the basal diet supplemented with phytase at 1000, 2000, and 4000 IU/Kg diet respectively, while T4 were fed on basal diet plus β-glugan at a concentration of 8.5 g/kg as well as the control group was fed basal diet without any addition of phytase. Results showed after 60 days of feeding period, that the addition of phytase enzyme was significantly (p<0.05) affected on daily growth (DG), specific growth rate (SGR) and feed conversion ratio (FCR) in T3 and T2 followed by T4 and T1 compared to control group. At the end of the experimental period (60 days) fish were challenged with Saprolegnia spp. After 15 days of challenge test, the best survival rate was recorded in T3 (100%) followed by T2 (80%) then T1 (70%) respectively. All treatment groups were better than the positive control group which recorded 40 %. Based on these results, this study approved the potency of the phytase enzyme on growth performance and survival rate against the Saprolegniasis in common carp.
Highlights
Saprolegniasis in teleost fish is a major problem affecting both wild and farmed freshwater fish productions (15, 31)
Phytase used as feed additives in diet of common carp to improve growth performance; phytase enzyme increased nutrient absorption and regulated nutrient excretion, such as phosphor, nitrogen, and minerals (5)
Food conversion efficiency (FCE) was significantly improved by 4000 units/kg of phytase (i.e. T3) more than other 1000 and 2000 IU/Kg of phytase (T1 and T2)
Summary
Saprolegniasis in teleost fish is a major problem affecting both wild and farmed freshwater fish productions (15, 31). Phytase used as feed additives in diet of common carp to improve growth performance; phytase enzyme increased nutrient absorption and regulated nutrient excretion, such as phosphor, nitrogen, and minerals (5). Supplementation of phytase in fish feeds has been generally reported to improve the bioavailability and utilization of plant phosphorus by fish (3, 19). Previous studies have not estimated the influence of phytase supplementation on immune response or resistance against disease and general health status of common carp. This study was planned to shed light on efficiency of the phytase on growth performance, and antifungal activity against Saprolegnia spp. in common carp. Until the appearance of the stress on fish, after two weeks of acclimation for the fish before starting the experiment.
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