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PHYTOGENIC COMPOUND IMPROVED THE SURVIVAL AND GROWTH OF NILE TILAPIA (Oreochromis niloticus) FRY DURING PARASITE INFESTATION  

Goncalo A. Santos1, Rui A. Goncalves1, Lumpan Poolsawat2 and Ram C. Bhujel2
1BIOMIN Holding GmbH, Erber Campus 1
3131 Getzersdorf, Austria
2Aqua-Centre, FABS, SERD, Asian Institute of Technology (AIT), Thailand
 

Phytogenic compounds may serve as alternatives to antibiotics and hazardous chemicals. A trial was conducted at the Asian Institute of Technology (AIT), Thailand to examine the efficacy of a phytogenic compound produced by Biomin Company on Nile tilapia fry before and after infesting with Trichodina sp. Four levels of the compound 0.0, 0.5, 1.0 and 1.5 g/kg feed as control, low, medium and high doses were assigned in three replicate aquaria. A total of 1,200 fry (avg. wt. 0.0064±5.77 g) were stocked in each of the 12 aquaria, and they were fed 5 times/day during 21 days. The phytogenic compound was mixed with standard feed prepared for sex-reversal. In the second phase, first group of 300 fry were sampled from each replicate aquarium and transferred to 12 nursing hapas installed in an earth pond where parasites were detected. Another 300 fry from each of the 12 aquaria were transferred to plastic tanks with clear water where no parasites were present. The numbers of parasite were counted every 3 days from caudal fin, mucus of whole body and 2 pieces of gill arches until 21 days. It was observed that the numbers of parasite after infection on 3rd day increased similar way in all the treatments in mucus of whole body, gill arches and caudal fins of the fry stocked in hapa-in-pond system.

Results showed that after the first 21 days of feeding trial, survival was not significantly affected by the tested doses of phytogenic compound. However, during the parasitic challenge phase, both the medium and high doses were able to raise the fry survival to the level of control i.e. without the parasites (Fig. 1). The medium dose (1.0 g/kg feed) is adequate to raise survival during parasitic infestation. Additionally less parasites were detected on the whole body mucous in the phytogenic treatments compared to the control treatments while this difference was not so clear in the gill arch and caudal fin. The phytogenic compound improved also the SGR during the parasitic challenge, and the lowest dose was most effective for growth. Therefore, more research is needed to further refine or determine the dose in various culture conditions and age groups.










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