Three strategic feeding during hatchering of Nile tilapia: effects on organs integrity, parasitism and performance parameters

Abstract

The effect of natural feed, artificial feed, and artificial feed with hormone 17 alpha-methyltestosterone on gill and liver integrity, parasite prevalence and performance parameters during the masculinization phase of Nile tilapia Oreochromis niloticus were evaluated. The experiment consisted of the three feeding strategies in triplicate. Water parameters, histopathological, parasitological and performance analyses were performed on day 7, 14, 28 and 60. Both artificial feeds (with and without hormone) were harmful to the hepatic and branchial integrity. The most significant change in liver was lipid degeneration, while in gills a significantly higher lamellar edema was observed when compared to fish that received the natural feed. Fish fed with the artificial diet (with and without hormone) showed a high prevalence (p \ 0.05) of trichodinids and Cryptobia, while fish that received natural feed showed no parasites after 28 days of study. Fries that received diet with hormone experienced damage to their health, which decreased the survival of this group. The anabolic effect of this molecule, however, improved significantly (p \ 0.05) their productive performance. Despite the absence of deleterious effects to fish health, the use of natural feed has a high risk of introducing predators. Introduction of odonate larvae drastically affected the survival of this group at the end of the study. All feeding strategies investigated have positive and negative effects that were discussed in the present study.

Trichodiniasis in Nile tilapia hatcheries: Diagnosis, parasite:host-stage relationship and treatment

“…This parasitism directly affects the larvae because their main defence mechanisms are not fully developed, such as their scales, which appear to be a major barrier to this type of parasitosis. In addition, the parasitism observed in the eyes and on sensitive ciliary structures of the larvae affects their ability to capture live food in earthen ponds and to escape from predators such as birds and odonata larvae, which are threats that are commonly found in aquaculture (Dias-Neto et al, 2015). Despite the greater intensity of infestation, the juveniles, which have more developed scales and tougher skin, showed a lower intensity of suction areas and lesions over their bodies.…”