TRYPSIN AND CHYMOTRYPSIN ACTIVITY IN THE HEPATOPANCREAS OF JUVENILE NILE TILAPIA FED ACIDIC OR FERMENTED TILAPIA WASTE SILAGES

Abstract

In Brazil, aquaculture is a rapidly expanding activity, gaining prominence as a viable, economical alternative for small, medium, and large producers. The increase in fish production and consumption also increases the amount of waste generated in the chain. Nile tilapia (Oreochromis niloticus), an exotic species of African origin, was introduced to Brazil and spread throughout all river basins, making its culture the main representative of fish production. Fish feed is expensive, particularly due to the use of fishmeal as a component in feed. However, alternative, economical, and sustainable protein sources have been sought to replace fishmeal. The use of waste generated in the fish production chain itself provides energy and protein, which can be converted into ingredients for the animal feed industry. Fillets make up an average of 30 to 33% of the fish, with the remainder considered filleting residue, consisting of fins, head, tail, backbone, and viscera. This study aimed to evaluate the enzymatic activities of trypsin and chymotrypsin obtained from the hepatopancreas of juvenile Nile tilapia fed with partial or total replacement of fishmeal with acidic and fermented silages made from tilapia filleting residue. A total of 384 15-gram fish were distributed across 32 450-L water tanks in a completely randomized design with eight treatments and four replicates. The results of trypsin and chymotrypsin activities did not show significant differences between the control and treatments, suggesting that the total or partial replacement of fishmeal by acidic or fermented silage from tilapia fillets is advantageous because, in addition to reducing costs and waste generated, it does not result in production losses.