Feed Technology
41
Functional feed additive strategies to optimise health in tilapia Can Asian farmers learn from their counterparts in Brazil? By Martin Guérin, Maria Mercè Isern-Subich and Waldo G. Nuez-Ortín.
Tilapia cage farming in São Paulo, Minas Gerais, Brazil (São Paulo, Minas Gerais, photo by N. Ishikawa)
I
n both Asia and Brazil, the tilapia’s main market is domestic, usually with relatively low selling prices and there is a need to focus on cost efficiency at the feedmill as well as the farm. Therefore, the key challenge for tilapia farmers is to maximise profit, which explains the tireless efforts to improve feed conversion ratio (FCR), growth, survival, productivity and fillet yields among other indexes. On the other hand, diseases, whether parasitic, bacterial or viral, remain the main challenge faced by all tilapia farmers during all production stages and threaten the sustainability of many farming operations.
Preventive strategies against fish diseases
Measuring the impact of disease outbreaks in fish farming is a complex task, since only a part of that impact is actually measured (e.g., apparent mortality and cost of drugs and chemicals). It is much harder for farmers to measure the hidden costs of diseases such as covert mortalities, loss of performance, under-utilised production facilities, lower fillet quality/yield, and opportunity costs from unavailability of fish during peak demand or market access limitations due to antibiotic use. In such situations, preventive strategies to manage disease problems not only improve profitability of the operation, but also help to reduce these hidden costs. Recently, Brazilian tilapia integrators have managed to control the impact of bacterial disease threats such as streptoccosis and francisellosis on productivity through the optimisation of using specific additives in feed to promote fish health throughout specific challenging periods. The purpose of this article is to highlight opportunities for Asian farmers to improve their profitability and sustainability under challenging farming conditions.
Tilapia farming in Brazil vs in Asia
While Asia dominates world production of farmed tilapia, Brazil, driven by a strong domestic demand quickly became the world’s 4th largest producer of tilapia, reaching around 490,000 tonnes in 2020. This was +78% in 6 years, i.e. growing faster than other leading tilapia producers. This expansion in the Brazilian tilapia industry was helped by the injection of Asian genetics including Chitralada and GIFT tilapia strains in the 1990s. The industry in Brazil differs from that in Asia by the fact that the preferred market size is for larger fish (600 to 1,200g/fish), mostly sold locally, whole or in fillets, fresh or frozen. This large fish farmed in cages or ponds, has helped the industry to move faster towards higher intensification, to use quality feeds and to implement sophisticated health management protocols. By comparison, Asian tilapia farmers harvest fish produced from a large variety of farm types and sizes, and domestically market often smaller fish (200 to 700g/fish) that are rarely filleted. However, some large intensive cage farming operations target larger sizes (1kg/fish), aimed at fillet markets and often for exports to the USA or Europe. Such companies have much to gain from emulating disease prevention programs as practised in Brazil. However even smaller Asian tilapia farmers can also benefit as they face similar disease threats.
Threats from Streptococcus and Francisella
The main threat for Brazilian tilapia farmers is the bacterial disease, streptococcosis during the warm months, caused by Streptococcus bacteria: S. agalactiae, S. iniae, and S. November/December 2021 AQUA Culture Asia Pacific
