The Nile tilapia (Oreochromis niloticus) is one of the most common aquacultural species in Nigeria and several African countries. Despite the remarkable growth of global aquaculture, the sector still faces serious health challenges in Nigeria and other sub-Saharan African countries, which undermines sustainability in those countries. With this, there is a constant need to improve existing knowledge and to develop new diets using sustainable additives such as yeast derivates. Brewer’s yeast is rich in nutrients and bioactive substances such as β-glucans, mannan-oligosaccharides, and nucleotides which have been demonstrated to improve growth performance, health, and immune response of farmed fish. The present study was conducted to evaluate the potential of dietary supplementation of autolysed brewer’s yeast (ABY) on Nile tilapia growth performance, feed utilisation and intestinal health.
A 5-week feeding trial was conducted in a RAS with Nile tilapia fry (0.45 g). Four diets were formulated to meet the known nutrient requirements of Nile tilapia (Table 1). The control diet had no brewer’s yeast while the other 3 diets were supplemented with ABY (CeFi® Pro, Leiber GmbH) at 1 g/kg (ABY1), 2 g/kg (ABY2), or 4 g/kg (ABY4). All diets were isonitrogenous and isocaloric. The fish (40 fish/15L tank) were fed one of the four diets (n = 3 tanks) at 5% of body weight per day. At the end of the feeding trial, intestinal samples were taken for gene expression and histological analyses (data not shown).
The growth data showed that the final body weight, specific growth rate, and FCR of the fish fed ABY1 was significantly better (P < 0.05) than fish fed the control diet (Table 2). Histological analysis of the mucosal fold height did not reveal any significant differences (P < 0.05) among the treatments.
Ongoing analysis on other histological parameters and gene expression is being undertaken to assess intestinal morphometrics and regulation of immunoregulatory genes. Results obtained so far indicate that the ABY investigated had a positive response on tilapia feed utilisation and growth performance during early life stage.