Pseudo-stem by-product from Canarian Banana crop (Musa acuminata colla): preliminary study on the inclusion for tilapia diets

Abstract

Banana culture is an important productive activity in the Canary Islands producing high amounts of waste, principally pseudo-stem, which is normally let dried on the land as a residue. In a scenario where resources are becoming scarce and more residues are generated, re-thinking and re-designing the way we produce is urgently required for the aquaculture sustainability. The objective of this study is to evaluate the inclusion of four dietary levels of processed banana pseudo-stem on tilapia feed acceptance and growth. Pseudo-stem was processed using two specialized fibre extraction machines. The by-product obtained (BT by-product) was lyophilized and pulverized. Afterwards, it was hydrolysed for 30 min at 100°C with 2% H2SO4 according to Elias et al. (2014). The feeding trial was performed at the Aquaculture Research Facilities, belonging to the ECOAQUA Institute of the ULPGC. Twelve fishes per tank (3.9 ± 0.64 g), were randomly distributed in 5 recirculation systems with 3 tanks each (80 L/tank). Fish were manually fed twice a day, six days a week, for 47 days with five isoproteic and isolipidic diets with increasing levels of BT by-product (Table 1). The inclusion of BT by-product decreases significantly tilapia growth as the dietary inclusion increase (Figure 1). Growth parameters in tilapia juveniles may be affected by diets containing high ash ingredients (Köprücü & Özdemir, 2004), which could explain the significant decreasing of growth by BT by-product inclusion. Nevertheless, growth values from diets BT2.5 and BT5 are in the range of growth rate expected for this specie and size (Ahmed et al., 2016; Harmantepe et al., 2016). On the other hand, liver and intestine histopathological analysis reveal no damage caused by the dietary inclusions on these structures according to Genc et al. (2007). According to these preliminary results, BT by-products seems to be a promising raw material to be included in tilapia diets, but further processing is required on this by-product to achieve a high-quality ingredient for tilapia diets. Likewise, studies are on going to better degrade the fibre content and to deeper clarify the fibre and minerals in BT-by product and their implication in the observed tilapia performance.