EXAMINING THE EFFECTS OF POULTRY MEAL AND PROTEASE SUPPLEMENTATION AS A MITIGATOR OF SOYBEAN MEAL IN RAINBOW TROUT DIETS

Aquaculture is now one of the fastest-growing food-producing industries, and it is seen as a sustainable way of addressing our future food security and climate impact. The development of circular-based (restorative and regenerative/waste residues from other industries) derived aquafeed ingredients for farmed aquatic animals is at the heart of pursuing this long-term sustainable aquaculture-based food production model. Agricultural waste, such as processed animal proteins (PAPs) from the rendering industry has been overlooked as a critical contributor in attaining a circular seafood production model.

A feeding trial was conducted on rainbow trout (Oncorhynchus mykiss ) in a 15 recirculating aquaculture system. Five diets were formulated, 1 Control and 4 experimental. T he soybean meal fraction of the experimental diets was replaced with two levels of poultry by-product meal (12.5% & 25%). On top of this, these diets were duplicated and then spray coated with a protease enzyme (12.5%+P & 25%+P). Fish were fed for the test diets for a total of 14 weeks and weight gain was measured fortnightly. At the end of the trial  full growth morphometrics was conducted as well as whole body proximate composition.

 Results showed that diet 12.5%+P performed best across weight gain, FCR and SGR. With respect to proximate composition, diet 12.5%+P  also yielded a higher lipid content than other diets. The authors believe that the replacement of soybean meal with poultry meal up to and beyond 12.5% of the total diet could increase on farm production rates . It is also clear that the supplementation of the diet with protease increases digestibility of the feed and creates a more efficient product for farmers.