Olive oil by-products in aquafeeds: Opportunities and challenges

The increment in world population has led to the increasing demands for fish supply as principal source of animal protein that represents about 17% of animal protein consumption globally. The world aquaculture industry has expanding remarkably but limited source of fishmeal and fish oil which known as important ingredients in fish feed has led to seeking of alternative sources for their replacement in aquafeed formulation. Many potential and cheaper ingredients derived from vegetable oils or agricultural by-products have been investigated to replace fish meal and fish oil which shown promising results in fish productivity and fish health status including olive oil by-products. Varies depending on its type, olive oil composes of antioxidants, healthy type of fats such as MUFA and PUFA, and high in vitamins that provide human health benefits for heart and liver, help in many diseases and reducing the risk of cancer. In agriculture industry, olive and olive oil production processes have resulted to by-products such as olive mill wastewater (OMW), olive leaf and olive pomace. The inclusion of these by-products in animal feeds is the solution for agricultural waste management. The first report of utilization of olive oil by-products in fish feed was documented in 2004 and since then, many researches has been conducted to investigate fish health benefits that showed improvement in fish carcass composition and fish immunity depending on type of by-products used and fish species. Additionally, antioxidant contents in olive oil extract were reported could provide antimicrobial, antifungal and antioxygenic characteristics which potentially improve the fish health. This review discussed the opportunities and challenges in application of olive oil by-products in aquafeed which provides significant prospects in fish growth performance that could boost aquaculture industry development.