Evaluation on Production Performance in Nile Tilapia Utilizing Saturated Fatty Acid-Enriched Soybean Oil As Full or Partial Replacements for Fish Oil

Fish oil (FO) is a high-quality source of essential fatty acids (FA), particularly n-3 long-chain polyunsaturated fatty acids (LC-PUFA), for aquaculture feeds but is economically and environmentally costly as a feed ingredient. Various alternative lipids can be utilized to minimize fish oil usage, however, fish oil replacement can affect growth and fillet fatty acid profile. Ultimately, sustainable fish oil alternatives should minimize the loss of beneficial LC-PUFA content, yet yield equivalent production performance in farmed-raised fish. In a previous study, we found that 50% of FO in Nile tilapia feeds could be replaced with standard, saturated fatty acid (SFA)-enriched, or low 18:3n-3 soybean oil (SO) without negatively affecting production performance, but that  fillet LC-PUFA content was best maintained among fish fed the SFA-enriched SO diet. Based on these findings, a we evaluated greater FO sparing with the SFA-enriched soy oil, feeding replicate tanks (n=3, 6 fish/tank) of juvenile (~35g) Nile tilapia diets containing  100% FO (100-FO) or 50, 75, or 100% SFA-enriched soy oil exclusively or in combination with the 100% FO feed in finishing periods of different lengths. Over the course of the 28-week production cycle neither degree of FO replacement or finishing significantly affected production performance (weight gain, 638% ± 102; FCR, 5.5 ± 1.2).  In some cases, production performance was even marginally improved by feeding the SFA-enriched SO-based diets. These results suggest that SFA-enriched SO may partially of fully replace FO in grow-out diets for Nile tilapia without negatively influencing production performance. Effects of FO sparing with SFA-enriched SO and finishing on fillet LC-PUFA content will be discussed.