Location: Cool and Cold Water Aquaculture Research
Project Number: 1930-31000-010-01
Start Date: Feb 15, 2014
End Date: Feb 14, 2019
Specific aim 1. Identifying production practices that affect the accumulation of LCn3 content in the fillet is critical for establishing rainbow trout as a dietary source of LCn3. In the United States, the rainbow trout industry raises primarily diploid (2N) and triploid (3N) fish. Diploid trout are harvested young while triploid rainbow trout fill the demand for larger fillets because the female triploids are unable to sexually mature, thereby avoiding the negative effects of sexual maturation on fillet quality. Understanding whether diploids or triploids, and at which stage of development, yield the greatest fillet LCn3 content will indicate production practices that maximize benefits on consumer health. Specific aim 2. Consumption of fish enriched with the long chain n-3 fatty acids (LCn3) is associated with prevention of inflammation and reduction of cardiovascular disease (CVD) risk. Prevention of CVD is a public health goal and comprises several avenues of action, of which inclusion of LCn3-rich fish in the diet is one of the most effective. A previous study indicated that consumption of Atlantic salmon improves LCn3 status in humans, which is an index of inflammation and cardiac health. To establish the health benefits of rainbow trout consumption, obese human volunteers will receive twice weekly meals containing either diploid or triploid rainbow trout fillets. Measures of inflammation and cardiac disease risk, specifically those related to LCn3 function, will be monitored to assess positive effects on health. Specific aim 2. As growth of the aquaculture industry increases, so does the demand for fish oil and fishmeal, ingredients which are collected from marine capture and forage fisheries. Vegetable oils like soy, canola, and flax can be produced in sufficient quantities and are generally less expensive than fish oil. However, many of the vegetable oils are rich in medium-chain omega-3 fatty acids (MCn3), not LCn3, therefore their incorporation in aquafeeds reduces the concentration of LCn3s in the diet and also in the fish itself, thereby minimizing one of the most attractive health benefits of rainbow trout. A strategy that partially reestablishes fillet LCn3 is to feed a fish oil finishing diet after consumption of a vegetable oil grower diet. However, it remains unknown if increased consumption of LCn3 fatty acids occurring during the transition from a low-LCn3 vegetable oil grower diet to a high-LCn3 fish oil finishing diet varies by fillet location. Determining how the fatty acid profile varies by fillet subsection and lipid storage location will indicate how dietary LCn3 content affects aspects of fillet quality, and contribute to the establishment of sustainable feeding strategies that aim to maximize aspects of fillet health and quality. Further analysis of the physiological basis for variations in fillet LCn3 content can be achieved by transcriptome analysis using RNAseq. Applying this technique in rainbow trout will determine how the liver transcriptome is affected by sustainable feeding strategies and indicate the nutrient-gene interactions regulating the fatty acid profile of the fillet.