Preharvest Feeding Strategy to Enhance Long‐Chain Polyunsaturated and Polyunsaturated Fatty Acid Composition of the Tail Muscle of Freshwater Prawns Macrobrachium rosenbergii Grown in Earthen Ponds

Abstract

AbstractThree independent experiments were sequentially conducted during separate growing seasons (2009, 2010, and 2012) to determine whether a preharvest change in feed could achieve a desired enhancement of the long‐chain (LC) polyunsaturated fatty acid (PUFA) content or the PUFA content of the tail muscle in freshwater prawns Macrobrachium rosenbergii. Juvenile freshwater prawns were stocked into 0.05‐ha earthen ponds, cultured for 111–122 d, and then harvested. For the first experiment, there were three treatments: exclusive feeding of a commercial prawn feed for 122 d after stocking; exclusive feeding of range cubes for 122 d after stocking; and administering range cubes for 84 d followed by prawn feed for the final 38 d prior to harvest. The second experiment consisted of four treatments: range cubes were fed exclusively for the entire growing season (116 d) or were fed until replaced by the prawn feed at 39, 24, or 17 d prior to harvest. The LC‐PUFA profile for the tail muscle of harvested prawns was equivalent between prawns given the prawn feed for the entire growing season and those given the range cubes substituted by the prawn feed for the final 38 or 39 d before harvest. The proportional levels of LC‐PUFA in the tail muscle of prawns that received the prawn feed during the final 24 or 17 d prior to harvest were slightly lower. In the third experiment (two treatments), range cubes were administered either throughout the growing season (112 d) or for 84 d followed by the feeding of range cubes sprayed with flaxseed oil (2% weight/weight) for the final 28 d. The percentage (as total fatty acids) of linolenic acid (18:3[n‐3]), the principal fatty acid in flaxseed oil, increased 7.8 times in the feed and 3.3 times in the tail muscle of harvested freshwater prawns.