Bioassay of different lecithins in the diet of juvenile Penaeus vannamei (Crustacea: Decapoda).

The effect of different lecithin sources and presentations on growth, food conversion ratio and survival of P. vannamei (290 mg plus or minus 0.02) was studied. The bioassay was designed in order to compare different dietary levels and different quality of lecithin. Squid lecithin, crude soybean (7%), deoiled soybean lecithin (3.48%) in combination with fish oil or squid neutral lipids, in a partially dilapidate formula. The isoenergetic diets were fed ad libitum to four replicate groups (tanks) of 15 shrimps each (5 x 4 x 15), during 28 days. The result of the bioassay with the partially dilapidate formulas was; the best growth rate (191%) and FCR (1.69 plus or minus 0.041) were obtained with the diet containing 7% of soybean crude lecithin as the unique lipid source. Followed by the diet countering 3.94% deoiled lecithin and 2.42% Menhaden oil (172% and 2.03 plus or minus 0.054 respectively). As expected, the worst results were obtained without the dietary lecithin 121% and 2.42 plus or minus 0.129). Crude soybean lecithin alone covered the phospholipid and neutral lipids requirements as well as the combination of deoiled soybean lecithin with fish or squid oil.