Effects of two dietary lipid levels on growth performance and body composition of pre-adult hatchery reared and wild-caught black sea bass
Presentation
Overview
Overview
Description
Two isonitrogenous (approximately 50% crude protein) formulated practical diets having different lipid levels (12% and 18%) were fed to pre-adult black sea bass to test their effects on growth performance and body composition of hatchery reared and wild-caught fish reared in pilot-scale recirculating sea water systems. In experiment 1, hatchery reared (approximately 395 g initial weight) were fed the respective diets for about 6.5 months in triplicate recirculating tanks (2.7 m3, 50 fish/tank) at the Center for Marine Science, University of North Carolina Wilmington (UNCW). In a separate experiment 2, wild-caught black sea bass (approximately 177 g initial weight) were fed these same diets for about 4 months in triplicate recirculating tanks (4.8 m3, 10 fish/tank) at the Aquaculture Research Center, University of New Hampshire (UNH). In both experiments, fish were fed two times a day to apparent satiation. At the end of the feeding trial, proximate composition for whole body, muscle, viscera and liver tissue were analyzed.
In experiment 1, after 82 days of feeding, weight gain (g) and lipid content of whole body, muscle, liver and viscera for hatchery-reared fish fed 18% lipid appeared to be higher than fish fed 12% but no significant differences were observed. After 193 days of feeding, hatchery reared fish fed 18% lipid showed significantly higher (P<0.05) weight gain (g) and lipid content in whole body, muscle and viscera compared to fish fed the 12% lipid diet. Fish fed the 12% lipid diet showed significantly higher crude protein in whole body and muscle than fish fed 18% lipid diet. In experiment 2, after 117 days of feeding, there were no significant effects of dietary lipid levels on body weight gain (g) and body proximate compositions of wild-caught black sea bass. However, after the experiments, the muscle lipid content of both captive wild caught and hatchery reared fish used in these experiments 1 and 2 were significantly higher than found in recently wild-caught fish. Specific growth rate, feed intake, feed conversion efficiency and protein efficiency ratio for both studies will be discussed.
Results suggested that irrespective of lipid levels (12% or 18%) in the diets, hatchery reared and captive wild caught black sea bass accumulated higher lipid levels in the body tissues than do black sea bass in the wild. Results also suggested that, in hatchery-reared fish, dietary lipid level may be manipulated to affect body lipid and protein composition. This study will help to formulate a finishing diet for black sea bass before harvesting to meet consumer preferences for flesh quality.
