Different Dietary Lipid Sources Affect Plasma Lipid Composition but Not Stress Tolerance or Growth of Hybrid Striped Bass

Abstract

To determine whether dietary lipid sources used in regimens to replace fish oil differentially impact the production performance and physiological status of hybrid Striped Bass (White Bass Morone chrysops × Striped Bass M. saxatilis), the growth performance and stress response of fish raised on diets containing oil from fish, canola, corn, or flaxseed were evaluated. Production performance was unaffected by diet. Net-chasing and handling stress challenges elicited changes in hematology consistent with the generalized stress response, and there was a significant main effect of stressor exposure (P < 0.01) on both plasma cortisol and osmolality, as well as a main effect of lipid source (P < 0.05) on plasma osmolality. Across diets, cortisol and osmolality levels were highest 1 h after stressor exposure (411 ng/mL and 385 mOsm/kg, respectively) but decreased significantly by 4 h poststressor (169 ng/mL and 332 mOsm/kg, respectively). The plasma lipid fatty acid (FA) profile was influenced by diet and generally reflected the FA profile in the feed. However, higher levels of saturated and monounsaturated FAs and lower levels of polyunsaturated FAs were typically observed shortly after stressor exposure. Although differences in hematology were associated with differences in lipid source and stressor exposure, neither obvious impairment of physiological function nor gross effects (i.e., morbidity and mortality) were observed.

Received November 16, 2015; accepted March 20, 2016

Acknowledgments

We thank John Boesenberg and Justin Rosenquist for their help in conducting the feeding trial, and Heidi Hill, Bonnie Mulligan, and Brian Gause for editorial suggestions provided during the preparation of this manuscript.