The Effects of Dietary Cottonseed Oil on Growth Performance of Juvenile Red Drum (Sciaenops ocellatus L.) and Hybrid Striped Bass (Morone chrysops × M. saxatilis S.)

Abstract

Various cottonseed products containing higher levels of protein and lipid than traditional cottonseed meal have been evaluated in recent years with several carnivorous marine fish species. In previous studies in this laboratory, distinct differences in the acceptability of diets containing those cottonseed products were noted for red drum and hybrid striped bass. Therefore, the present study consisted of two concurrent feeding trials in which the effects of increasing levels of dietary cottonseed oil were evaluated with both juvenile red drum and hybrid striped bass. Three experimental diets were formulated to contain either 0, 2, or 4% of cottonseed oil in place of menhaden fish oil. All diets were formulated to contain approximately 9% lipid, with that of the basal diet (0% cottonseed lipid) primarily contributed by menhaden fishmeal and menhaden oil. In concurrent trials, each diet was fed twice a day to triplicate groups of juvenile red drum and hybrid striped bass initially averaging 1.86 g/fish and 1.41 g/fish, respectively, for 6 weeks. Results of the feeding trial showed that there were no significant differences among red drum fed the different dietary treatments based on growth parameters (weight gain and feed efficiency) or whole-body proximate composition. On the contrary, hybrid striped bass showed significant ( $P\le 0.05$ ) differences in responses to the dietary treatments with weight gain decreasing as the inclusion levels of cottonseed oil increased while their hepatosomatic index significantly increased. Thus, results of this study showed distinctly different responses of red drum and hybrid striped bass to increasing levels of dietary cottonseed oil, with hybrid striped bass being much more sensitive than red drum in terms of reduced weight gain and altered body condition which appeared to be related to reduce diet palatability from cottonseed oil.