Replacement of Fish Meal with Ethanol Yeast in the Diets of Sunshine Bass

Abstract

Increasing demand and rising costs of fish meal (FM) coupled with static landings of reduction fisheries have made continued use of FM-rich aquaculture feeds environmentally and economically unsustainable. Animal- and plant-derived proteins have been investigated as alternatives to FM, with variable success. Observed limitations of commonly used alternative proteins have led nutritionists to investigate new alternatives to FM. Ethanol yeast, a co-product of bioethanol production and potential new alternative protein source, was evaluated as a FM replacement in the diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Five diets were evaluated, including a control diet containing 30% FM and four experimental diets (22.5, 15, 7.5, and 0% FM) in which 25, 50, 75, or 100% of the FM content was replaced with ethanol yeast. Juvenile sunshine bass (∼16 g) were fed twice daily to apparent satiation for 45 d. Production performance of sunshine bass was not impaired by partial FM replacement and in some cases was marginally improved by dietary inclusion of ethanol yeast. Feed conversion ratio, specific growth rate, and feed intake were equivalent among fish fed the control, 22.5% FM, 15% FM, and 7.5% FM feeds; weight gain was significantly increased in the 15% FM group compared with the control. However, complete replacement (0% FM) resulted in significantly impaired growth performance and conversion efficiency. Whole-body composition did not differ with respect to moisture, ash, or protein content; however, crude lipid content was significantly elevated in the 7.5% FM treatment, suggesting a protein–energy imbalance in this formulation. Although our study was a short-term screening trial, based on our results we suggest that an optimal level of FM in ethanol-yeast-based feeds for sunshine bass would be between 7.5% and 15%.

Received March 15, 2010; accepted June 5, 2010

ACKNOWLEDGMENTS

We thank Andrew Yung for his assistance with daily feeding, Heidi Lewis and Bonnie Mulligan for their assistance in data collection, and Andrew Coursey and Matt Noatch for their assistance in obtaining the fish used in this study. We thank Omega Protein, Inc., for the donation of FM and fish oil. We also thank the Archer Daniels Midland Company and Stephanie Block and Mike Cecava for providing technical support and supplying the ethanol yeast used in this study.

Notes

^aArcher Daniels Midland Co., Decatur, Illinois.

^bOmega Protein, Inc., Houston, Texas.

^c48% protein; Seimer Enterprises, Teutopolis, Illinois.

^dPurina Test Diet, Richmond, Indiana.

^eFormulated to contain 25% L-ascorbyl-2-polyphosphate, 13.16% vitamin K, 12.5% inositol, 12.5% nicotinic acid, 7.5% riboflavin, 6.25% calcium pantothenate, 2.5% pyridoxine hydrochloride, 1.25% thiamine mononitrate, 1% vitamin A palmitate, 0.5% cyanocobalamin, 0.45% folic acid, 0.125% biotin, and 0.01% cholecalciferol in a cellulose base.

^fFormulated to contain 24.897% zinc oxide, 14.933% ferrous sulfate, 3.470% manganese oxide, 0.967% cupric carbonate, 0.262% potassium iodide, 0.06% sodium selenate, and 0.03% cobalt carbonate in a cellulose base.

^aWeight gain = [(final weight − initial weight)/initial weight] × 100.

^bFeed conversion ratio = (consumption/weight gain).

^cSpecific growth rate = [log _e (final weight) − log _e (initial weight)]/days.

^dFeed intake = [total dry mass intake/(initial body weight × final body weight)^0.5/number of days fed] × 100.

^eHepatosomatic index = [(liver mass/whole-body mass) × 100].

^fLiposomatic index = [(intraperitoneal fat weight/body weight) × 100].

^aCalculated on wet matter basis.

^bCalculated on dry matter basis.