Location: Warmwater Aquaculture Research UnitTitle: Optimizing soybean meal levels in alternative diets for pond-raised hybrid catfish) Author
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2013
Publication Date: 1/1/2014
Citation: Li, M.H., Robinson, E.H., Bosworth, B.G., Oberle, D.F., Lucas, P.M. 2014. Optimizing soybean meal levels in alternative diets for pond-raised hybrid catfish. North American Journal of Aquaculture. 76:61-66. Interpretive Summary: Catfish farming is the largest aquaculture enterprise in the USA, but production has decreased by more than 50% over the last decade primarily due to increased feed and energy costs, low fish prices, and competition from imported catfish or other aquaculture products. To remain competitive and sustainable, U.S. catfish producers must reduce production costs. Because feed represents the largest single expenditure in catfish production, accounting for more than 50% of total variable operation cost, it is imperative that feed cost be reduced to achieve significant reduction in overall production cost. The dramatic increase in catfish feed prices in recent years is dictated by the unprecedented increase in the prices of soybean meal and corn, the two primary feedstuffs used in catfish feeds. Using less expensive, alternative feedstuffs to replace soybean meal and corn without compromising fish growth and product quality would reduce catfish feed cost. The objective of our study was to examine decreasing levels of soybean meal as replaced by the use of a combination of cottonseed meal and CGM for pond-raised hybrid catfish. The project is part of our continuing effort to build the database on the utilization of alternative feedstuffs by catfish. Results demonstrate that reducing soybean meal levels from 40% to 15% in the diet by the use of a combination of cottonseed meal and CGM did not significantly affect total amount of diet fed, gross yield, weight gain, survival, and fillet proximate composition, but significantly increased FCR and decreased processed yield of hybrid catfish. It appears that a 28% protein diet containing 25% soybean meal can support maximum growth of hybrid catfish without marked impact on FCR and processed yield.
Technical Abstract: We evaluated decreasing soybean meal levels by the use of a combination of cottonseed meal and corn germ meal for pond-raised hybrid catfish (channel catfish Ictalurus punctatus × blue catfish I. furcatus). Five 28% protein diets containing 40, 30, 25, 20, 15% of soybean meal were formulated based on digestible nutrients and energy to meet or exceed all known nutrient requirements of channel catfish. Fingerling hybrid catfish with a mean initial weight of 25.1 g/fish were stocked into 25, earthen ponds (0.04 ha) at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation over a 184-d growing season. Reducing soybean meal levels from 40% to 15% in the diet by the use of a combination of cottonseed meal and corn germ meal did not significantly affect total amount of diet fed, gross yield, weight gain, and survival of hybrid catfish by ANOVA or regression analysis. However, feed conversion ratio was significantly higher in fish fed diets containing =30% soybean meal than those fed the control diet (40% soybean meal), and feed conversion ratio increased linearly as soybean meal levels decreased. Hybrid catfish fed diets containing 20% and 15% soybean meal had significantly lower carcass yield than fish fed the control diet. Fish fed the diet containing 15% soybean meal also had significantly lower fillet yield. Regression analyses show that both carcass and fillet yields decreased linearly with decreasing soybean meal levels in the diet. No significant differences were observed for fillet protein, fat, and moisture levels among fish fed the diets containing various levels of soybean meal. A 28% protein diet containing 25% soybean meal appears to support maximum growth of hybrid catfish without marked impact on feed conversion ratio and processed yield.