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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #317892
Research Project: Evaluating Nutritional Requirements, Identifying Alternative Ingredients and Improving the Production Environment for Hybrid and Channel Catfish Production

Location: Warmwater Aquaculture Research Unit

Title: Apparent phosphorus availabilities of selected traditional and alternative feedstuffs for channel catfish

Author
item LI, MENGHE - Mississippi State University
item ROBINSON, EDWIN - Mississippi State University
item LUCAS, PENELOPE - Mississippi State University

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2014
Publication Date: 2/20/2015
Citation: Li, M.H., Robinson, E.H., Lucas, P.M. 2015. Apparent phosphorus availabilities of selected traditional and alternative feedstuffs for channel catfish. North American Journal of Aquaculture. 77:136-140.

Interpretive Summary: Digestibility–availability values for energy and various nutrients (including phosphorus) for traditional feedstuffs used to formulate commercial feeds for channel catfish have been previously reported by various researchers. More recently, to diminish the effect of increasing prices of traditional feedstuffs (primarily soybean meal and corn), the amount of cottonseed meal has increased, and previously seldom-used feedstuffs, such as corn gluten feed (CGF) and corn distillers dried grains with solubles (DDGS), are now commonly used. Apparent digestibility–availability coefficients (ADCs–AACs) of energy, protein, amino acids, and lipid have been determined for these feedstuffs. While these data are essential to formulating catfish feeds, there is a lack of information on AACs for phosphorus (a key nutrient in setting restrictions for least-cost catfish feeds) from CGF and DDGS for catfish. Knowing phosphorus availabilities of these alternative feedstuffs is essential to formulating diets that not only meet the dietary requirement but also minimize the amount of phosphorus released into the environment. The main objective of this study was to determine phosphorus AACs for CGF and DDGS for channel catfish; however, other feedstuffs (soybean meal, cottonseed meal, and wheat middlings) were used as a basis for comparison. Results show apparent availability coefficients of phosphorus were 36, 22, 20, 75, and 77% for soybean meal, cottonseed meal, wheat middlings, CGF, and DDGS, respectively. Corn by-products CGF and DDGS had considerably greater phosphorus AACs than soybean meal, cottonseed meal, and wheat middlings, likely because the wet milling and fermentation processes that result in these by-products degrade the phytate form of phosphorus making it more available to the fish. It appears that phosphorus AACs of these ingredients for channel catfish are generally correlated to their nonphytate phosphorus levels. Phosphorus AACs obtained from the present study can be used in formulating commercial channel catfish feeds to optimize available phosphorus levels.

Technical Abstract: A digestibility trial with channel catfish Ictalurus punctatus was conducted to determine apparent availability coefficients (AACs) of phosphorus for selected common feedstuffs: soybean meal, cottonseed meal, wheat middlings, corn gluten feed (CGF), and corn distillers dried grains with solubles (DDGS). A 32% protein diet containing mostly chemically defined ingredients was used as a reference diet. Test diets were formulated to contain 70% of the reference diet mix and 30% of the test ingredient. Chromic oxide was used at 0.75% of the diet as a marker. Fifteen channel catfish of a mean weight of 316 g/fish (SD, 5) were placed into 110-L flow-through aquaria. Water temperature and dissolved oxygen were maintained at approximately 30'C and = 5 mg/L, respectively. Each diet had three replicated tanks. Apparent availability coefficients of phosphorus were 36, 22, 20, 75, and 77% for soybean meal, cottonseed meal, wheat middlings, CGF, and DDGS, respectively. Corn by-products CGF and DDGS had considerably greater phosphorus AACs than soybean meal, cottonseed meal, and wheat middlings, likely because the wet milling and fermentation processes that result in these by-products degrade the phytate form of phosphorus making it more available to the fish. It appears that phosphorus AACs of these ingredients for channel catfish are generally correlated to their nonphytate phosphorus levels. Phosphorus AACs obtained from the present study can be used in formulating commercial channel catfish feeds to optimize available phosphorus levels.