|Rawles, Steven - Steve|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2007
Publication Date: 6/1/2008
Citation: Thompson, K.R., Rawles, S.D., Metts, L.S., Smith, R., Wimsatt, A., Gannam, A.L., Twibrll, R.G., Johnson, R.B., Bardy, Y.J., Webster, C.D. 2008. Digestibility of dry matter, protein, lipid, and organic matter of two fish meals, two poultry by-product meals, soybean meal, and distiller's grains with solubles in practical diets for sunshine bass. Journal of the World Aquaculture Society. 39:352-363. Interpretive Summary: Information is needed on the digestibility of nutrients in practical feed ingredients for commercially-important fish, like hybrid striped bass. This information is critical for improving least-cost diet formulas and for reducing the amount of fish meal in the feed. Most digestibility studies concentrate on small fish, so that little information is available for market-sized fish. A study was conducted with market-sized (2 lb) hybrid striped bass to determine the digestibility of nutrients in a variety of ingredients for floating commercial diets. The ingredients tested were menhaden fish meal (MEN), anchovy fish meal (ANCH), pet-food grade poultry by-product meal (PBM-pet), feed-grade poultry by-product meal (PBM-feed), dehulled soybean meal (SBM), and distiller’s dried grains with solubles (DDGS). The digestibility of protein ranged from a high of 86% for MEN to a low of 66% for DDGS. The digestibility of fat ranged from 92% in MEN to 57% in SBM. The digestibility of organic matter ranged from 90% in MEN to 17% for DDGS. This information will assist feed mills and fish producers in formulating more efficient, economical diets for hybrid striped bass.
Technical Abstract: Limited information is available on the digestibility of nutrients in various practical ingredients used in diets for commercially-important finfish species. This information is especially needed for sunshine bass, Morone chrysops X M. saxatilis, to improve least-cost diet formulations and to allow effective substitution of feedstuffs. A study was conducted with large (867 g) sunshine bass to determine the apparent digestibility coefficients (ADCs) for moisture, protein, lipid, and organic matter in a variety of ingredients in floating, extrusion-processed, diets. The practical ingredients tested were menhaden fish meal (MEN), anchovy fish meal (ANCH), pet-food grade poultry by-product meal (PBM-pet), feed-grade poultry by-product meal (PBM-feed), dehulled soybean meal (SBM), and distiller’s dried grains with solubles (DDGS). Test diets consisted of a 70:30 mixture of reference diet to test ingredient with chromic oxide (1.0%) as the inert marker. Reference and test diet ingredients were mixed and extruded on a Wenger X85 single-screw extruder to produce floating pellets. The digestibility trials were conducted in twelve 1200-L circular tanks. Diets were randomly assigned to tanks of 30 sunshine bass and were fed once daily to satiation. Protein digestibility coefficients were significantly (P < 0.05) different among test ingredients and ranged from 86% for MEN to 65% for DDGS. Lipid ADCs were significantly different (P < 0.05) among test ingredients and ranged from 92% for MEN to 57% for SBM. Organic matter ADCs were significantly different (P < 0.05) among test ingredients and ranged from (90% for MEN to 17% for DDGS. This information will assist in the formulation of more efficient, economical diets for sunshine bass.