|Rawles, Steven - Steve|
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2007
Publication Date: 2/9/2008
Citation: Thompson, K.R., Rawles, S.D., Metts, L.S., Simth, R., Wimsatt, A., Gannam, A.L., Twibell, R.G., Johnson, R.B., Brady, Y.J., Webster, C.D. 2008. Comparison of two different fecal collection methods for protein digestibility and amino acid availability coefficients of three animal protein sources for sunshine bass (Morone chrysops x Morone saxatilis) [abstract]. Book of Abstracts Aquaculture America. p. 396.
Technical Abstract: Apparent digestibility coefficients (ADCs) for protein and individual amino acid availabilities in menhaden fish meal (MEN) and two grades of poultry by-product meal (PBM) were determined for market-size (500 g) sunshine bass using two different fecal collection methods, passive netting (net) or manual stripping (strip) of feces. The two grades of PBM tested were pet-food grade (PBM-pet) and feed-grade (PBM-feed). Test diets consisted of a 70:30 mixture of a reference diet and test ingredient. The reference diet resembled a commercial diet which met or exceeded all known nutritional requirements of sunshine bass. Each diet by collection method combination was randomly assigned to triplicate tanks. Fish were fed their respective diets twice daily to apparent satiation for 6 d and then given a single meal on the morning of the seventh day prior to fecal collection. There was no significant interaction (P = 0.29) between test diet and fecal collection method for protein digestibility, but both factors independently influenced protein digestibility. Digestibility of protein ranged from a low of 51% (PBM-feed) to a high of 87% (PBM-pet) in the net method, and from a low of 79% (PBM-feed) to a high of 98% (MEN) in the strip method. Regardless of method, protein digestibility in MEN and PBM-pet were not different but were greater than that of PBM-feed. Regardless of test diet, protein digestibility was significantly greater for manual stripping (87.4%) than for net collection (72.8%). Apparent amino acid availabilities were highly variable among the tested products in both collection methods. Availability of glycine, threonine, valine, phenylalanine, isoleucine, and leucine were significantly different among test diets. There were no significant differences among availabilities of nine additional amino acids measured in the test diets. Amino acids in MEN were generally more available than those of both PBMs. These data indicate that net collection of fecal matter is not recommended for determining digestibility coefficients for market size hybrid striped bass. ADCs determined from the strip method, however, should help improve diet formulations for market size hybrid striped bass.