Author
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Riche, Martin |
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Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only Publication Acceptance Date: 2/6/2013 Publication Date: 2/21/2013 Citation: Riche, M.A. 2013. Amino acid availability from select feed ingredients in the euryhaline Florida pompano Trachinotus carolinus adapted to seawater and low salinity [abstract]. Book of Abstracts Aquaculture America. Abstract No. 1263. Available: https://www.was.org/wasmeetings/meetings/ShowAbstract.aspx?Id=29702. Interpretive Summary: Technical Abstract: As with most marine carnivores, Florida pompano require relatively high crude protein diets to obtain optimal growth. Precision formulations to match the dietary indispensable amino acid pattern to a species' requirements can be used to increase protein efficiency and lower overall dietary protein. However, these formulations must be based on an available amino acid (AA) basis. Digestibility and availability coefficients for only a few ingredients have been reported for this species. Moreover, there is some evidence to suggest these coefficients may vary with environmental salinity. The objective of this study was to determine digestibility and AA availability coefficients from a variety of plant- and animal-based proteins considered potential feed ingredients for pompano diets, and to determine the effects of salinity on the coefficients. A randomized complete block design with two replicate systems each, for seawater (28 ppt) and low salinity (3 ppt) served as blocks, with two replicates per block (N=4). Coefficients were determined for a reference diet, Special Select TM menhaden fish meal, fishery processing by-product, yeast protein, barley protein concentrate, corn protein concentrate, canola protein concentrate, and spirulina in compounded, extruded diets. The reference diet was blended with the test ingredients in a 70:30 ratio to form the test diets. All diets included yttrium oxide (0.1 % of diet) as an inert marker. Following acclimation to their respective salinities, 25 fish (36 +/= 4 g) were stocked per tank. Fish were fed twice daily (5% BW) and fecal samples collected by manual stripping 3 h after feeding on day 5 and 7. Samples were pooled and freeze-dried for analysis. Ingredient, diet and fecal nutrient compositions and digestibility coefficients were determined by standard methods. Coefficients were tested as pair-wise comparisons between salinities and declared significantly different at the P<0.05 level. No differences were detected between salinities for the coefficients for arginine, methionine, or tyrosine among any of the ingredients. Where differences were detected, coefficients generally tended to be higher among fish adapted to seawater, with the exception of the canola protein concentrate where alanine and histidine were higher in low salinity adapted fish. Most all of the AA coefficients in the menhaden meal and yeast protein were higher in saltwater adapted fish. Coefficients for alanine, glutamate + glutamine, and proline were higher in seawater adapted fish for most of the ingredients evaluated, as were the branch chain amino acids in menhaden meal, yeast protein concentrate, and barley protein concentrate. There are several possible mechanisms for these observed differences. Nevertheless, these results suggest there are practical implications for consideration by feed manufacturers and industry in formulating diets for euryhaline species reared at different salinities. |
