Effect of dietary phosphorus and vitamin D3 on phosphorus levels in effluent from the experimental culture of rainbow trout (Oncorhynchus mykiss)
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Excessive phosphorus (P) levels in aquaculture effluents violate federally mandated limits and pose a serious threat to the freshwater environment. In rainbow trout culture, effluent P probably originates as fecal and metabolic waste product because assimilation of dietary P is relatively low. We therefore decreased dietary P and increased dietary vitamin D3 levels, methods that enhance P assimilation in mammals, in purified and semi-purified trout diets, then monitored effluent P. Soluble effluent P reached a peak right after feeding and returned to baseline levels in between feeding times. The peak and average concentrations of soluble P in the effluent were mainly influenced by dietary P. Average P in fecal dry matter also decreased with dietary P. Neither dietary P nor vitamin D3 under the conditions of the experiment had significant effects on whole body P content but P deposition (as a percentage of P intake) decreased with increased dietary P. The dietary combination of low P and high vitamin D3 decreased soluble and fecal P levels in the effluent indicating a strategy whereby effluent P concentrations can be reduced by regulation of P metabolism.
CitationColoso, R. M., Basantes, S. P., King, K., Hendrix, M. A., Fletcher, J. W., Weis, P., & Ferraris, R. P. (2001). Effect of dietary phosphorus and vitamin D3 on phosphorus levels in effluent from the experimental culture of rainbow trout (Oncorhynchus mykiss).
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