Effects of organic acids on growth and phosphorus utilization in red sea bream Pagrus major

A feeding experiment was conducted to investigate the effects of various organic acids and supplements on the growth, phosphorus (P) utilization, and environmental loading of nitrogen (N) and P in red sea bream Pagrus major. Seven diets designated as PA (0.5% inorganic P as Ca[H₂PO₄]₂), PO (no inorganic P), CA (1% citric acid), MA (1% malic acid), LA (1% lactic acid), MHA (1% methionine hydroxy analog) and LTE (1% liquid trace elements) were formulated. Duplicate groups of 25 fish were fed four times daily to near satiation for 75 days. Fish fed CA and LTE diets showed significantly better weight gain and feed conversion ratio compared to fish fed diet PO. Absorption of P was significantly improved in all organic acid-supplemented groups compared to the PA and PO groups. The P retention in CA and LTE groups were significantly higher compared to PA and PO diets. The P excretion was also significantly decreased in all organic acid-supplemented groups. Thus, use of organic acids, in particular CA and LTE, in red sea bream diets can reduce the use of inorganic phosphorus and contribute to the development of much-desired eco-friendly diets.