Effect of different inorganic phosphorus sources on growth performance, digestibility, retention efficiency and discharge of nutrients in rainbow trout (Oncorhynchus mykiss)

This study aims to evaluate the effect of different sources of inorganic phosphate, monosodium phosphate (MSP), monocalcium phosphate (MCP) and monoammonium phosphate (MAP), included in a diet for rainbow trout, on growth performance, nutrient digestibility, nutrient retention efficiency and discharge of nutrients to the water. Juvenile rainbow trout (Oncorhynchus mykiss) with an initial weight of 120 g were fed for 56 days four experimental diets: basal diet containing 430 g kg−1 protein, 210 g kg−1 lipids and 6.7 g kg−1 total phosphorus (P) (Control), and three experimental diets consisting in the basal diet plus 4 g P kg−1 from MSP, MCP and MAP, respectively. Both MSP and MAP resulted in higher levels of P apparent digestibility (≈90%) compared to MCP (70%), increasing the dry matter digestibility of the nutrient in the feed. The retention efficiency of P in fish tissues was increased by nearly 15% units over the Control when MSP and MAP were used as P supplement, whereas in agreement with the lower digestibility observed in MCP, P retention efficiency from this phosphate source was lower than the other sources. Total P discharge to the water was similar for MSP, MCP and MAP (4.12–4.58 g kg−1 BW fish gain). However, fish fed with MCP showed higher solid/particulate P discharge to the water through faeces due to the lower digestibility of this P–source within the gut of the fish. Among the phosphate salts evaluated, fish fed MSP and MCP did not show differences for soluble or solid N discharged fractions. However, fish fed the diet supplemented with MAP released a higher amount of non–protein N fraction to the water, probably as undigested ammonium through the faeces released by fish.Fil: Morales, Gabriel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Azcuy, Rosendo Lucas. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casaretto, Matías Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Márquez, Lorenzo. Universidad Católica de Temuco; ChileFil: Hernández, Adrián J.. Universidad Católica de Temuco; ChileFil: Gómez, Federico. Yara International ASA; NoruegaFil: Koppe, Wolfgang. Simplyfish AS; NoruegaFil: Mereu, Alessandro. Yara International ASA; Norueg

In vitro characterization of Acrocomia totai defatted kernel meal as a novel raw material in Nile tilapia Oreochromis niloticus feed and the effect of exogenous phytase inclusion over nitrogen and phosphorus bioavailability

This work aimed to explore the potential value of the Acrocomia totai defatted kernel meal as an alternative feed ingredient for Nile tilapia (Oreochromis niloticus) diet. In vitro assays were conducted simulating tilapia digestion. Soybean meal was included as a reference and two phytase doses were assayed. After running the gastrointestinal simulations, amino acids bioavailability from soybean meal with phytase addition was higher than in the other treatments. However, when expressed on a crude protein content basis, the relative performance of the treatments with A. totai improved. The protein composition of the raw materials affected their performance because of globulins and specific amino acids such as arginine, lysine and histidine. A higher relative contribution of these last in Acrocomia kernel protein determined their lower compared performance. Phosphorus bioavailability from Acrocomia, expressed on a dry matter basis, was the highest, but increments resulting from phytase addition, expressed on a phytic acid basis, were not significantly different between raw materials. Therefore, no specific affinity between phytase and the raw materials’ phytic acid was evidenced. This study demonstrated that A. totai kernel meal has potential as a protein source in aquafeed but also it has limitations: it is a big phytic phosphorus source that is only available with phytase addition.Instituto de Investigación de Tecnología de AlimentosFil: Casaretto, Matías Ezequiel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Acuicultura; Argentina.Fil: Casaretto, Matías Ezequiel. CONICET - Universidad de Buenos Aires. Instituto de Investigaciones en Producción Animal; Argentina.Fil: Travaini, Franco Luciano. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Acuicultura; Argentina.Fil: Wassner, Diego Fernán. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Vegetal. Cátedra de Cultivos Industriales; Argentina.Fil: Pazos, Adriana Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación Tecnología de Alimentos; Argentina.Fil: Azcuy, Rosendo Lucas. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Acuicultura; Argentina