Abstract
The objective of this work was to determine the dietary lysine (DL) and dietary arginine (DA) requirements of dourado (Salminus brasiliensis), through dose-response trials using the amino acid profiles of whole carcasses as a reference. Two experiments were carried out in a completely randomized design (n=4). In the first experiment, groups of 12 feed-conditioned dourado juveniles (11.4±0.2 g) were stocked in 60 L cages placed in 300 L plastic indoor tanks in a closed circulation system. Fish were fed for 60 days on diets containing 1.0, 1.5, 2.0, 2.5, 3.0, or 3.5 % dietary lysine. In the second experiment, dourado juveniles (27.0±0.8 g) were fed for 60 days on semipurified diets containing arginine at 1.0, 1.5, 2.0, 2.5 or 3.0%, in similar conditions to those of the first experiment. Optimal DL requirements, as determined by broken-line analysis method for final weight, weight gain and specific growth rate, were 2.15% DL or 5% lysine in dietary protein, and 1.48% DA or 3.43% arginine in dietary protein. The best feed conversion ratio is attained with 2.5% DL or 5.8% lysine in dietary protein and 1.4% DA or 3.25% arginine in dietary protein.
Highlights
Dourado [Salminus brasiliensis (Cuvier, 1816)] is one of the largest South American Characins, it dwells in the Paraná, Paraguay, and Uruguay rivers, the segments of the greater Prata Basin, as well, in Brazilian São Francisco River Basin (Fracalossi et al, 2004)
No external deficiency signs or body deformities were registered for dourado juveniles in the present study, regardless of dietary lysine (DL) level
Citations in the literature show DL values that vary between 1.36% (4.5% LPD) for jundiá [Rhamdia quelen (Quoy & Gaimard, 1824)] (Montes‐Girao & Fracalossi, 2006) and 2.83% (5.56% lysine in the dietary protein (LDP)) for grouper [Epinephelus coioides (Bloch, 1793)] (Luo et al, 2006), as well
Summary
Dourado [Salminus brasiliensis (Cuvier, 1816)] is one of the largest South American Characins, it dwells in the Paraná, Paraguay, and Uruguay rivers, the segments of the greater Prata Basin, as well, in Brazilian São Francisco River Basin (Fracalossi et al, 2004). Dourado is a highly valued species for sport fishing, and prized for its excellent flesh quality and accelerated growth rate, which triggered interest in the use of the species for farming purposes in the late 1990s. Proteins represent 65‐75% of any given fish carcass dry mass. The biological value of any dietary protein varies with its amino acid composition and availability. Requirements for a given amino acid are the sum of requirements for maintenance processes and for tissue growth (Liebert, 2005). Dietary deficiency or low‐essential amino acid availability hampers protein use by fish and, reduces feed efficiency and growth rate
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