Varying protein sources and application of ideal protein concept in formulation of feeds for largemouth bass (Micropterus salmoides)

Author(s)

Leandro Portz

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2001-10-26
• Advisor: Jose Eurico Possebon Cyrino

Abstract

The development of processed feeds of high nutritional value and economical feasibility depends on the in-depth knowledge about the nutritional requirements of intensively farmed fish. This work aims to determine nutritional amino acids requirements of the black bass Micropterus salmoides based in the ideal protein concept. Nutrients and amino acids contents of roe and of the carcass of different size classes of the black bass were determined and compared to results of selected, classic works related to the concept of ideal protein, dealing with different, commercially farmed fish. Protein contents in the roes of the black bass were higher in comparison to the carcass, but the contents of lipids of the roes and of the carcass did not present significant difference (P>0,01). Black bass showed significantly higher muscle protein and amino acids contents in comparison to tilapia, surubim (P<0,05); values of the relationship between the contents of individual, essential amino acids and the total contents of essential amino (A/E) followed the same trend. Results herein presented indicate that the amino acids profile of largemouth bass and surubim could be used as complementary tool for balancing amino acids in formulated feed for these species, and in the validation of amino acids requirements determined in performance studies. Another trial was set up to evaluate apparent digestibility coefficients of dry matter, protein, lipids, energy, calcium and phosphorus, and both essential and non-essential amino acids availability of animal and vegetable protein sources used in practical diets of carnivorous fish. Juvenile black bass (8,0 &#177; 0,5 g; 10,0 &#177; 0,3 cm) conditioned to accept artificial feed and stocked in plastic cages were fed with pelleted test diets - 30% of the ingredient tested mixes with 70% of a reference ration (RR), containing 40% CP and 4.741 kcal/kg GE and 0,5% Cr203. Cages were transferred to cylinder, conical-bottomed aquaria (200 L) where the feces were collected by sedimentation in refrigerated container. Protein sources presented high apparent digestibility coefficients (ADC) for protein and lipid; ADC of tested amino acids presented significant differences (P<0,01). Results allow to infer that the soybean meal and com gluten me ai can partially replace animal protein sources in carnivorous fish diets, reducing final production costs. One last assay aimed to evaluate the effects of the substitution of fish meal - FM by poultry by product me ai - PM in camivorous fish feeds, formulated by the concept of ideal protein. Six commercial, iso-nitrogenous (43% CP) and iso-energetic (3.870 kcal/kg GE) diets, containing increasing contents of PM - 20FM:OPM; 0FM:20PM; 5FM:20PM; 10FM:15PM; 15FM:10PM; 20FM:5PM, were fed to largemouth (21,0 &#177; 1,5 g) in a completely randomized design (n=4). Diets containing PM led to better performance and feed conversion ratio (P<0,05), dietetic protein and energy retention. Except for the phosphorus, differences were detected (P<0,05) for the ADC of dry matter, protein, carnivorous fish is technically possible and economically feasible. (AU)