Mô hình sinh năng lượng học cho cá mú chấm đen (<i>Epinephelus malabaricus</i>): Dự báo sinh trưởng, lượng thức ăn cá sử dụng, thành phần của mức tăng khối lượng và thể trọng chuyển hóa

Abstract

    Malabar grouper, which is a commercially important candidate for mariculture, has been farmed in Vietnam since 1988. In order to develop effective and environmentally friendly feeds, the grouper’s requirements for key nutrients have been quantified. Based on 15 data sets collected from grouper farms and experiments in Viet Nam between 2005 and 2017, the daily weight gain as a function of body weight (g) and water temperature (^oC) was predicted by the equation: WG (g) = (0.000179*T³ – 0.01714*T² + 0.522468*T – 5.00525)*BW^0.56. Similarly, the daily feed intake was predicted by the equation: FI (g) = (-0.00021*T³+0.014847*T²-0.33092*T+2.411174)*BW^0.7, in which T is water temperature (24-31^oC). The composition of the gain was measured by analyzing whole fish ranging from 5 to 700g. While the protein content remained constant at 169.4 mg g^-1, the energy content was dependent upon fish weight and increased from 4.4 to 7.0 kJ g^-1 body mass and can be expressed by the equation: y (kJ g^-1) = 3.51*BW^0.102. Metabolic rate depends largely on the size of the fish and is proportional to the metabolic body weight in the form of a*BW(kg)^b. To define the exponent b of the metabolic body weight the relationships between energy and protein loss at starvation for fish at increasing weights were determined. The daily loss of energy and protein was presented by the equations: Energy loss (kJ fish^-1 day^-1) = 0.111× BW^0.827; and Protein loss (g fish^-1 day^-1) = 0.003×BW^0.701. The exponents of (kg)^0.8 and (kg)^0.7 can thus be described for malabar grouper as the metabolic body weights for energy and protein, respectively. Based on those results, a bioenergetic model can be built preliminarily to develop feed formulations for malabar grouper.

Keywords: Weight gain; Feed intake; Growth prediction; Energy loss; Protein loss.