Effect of simultaneous variation of weight, density, temperature and O₂ concentration on rainbow trout (Oncorhynchus mykiss) body composition

Abstract

Summary &horbar; The simultaneous effect of weight, initial density (kg/m 3 , temperature and 0 2 concentration on rainbow trout body composition (fat, protein, moisture and ash) has been studied. In 3 successive experimental phases fish were kept in different lots of varying initial weight (178-372 g), initial density (7.2-38.8 kg/m 3 ) and temperature (15-20 °C). Slmple correlations were statistically significant for weight vs fat (r = 0.56; P < 0.001 ) and moisture (r = -0.57; P < 0.001 temperature vs fat (r = 0.73; P < 0.001) moisture (r = -0.73; P < 0.001) and ash (r = -0.26; P < 0.02); and 0 2 concentration vs fat (r = 0.22; P < 0.05). Multivariant equations for the different compounds were obtained. Only fat and moisture percentages showed significant differences (r m = 0.75; P < 0.00005); an inverse relation existing between them (r = -0.94; P < 0.001 Temperature is the factor which has the strongest influence on fat and moisture when it varies simultaneously with weight, initial density and 0 2 concentration, which is shown by its equation coefficients (P < 0.00005).rainbow trout / body composition / temperature / weight / density / 0 2 concentration Résumé &horbar; Effet de différents facteurs sur la composition corporelle de la truite arc-en-ciel.L'effet simultané du poids, de la densité de population initiale (kgI M 3 ), de la température et de la concentration d'oxygène a été étudié sur la composition corporelle de la truite arc-en-ciel (graisses, protéines, humidité et cendres). Les poissons ont été maintenus pendant 3 périodes expérimentales successives en lots séparés différant par le poids initial (178-372 g), la densité initiale (7,8 kgl m 3 ) et la température (15-20 °C).Les corrélations simples sont statistiquement significatives entre le poids des animaux et le pourcentage des graisses (r = 0,56; P < 0,001) et celui de l'humidité (r = -0,57; P < 0,001), et entre la tempé-rature et le pourcentage des graisses (r = 0,73, P < 0,001), de l'humidité (r = -0,73; P < 0,001) et des cendres (r =-0,26, P < 0,02). Des équations multivariantes ont été obtenues pour les différentes composantes. Seuls les pourcentages de graisse et d'humidité changent significativement en relation inverse (r = -0,9 4 , P < 0,001), ), sous l'effet des facteurs considérés (r m = 0,75, P < 0,00005).

The chemical composition of two commercial fish species – pikeperch (Sander Lucioperca) and rainbow trout (Oncorhynchus Mykiss) cultivated in artificial conditions

“…As mentioned above, in the different periods of cultivation the water temperature in cages rose up to 26 °C exceeded the thermal optimum for this species. As a result it had an impact on higher lipid content, which is corresponds with the data obtained by Martinez et al (1992) Based on the foregoing, we can say that both farmed species had high nutritional value and concede nothing to wild specimens or a previous cultivation experience.…”

“…This explains the relatively reduced moisture (69.61%), since it is well known that quantity of water is inversely proportional to the quantity of fat (Shafi, 2003). One of the factors responsible for the increase in fat is the rise of temperature (Martinez et al, 1992). As mentioned above, in the different periods of cultivation the water temperature in cages rose up to 26 °C exceeded the thermal optimum for this species.…”

Fatty acids in muscle of wild and farmed red porgy, Pagrus pagrus

“…This difference in the fat content of white muscle may be due to two factors. First, fish fed with commercial diets show a greater body fat content than their wild equivalents (Ackman 1989;Shearer 1994), and second, the percentage of lipids in fish tended to increase with fish size (Martínez et al 1992;Shearer 1994). The size of the individual fish used in our experiment varied.…”

Manipulation of end-product quality of rainbow trout with finishing diets

“…During development, various physical and physiological parameters in rainbow trout alter. Good examples of such ontogenetic change include lipid content (Denton & Yousef 1976;Weatherley & Gill 1983b;Kim & Kaushik 1992;Martinez et al 1992;Rùnsholdt 1995) and visceral fraction (Weatherley & Gill 1983a). The present study evaluated ®sh of the same size, thereby avoiding size-dependent in¯uences on quality characteristics.…”