Effect of water temperature on growth and nutrient utilization of sunshine bass (Morone chrysops ♀ X Morone saxatilis ♂) fed diets containing different energy/protein ratios

An experiment was conducted to examine the effect of dietary energy/protein (E/P) ratio on the growth of fingerling sunshine bass (about 3-4 g/fish) held at water temperatures of 26.7 and 32.2 degrees C, Six semipurified diets were prepared combining three protein levels (35%, 40% and 45%) and two lipid levels (5% and 15%) to yield E/P ratios of 6, 7, 8, 9, 10 and 11 kcal estimated available energy/g protein. Fish were held in 110-1 aquaria (25 fish/tank), supplied with continuous flow of filtered, fresh water. Each diet was randomly assigned to triplicate groups of fish and fed to satiation twice a day for 8 weeks. Feed consumption decreased with increasing dietary E/P ratio. Growth and nutrient utilization were Significantly higher in fish maintained at 26.7 degrees C than those held at 32.2 degrees C, Feed efficiency (FE), protein efficiency ratio (PER), and protein conversion efficiency (PCE) were optimum at a dietary E/P ratio of 9 kcal/g protein. Whole-body lipid deposition and intraperitoneal fat accumulation (IPF ratio) increased as dietary lipid increased. Hepatosomatic index (HSI) changed differently at these two temperatures but HSI and liver glycogen at each temperature were positively correlated. At 32.2 degrees C liver glycogen deposition was positively correlated with dietary carbohydrate (dextrin) levels. The higher feed consumption and lower energy conversion efficiency (ECE) of fish held at 32.2 degrees C indicates an increased energy requirement for maintenance and/or activity in these fish. (C) 1998 Elsevier Science B.V. All rights reserved.