Effects
of Dietary Lipid Levels and Energy:Protein Ratios on Growth and Feed
Utilization of Juvenile Nassau Grouper Fed Isonitrogenous Diets at Two
Temperatures
E.G. Johnson,
W.O. Watanabe, S.C. Ellis-2002
North American Journal of Aquaculture, 64(1): 47–54
Abstract:
The growth and feed
utilization of juvenile Nassau grouper Epinephelus striatus
(mean weight = 2.12 g; N = 9) were compared for 75 d in laboratory aquaria
supplied with flow-through seawater. Fish were fed four isonitrogenous (45%
crude protein) diets differing in lipid content (6, 9, 12, or 15% dry
weight) and energy:protein (E:P) ratio (28.4, 31.0, 33.5, or 36.0 kJ/g
protein) at two temperatures (25°C and 30°C). Specific growth rates and
final weights increased (P < 0.001) with decreasing dietary lipid and E:P
ratios, from a minimum of 1.20% of body weight (bw) per day (5.21 g) for
fish fed the 15% lipid diet to a maximum of 2.04% bw/d (9.31 g) for fish fed
the 6% lipid diet. The specific growth rate was greater (P < 0.01) at 30°C
(1.38–2.09%/d) than at 25°C (1.02–1.99%/d). Feed consumption
(2.16–3.30% bw/d) was inversely correlated (P < 0.001) to dietary lipid
content and E:P ratio and was greater (P < 0.005) at 30°C than at 25°C.
Feed conversion ratio (1.91–2.74) was positively correlated and protein
efficiency ratio (1.01–1.45) negatively correlated with dietary lipid
content and E:P ratio (P < 0.01). Thus, for diets consisting of 45%
protein, those with lipid contents of 6–9% produced greater feed
consumption, efficiency, and growth of juvenile Nassau grouper than those
with 12–15% lipids. Feed consumption and growth were greater at 30°C than
at 25°C.
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