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Growth, faecal production, nitrogenous excretion and energy budget of juvenile cobia (Rachycentron canadum) relative to feed type and ration level  [2006]

Sun, L. Chen, H. Huang, L. Wang, Z.

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Growth, faecal production, nitrogenous excretion and energy budget of juvenile cobia (initial body weight approximately 28 g) at different ration levels (RL, % per day) ranging from starvation to ad libitum for three feed types, i.e., natural sardine fish (NSF), commercial eel formulated feed (CEFF) and commercial marine-fish formulated feed (CMFF), were investigated in this study. Both feed type and ration level affected significantly faecal production (f, mg g-1 day-1), and nitrogenous excretion (mu, mg g-1 day-1). Feed type, not ration level, for the NSF-fed and CEFF-fed groups and both feed type and ration level for the CMFF-fed group affected significantly feed absorption efficiency (FAE, %). For each feed type group, faecal production and nitrogenous excretion increased whereas feed absorption efficiency in dry weight (FAE(d), %), protein (FAE(p), %) and energy (FAE(e), %), with a small variation, tended to decrease as ration increased. Specific growth rate in wet weight (SGR(w), % per day), dry weight (SGR(d), % per day), protein (SGR(p), % per day) and energy (SGR(e), % per day) for the NSF-fed and CEFF-fed groups was much higher than that for the CMFF-fed group, and the growth-ration relationship was a decelerating curve described as a logarithmic equation for the NSF-fed and CEFF-fed group, and a linearity described as a simple equation for the CMFF-fed group. There was a significant difference of the slopes in the regression equations among thre
e feed type groups by analysis of covariance. Multiple regression analysis showed that the relationships between specific growth rate (SGR, % per day) and ration level in dry weight (RL(d), % per day) as well as feed type (D1 D2) were SGR(w) = - 2.226 + 4.022ln(RL(d) + 1) - 0.895D1 - 2.705D2, SGR(d) = - 2.686 + 4.422ln(RL(d) + 1) - 1.014D1 - 2.969D2, SGR(p) = - 2.481 + 4.316ln(RL(d) + 1) - 1.122D1 - 2.943D2 and SGR(e) = - 3.239 + 4.972ln(RL(d) + 1) - 0.954D1 - 3.053D2. Feed conversion efficiency in wet weight (FCE(w), %), dry weight (FCE(d), %), protein (FCE(p), %) and energy (FCE(e), %) for the NSF-fed and CEFF-fed groups was much higher than that for the CMFF-fed group, and with increased ration FCE increased or first increased then decreased for the NSF-fed and CEFF-fed groups and increased significantly for the CMFF-fed group. Energy budgets of juvenile cobia at satiation ration were 100A = 59R + 41G for NSF-fed group, 100A = 67R + 33G for CEFF-fed group and 100A = 83R + 17G for CMFF-fed group, where A is assimilated energy R is energy spent in metabolism and G is energy stored as growth.

From the journal

Aquaculture

ISSN : 0044-8486

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