Effect of alternative lipids and temperature on growth factor gene expression in yellowtail kingfish (Seriola lalandi)
2014
Collins, Geoffrey M | Ball, A. S. | Qin, Jian G | Bowyer, Jenna N | Stone, David A J
This study was undertaken to assess the efficacy of utilizing insulin‐like growth factor 1 (IGF‐I) and insulin‐like growth factor binding protein 1 (IGFBP‐1) as endocrine biomarkers to provide a rapid indication of yellowtail kingfish growth using real‐time, reverse‐transcriptase quantitative PCR (RT‐qPCR). Two experiments were conducted separately (5 weeks each) at an optimal water temperature (22°C) using fish weighing 95.6 ± 0.1 g (mean ± standard deviation, n = 3) and at a sub‐optimal water temperature (18°C) using similar‐sized fish (101 ± 0.1 g, n = 3). Four experimental diets were formulated to contain poultry oil (PO) or canola oil (CO) at 50% or 100% inclusion as a substitute for fish oil (FO). A diet containing 100% FO was used as a control. Irrespective of diet, fish grew faster at 22°C than at 18°C. The 100% replacement of FO by CO resulted in the poorest fish growth at both temperatures. IGF‐I expression correlated with growth rate at 22°C, but the same trend was not seen at 18°C. Hepatic IGF‐I and IGFBP‐1 mRNA expression were also positively correlated. This study suggests that hepatic IGF‐I mRNA assessed by RT‐qPCR with additional methodological development may be used to accurately assess the influence of diet on growth of some fish species used in aquaculture.
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