Effects of ration on somatotropic hormones and growth in coho salmon

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 128; no. 2; pp. 255 - 264
• Main Authors: Pierce, Andrew L., Beckman, Brian R., Shearer, Karl D., Larsen, Donald A., Dickhoff, Walton W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01-02-2001
• Subjects: Analysis of Variance; Animals; Body Constitution; Coho salmon ( Oncorhynchus kisutch); Diet; Growth; Growth hormone (GH); Growth Hormone - metabolism; Hatchery; Insulin-Like Growth Factor I - metabolism; Insulin-like growth factor-I (IGF-I); Nutrition; Oncorhynchus kisutch; RNA, Messenger - metabolism; Somatotrophic; Time course; Time Factors; Insulin-like growth factor-I (IGF-I); Time course; Nutrition; Growth; Coho salmon ( Oncorhynchus kisutch); Growth hormone (GH); Hatchery; Somatotrophic
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/S1096-4959(00)00324-9

We examined the response of growth hormone (GH), total plasma insulin-like growth-factor I (IGF-I), and growth rate to a change in ration in coho salmon. Tanks of individually tagged fish were placed on high, medium, or low ration, and sampled every 2 weeks for 8 weeks to create a range of growth rates. Some fish received non-lethal blood draws, while others were sampled terminally. Plasma IGF-I levels were higher in high ration fish than in low ration fish from 4 weeks after the beginning of experimental diets to the end of the experiment. GH levels were low and similar in all fish after changing rations, except for the fish in the low ration group at week 2. IGF-I was strongly correlated with specific growth rate in weight in terminally sampled fish after 4 weeks. GH did not correlate with growth rate or IGF-I levels. Growth parameters (length, weight, specific growth rates in weight and length, and condition factor) responded to ration. Serial sampling reduced growth rates and hematocrit, but did not change hormone levels. This study shows that IGF-I responds to changed rations within 2–4 weeks in salmonids.