Relationship between blood and muscle levels of astaxanthin in dorsal aorta cannulated Atlantic salmon Anders Kiessling a,d, ⁎ , Bakshish Dosanjh b,e , Wolfgang Koppe c , Dave Higgs b a Department Aquaculture, Swedish University of Agricultural Sciences (SLU), S-901 87 Umeå, Sweden b West Vancouver Laboratory, Department of Fisheries and Ocean (DFO), 4160 Marine Drive, V7V 1N9 West Vancouver, B.C., Canada c Nutreco Aquaculture Research Centre AS, P.O. Box 48 Sentrum, N-4001 Stavanger, Norway d Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences (UMB), P.O. Box 5003, N-1432 Ås, Norway e EWOS Canada Ltd., 7721 132nd Street, V3W 4M8 Surrey, B.C., Canada Received 11 May 2005; received in revised form 31 October 2005; accepted 31 October 2005 Abstract Twelve previously unpigmented Atlantic salmon with a body weight of 545±39 (SE) g were kept individually and fed a diet containing 69 mg·kg - 1 astaxanthin for 63 days. On day 35 each fish was fitted with a dorsal aorta cannula. During the last 28 days blood levels of astaxanthin were measured on three separate occasions. At 63 days the fish were slaughtered and muscle content of astaxanthin was analysed. The fish had grown by an average of 171 ± 29 g, with an SGR of 0.61 ± 0.08, with a feed conversion ratio of 0.84 ± 0.10 and astaxanthin retention of 7–10%, during the 63-day period. The average blood concentration of astaxanthin was 0.65 ± 0.09 μg·g - 1 and muscle content was 0.68 ± 0.12 mg·kg - 1 . Muscle content and retention of astaxanthin varied closely with that of blood concentration (R 2 = 0.92, p b 0.0001, R 2 = 0.88, p b 0.0001, respectively) independent of fish size and feed intake. On the other hand, the effect of feed intake on astaxanthin blood level was less clear. Only SGR (R 2 b 0.1) among the other factors measured, such feed conversion, body size or feed intake (expressed as percent of body weight) were significant (p N 0.05) related to either astaxanthin blood or muscle level. On the basis of the data and provided that feed intake and fish is included in the analysis, we concluded that the level of astaxanthin in blood is indicative of long-term muscle deposition and can be used as a rapid scanning method to distinguish between the effects of different dietary treatments on long-term deposition of astaxanthin in muscle. © 2005 Elsevier B.V. All rights reserved. Keywords: Dorsal aorta cannulation; Atlantic salmon; Pigment retention; Carotenoids; Feed intake 1. Introduction Understanding the effects of muscle deposition of carotenoids in salmonids demands long-term studies involving large numbers of animals. This is because deposition is slow and intra-individual variations are large (Choubert et al., 1994; Gobantes et al., 1997). Blood levels of carotenoids have therefore been used in order to decrease the length of time of observations between dietary alterations and their effects on uptake. Moreover, measurements of blood levels with repeated sampling from the same individuals allow measure- ments to be made before and after application of an effector and thereby paired statistics tests, reducing the error factor due to inter-individual variations (Kiessling Aquaculture 254 (2006) 653 – 657 www.elsevier.com/locate/aqua-online ⁎ Corresponding author. Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway. Tel.: +47 64965186; fax: +47 64965101. E-mail address: anders.kiessling@umb.no (A. Kiessling). 0044-8486/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2005.10.038