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Title: Analysis of retinol, 3-hydroxyretinol and 3,4-didehydroretinol in North American farm-raised freshwater fish liver, muscle and feed

Author
item Lafrano, Michael
item Burri, Betty

Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2013
Publication Date: 12/1/2014
Citation: Lafrano, M.R., Burri, B.J. 2014. Analysis of retinol, 3-hydroxyretinol and 3,4-didehydroretinol in North American farm-raised freshwater fish liver, muscle and feed. Aquaculture Nutrition. 20(6):722-730. DOI: 10.1111/anu.12126.

Interpretive Summary: Vitamin A is an essential nutrient. Retinol (ROL) and retinyl palmitate are important forms of vitamin A in animals and humans. Freshwater fish also use retinol and retinyl palmitate. However, they also make and use uncommon forms of vitamin A. These uncommon forms include 3,4-didehydrotinol (DROL) and 3-hydroxyretinol (3ROL). Little information is available about the concentrations of DROL and 3ROL in fish tissues or food. The concentrations of ROL, DROL and 3ROL were measured in the muscle, liver, and feed of several North-American farm-raised freshwater fish. Concentrations varied widely within fish species, and between fish species. Silver carp typically had low retinoid concentrations, while catfish had high concentrations. Interestingly, DROL concentrations were lower than ROL in fish feed, but often substantially higher than those of ROL in fish liver. This suggests that ROL converts to DROL in the liver, or that DROL is stored there preferentially. Low concentrations of 3ROL was detected in all fish liver (2.1 – 14.9 ug/g) but not in muscle and feed. To our knowledge, this is the first comparison of DROL and ROL concentrations in fish versus fish feed. It is also the first to identify DROL concentrations in North American farm-raised fish and commercial fish feed.

Technical Abstract: Vitamin A (retinol; ROL) is an essential micronutrient in fish, vital for vision and cell growth. Freshwater fish species also synthesize uncommon forms of VA, such as 3,4-didehydrotinol (DROL) and 3-hydroxyretinol (3ROL) that have biological activity. However, little information is available about the concentrations of these retinoids in fish tissues or food. The concentrations of ROL, DROL and 3ROL were measured in the muscle, liver, and feed of several North-American farm-raised freshwater fish. The concentrations of retinoids varied widely within and between fish species and tissues. However, silver carp typically had low retinoid concentrations, while catfish had high concentrations. Interestingly, DROL concentrations (mean ± SD; 22.1 mg/kg ± 11.3) were lower than ROL (54.4 mg/kg ± 25.0) in fish feed, but often substantially higher (237.2 µg/g ± 292.7) than ROL (81.0 µg/g ± 77.1) in fish liver. This suggests that these freshwater fish may have converted ROL to DROL, or that DROL may be stored preferentially. Concentrations of ROL and DROL were similar in muscle. 3ROL was detected in all fish liver (2.1 – 14.9 µg/g) but concentrations were below detection in muscle and feed. To our knowledge, this is the first comparison of DROL and ROL concentrations in fish versus fish feed, and the first to identify DROL concentrations in North American farm-raised fish and commercial fish feed.