The effects of
dietary retinoic acid on body lipid deposition in juvenile red sea bream
(Pagrus major); a preliminary study
Hiroshi Y. Ogata, Hiromi Oku-2001
Aquaculture, 193 (3-4): 271-279
Abstract:
A 6-week feeding trial was conducted to investigate
the effects of dietary retinoids, especially retinoic acid, an
anti-adipogenic factor in mammals, on lipid deposition in juvenile red sea
bream (initial body weight: 8.5 g). The fish were fed either a commercial
diet (control: diet 1, crude protein 61.7%, crude fat 13.9%), or diets
supplemented with 100 mg retinyl acetate (diet 2), 10 mg all-trans-retinoic
acid (diet 3), or 100 mg all-trans-retinoic acid/kg diet (diet 4) for the
test period. A low mortality (2.5%) was observed with diets 3 and 4 through
the period. Weight gain, daily feed intake, feed efficiency, whole body
crude protein, and crude fat content were not affected by the treatments.
Visceral adiposomatic index of the fish was highest in fish fed diet 4 as
follows: 2.90 in diet 1 fish, 3.46 in diet 2 fish, 3.28 in diet 3 fish, and
4.19 in diet 4. The treatments did not affect hepatosomatic index. Lipid in
the dorsal white muscle was lowest and those in the visceral adipose tissue
highest in fish fed diet 4. Liver lipid content was not affected by the
treatments. Average plasma free fatty acid levels in fish fed diet 4 (60
µEq/l) were lower than those of the other groups (113--148 µEq/l). Plasma
triacylglycerol levels in fish fed diet 2 (1845 mg/l) were lower than those
of the other groups (2944--3130 mg/l). Subsequently, to confirm that dietary
retinoic acid was internally absorbed, plasma retinoic acid levels at 6-h
post-feeding were determined by HPLC. These were 4±0 ng/ml in diet 1, 6±0
ng/ml in diet 2, 20±0 ng/ml in diet 3, and 223±34 ng/ml in diet 4. The
present results suggest that dietary retinoic acid was directly incorporated
into the body, and that retinoic acid up-regulated development of the
visceral adipose tissue and down-regulated lipid deposition in the dorsal
white muscle.
(Fish Nutrition Division, National Research Institute
of Aquaculture, Nansei, Mie 516-0193, Japan)
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