Sole farming is hampered by poor growth and high sensitivity to
stress and infectious diseases. Hence, supplementing diets with
health promoting additives such as antioxidants could be worth
studying to improve the growth performance of this species.
Grape seed proanthocyanidin extract (GSPE), a natural polyphenolic
antioxidant, has been used as a human food supplement for
health promotion, but few data are available on its application in
animal nutrition and none in fish. The present study was aimed
at investigating the effect of supplementing a commercial dry
extruded feed formulated for sole (Diet E) with GSPE at a dose of
50 mg/kg (Diet E+GSPE) on the growth performance, blood plasma
lipid profile and total antioxidant activity of Solea solea. Two
hundred eighty four fishes (mean weight 38.1±0.6 g) were randomly
distributed in 8 rectangular troughs (0.37 m2) at 3.7 kg/m2
stocking density, and fed at 1% body weight/day over 147 days,
according to a single-factor experimental design with 4 replicates
per diet. Survival rate, feed conversion ratio (FCR) and
specific growth rate (SGR) were calculated per group at the end
of the trial, whereas plasma levels of total, HDL, LDL-cholesterol,
triglycerides and total antioxidant activity were measured at days
87 and 147 on 8 fish samples per treatment. All dietary groups
had similar, high survival rates (95.8 vs 97.1%, P>0.05). Diet
E+GSPE resulted in a slight but significantly impaired SGR over
diet E (0.28 vs 0.31, P<0.05), but in the same FCR (P>0.05).
Blood lipid profile was also unaffected by the dietary treatment,
while the addition of GSPE to the diet resulted in significantly
increased antioxidant activity in plasma (P<0.05) suggesting the
usefulness of grape seed extract in promoting resistance to
oxidative stress in common sole.
