Effects of dietary n-3 and n-6 fatty acids levels on egg and larval quality of Eurasian perch pdf

Effects of dietary n-3 and n-6 fatty acids levels on egg and larval quality of Eurasian perch by Émilie Henrotte 1, Julia Lynne overton 2 & Patrick Kestemont 1 AbsTrAcT.. - three groups

Effects of dietary n-3 and n-6 fatty acids levels on egg

and larval quality of Eurasian perch

by Émilie Henrotte (1), Julia Lynne overton (2) & Patrick Kestemont (1)

AbsTrAcT - three groups of 40 perch breeders were reared in order to study the effects of 3 different levels of dietary

n-3 and n-6 fatty acids on egg quality two experimental diets, r1 and r2 (n-3/n-6 = 0.13 and 35.54, respectively), were compared to one commercial food, r3 (n-3/n-6 = 3.48) spawning and fertilization rates were high for diets r1 and r3, which displayed a n-3/n-6 ratio of 0.77 and 2.34 in the eggs, respectively, by comparison with r2 (n-3/n-6 = 4.87), which produced low reproductive performances We can conclude that dietary n-3 and n-6 FA levels influence egg and larval quality of eurasian perch.

Key words - Perca fluviatilis - egg quality - Fatty acids

Cybium 2008, 32(2) suppl.: 271-272.

(1) the University of namur, 61 rue de Bruxelles, 5000 namur, Belgium [emilie.henrotte@fundp.ac.be]

(2) Danish Institute of Fisheries research, Dept Aquaculture and marine ecology, Kavalergården 6, 2920 Charlottenlund, Denmark.

Introduction

one of the major constraints for the development of

eur-asian perch culture is the supply of good quality eggs the

importance of 3 fatty acids (FAs; docosahexaenoic (22:6n-3;

DHA), eicosapentaenoic (20:5n-3; ePA) and arachidonic

(20:4n-6; ArA) acids) in the reproduction and egg quality

has been demonstrated (Bell et al., 1997) As a result of

chemical similarities among these particular FAs, leading to

competitive interactions, the optimal requirement for each

individual FA is difficult to assess the objective of this

study was to determine the FA composition of eggs obtained

from broodstock fed different n-3 and n-6 FAs levels in

rela-tion with reproductive performances, egg quality and larval

robustness

Methods

three groups of 40 perch breeders were reared in order

to test different levels of dietary n-3 and n-6 FAs (16%

lip-ids) during 9 months (from march to november 2006) two

experimental diets, r1 and r2 (n-3/n-6 = 0.13 and 35.54,

respectively), were compared to one commercial fish diet,

r3 (n-3/n-6 = 3.48) spawning and fertilization rates were

checked in november, and larval robustness was evaluated

by osmotic shock (1 hour in naCl 2%, 20°C) two days after

hatching total lipid and FAs were extracted from the eggs

and tested diets Data were compared by analysis of variance

AnovA1 (statistica 5.5)

results and discussion

the survival of broodstock was similar among the

three diets the spawning rate was high for r1 and

r3 (85.7 and 73.3%, respectively) while only few

spawnings were obtained for r2 (33.3%) For 12 egg

strands, only one was fertilized in r2, while 38.9 and

72.7% of the spawnings were fertilized in r1 and r3,

respectively, with similar fertilization rates in these

groups (88.6 ± 10.4 and 87.4 ± 15.1%) Larval

robust-ness was comparable between r1 and r3 (74.2 ± 25.0% and 69.0 ± 24.2% survival, respectively) the present results show the same relationship between fish diet and FA compo-sition of the eggs produced r1 and r3 displayed a n-3/n-6 ratio of 0.77 and 2.34 in the eggs respectively, while the spawnings obtained for r2 displayed a ratio of 4.87 (tab I), which can be correlated to low reproductive performances, specifically regarding the spawning rate, but also regarding the percentage of fertilized spawnings our results indicate that the spawning quality of perch is directly affected by the n-6 FA content of broodstock diet As opposed to mammal cells, which contain essentially n-6 FAs in their PUFA, fish cells contain a high level of ePA and DHA, and,

consequent-ly, need those FAs in their diet However, despite the

elevat-ed levels of ePA and DHA, ArA is the chief precursor of the eicosanoids, generating 2-series prostanoids (Lands, 1989), which may act on the induction process of the ovulation as well as on spawning

conclusion

It is possible to improve the reproductive performances

as well as the egg and larval quality in eurasian perch by manipulating the fatty acid composition of the broodstock diet

Acknowledgements - this work was support by the european

Union CrAFt Percatech project (CooPt-Ct-2004-512629) and

by a FrIA grant.

table I - Fatty acid composition of eggs of eurasian perch (% of total FAs) Significant differences (p < 0.05) are indicated with different letters.

BeLL J.G., FArnDALe B.m., BrUCe m.P., nAvAs J.m & m

CArILLo, 1997 - effects of broodstock dietary lipid on fatty

acid compositions of eggs from sea bass (Dicentrarchus

labrax) Aquaculture, 149: 107-119.

LAnDs, W.e.m., 1989 - Differences in n-3 and n-6 eicosanoid

precursor In: Advances in prostaglandin, thromboxane and

leu-kotriene research (samuelsson B., Wong P.Y.K & F.F sun,

eds), pp 602-605 new York: raven Press.

Eurasian perch egg and larval quality Henrotteet al