Modulatory effect of temperature on the influence of dietary linolenic (18:3 n-3) and linoleic (18:2 n-6) acids on the gonadal recrudescence in Clarias batrachus (L.)

Abstract

During the late postspawning phase, freshwater catfish Clarias batrachus fed a diet rich in linseed oil (18 : 3 n-3) (LSO) and 13L : 11D photoperiod and at 28 C showed increases in ovarian weight and plasma levels of testosterone and oestradiol-17 , and in concentrations of free fatty acids (FFA), monoglycerides (MG), diglycerides (DG), triglycerides (TG), phospholipids (PL) and esterified cholesterol (CE) in the liver, plasma and ovary. In fish fed a diet rich in sunflower oil (18 : 2 n-6) (SFO) under the same conditions, plasma testosterone decreased sharply, concentrations of FFA, DG and TG increased in the liver and plasma and ovarian levels of TG and CE decreased. Neither diet was gonadostimulatory when fed at 18 C. 2000 The Fisheries Society of the British Isles

Differential Role of Dietary Fatty Acids on Gonadal Recrudescence in the African Catfish <i>Clarias gariepinus</i> (Bloch.)

“…The present study indicated that dietary fatty acids play a determinant role in modulating the reproductive activity in the male African catfish, C. gariepinus during the pre-spawning phase. A significant increase in GSI as well as T and T3 in the C18 n-3 PUFA fed fishes showed that LSO plays a stimulatory role in gonadal recrudescence which is consistent with our earlier report (Acharia et al, 2000) in another catfish, C. batrachus. Since elevation in GSI by SO oil compared to basal diet was not statistically significant it was considered that this particular fatty acid had no effect on gonadal recrudescence at this phase.…”

“…Since body weight remained unaltered (data not shown) in response to any of the experimental fatty acid supplemented diets, it is assumed that C18:3 n-3 or C18:2 n-6 or C12:0 had no impact on the somatic growth in this fish during the pre-spawning phase particularly. Similar observation was reported in the earlier studies performed in the Indian female catfish C. batrachus (Acharia et al, 2000(Acharia et al, , 2001. However, in this species the differential role of n-3 or n-6 PUFA for gonadal activity was temperature dependent.…”

“…As reported by Acharia et al (2000), the influence of dietary PUFAs (C18:3 n-3 or C18:2 n-6) on the gonadal or somatic growth was temperature dependent in the Indian female catfish, Clarias batrachus. Dietary C18:3 n-3 was gonado-stimulatory whereas C18:2 n-6 was favourable for somatic growth when fish were maintained at high temperature.…”

“…Basal diet was prepared by mixing maize powder (75% wt/wt), linseed oil cake powder (12.5% wt/wt) and dry fish powder (12.5% wt/wt). Agrimin (1% wt/wt) (Glaxo India) was added as a source of vitamins and minerals (Acharia et al, 2000). Test diets were prepared by incorporating linseed oil (LSO), sunflower oil (SO) and coconut oil (CO) to the basal diet at 5% (W/W).…”

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“…Balance in the diet of both of n-3 and n-6 which are critical during organogenesis in embryos and larvae is required in the broodstock diet for optimum reproductive success of fish (Acharia et al, 2000;Bell et al, 1997;Nandi et al, 1999). Our results showed that n-3/n-6 ratios of all samples in PL and NL within a narrow range (0.44-1.80), with one exception in NL for African catfish ovary which had (9.23) value.…”