Supplementation of soy based feed with linseed and its effects on growth and fatty acid profile in grass carp (Ctenopharyngodon idella)

Abstract

Linseed is an economically important plant source of n-3 polyunsaturated alpha-linolenic acid (ALA) which can be used as supplemental dietary lipid in fish feed particularly carps. In developing countries where fish oil is not an ingredient of fish feed due to its high cost, the addition of economical plant oils rich in n-3 PUFA in fish diet can remarkably improve its quality. The present study evaluated the effect of the addition of linseed in fish feed on growth and fatty acids profile in grass carp (Ctenopharyngodon idella); an important commercial carp in Asia. The present study investigated the effects of three different diets (A, 5% linseed flour; B, 5 % LO; C, 2.5 % linseed flour + 2.5% LO) on growth and fatty acids profile (C12:0– C22:6) in grass carp (age = 12 months). The trial continued for 31 days at ambient temperature. The control group was fed with soybean based commercial diet. No significant effect of diet A and C was observed on fish growth and profile of n-3 and n-6 PUFA in total liver lipids. However, the treatment group fed with diet B showed a significant increase in K (1.75 ± 0.14 %), FCR (0.97) and HSI (0.62 ± 0.1%) as compared to those in the control group. A high profile of DHA (C22:6) was observed in total liver lipids of fish in all three treatments groups (A: 0.31%, B: 0.41%, C: 0.40%) in comparison to the control group where DHA was not observed in the fatty acids profile. Similarly, high profiles of EPA (C20:5) were observed in all three treatment groups (A: 0.56%, B: 1.64%, C: 1.35%) as compared to those in control group. Therefore, the present study indicates that linseed can be a suitable source of n-3 and n-6 PUFA in carp feed, improving the condition and flesh quality of fish.