Growth response and fatty acid composition of juvenile red claw crayfish (Cherax quadricarinatus) fed different sources of dietary lipid

Abstract

A study was conducted to determine the effects of different sources of dietary lipid that differ in fatty acid (FA) composition on growth, feed conversion ratio (FCR), survival, and whole-body proximate and FA composition of juvenile red claw. Juvenile red claw (0.55 ± 0.02 g) were reared over a 12-week period. Five practical diets were supplemented with 70 g kg−1 oil (by weight) from either linseed oil (LO), canola oil (CAO), corn oil (CO), beef tallow (BT) or menhaden oil (MO) and formulated to contain 400 g kg−1 crude protein. Red claw were fed three times daily (800, 1200 and 1600) to controlled excess. At the conclusion of the experimental period, there were no significant differences (P > 0.05) found in percentage survival and FCR among dietary treatments and values averaged 85.4% and 3.4, respectively. However, final mean weight and specific growth rate of red claw fed Diet 1 (LO) was significantly higher (16.44 g and 3.95% day−1, respectively) compared with that of red claw fed Diet 4 (BT; 12.24 g and 3.43% day−1, respectively), but not different from red claw fed the other three diets. Likewise, red claw fed Diets 1 (LO) and 2 (CAO) had significantly higher percentage weight gain (2990 and 2880%, respectively) compared with the BT diet (2124%), but not different from red claw fed Diets 3 (CO) and 5 (MO). Whole-body fat and ash composition was significantly affected (P < 0.05) by source of added lipid, but no differences were found in whole-body moisture and protein. Moreover, whole-body FA composition showed differences among the varying oil sources and primarily reflected the FA in the diets. Results of the present study indicate that plant oils LO, CAO and CO rich in linolenic acid (18:3n-3), linoleic acid (18:2n-6) and oleic acid (18:1n-9) perform as well as MO containing high levels of n-3 highly unsaturated fatty acids eicosapentanoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) for juvenile red claw crayfish grown indoors lacking natural food items. Further, red claw fed a diet containing BT, which has a high percentage of saturated FA, performed poorly compared with LO and CO in regards to weight gain. It appears that juvenile red claw can be fed diets containing less expensive plant-based oils with high levels of 18-carbon unsaturated fatty acids. This could reduce diet costs for producers and allow for profitability.