Incorporation of n-3 long-chain polyunsaturated fatty acids into duck egg yolks

The objective of this experiment was to determine the effects of different levels of refined cod liver oil (RCLO) on laying performance, n-3 polyunsaturated fatty acids composition (n-3 PUFAs) and the organoleptic evaluation of duck egg yolks. A total of 180 30 wk old laying Tsaiya ducks, at the beginning of peak production, were allotted into 6 treatments with 3 replicates each. Ducks were fed one of the 6 experimental diets, supplemented with 2% tallow (control) and graded levels of RCLO at 2, 3, 4, 5, and 6% to a corn-soybean diets, respectively, for 6 wks. All of the experimental diets were formulated to be both isocaloric and isonitrogenous. Feed and water were supplied ad libitum throughout the experimental period. The results indicated that the RCLO supplementation levels did not affect (p>0.05) egg production, egg mass, feed intake, feed efficiency or body weight change. Egg weight was the lightest when the ducks received the 6% RCLO diet. The eicosapentaenoic acid, docosahexaenoic acid, and total n-3 PUFAs contents in the yolks increased with increasing RCLO supplementation. The taste and general acceptability of the hard-boiled eggs were not significantly different among the treatments. However, a fishy flavor was much higher when ducks were fed diets supplemented with 5% and 6% RCLO diets.