Biotransformation of fish oil in layers

Two years old Hisex layers, fed with feed containing fish meal, were divided into three groups. Six layers were killed at the beginning of experiment (Group A) as a control group. Twelve layers were thereafter fed with feed containing 8% soybean oil (Group B) for two weeks or four weeks and each time six layers were killed. Another twelve layers fed with feed containing 8% fish oil (Group C), other treatments were the same as in Group B. Samples of light meat, cerebrum, cerebellum and egg were taken from each group to analyse the composition of fatty acids. After two weeks, as compared with Group A, DHA contents in eggs of Group B were decreased (P0.001). DHA contents in light meat, cerebrums and cerebellums were unchanged. The DHA content in eggs of Group C was increased (P0.001). DHA increased slightly in light meat and cerebrum, and was unchanged in cerebellum. THe DHA content in eggs of Group D was only 31.58% of that in Group A (P 0.001). After four weeks, DHA content in eggs of Group B was also decreased (P0.001). DHA contents in light meat and cerebrums were increased (P0.01, P0.01), DHA in cerebrums was decreased (P0.01). For Group C, DHA contents in eggs, light meat and cerebrums were increased P0.01, P0.001, P0.001), DHA in cerebellums was decreased (P0.05). We have found that layer itself has a regulating action on the DHA content in eggs, a little DHA in feed can increase this content to a high level, but feed supplemented with a great quantity of fish oil can not increase this content by several times. Fish oil can raise DHA contents in light meat and cerebrums more powerfully than soybean oil, but DHA content in cerebellums was an exception. Ratio of DHA/AA was an important value. In Group C it was remarkably increased in eggs, light meat, cerebrums and cerebellums. In Grop B, the ratio raised only in light meat after four weeks. In conclusion, layers fed with feed containing fish oil may produce new nutritious products