The influence of dietary mackerel oil on the condition of organs and on blood lipid composition in the young growing pig.

A feeding experiment was carried out in which piglets were fed to a diet enriched with either mackerel oil or olive oil. The oil consumption amounted to about 100 g per animal per day. The aim of this experiment was to study the effect of feeding high amounts of fish oil rich in polyunsaturated and long-chain monoenoic acids in order to determine if any morbid changes occurred in the animals as a result of this addition. The piglets fed olive oil served as controls. After 4 weeks, blood hemoglobin, plasma glucose, and serum triglycerides were significantly lower in the mackerel oil group as compared with the control group. There was no difference in serum cholesterol and serum lipid composition. Very low density lipoproteins were lower in the mackerel oil group. The fatty acid composition of blood serum, heart muscle, and liver showed considerable differences, omega3 acids being higher and both omega6 and omega9 acids being lower in the mackerel oil group than in the control group. Some increase in the amount of triglycerides in the heart muscle was observed in the mackerel oil group. Some characteristics of "yellow fat disease" developed in the mackerel oil group. This type of vitamin E deficiency seems to be the result of the considerable amount of omega3 fatty acids present in the mackerel oil. No clinical symptoms due to ingestion of long-chain monoenoic acids were observed.