A feeding experiment was conducted to investigate the relationship between the α-tocopherol requirement of carp and the dietary levels of unsaturation.
The fish receiving the diet without supplement of lipid showed the lowest growth rate, because of a lower caloric content and the absence of essential fatty acids. Addition of 5% methyl esters of pollock liver oil to the diet supplemented with 5mg of α-tocopherol increased the growth rate of fish and feed conversion. However, addition of 10% methyl esters slightly depressed growth and resulted in tocopherol deficiency, judging from the appearance of apparent muscular dystrophy, along with convulsions, and from the α-tocopherol content of hepatopancreas. The fish receiving the diets with methyl esters of Pollock liver oil at more than 10% began to show apparent muscular dystrophy from the 8th week of feeding period and about 67% of the fish were diseased in the group fed on the diet containing 20% lipid also resulted in low growth rate and low feed conversion.
These result of feeding clearly indicate that elevated levels of dietary lipid, equivalent to an increase of unsaturation in the diet, increase the requirement of carp for α-tocopherol.