Effects of maternal dietary fatty acids on the fatty acid content of rat milk

The effects of maternal dietary fatty acid composition on milk fatty acids in rats were evaluated. Female rats, during pregnancy and lactation, were fed on one of eight diets: a stock diet with 5% various added proportions of fatty acid ethylester mixture of C16: 0, C18: 1ω9 and C18: 3ω3 in addition to C18: 2ω6 or C18: 3ω6. Increases in the C18: 1ω9, C18: 2ω6 and C18: 3ω3 contents of rat milk apparently reflected an increase in the intake of these acids. A significantly high correlation was found between the contents of these acids in milk and their intakes, although the C16: 0 content was independent of dietary C16: 0. Increase in the intakes of C18: 3ω6 and C18: 3ω3 produced a steady increase in the content of each family of polyunsaturated fatty acids (PUFA) in milk, and the content of ω6-PUFA in milk showed a more significant correlation with dietary C18: 3ω6 than with C18: 2ω6. This suggested that C18: 3ω6 in the diet was more easily metabolized to PUFA in milk, than C18: 2ω6 by lactating rats. The contents of C8: 0, C10: 0, C12: 0 and C14: 0 in the milk of rats fed on a fatfree diet were significantly increased as a result of endogenous fatty acid synthesis within the mammary gland, stimulated by the fat-free diet.