FATTY-ACID COMPOSITION OF MILK FROM GENETICALLY NORMOTENSIVE AND HYPERTENSIVE RATS

To assess milk fatty acid composition in genetically normotensive (Wistar Kyoto, WKY) and spontaneously hypertensive (SH) rats, WKY and SH dams (n = 10/strain) were milked under halothane anesthesia on d 5, 13 and 21 postpartum. Milk samples of 0.5-1.0 mL were then analyzed by gas-liquid chromatography. Additional WKY and SH dams (n = 2/strain) were milked on d 5 and 21 postpartum for assessment of total milk fat. In both WKY and SH strains, the amount of 8:0 and 10:0 fatty acids increased from d 5 to 21 (p < 0.001), whereas the quantity of 18:3(n-6), 20:3(n-9), 20:3(n-6), 22:4(n-6), 22:5(n-3) and 22:6(n-3) fatty acids declined over the same period (p<0.001). Milk from SH rats had higher levels of 10:0 and 20:4(n-6) fatty acids on all sampling days than did milk from WKY rats (p<0.001), and milk from SH rats had lower levels of 16:1(n-7), 18:1(n-9) and 18:2(n-6) fatty acids on d 13 and 21 (p < 0.001). There were no differences in milk fat content between strains. These data suggest that genetically hypertensive rat pups obtain significantly greater amounts of 20:4(n-6) and significantly lower amounts of 18:2(n-6) fatty acids from maternal milk than do their normotensive counterparts.