UBC Theses and Dissertations
The effect of a maternal dietary lysine deficiency on tissue carnitine levels in the rat Taylor, Mary Jane Muise
The effect of a maternal dietary lysine deficiency on milk carnitine levels and on plasma and liver carnitine levels in dams, fetuses and neonates was studied. Experimental animals were fed either a low-lysine diet (0.27% lysine), a high-lysine diet (1.07% lysine) ad libitum, or the high-lysine diet pair-fed to the low-lysine group. All diets contained 20% wheat gluten, 20% corn oil and negligible carnitine. Dams fed a diet, either low in lysine or restricted in total food intake, consumed significantly less food during pregnancy and lactation than high-lysine dams. When compared to high-lysine dams the low-lysine dams and their pair-fed controls gained significantly less weight during pregnancy and lost weight during lactation whereas the high-lysine dams gained weight during lactation. Litter size was not affected by either a dietary lysine deficiency or by the small reduction in total food intake during gestation. However, birth weight of offspring in the low-lysine and high-lysine restricted groups was significantly lower than that of the high-lysine controls. On day 15 of lactation the high-lysine pups weighed significantly more than the high-lysine restricted pups, which in turn weighed significantly mere than the low-lysine pups, suggesting a superior lactation performance for those dams fed the high-lysine control diet and the poorest lactation performance for those dams consuming the low-lysine diet. Liver and heart tissue samples were obtained from dams and their offspring on day 21 of pregnancy and day 15 of lactation. When liver weight or heart weight were expressed as a percentage of total body weight for dams or pups, no significant difference between dietary groups was detected. These results indicate that liver and heart weights were proportional to body weight. The low-lysine diet had no significant effect, on day 21 of gestation, on maternal plasma or liver carnitine levels or on fetal liver carnitine levels, whereas fetal plasma carnitine showed a small but significant increase compared to the high-lysine group. On day 15 of lactation plasma and liver carnitine levels were significantly higher in both dams and offspring fed the low-lysine diet, than in their respective controls. This increase in plasma and liver carnitine levels was probably due to a lowered food intake since animals fed the high-lysine diet pair-fed to the low-lysine group showed the same tissue carnitine response as did animals fed the low-lysine diet. Milk carnitine levels on day 2 of lactation were highest in the high-lysine group and lowest in the high-lysine restricted group. On days 8 and 15 of lactation milk carnitine levels were significantly higher in dams fed the low-lysine diet than in those fed the high-lysine or the high-lysine restricted diet. The results of this research indicate that plasma and liver carnitine levels in both dams and offspring and milk carnitine levels in dams, are not limited by the lysine content of the maternal diet under the experimental conditions of this study.
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