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The effect of diet during pregnancy on lactation performance Hartnett, Carol Elsie Calder


The purpose of this research was to determine the effect of dietary restriction during pregnancy on the ability of the rat to lactate. This was based on the thesis that a failure to increase "maternal fat stores" over gestation would reduce the energy available for milk production. The study was conducted in two parts. In the first part, the effect of a protein or calorie deficiency during pregnancy on maternal body fat was determined. In the second part, rats were fed either a low calorie-adequate protein or a low protein-adequate calorie diet throughout pregnancy. After delivery they were maintained on a normal diet, pair-fed with a non-restricted nursing littermate, and allowed to suckle eight foster pups for twenty-one days. The protein and lipid content of the dam's milk, and the rate of growth, carcass composition, and the weight of the litter's cerebellums were measured to determine whether adequate milk for growth and development of the pups was provided. The lipid content of the mother's carcass was analyzed to see if there was any change due to lactation. From the findings of this study, it appears that the diet during pregnancy affects the weight gain and body fat content of the mother, as well as the birth weight of her pups. Body fat, in all dietary treatments, was catabolized during the suckling period. The weight loss during lactation was inversely proportional to the fat content of the rat's body at the end of pregnancy. Adequate lactation appears to involve an interaction of the diets during pregnancy and lactation, with a deficiency in one being overcome by an adequate diet in the other. The possibility exists of a transitory lag in milk production during initial lactation for those animals on a poor diet during gestation. It is likely that the fat deposited over pregnancy, in well nourished animals, is used to supplement early lactation. During lactation the mother's diet affects her weight loss, and the gain of her pups, by influencing the volume of milk she produces. The protein and fat composition of the milks are not affected by diet during pregnancy, but rather are determined by the animal's genetic potential within a normal range.

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