title: Interactions between major nutrients in the diet and the lactational performance of rats.
abstract: The effect on lactational performance of replacing feed carbohydrate with fat at two different protein levels was studied. Lactating Sprague-Dawley rats with a standardized litter size of thirteen pups were allocated one of eight feeds containing either 300 or 150 g protein/kg organic matter (OM) and ranging in fat content from 100 to 550 g/kg OM from day 2 until day 14 of lactation. Daily food intake, live-weight gains, and changes in body composition of both dams and litters were measured. Feeds of low protein content resulted in a significant decline (P < 0.001) in lactational performance despite a significant increase (P < 0.001) in maternal protein mobilization. Maternal lipid mobilization was not significantly affected by feed composition. Litter lipid gain was significantly increased (P < 0.05) as fat replaced carbohydrate in the high-protein feeds, due to an increase in maternal energy intake. In contrast, lactational performance was severely depressed (P < 0.001) as fat replaced carbohydrate in the low-protein feeds. This interaction between feed components on lactational performance was in accordance with the hypothesis that the heat production of lactating rats is maximal and, hence, constraining intake.
authors.affiliation: Scottish Agricultural College, Edinburgh.
authors.forename: N C
authors.initials: NC
authors.lastname: Friggens
authors.forename: D E
authors.initials: DE
authors.lastname: Hay
authors.forename: J D
authors.initials: JD
authors.lastname: Oldham
mesh_terms: D000818:Animals; D001823:Body Composition; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating; D005260:Female; D007774:Lactation / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015430:Weight Gain
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins