The effect of reproduction on the interaction of dietary protein and calcium

Abstract

I. Rats were maintained from the age of 3 weeks until the end of a second reproductive cycle on diets having different protein values and Ca concentrations. 2. Reproductive performance was judged from the number of viable young, their size, body composition and rate of growth during suckling. 3. The size and quality of the bones of the mothers and offspring were assessed from radiographs, histological appearance, total weight of ash, ash/cm3 and ash:organic matter ratios of dry fat-free bone. 4. At the end of gestation the mean numbers and total weights of foetuses were low when the mothers had received diets of low protein value: there were smaller differences in the body-weight, water, ash and N contents of the individual foetuses. 5 . When 0.44 yo Ca was included in the diet of low protein value, only one (three rats) of the six litters born survived beyond I week of age. 6. At weaning, the young born of and suckled by the protein-calorie deficient dams were only about half the weight of those from mothers receiving the high-protein diets ; Ca deficiency produced relatively minor changes. 7. All the mothers lost weight during lactation irrespective of the protein value or Ca concentration of the diet; their bones had lower radiographic densities and less ash/cm3 than is usual in non-pregnant rats of similar age. 8. The interaction of protein and Ca and their relative importance in maintaining the skeletal structure of mother and offspring during pregnancy and lactation are discussed.In a previous publication (El-Maraghi, Platt & Stewart, 1965) it was reported that osteoporosis could be produced in the bones of rats maintained on diets which were deficient in calcium or of low protein value. The type of osteoporosis varied, diets deficient in protein leading to matrix-osteoporosis and those deficient in Ca to mineral-osteoporosis.Either form was easily produced in young growing rats, but under the conditions tested (Ca not less than 0.1 I % of the diet) only matrix-osteoporosis was found in the adult and aged rats. The adult animals were apparently able to maintain a normal skeletal structure when given diets having about one-half the protein value and one-quarter the concentration of Ca required by young growing rats for normal bone formation. It would be expected that any additional 'stress' such as reproduction would lead to frank deficiencies, and the present report deals with the effects on the bones of the mother and offspring of diets supplying only the protein and Ca requirements of non-pregnant adults. E X P E R I M E N T A LAnimals and diets Rats of a black and white hooded colony which had been maintained on the MRC cube diet no. 41B (Bruce & Parkes, 1947) were used in all the experiments. Diets having Ca concentrations of 0.44 and 0'1 I % were prepared at each of the two protein https://www.cambridge.org/core/terms. https://doi

Protein-Calorie Deficiency and Disorders of the Endocrine Glands

“…Protein-calorie deficient rats release fewer ova during each repro ductive cycle and amongst these there is a higher than normal pre-implan tation loss [18] and. even after implantation, losses may be increased in ani mals receiving inadequate supplies of protein [13]. In malnourished dogs, the bitches reach sexual maturity later and have longer intervals between oestrus than do normally fed littermates.…”