Maternal Dietary Protein Intake Research Articles

Effect of Chronic Maternal Calcium (Ca) Supplementation on Fetal Bone Mineralization (FBM). † 1535

Pregnancy is a time of physiologic stress on Ca homeostasis but there has been no systematic study on the effect of maternal Ca intake on FBM. We tested the hypothesis that maternal Ca supplementation increases FBM as indicated by dual energy X-ray absorptiometry (DXA) measurements of the neonate. Two hundred eighty-nine women enrolled in a randomized trial of Ca supplementation during pregnancy were approached to participate in a study of FBM; 276 agreed. The women had been randomized to receive 2-g elemental Ca or placebo tablets daily from 13-21 wks gestation until delivery. At each prenatal visit compliance was determined by pill counts. The treatment grp received an average of 1284 mg supplemental Ca/d. All mothers were provided with the same prenatal vitamin supplement. There were no significant differences in maternal dietary Ca, protein and energy intake between grps based on the average of 24-hr recalls conducted at randomization and at 32-33 wks gestation. There was also no significant difference between grps in maternal body mass index and wt gain during pregnancy. Eight neonates were not studied because of 2 deaths, 5 technical problems with DXA and learly discharge. Twelve infants had delayed DXA studies beyond one week after birth because of illness. Of the remaining 256 infants (128/grp), DXA measurements were performed by the same operator at 1.75 (mean) ± 0.1 (SEM) d. Scan acquisition used Hologic 1000/W densitometer (Hologic Inc., Waltham, MA) and infant platform. Quality control scans using manufacturer supplied phantom showed a long term (>3 yrs) CV of<0.5%. Only scans without movement artifact were analyzed using software(v5.64 for total body and v4.57Q for spine) developed in conjunction with the manufacturer. General linear modeling showed that the mean total body bone mineral content (BMC) and lumbar spine BMC were significantly (p<0.05) higher in the treatment grp (13.4% and 14.6%, respectively) at the lowest quintile of maternal dietary Ca intake (mean 504 [treatment] vs 555 [placebo] mg/d). The effect of Ca supplementation on FBM was not significantly different at the highest quintile of dietary Ca intake. We conclude that FBM can be significantly improved by Ca supplementation at low maternal dietary Ca intake.

Physiological responses of neonatal white-tailed deer reflective of maternal dietary protein intake

Previously, we observed a strong correlation between immunity parameters of neonatal white-tailed deer (Odocoileus virginianus) fawns and probability of survival in an overpopulated herd. As a result, we monitored age-related changes in neonatal fawn physiology, with an emphasis on measures of passive immune transfer, to test the hypothesis that maternal protein malnutrition adversely influences the vigor and immunocompetence of newborn fawns. Body mass and physiological data were collected from 55 neonatal fawns (1–28 days old) born to captive does on either a high-protein (16%) or low-protein (6.5%) diet during the latter half of gestation through lactation (15 March – 1 September). The study was conducted over two breeding seasons (1992 and 1993), with does receiving the same diet the second year to assess diet × year interactions. We found little evidence of compromised immunocompetence of neonatal fawns born to protein-malnourished does in either year. The absence of any sign of suppressed in utero development suggested that the nutritional deficiencies of the diet regime we used may not have been chronic enough to mirror conditions that exist in the wild. Birth mass, hematology, and serum chemistries of fawns suggested that low-protein diets caused reductions in maternal nutritional status by the second year. The results of this study and those of preliminary field observations suggested that compromised immunocompetence of neonatal fawns may be manifested only during chronic malnutrition, when the protein reserves of does become depleted or insufficient.

Restriction of Maternal Dietary Carbohydrate Decreases Fetal Brain Indoles and Glycogen in Rats

In spite of evidence that dietary carbohydrate can increase brain tryptophan and 5-hydroxytryptamine in adult rats, the possible influence of maternal dietary carbohydrate on fetal brain indoles has received little attention. We studied the effect of graded levels (0, 4, 12 and 60%) of maternal dietary fructose or glucose fed throughout pregnancy on fetal brain glycogen and indoles. The diets were isoenergetic and met the NRC energy requirements for pregnant rats. The results demonstrated that low maternal dietary carbohydrate, with adequate energy intake, reduced fetal brain weight and concentrations of glycogen, tryptophan, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid. There were no significant differences between glucose and fructose feeding at any dietary carbohydrate level for any fetal brain measurements, showing that it was the level and not the type of dietary carbohydrate that was important. Significant correlations between fetal brain 5-hydroxytryptamine and brain glycogen, and between fetal brain 5-hydroxytryptamine and brain weight, suggested that lowered brain 5-hydroxytryptamine was only one symptom of disrupted brain development in fetuses of dams fed low levels of carbohydrate. The results show that dietary carbohydrate restriction during pregnancy can have adverse effects on fetal brain development, glycogen levels, and neurotransmitter synthesis even when maternal dietary protein and energy intake are adequate.

Studies on the energy metabolism of the pregnant sow. 1. Uterus and mammary tissue development.

Twenty-six gilts were used in an experiment to study the effects of level of feed intake on the growth and chemical composition of the gravid uterus and mammary tissue at several stages of gestation. The animals were given either 1.8 or 2.5 kg feed/d (20 or 30 MJ metabolizable energy (ME) respectively) and were slaughtered at intervals between days 40 and 110 of gestation. The gravid uterus was dissected into fetal, placental, fluid and empty uterus components. From day 70 of gestation the mammary tissue was also dissected. The fresh weight and dry matter (DM), energy and nitrogen contents of the various tissues were determined. With the exception of the fluid component, there was a significant increase (P less than 0.01) in the fresh weight of each tissue with both stage of gestation and level of feeding. At comparable litter sizes the total weight of the fetuses in late gestation was 16% higher with the higher feed intake. The DM content of the individual uterine tissues increased significantly (P less than 0.01) with increase in stage of gestation so that the mean DM content of the gravid uterus increased from 74.6 g/kg at day 50 to 103.1 and 159.0 g/kg at days 90 and 110 of gestation respectively. Neither stage of gestation nor feeding level influenced the respective energy contents of the individual uterine tissues, when expressed per g DM. The mean energy content of the total gravid uterus was 19.5 kJ/g DM. The N content (g/g fresh weight) of the tissues increased with stage of gestation and was generally higher at the higher feeding level. The mean N contents (g/g DM) of the fetal, placental, fluid and empty uterine tissues were 0.090, 0.101, 0.098 and 0.128 respectively. The mammary tissue was the most variable of all the tissues investigated. Whereas the fresh weight and N content increased with stage of gestation, both the DM and energy content decreased. Gompertz equations were fitted to describe the effects of stage of gestation, level of feed intake and liter size on the fresh weight and chemical content of the individual uterine tissues, total gravid uterus and mammary tissue. The use of these equations for calculating the nutrient requirements of pregnancy is demonstrated. It was calculated that between days 50 and 110 of gestation the ME requirement for reproduction increased from 3 to 12% of maternal energy intake. The calculated requirement for protein was from 7 to 41% of maternal dietary protein intake respectively.