Evidence That Undernutrition During the First Trimester of Pregnancy Influences Development and Function of the Cardiovascular System in Female Offspring in Cattle.
Environmental perturbations during gestation negatively impact offspring development including size of the ovarian reserve, metabolism and cardiovascular health, but little is known about the relationships between suboptimal maternal environment and long-term health of offspring in cattle. We tested the effects of restricting maternal nutrient supply from shortly before conception to the end of the first trimester of pregnancy on arterial blood pressure and cardiac and aortic dimensions in the offspring. Cross-bred beef heifers (n = 60), of similar age and weight, were randomly assigned to one of two nutritional treatments: control (C; n = 25) or restricted (R; n = 35) and were individually fed at 1.2 or 0.6 of their maintenance (M) energy requirements, respectively, from 11 days before artificial insemination to Day 110 of gestation (period encompassing the peak in oocyte numbers in fetus). Estrous cycles were synchronized and heifers were artificially inseminated with sex-sorted semen from a single sire to increase the proportion of female calves born. Fetal cardiac maximal length and width and diameter of the aorta were measured on a four chamber view (longitudinal cardiac section showing both ventricles and atria) using high resolution transrectal ultrasonography on Day 94 of pregnancy. Systolic (SBP), diastolic (DBP) and mean (MBP) blood pressure were assessed (using the tail-cuff system), and body weight (BW) and body mass index (BMI) were measured every 2 to 3 wks, from 20 wks of age. Offspring were slaughtered at 95 weeks of age to measure heart weight and circumference of the base of the aorta. A mixed model repeated measures ANOVA was used to determine differences between groups. Fetal aortic diameter (mean ± SE) was larger (P<0.05) in the R (3.2 ± 0.17 mm, n=7) compared to C (2.6 ± 0.11 mm, n=10) groups, while cardiac length and width were similar between groups. Twenty-three single female calves were born and there was no effect of treatment (C n=13, R n=10) on gestation length or birth weight. Between 20 and 85 weeks of age SBP, DBP and MBP were higher (P<0.01) in offspring from the R vs C group, while BW and BMI did not influence any of the BP parameters. In adult offspring, aortic circumference was larger (P=0.01) in the R compared to C groups (R, 96.3 ± 3.0 mm, n=10; C, 87.4 ± 2.2 mm, n=13), whereas heart weight was similar between groups. In summary, maternal nutritional restriction in early pregnancy significantly increases arterial blood pressure and aortic dimensions in female offspring in cattle. It remains to be established if these effects impact negatively on the physiology of other systems (i.e. reproductive) or on cattle health and production traits. Funded by the Irish Department of Agriculture, Fisheries and Food (RSF 06-328). (poster)