Metabolism of the gravid uterus, foetus and utero-placenta at several stages of gestation in cows

Abstract

To quantify changes in rates of metabolism and nutrient uptake of gravid uteiine, foetal and utero-placental tissues throughout gestation, mature Hereford cows received surgery at 132 ±0-6 (w = 12), 176 + 0-5 (n = 8), 220 ±0-4 (n = 11) and 245 ±1-5 (n = 7) days after mating. Indwelling catheters were implanted into a uterine artery and vein of all cows. Foetal catheters also were implanted into an umbilical vein and foetal femoral artery and vein (days 176 and 220) or into a placental artery and two placental veins (days 132 and 245). Approximately 5 days after surgery, deuterium oxide was infused into a foetal femoral venous or placental venous catheter during a 3 h period to quantify uterine and umbilical blood flows by steady-state diffusion methods. Oxygen, glucose, lactate and a-amino acid nitrogen concentrations were determined for uterine and foetal blood samples collected during this procedure.Uterine blood flow increased 4-5-fold (2-92-13-18 1/min) and umbilical blood flow increased 21-fold (0-28-5-861/min) during the interval of gestation studied. The relative rate of increase of umbilical blood flow was about twice as great as that of uterine blood flow. Uterine arterial and umbilical venous concentrations as well as uterine arterial-venous and umbilical venous-arterial concentration differences in metabolites changed little with stage of gestation. However, because rates of blood flow increased, uptakes of O a , glucose and a-amino N by the gravid uterus and foetus increased as gestation advanced. The proportion of gravid uterine uptakes utilized by the foetus increased from day 137 to 226 for O 2 (24-58 %) and from day 137 to 180 for glucose (4-19%), then remained relatively constant. The proportion of gravid uterine a-amino N uptake utilized by the foetus remained relatively constant and averaged 60 %. A net secretion of lactate from the utero-placenta to the uterine and foetal circulations was observed and increased as gestation advanced. These data indicate that increased rates of uptake or secretion of metabolites by tissues of the gravid uterus can be explained primarily by increased rates of uterine and umbilical blood flows.

Secretion of angiogenic activity by placental tissues of cows at several stages of gestation

“…In the cow, caruncular vascular development continues throughout gestation (Hutchinson, 1962). Rates of uterine and umbilical blood flows also increase throughout gestation (Reynolds et al, 1986). In addition, rate of placental blood flow is an important determinant of the rate of transplacental exchange (Bell et al, 1986; The present paper and also a previous report (Reynolds et al, 1987b) indicate that stimulatory angiogenic activity is produced primarily by maternal placental tissues.…”

“…Previous work has shown that size ofthe placental blood supply is a primary determinant of the rate of physiological exchange between the maternal and fetal systems (Bell et al, 1986;Reynolds et al, 1986;. Conditions associated with reduced rate of fetal growth (e.g.…”

Uterine blood flow in sows: effects of pregnancy stage and litter size

“…In rabbits, a 2.5-fold increase was reported between day 24 and 30 of gestation [28]. In sheep, UBF increases linearly over time during the For instance, Reynolds et al [49] showed that UBF increased until 250 days of gestation in cows by using the steady-state diffusion procedure with deuterium oxide, whereas Ferrell and Ford [20] did not find any increase of UBF after day 178 when measured with electromagnetic transducers. Moreover, UBF varies with time during the same day, with sow position, and between night and day (Père, unpublished data), and it was measured during 10 min per day by Ford et al [26] and Reynolds et al [48] instead of 24 h as in the present study.…”

“…kg -1 FPU does not change during the second half of pregnancy, which means that absolute UBF increases. In cows, Reynolds et al [49] and Reynolds and Ferrell [45] reported that UBF increases exponentially during gestation (4.5-fold greater at 250 than at 137 days of gestation). All these results show that uterine blood flow increases during a period of intense development and growth of the foetuses.…”

Prenatal and pre-weaning growth and nutrition of cattle: long-term consequences for beef production

“…Placental weight and birth weight are highly correlated in cattle (Anthony et al, 1986b;Echternkamp, 1993;Zhang et al, 1999); however, the functional capacity of the placenta is closely related to placental perfusion. Bovine uterine and umbilical blood flow increases exponentially during the second half of gestation, which equates to relatively constant rates of umbilical blood flow on a foetal weightspecific basis during this period (Reynolds et al, 1986). A more detailed account of placental function and metabolism in cattle is provided by Ferrell (1989), and of foetal macronutrient requirements and metabolism in cattle and sheep, and of placental function and metabolism, by Bell et al (2005).…”