Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 19 CONCENTRATIONS OF PLASMA METABOLITES IN FETAL SHEEP DETERMINED FROM FETAL HEART SAMPLES TAKEN USING ULTRASOUND GUIDANCE R.W. KELLY and J.P. NEWNHAM W.A. Dept of Agriculture, Sheep and Wool Branch, South Perth, W.A. 615 1 Unlike humans, umbilical vessels in sheep do not have an ideal location for remote introduction of a needle to collect fetal blood. Consequently research on fetal sheep has been based on chronic catheterization of fetal blood vessels. We have recently developed a simple technique to obtain samples from the heart of fetal sheep (Newnham et al. 1989). This abstract reports the urea and glucose concentrations in plasma collected from the fetal heart and maternal jugular vein at day 128 of pregnancy, and the association between these fetal and maternal values. Fifteen 4-6 year old Merino ewes bearing a single fetus were housed in individual pens and fed at either maintenance (n=8,50.7 kg, condition score 2.3) or 0.5 maintenance (n=7,49.6 kg, condition score 2.1) from day 95 of pregnancy. Weights of these ewes at day 128 of pregnancy were 56.4 and 48.5 kg (s.e.d. = 2.4, PcO.O06), respectively. There was 1 fetal mortality as a result of the procedures (fetus alive 4 days after sampling, but the ewe aborted 10 days after sampling). Mean fetal and placental weights (corrected for the effect of sex of the fetus) at day 143 of pregnancy were 4.6 and 4.1 kg (s.e.d. = 0.28, P=O.12) and 460 and 499 g (s.e.d. = 55.7, n-s.), respectively. The plasma metabolite concentrations are summarised in Table 1. Table 1. Mean fetal and maternal plasma urea and glucose concentrations (mmol/L) on day 128 of pregnancy The between animal relationships of fetal with maternal plasma values in mmol/L were: Fetal urea = 0.59 + 1.04 maternal urea (J. = 0.98, P<O.OOl) Fetal glucose = -0.47 + 0.70 maternal glucose (r = 0.81, P<O.OOl) The concentrations and associations between maternal and fetal plasma metabolites are similar to those recorded by other workers for catheterized animals (e.g. Faichney and White 1987). We conclude that fetal heart blood can be used to establish the nutrient status of fetal sheep. In comparison with catheterization, fetal heart sampling has the advantages of being rapid (l-2 mm/sample) and without the need for intensive animal care, so facilitating studies using large numbers of ewes under field conditions. The Wool Research and Development Corporation supported this work. FAICHNEY, G.J. and WHITE, G.A. (1987). Aust. J. Biol. SC. 40: 365-77. NEWNHAM, J.P., KELLY, R.W., BOYNE, P. and REID, S.E. (1989). Aust. J. Agric. Res. 40: 401-7. 201