Abstract:
Proc, Aust. Soc. Anim, Prod, Vol. 18 THE EFFECT OF MATERNAL BODY CONDITION ON GLUCOSE METABOLISM AND FOETAL GROWTH DURING LATE PREGNANCY G.J, McCRABB*, A.R. EGAN* and B.J. HOSKING* Construction of strategic feeding systems requires an understanding of the factors regulating voluntary intake and partition of nutrients in ewes in various physiological states. This experiment was designed to investigate the effect of previous maternal undernutrition to day 96 of pregnancy on metabolism of glucose, a substrate of critical importance (Battaglia and Meschia 1981) during late pregnancy; and on deposition to various energy sinks under ad libitum feeding conditions. Group C A flock of 24 Corriedale/Comeback ewes were mated on known dates. (Control n = 12) ewes were fed chaffed lucerne (Xedicago sativa) hay for the duration of pregnancy, while Group R (Restricted n = 12) ewes were underfed between days 30 and 96 of pregnancy to lose 7 kg live weight, then fed ad libitum the same chaffed lucerne hay. Ewes were slaughtered at day 96 (n = 6C, 5R) and day 140 (n = 6C, 6R), and dissected into the various body components. On day 126 50 uCi of 6-(%)-glucose was injected into the maternal jugular Jugular blood samples were taken via a PVC catheter over the following vein. 24 hours, nine samples during the first 3.5 hours and eight further samples at increasing intervals until 24 hours. Voluntary feed intake of C ewes was lower than that of R ewes at days 121-125 1693t167.5, P<O.OS) (1271+78.6, 1773+123,4, P<O.Ol) days 126-130 (1261269.3, Various and &ys 131-135 (1379+80-O, 1671k132.6, P<O.lO) respectively. production parameters are shown in Table 1. There was no significant difference between C and R ewes in maternal blood concentration, pool size, entry rate and irreversible loss of glucose. Entry rate (3.0~0.26, 2.0~0.08 mg/min/kg) and irreversible loss of glucose (2.5+0.27, 1.8+0.06 mg/min/kg) were higher for R ewes than for C ewes when expressed as a proportion of body weight. Table 1 Live weight, muscle and fat deposits, foetal weight and wool growth Between days 96 and 140, C ewes were mobilizing more fat deposits, depositing less muscle tissue and growing more wool than their restricted counterparts. Despite differences in the settings regulating the partition of nutrients during late pregnancy there was no difference in foetal growth. The factors controlling these settings need to be understood to evaluate the cost/benefit ofaupplementary feeding during late pregnancy. BATTAGLIA, F-C. and MESCHIA, G. (1981). Physiol. Rev. 58:449. * School of Agriculture and Forestry, University of Melbourne, Vic. 3052. 519