BLOOD METABOLITE CONCENTRATIONS IN LATE PREGNANT EWES AS INDICATORS OF NUTRITIONAL-STATUS

In a feeding experiment beta-hydroxybutyrate (BHB), glucose, albumin, total protein, globulin and urea concentrations in the plasma of twin- bearing ewes were analysed. Mature Suffolk cross ewes were given eithe r formic acid (FA)-treated grass silage or grass/molassed sugar-beet p ulp (MSBP) silage in late pregnancy. The experiment commenced on day 9 1 of pregnancy and the dietary treatments were FA-treated silage (T1), FA-treated silage + soya-bean meal (SBM) (T2), MSBP silage (T3), MSBP silage + SBM (T4), FA-treated silage + MSBP (T5), FA-treated silage MSBP + SBM (T6) or FA-treated silage + 150 g crude protein (CP) per k g concentrate (T7). SBM was given only in the last 21 days of pregnanc y aiming for a total CP intake of 220 g per ewe per day. Blood samples were collected by jugular venipuncture from each ewe 3 h following co nsumption of the morning dietary allowance on days 121, 128, 135 and 1 42 of pregnancy. Daily metabolizable energy (ME) intakes of 6.8, 11.4, 9.6, 12.8, 10.5, 13.7 and 14.7 (s.e. 0.58) MJ per ewe were recorded f or T1 to T7 respectively over the last 3 weeks of pregnancy. Respectiv e CP intakes of 72, 213, 110, 225, 109, 215 and 175 (s.e. 5.64) g per ewe were recorded for T1 to T7 respectively over the last 3 weeks of p regnancy. BHB concentrations (mmol/l) on day 121 of pregnancy of 1.18, 1.25, 0.52, 0.52, 0.56, 0.39 and 0.45 (s.e. 0.17), on day 128 of preg nancy of 1.17, 0.94, 0.52, 0.51, 0.72, 0.62 and 0.39 (s.e. 0.20), on d ay 135 of pregnancy of 1.53, 0.68, 0.68, 0.66, 0.71, 0.62 and 0.46 (s. e. 0.20) and on day 142 of pregnancy of 1.43, 0.60, 0.62, 0.56, 0.62, 0.56 and 0.63 (s.e. 0.20) were recorded for T1 to T7 respectively. The re teas a quadratic relationship between plasma BHB concentration and ME intake on days 121 (R-2 = 0.538, P < 0.001), 128 (R-2 = 0.324, P < 0.001), 135 (R-2 = 0.429, P < 0.001) and 142 (R-2 = 0.344, P < 0.001) of pregnancy. There was a positive relationship between plasma glucose concentration and ME intake on day 121 (R-2 = 0.208, P < 0.001), 128 (R-2 = 0.103, P < 0.05), and 135 (R-2 = 0.160, P < 0.01) of pregnancy. Albumin concentrations (g/l) on day 128 of pregnancy of 21.8, 21.7, 2 3.6, 22.9, 22.5, 22.9 and 24.3 (s.e. 0.75), on day 135 of 20.9, 23.6, 24.2, 24.1, 22.4, 24.1 and 23.8 (s.e. 0.75), and on day 142 of 16.9, 2 2.9, 20.7, 22.1, 20.4, 22.7 and 21.1 (s.e. 1.05) were recorded for T1 to T7 respectively. Plasma albumin concentrations were significantly a ffected by SBM supplementation (P < 0.05). Despite the lower than gene rally recommended energy concentrations in T2 to T7, the concentration s of plasma BHB were within the normal range for healthy sheep.