A comparison of plasma growth hormone, insulin, free fatty acid and glucose concentrations during oestrus and early pregnancy in Clun Forest ewe lambs and ewes

An experiment was conducted to compare plasma growth hormone, insulin, glucose, and free fatty acid concentrations in Clun Forest ewe lambs (n = 6) and ewes (n = 5) during oestrus (Day 0) and early pregnancy. Overall mean growth hormone concentrations were similar in both groups. However, overall mean insulin concentrations were higher during oestrus and early pregnancy in ewes (ranges of 0.15 +/- 0.04-0.97 +/- 0.12 mug/l) compared with ewe lambs (range of 0.06 +/- 0-0.78 +/- 0.21 mug/l) (P < 0.05). In addition, insulin concentrations gradually declined in both groups from Day 0 to 30 (P < 0.05). Overall mean free fatty acid concentrations were higher in ewe lambs (range of 142.5 +/- 12.0-678.3 +/- 86.6 mum/l) compared with ewes (range of 100.0 +/- 9.49-510 +/- 46.3 mum/l) throughout oestrus and early pregnancy (P < 0.05). Furthermore, concentrations declined in both groups from Day 0 to 30 of pregnancy. Overall mean glucose concentrations were higher in ewe lambs (range of 3.14 +/- 0.07-4.06 +/- 0.04 mmol/l), compared with ewes (range of 2.85 +/- 0.13-3.67 +/- 0.07 mmol/l), prior to Day 18 and higher in ewes (ranges of 1.58 +/- 0.45-3.25 +/- 0.12 mmol/l and 3.0 +/- 0.06-3.83 +/- 0.31 mmol/l, respectively for ewe lambs and ewes) from Day 18 to 30 (P > 0.05). These results indicate that hormone (insulin) and metabolite (free fatty acid and glucose) profiles differ during oestrus and early pregnancy in ewe lambs and ewes maintained under identical conditions. (C) 2003 Elsevier Science B.V. All rights reserved.