PLASMA INSULIN AND GROWTH HORMONE CONCENTRATIONS IN PREGNANT SHEEP I:

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Abstract
Two or 3 fetal lambs regularly result in a varying degree of carbohydrate shortage in mother ewes in late pregnancy. The correlation between plasma insulin [I], growth hormone [GH] and energy substrate concentrations in ewes 8 and 1 wk before lambing was examined. Plasma GH was fairly constant (2-3 ng/ml) throughout the 24 h cycle 8 wk before parturition. Seven weeks later higher average levels and increased diurnal fluctuations were observed in 3 of 4 multiparous ewes. The average post-absorptive insulin levels were reduced by 50% during the same interval. Simultaneously decreased post-absorptive sugar and increased acetoacetate levels were observed. The hormonal adaptations to the increasing carbohydrate deficit in late pregnancy, especially among multiparous ewes, include reduced post-absorptive plasma I levels, reduced I responses to feeding and increased plasma GH levels.