Influence du niveau des apports énergétiques pendant la fin de la gestation sur l'insulinémie et l'aminoacidémie des brebis et de leurs agneaux

This 2 x 2 factorial experiment (table 1) was carried out in the autumn on 22 Limousine ewes during pregnancy and lactation. The animals bore or were suckling twins. The experimental treatments included 2 levels of energy intake during 7 weeks prepartum (high : H ; low : B) and 2 states of body reserves at 8 weeks prepartum (fat : G ; lean : M). Jugular blood samples were taken from ewes at 34, 20 and 6 days prepartum, and from lambs at lambing and at 6 hrs., 24 hrs., 12 days and 24 days after lambing. Blood glucose, urea and free amino acids and plasma insulin were recorded. Reducing dietary energy supply did not change lamb birth weight in autumn (fig. 1 A). It contrasted with a large diminution in the spring (Grizard et al., 1979a, b). There was a decrease of glucose and of some non-essential free amino acids (alanine, glutamate, proline, citrulline) in the blood of the ewes. Most of the non-essential free amino acids decreased during the first day of life in the blood of lambs (fig. 2A). Reducing body reserves resulted in an increase of glucose and glutamine but in a decrease of some other free amino acids (glutamate, ornithine, histidine) in the blood of ewes (fig. 1 B). It increased daily weight gain during the first 3 weeks of life in lambs (fig. 2B). At the beginning of life, plasma insulin in lambs seemed to be related to birthweight and to blood glucose in the mothers.