Insulin-like growth factor I plasma concentrations in newborn healthy donkey and horse foals

In different species the insulin-like growth factor I (IGF-I) is animportant regulatory factor in fetal and neonatal growth, especially inskeletal and gut development. This study was carried out to assessplasma IGF-I profile in newborn healthy donkey and horse foalsduring the first 2 weeks of age. The study was conducted on 32 horseand 19 donkey foals, born at term, after spontaneous parturition,mature and viable. Blood samples were collected from the jugular veinat 10, 20 and 30 min, 3 and 12 h and at day 3, 7, 10, 14 of life. IGF-Ilevels were evaluated by RIA. IGF-I showed an increasing profile inboth species, with lower levels (p < 0.05) during the first 3 days of life.Plasma IGF-I levels were found to vary widely between subjects bothin donkey and horse foals. Mean plasma levels were higher(p < 0.001) in horses than in donkeys during the first week. Howeverdonkey foals showed a greater mean percentage increase (681%) thanhorse foals (114%). These results evidenced increase of IGF-Iconcentrations during the first 2 weeks of life that could be associatedwith a number of physiological challenges in adapting to extrauterinelife. Moreover, although horses and donkeys belong to the same genus,these results seem to indicate the presence of some differences in theirsomatotropic axis activation.P129Effect of artificial insemination site[...]