Growth hormone secretory pattern and somatomedin C plasma concentrations in newborn calves.
Plasma growth hormone (GH) and somatomedin-C (IGF-1) concentrations were measured by radioimmunoassay in 16 dairy calves during the first 20 days of postnatal life. The lowest plasma GH concentration (0.07 +/- 0.01 nmols . l-1) occurred 4 h after birth. It increased gradually until the 3rd day, to reach values similar to those measured in adult males (0.15 +/- 0.05 nmoles . l-1) and remained stable until 20 days. The lowest plasma IGF-1 concentration (3.1 +/- 0.5 nmol . l-1) was measured at 3 days, then increased at 4 days (7.6 +/- 0.6 nmol . l-1) and remained stable until 20 days of age. In nine 2-10 days-old calves, the GH secretory profile observed in blood samples collected every 30 min over a 24-h period showed 8-13 secretory spikes, without periodicity. No relationship could be demonstrated between plasma GH and IGF1 concentrations. A marked increase in plasma GH concentrations followed every morning milk feeding.
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002940:Circadian Rhythm; D004435:Eating; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000097:blood*; D008297:Male; D013002:Somatomedins / Q000097:blood*
D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone