RELATIONSHIP BETWEEN AGE, NUTRITIONAL-STATUS AND DAIRY MERIT WITH PLASMA PROFILES OF GROWTH-HORMONE (GH) AND FREE FATTY-ACIDS (FFA) IN BULLS

Blood plasma levels of growth hormone (bGH) and of free fatty acids (F FA) were measured in repeated samples drawn every 15' for bHG, every 1 h for FFA one day after morning feeding and after 3 days of severe fe ed restriction of 7 young (< 2 years) and 14 old (> 5 years) bulls. Th e numerous data were condensated by the PULSAR program Of MERRIAM and WACHTER (1982) to mean level, average baseline concentration, number, average amplitude and average duration of secretory peaks. Young bulls had higher values for all of these parameters except peak duration an d increased these after fast except for peak duration, baseline and in tegral while mature bulls reacted little to food restriction. FFA plas ma levels were higher in young bulls under normal feeding when mature bulls had more frequent peaks. After feed restriction mature bulls inc reased the mean plasma level to the increased level of young bills but decreased the peak frequency. The milk protein yield breeding values are related significantly to mean level, integral and the peak duratio n of plasma bGH levels but in different directions in young and in mat ure bulls.