Growth-related hormones in plasma of bulls, steers and heifers given food with two different energy levels

Abstract

Concentrations of growth hormone (GH), insulin-like growth factor , insulin and glucagon were determined in the plasma of growing bulls, steers and heifers (no. = 138 in total, German Simmental breed). The animals were offered either a high level or a low level of energy resulting in relatively high and low average daily gain. Trials were subdivided into two experimental series and started at approximately 3 months of age at an average live weight of 110 kg. The animals were slaughtered at different body weights from 200 to 510 kg (heifers) or 660 kg (bulls, steers) . Blood samples (needle puncture) were collected at biweekly intervals. Frequent samples for time-course analysis of GH were taken by catheter from nine animals in total. Concentrations of GH declined during growth in steers and heifers as well as in bulls in blood samples collected by means of a catheter. IGF-1 and insulin concentrations increased from the start of the trial onwards up to different ages among the groups.Concentrations of glucagon constantly decreased from the start of the trial until slaughter. Significant differences (P < 0-05) in concentrations ofGH, IGF-1 and insulin could be observed between sexes and levels of nutrition, with the highest GH and IGF-1 levels in bulls followed by steers and heifers. In contrast insulin values were highest in heifers followed by steers and bulls. A high level of nutrition increased concentrations of IGF-1 and insulin in all sexes.

Effect of feed restriction on plasma concentration of hormones and metabolites in steers fed grass silage

“…This contrasts with the decline observed by Röpke et al (1994) in cattle from 3 to 18 mo of age. On the other hand, Lapierre et al (1992a) reported no significant change in glucagon concentration in heifers between the ages of 3 and 9 mo.…”

Insulin Sensitivity of Heifers on Different Diets

“…In contrast to the results of the present study, [20] reported a significant insulin response to the diets in heifers. Animals of similar body weights as in the present study and with a daily gain of about 1 200 g showed significantly higher insulin levels than animals gaining about 800 g/day.…”

Sexual dimorphism of the somatotrophic axis

“…Humans are unusual in that mean plasma GH concentrations and GH pulse amplitude are greater in adult females than in adult males (Zadik et al 1985, Ho et al 1987, Albertsson-Wikland & Rosberg 1988, Costin et al 1989, Winer et al 1990, Rose et al 1991. In contrast, mean GH concentrations and GH pulse amplitude in blood are greater in adult males than in adult females in rats (Tannenbaum & Martin 1976, Edén 1979, Jansson et al 1984, Gabriel et al 1992, Leidy et al 1993), mice (MacLeod et al 1991, cattle (Plouzek & Trenkle 1991, Röpke et al 1994), horses (Thompson et al 1994 and chickens (Pampori & Shapiro 1994). Mean plasma GH concentrations are also greater in male than in female in late-gestation fetuses in sheep and pigs (Bassett & Gluckman 1986, Bauer & Parvizi 1996 and in prepubertal sheep (Gatford et al 1996(Gatford et al , 1997a.…”

“…Mean plasma GH concentration, area under the GH profile and GH pulse amplitude are all increased by androgens in humans (Illig & Prader 1970, Parker et al 1984, Ulloa-Aguirre et al 1990, rats ( Jansson et al 1984( Jansson et al , 1985, cattle (Plouzek & Trenkle 1991, Schwarz et al 1992, Röpke et al 1994), sheep (Davis et al 1977, Gatford et al 1996, pigs (Dubreuil et al 1989) and chickens (Pampori & Shapiro 1994). In humans, administration of testosterone to males increases mean plasma GH and GH secretion rate by increasing GH pulse amplitude (Illig & Prader 1970, Liu et al 1987, Ulloa-Aguirre et al 1990, whereas in rats androgens also reduce interpulse GH concentrations ( Jansson et al 1984( Jansson et al , 1985.…”

“…Plasma concentrations of IGF-I are greater in males than females in postpubertal rats (Gabriel et al 1992, Hu et al 1993, mice (Blair et al 1987), pre-and postpubertal sheep (Roberts et al 1990, Medrano & Bradford 1991, Gatford et al 1996, 1997b, cattle (Bishop et al 1989, Hannon et al 1991, Schwarz et al 1992, Röpke et al 1994, Davis et al 1995, late-gestation fetal and postnatal pigs (Owens et al 1990, Lamberson et al 1995, Bauer & Parvizi 1996 and in turkeys from 1 week of age (Bacon et al 1993). In contrast, most, although not all ( Juul et al 1994) studies in primates have found that plasma IGF-I concentrations are greater in postpubertal females than in males (Copeland et al 1985, Merimee et al 1987, Yamamoto et al 1991, Schwartz & Kemnitz 1992.…”