Effect of Bovine Growth Hormone Administration on Metabolism of Growing Hereford Heifers: Protein and Lipid Metabolism and Plasma Concentrations of Metabolites and Plasma Concentrations of Metabolites and Hormones

Abstract

The objectives were to determine the effects of daily injection of bovine growth hormone (bGH) on the metabolism of [1-14C]leucine and [1-14C]palmitate and on hormone and metabolite concentrations in growing Hereford heifers. The experimental design was a 28-d single reversal with two 14-d injection periods of placebo or bGH. Energy intake was restricted to a level slightly above maintenance. Injection of bGH did not affect circulating concentrations of glucose, beta-hydroxybutyrate, urea nitrogen, prolactin, triiodothyronine or thyroxine. Plasma concentrations of insulin and nonesterified fatty acids (NEFA) were chronically elevated whereas leucine concentration was chronically decreased after 1 wk of bGH injection compared to placebo injection. Leucine oxidation was lower and whole-body protein synthesis was higher during bGH injection than during placebo injection. There were increases in both total irreversible loss and oxidation of NEFA during bGH injection compared to placebo injection. These results suggest mobilization of stored fatty acids and increased reliance on NEFA to provide energy for cellular processes. The dual and reciprocal effects of bGH on nitrogen and NEFA metabolism demonstrate its role as a homeorhetic regulator, affecting metabolism of several body tissues to support lean body accretion in Hereford heifers at near-maintenance intake of metabolizable energy.

Somatotropin-induced protein anabolism in hindquarters and portal-drained viscera of growing pigs

“…Our current findings of the effects of ST on whole body accretion rates and amino acid oxidation are in accord with the majority of previous studies in animals and humans (4,6,17,24,25,29,37,38,45,46). However, less is known about the specific effects of ST on whole body proteolysis rates in the postabsorptive and postprandial states.…”

“…Less is known about its effects on protein degradation, particularly at the tissue level. The equivocal findings of the ST-induced effects on protein synthesis and protein degradation in previous studies may be due to different developmental stages of the subject population (i.e., growing vs. mature), species studied, nutrient status of the subject (i.e., fasted or fed), tissues analyzed, and length and/or mode of ST treatment (4,5,17,24,25,30,37,38,42,45).…”

Peso vivo final, ganho de peso, características de carcaça e concentrações plasmáticas de IGF-I e hormônios tireoideanos de bezerros mestiços Angus-Nelore recebendo somatotropina bovina recombinante (rbST) até a desmama

“…Eisemann et al (1989) sugeriram que o incremento da taxa fracional de síntese protéica propiciado pelo GH depende do mús-culo estudado. Elsasser et al (1998) observaram, em novilhos confinados, aumento de peso e maior taxa de deposição protéica nos músculos Rectus femoris e Tríceps brachii mediante o fornecimento de rbST (0,1 mg/kg/dia), sendo que o Supraspinatus, Psoas major e Semitendinosus não apresentaram alteração de peso ou mudança na taxa de deposição protéica em relação ao grupo controle.…”

Beef cattle selected for increased muscularity have a reduced muscle response and increased adipose tissue response to adrenaline

“…An alternative theory is that more muscular cattle may also be leaner due to higher circulating growth hormone (GH) concentrations. Sejrsen et al (1983) and Johnsson and Hart (1985) demonstrated that a decrease in serum GH was associated with increased body fat in grain-fed heifers, while protein accretion was higher in animals with increased concentrations of GH (Eisemann et al, 1986). GH treatment also causes an increased lipolytic response to adrenaline in growing pigs and lactating cattle Novakofski et al, 1988;Sechen et al, 1990).…”