Leadership—Management Superstructure

Abstract

Abstract:The liver is one of the most important visceral organs, which represents a large contribution to whole animal energy expenditure and the major synthetic site of insulin-like growth factor-1 (IGF-1) peptide. Decreased plane of nutrition acts by reducing the metabolic rate and mass of metabolic tissues, such as liver. Also, undernutrition results in the reduced circulating IGF-1 concentrations, due to the uncoupled growth hormone-IGF (GH-IGF) axis. This study investigated whether a 22-day period of undernutrition (half maintenance) could affect liver mass and IGF-1 protein and gene expression. Sixteen pregnant ewes fed all (n = 9) or half (n = 7) of their maintenance energy requirements were slaughtered on day 7 of pregnancy (oestrus = day 0). Body and liver mass, IGF-1 plasmatic concentrations and liver IGF-1 mRNA and protein expression were determined. Liver mass and the proportion of liver mass to empty body weight were lower in underfed animals. While IGF-1 plasmatic concentrations were lower in undernourished ewes, no differences in liver mRNA expression were found. This is the first time that differences in immunohistochemistry intensity and total content are reported in sheep. In summary, the decreased plasma IGF-1 concentrations induced by undernutrition in ewes was not associated with its reduced hepatic mRNA or protein expression, but to a decrease in liver mass.