A decrease in dry matter intake is a major physiological change in ruminants. This may lead to several metabolic disorders such as ketosis, fatty liver and hypocalcemia. Insulin is the principal hormone responsible for the control of glucose metabolism. Secretion of insulin is mainly controlled by plasma glucose concentrations, and the hormone has a number of important metabolic actions. Extensive research on how to improve the nutritional, metabolic and health status of ruminants has been of great interest for a long time (Armitage et al. 2004; Husted et al. 2008; Lassala et al. 2011; Seabrook et al. 2011; Sébert et al. 2009).
Sheep are a good animal model for the study of major physiological systems, such as the cardiovascular, respiratory, renal, reproductive and endocrine systems. The baseline anatomy and physiology of sheep has been well-defined, its size allows for good access for the insertion of physiological monitoring and sampling devices, and it is a species that recovers quickly and well from general anesthesia and invasive surgery. Moreover, sheep pregnancies are usually singleton or twin. The careful choice of sheep breed, maternal age, pre-pregnancy nutrition and body condition are critical aspects of studies designed to answer key questions about human pregnancy. (Armitage et al. 2004; Husted S et al. 2008; Lassala et al. 2011; Seabrook et al. 2011; Sébert et al. 2009).