ABSTRACT
Adipose tissue, also known as fat, is a connective tissue of mesenchymal origin. Although adipose tissue contains various cell types, adipocytes predominate and are the primary storage site for triacylglycerols. Subcutaneous, internal, and intramuscular adipose tissue depots are all economically and physiologically important in meat animal production. Brown adipose tissue (BAT) is also present in the neonate of some species and is considered important for thermoregulation of the newborn. Advancements in meat production have attempted to shift energy use for maximal muscle accretion while limiting adipose accretion resulting in enhanced feed efciency and improved growth rates. Marbling fat is one important meat quality factor that has suffered as a result of advances made to improve the efciency of animal production. Also known as marbling fat, intramuscular lipid is lipid stored in adipocytes found within skeletal muscle that impacts meat avor and tenderness. It is known that adequate adipose accumulation is essential. Adipose tissue is considered an endocrine organ that secretes or expresses many endocrine factors, including leptin, growth factors, and various cytokines. The discovery that adipose tissue is the major source of circulating leptin (OB), a hormone that inuences growth, metabolism, and behavior, has provided a new perspective on adipose tissue function (Trayhurn et al. 2006). Furthermore, the expression of growth factor genes by adipose tissue and presence of the resulting proteins further indicates that adipose tissue has endocrine functions. For example, adipose tissue in the pig fetus produces more IGF-1 mRNA than all other tissues studied (Ramsay et al. 1994). It now appears that adipose tissue expresses and secretes cytokines, growth factors, and leptin beginning early in life and continuing throughout life (Hausman et al. 2006; Hausman et al. 2007). The coincidental expanse of vascular development as adipose tissue develops (Crandall et al. 1997; Hausman and Richardson
3.1 Introduction ............................................................................................................................ 67 3.2 Adipose Tissue Development .................................................................................................68
