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Defining the nutritional regulation of adiprogenesis in livestock species.
Dietary fatty acids have profound effects on lipid metabolism in animals, and may influence cardiovascular function, hence longevity. The individual effects of the primary fatty acids that naturally occur in foods have not been demonstrated completely, and the information the consumer receives rarely is based on scientific fact. Misinformation from the popular press has led the consumer to perceive some foods, such as beef, as unhealthful, when in fact they are a vital part of a balanced diet. Several projects are underway to specifically address the influence of the effects of dietary fats on lipid metabolism in animals. Other, related projects have the long range goal of reducing the deposition of body fat in meat-bearing animals without reducing the quality of the meat we obtain from those animals. The following is a list of projects for which we currently have funding..
Fatty Acids and Serum Cholesterol - Because meat contains significant quantities of palmitic, stearic, and oleic acids, the meat industry is especially vulnerable to interpretations of the effects of specific fatty acids on serum cholesterol. Currently, stearic acid is viewed as an exception to the saturation/unsaturation rule. We have fed pigs (which serve as excellent models for cholesterol metabolism in humans) several diets differing in specific fatty acid composition. Earlier work demonstrated that fatty acid chain length, rather than degree of saturation, determined the cholesterolemic effect of the fatty acid. More recently, we are establishing the cellular mechanisms by which conjugated linoleic acid (enriched in meat and dairy products) depresses serum cholesterol in animal models.
Differentiation of Interfascicular Adipocytes in Longissimus Muscle - The United States' livestock industry produces almost 5 billion pounds of excess fat annually. Yet many breeds of cattle that accumulate excess fat in the subcutaneous and abdominal areas do not deposit sufficient marbling (interfascicular) adipose tissue to grade USDA Choice. Because of the profound economic importance of marbling adipose tissue, the overall project goal is to document the factors regulating the development of this tissue in longissimus muscle. Supporting objectives are to clone cDNAs and genes of proteins that regulate differentiation of adipose tissue and the use of standard biochemical and histochemical techniques to document cell differentiation and hyperplasia in bovine adipose tissue.
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