DIETARY LIPIDS FOR RUMINANTS - PROTECTION, UTILIZATION AND EFFECTS ON REMODELING OF SKELETAL-MUSCLE PHOSPHOLIPIDS

Processes have been developed which protect dietary fat from ruminal metabolism, enabling greater quantities of lipid to be included in the diet of ruminants without causing deleterious effects on cellulose digestion and methane formation in the rumen. The inclusion of both protected fat and protected protein in the diet of lactating ruminants increased the percentage of milk fat and eliminated the reduction in protein content which is often observed as a result of feeding protected fat by itself. The inclusion of protected fat and protected protein in the diets of feedlot cattle increased metabolizable energy and rumen non-degradable protein. This resulted in improved feed conversion and dressing percent. There were substantial changes in the fatty acid composition of triacylglycerols of milk and adipose tissue as a result of feeding oil seeds protected from ruminal hydrogenation. The inclusion of protected fats containing linoleic or eicosapentaenoic acids in the diet of lotfed cattle resulted in major alterations in the fatty acid composition of the molecular species of muscle phospholipids. The significance of these changes in relation to phospholipid remodelling, signal transduction pathways and the characteristics of lipid-derived second messengers is discussed.