In ruminants, microbes in rumen are capable of altering dietary FAs, any carbon in the chain that is unsaturated will be fully saturated. Encapsulated fats which bypass the rumen are not saturated. Can be fed more if fed as bypass fat. Symptoms of deficiency are scaly skin, reduced growth and reproduction, edema, subcutaneous hemorrhage, poor feathering. The symptoms do not occur in ruminants even on a fat-purified diet, because microbes capable of synthesizing all the fats they need.
Lipids are the only nutrient that the body has an unlimited capacity to store excess.
The form of dietary fat for the most part does not affect body fat composition in ruminants, because microbes saturate everything, so body fat is primarily saturated. Can be manipulated somewhat if you feed bypass fats, but not a whole lot. Dietary fat composition will affect body fat composition in monogastric species. Animals, particularly poultry and swine, fed primarily unsaturated fats will have higher degree of unsaturated FAs in body fat. This affects the characteristics because unsat are softer, have lower melting point, which affects processing and carcass quality.