Methods for reducing the amount of ruminal saturation of unsaturated fatty acids and poly-unsaturated fatty acids in a ruminant by administering compositions that interfere and reduce lipolysis and/or biohydrogenation are provided. In one embodiment, the composition is antibodies that bind to immunogens involved in lipolysis and/or biohydrogenation. In another embodiment, the composition is an immunogenic composition containing immunogens involved in lipolysis and/or biohydrogenation. Method for producing the antibodies are also provided.
