Of course I can't resist....
Margerine by government regulation (USDA), thus by definition, is made with vegetable oil and not animal fat. By law, if a "spread" is made with animal fat it is not and cannot be called margarine.
Then again.....you're actually wrong about this.
According to the FDA standard "
21 CFR 166.110", margarine can contain:
(1) Edible fats and/or oils, or mixtures
of these, whose origin is vegetable
or rendered animal carcass fats,
or any form of oil from a marine species
that has been affirmed as GRAS or
listed as a food additive for this use,
any or all of which may have been subjected
to an accepted process of
physico-chemical modification. They
may contain small amounts of other
lipids, such as phosphatides or unsaponifiable
constituents, and of free
fatty acids naturally present in the fat
or oil.
And of course, there is the USDA specifications which say that margarine shall adhere to the FDA specification Title 21, Part 166 as listed above. The USDA also says:
Margarine can contain dairy ingredients.
Dairy Ingredients.
Dry dairy products used as ingredients for which there are U.S. grades established (nonfat dry milk, dry whole milk, and dry whey) shall meet the criteria of U.S. Extra Grade.
And the USDA states that dry whole milk must contain at least 26% fat (that would be animal fat).
(1) Milk fat Not less than 26.0%
And even the margarine blends have to adhere to the FDA specification which allow animal fats.
Margarine/butter blend shall comply with all applicable Federal regulations including the pertinent sections contained in CFR Title 21 Part 166 for Margarine, and the Federal Definition of Butter, Public Law 519 of 67th Congress, March 4, 1923.