Here is a collection of undated small solid plastic farm animals from pigs to horses to cows from as far as I can tell 2 different manufacturers. The ones that are sand colored are quite old and of solid rubber and have the name of the animal type stamped into their belly bottoms: "Clydesdale", "Hereford", "American Guernsey", "Merino Ram" (he is tiny!), "Poland China", "Brown Swiss", ""American Short Horn", and the 3 piglets in sand are too tiny for anything to be printed on them, as is the tiny lamb (3/4"). They are very detailed especially in their texture... ribs showing through, fur lines, etc... and date pre-1960s and are quite rare collectibles.
Then there are the more recent plastic dark brown ones whose mold lines are quite visible: grazing cow, standing horned cow with ear and nose chewed on, horse with chewed ears, long-horned bull (a slightly redder brown), a match for the standing horned cow without the chewed marks, and a pair of matching foals.
Then 1 terra cotta red-brown, a magnificent strong and proud "made in Hong Kong" marked bull with, ahem, quite a hefty load.
All in all 20 aminals!! Most are about 2 1/2" to 3" long and 1 1/2" tall.
** These make awesome photo props!