Engl. stud [stad] (pastuv) od slov. stado
stud (n.2) 
"horse used for breeding,"
Old English stod "herd of horses, place where horses are kept for breeding,"
from Proto-Germanic *stodo (source also of Old Norse stoð, Middle Low German stod,
Old High German stuot "herd of horses," German Stute "mare"), from PIE root
*sta- "to stand, make or be firm," with derivatives meaning "place or thing that is standing" (source also of Old Church Slavonic stado "herd," Lithuanian stodas "a drove of horses").
Sense of "male horse kept for breeding" is first recorded 1803; meaning "man who is highly active and proficient sexually" is attested from 1895; that of "any young man" is from 1929. Stud-poker (1864) is said to be from stud-horse poker, but that phrase is not found earlier than 1879.
- - - - - - - - - -
Engl. (live)stock (stoka) od slov. stoka < steći
livestock (n.) 
"domestic animals kept for use or profit," 1520s, from
live (adj.) +
stock (n.2). Also, in old slang, "fleas, lice, etc." (1785).
stock (n.2) 
"supply for future use" (early 15c.), "sum of money" (mid-15c.), Middle English developments of
stock (n.1), but the ultimate sense connection is uncertain. Perhaps the notion is of the "trunk" from which gains are an outgrowth, or from stock (n.1) in obsolete sense of "money-box" (c. 1400). Meaning "subscribed capital of a corporation" is from 1610s.
In stock "in the possession of a trader" is from 1610s. Meaning "broth made by boiling meat or vegetables" is from 1764. Theatrical use, in reference to a company regularly acting together at a given theater, is attested from 1761. Figurative phrase take stock in "regard as important" is from 1870. As the collective term for the movable property of a farm, it is recorded from 1510s; hence
livestock.