The Collaborative International Dictionary of English v.0.48:

Farrow \Far"row\, v. t. & i. [imp. & p. p. Farrowed; p. pr. &
   vb. n. Farrowing.]
   To bring forth (young); -- said only of swine. --Tusser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

farrowing
    n 1: the production of a litter of pigs [syn: farrow,
         farrowing]