Lewis & Short

sēmĭnĭum, ii, n. [semen],

  1. I. a begetting (of animals), procreation (ante-class.), Plaut. Mil. 4, 2, 68; Varr. R. R. 2, 6, 1.
  2. II. Transf., a race, stock, breed (of animals), Varr. R. R. 2, 1, 14; 2, 3, 3; 3, 9, 6; Lucr. 3, 742; 3, 746; 4, 1005.