The Collaborative International Dictionary of English v.0.48:

dioestrous \dioestrous\ dioestrual \dioestrual\adj.
   in a period of sexual inactivity; -- of animals that have
   several estrous cycles in one breeding season.

   Syn: diestrous, diestrual.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

dioestrual
    adj 1: (of animals that have several estrous cycles in one
           breeding season) in a period of sexual inactivity [syn:
           diestrous, dioestrous, diestrual, dioestrual]