Van Rensburg, S.W.J.; Van Heerden, J.S.; Alexander, R.A.; Clark, R.; Louw, J.G.; De Kock, V.E.
(Published by The Government Printer, Pretoria, 1953)
(1) The ovaries of 24 mares were examined rectally during a total of 52
oestrous periods in the 1949-51 breeding seasons. Only 27 of the 52 periods ended
in ovulation. In 24 of the 27 normal periods the mares were mated ...