Fertility and infertility of thoroughbred mares under the environmental conditions prevailing in the Karroo Midlands of South Africa

Abstract

The history, growth and present development of the Thoroughbred industry of South Africa are described. The reasons for the establishment of Thoroughbred studs in the Karroo Midlands are discussed. A study is made of various psychological, physiological and ecological factors in relation to breeding results. The data on oestrus, ovulation, pregnancy and related phenomena were obtained at the Askania Nova Stud, Middelburg, Cape, between 9th September, 1952 and 7th March, 1953, and are the results of observations combined with consistent rectal and vaginal examinations carried out on 27 Thoroughbred mares. Management of the stud is described and data are presented recording observations on the oestrous cycle and its hormonal control, with details on the application of various endocrine substance, treatments and surgical interventions in the correction of irregularities of the cycle, The hormonal control of the oestrous cycle is reveiwed and another theory proposed. Information is also presented on some aspects of pregnancy, including the occurrence of foetal migration and foetal death. These findings are discussed.