Onset of the first post-partum oestrus in Hutsul mares kept at the National Stud Farm in Topol'cianky.

摘要

The onset of the first post-partum oestrus occurs in mares on days 5 to 20 post-partum. It is affected by the long-lasting suppression of the function of the hypothalamic-hypophyseal-ovarian axis during gravidity. This first post-partum oestrus is advantageous due to its reliability, early onset, good conception rate and regularity. Its disadvantages are the high incidence of embryonic mortality in mares suckling their foals and the subsequent anoestrus. An opinion prevails that this first post-partum oestrus should not be used or used only to a limited extent. The onset of the first post-partum oestrus was affected by the date of parturition and the day from parturition when this first oestrus began. Observation of the herd of 21 Hutsul mares kept at National Stud Farm (NSF) in Topol'cianky revealed the following information about 17 gravid mares: * Onset of the first post-partum oestrus was recorded no earlier than on day 8 and no later than on day12 post-partum, * The length of the first post-partum oestrus was a minimum of 3 days with two mating attempts and no longer than 11 days, with the number of mating attempts equal to 6, * The successfulness of mating attempts during this first post-partum oestrus was low and reached only 35.3%.