Evaluation of the effect of two training regimes on the resumption of the ovarian activity by analysis of faecal 20a-hydroxyprogesterone in trotter mares

Abstract

Onset of cyclic ovarian activity in mares, after seasonal anoestrus is characterized by the appearance of the first heat and thebeginning of seasonal breeding activity. The aim of this work was to evaluate the effect of different training regimes on theresumption of ovarian activity by analysis of 20a-hydroxyprogesterone in faeces. Sixteen trotter mares, housed in singleboxes, were allocated into two groups: in group A, mares (n = 8) were trained outside for one hour each day while in groupB (n = 8), the mares were remained inside their boxes all day. Faecal and plasma samples were collected every Monday andFriday morning from the 16th of February until the 13th of May and stored at -20 °C until used for hormone assay. Plasmalevels of progesterone and faecal level of 20a-hydroxyprogesterone were measured by radioimmunoassay. In group A, theonset of cyclic activity occurred one month earlier than in group B (P < .001). Moreover, during the reproductive season, theresumption of the cyclic activity was more gradual in group Athan in group B, in which cyclic activity was enhanced betweenthe 15th and 30th of April. In conclusion, 20a-hydroxyprogesterone concentrations in faeces can be used to evaluate cyclicactivity in mares. Resumption of cyclic ovarian activity was positively affected by regular physical work.

Keywords

• Mare
• cyclic activity
• 20a-hydroxyprogesterone
• faeces
• training