Ghrelin concentration in half-blood jumping horses during moderate and intense training exercise

The aim of the study was to assess the impact of varying intensity of exercise on ghrelin levels in half-blood jumping horses during training season. Blood samples were collected in the period of intense and moderate exercise. Serum concentrations of active and total ghrelin were measured using commercial RIA kits. Exercise did not cause the disruption in energy homeostasis, which was confirmed by the conducted tests. Total concentration of ghrelin measured during the increased effort intensity elevated in stallions (from 1031.45 to 1732.19 pg/mL at P ≤ 0.05). The opposite situation occurred in the case of active ghrelin, which concentration did not increase significantly in mares (from 26.21 to 28.46 pg/mL), whereas an insignificant decrease was noted in stallions (from 24.19 to 22.54 pg/mL). The only significant difference between stallions and mares was noted in the 2^nd sampling (P = 0.015). The research proved that the fluctuations of both studied parameters did not reflect a negative impact of the increased effort.