PSXV-18 - Dynamics of steroid hormones in young fine harness horses during the preparatory period of the race-course training

The aim of the study was to determine the dynamics of steroid hormones (pg /ml) in 2-year-old mares and stallions. During preparatory training, at rest, stallions and mares had similar testosterone levels (0,98±0,745-0,82±0,013), estradiol (21.18±5.05-22.50±3.01) and cortisol (90.17±2.11–83.26±2.48), respectively. In response to submaximal power, stallions and mares expend their reserves uneconomically, expressed in an increase of testosterone (9.54±0.353 – 19.59±1.85) and cortisol (203.07±8.70 -245.57±18.60). The estradiol in stallions fell 27% to 16,68±3,01, and in mares increased by 9% (24.50±0,89). At the end of the preparatory period, stallions showed increase in testosterone by 13 (to 13.47±2,21), cortisol 1.5 times (139,12 ±of 12.97), a fall in estradiol levels 5.3 times (to 4.00± 1,72). The content of testosterone in mares increased by 8.6 times (to 7.09±0.97), cortisol by 2.2 times (to 185.24±3.78), and estradiol fell by 6.8 times (to 3.30±0.84). The swing movement at the end of the preparatory period caused a significantly (P ≥ 0.999) less increase in testosterone in stallions (up to 2.63±0.42) and mares (9.39±3.09) in contrast to the previous period. The cortisol content in stallions increased by 88% (to 381.5±17.3), in mares by 384% (to 711.80±47.50). Estradiol concentration decreased 10-fold in stallions (to 1.40±0.576; P ≥ 0.999), and 3.5-fold (to 6.94±0.829; P ≥ 0.999) in mares.

Conclusion: the training is sufficient for adaptation of stallions to the racetrack. For mares, the duration of the preparatory training is not sufficient.