Behaviours exhibited during training predict physical tiredness in harness trotter horses

Abstract

Physical activity, especially high-intensity training (HIT), leads to physiological and behavioural changes. The objectives of this randomized cross-over study were to investigate i) the effects of physical exercise on weight, behaviours, and head and ear positions on the days after low-intensity training (LIT) or high-intensity training; and ii) to explore if behaviours, and/or physiological parameters (sweat, salivation and blood lactate levels) during training can predict post-training behaviours. A total of nineteen French trotter horses housed in four different training centres were studied the day before (Dpre) and after LIT or HIT (afternoon after training (Dtraining) and 2 days after training (D1Post and D2Post)). The results showed that horses exhibited i) longer durations of resting and head below the withers (HBW) on Dtraining and D1Post than on Dpre and ii) shorter eating durations on D1Post and D2Post than on Dpre after HIT. This was associated with significant weight loss on D2Post. Several behaviours associated with discomfort (e.g., head conflict behaviours, nose behind the vertical, and open mouth), as well as amount of sweat, seemed to predict the durations of resting, HBW and eating on D1Post. Thus, behaviours are impacted by training, and a combination of behaviours and visible physiological parameters exhibited during training have the potential to predict physical tiredness in harness racing horses.