2.1. Animals and Experimental Design.

All the treatments, housing and animal care during the study were in accordance with the standards recommended by the European Directive 2010/63/EU for animal experiments. After the informed consent of the owners, 30 Italian Saddle geldings (6–10 years of age; mean body weight 449 ± 10 kg) were included in the study. All horses were managed similarly in the same place (a horse training center in Sicily, Italy, latitude 38°10′ 35′′ N; longitude 13°18′14′’ E), housed in individual boxes (3.5 × 3.5 m), subjected to the same environmental conditions (natural photoperiod, mean temperature 25 ± 4 °C, mean relative humidity 65 ± 5%).

The animals were fed twice per day (08.00 a.m.; 06.00 p.m.) with a total amount of approximately 2.5% of their body weight in dry matter intake (forage:concentrate ratio 70:30) and water was available ad libitum.

All the animals were clinically healthy (based on a thorough clinical examination) and free of internal and external parasites.