Evaluation of the sexual behavior and testosterone concentrations of Mangalarga Marchador stallions

Assessing the sexual behavior of stallions is extremely important because sexual behavior is linked to reproductive efficiency. The objective of this study was to evaluate the sexual behavior, testosterone concentration and libido of Mangalarga Marchador stallions from northern Rio de Janeiro State, Brazil. The sexual behavior of 10 stallions was evaluated during semen collection while mounting a mare in estrus. Blood samples from each animal were collected for the evaluation of serum testosterone. The study was conducted during the breeding and non-breeding seasons with animals separated into two age categories: young (<4 years) and adult (>5 years). The libido of the stallions was evaluated using the observations of reaction time (RT), mount time (MT) and mount and ejaculation time (MEjT). Analysis of variance and analysis of data frequency were performed. The stallion behavior and testosterone concentrations were not affected by the breeding season or stallion age (p > 0.05). The overall mean of RT was 14.0 ± 2.4 s, MT was 32.7 ± 3.5 s and MEjT was 24.3 ± 0.8 s. We observed a few instances of a mount without an erection and a mount without ejaculation a maximum of 4 and 1 times, respectively. The percentage of stallions that did not perform Flehmen, biting, kicking, sniffing and vocalization were 72, 93, 93, 34 and 45% respectively. The average testosterone concentration was 0.64 ± 0.06 ng/mL. We concluded that the animals exhibited good libido overall, thereby indicating that they were well adapted to the environmental conditions of northern Rio de Janeiro state, Brazil.