Analysis of trotter gait on the track by accelerometry and image analysis

The aim of this study was to describe the correlation between the phases of the limb cycle of trotters on the track and specific points on the acceleration curves obtained from a new gait analysis system. We compared kinematic data obtained by video image analysis and 3-dimensional acceleration recordings made on 3 French trotters in training. They trotted on a race track at speeds of 8.33, 10 and 11.66 m/s, with a final stretch at maximum speed. Their locomotion was recorded with a synchronised video camera at a frame frequency of 200 Hz and with the Equimétrix gait analysis system. The gait variables were calculated using 3-dimension acceleration data recorded at the sternum (dorso-ventral, longitudinal and lateral axes) at a sampling rate of 100 Hz. Three phases of the stride were clearly identified on the dorsoventral acceleration signal: hoof-landing, midstance phase and toe-off. Braking and propulsion phases were identified on the corresponding longitudinal acceleration signal. The weight-bearing diagonal was identified by observing the lateral signal. The stride temporal variables (stride, stance, braking and propulsion durations for both diagonals), measured by video analysis and by acceleration signal analysis, were not significantly different (P>0.05). The identification of specific points on the acceleration pattern allowed an accurate temporal analysis of the stride. Potential applications could be the determination of locomotor factors related to racing performance or assessment of locomotor disorders at high speed.

Effects of bromocriptine treatment on the expression of sexual behavior in male sheep (Ovis aries)

Twenty-three rams were treated twice daily with subcutaneous injections of bromocriptine or vehicle over 30 d during two seasons, spring and fall. Sexual behavior was observed and quantified to determine the effects of bromocriptine-induced hypoprolactinemia on mount attempt (MA), mount (M), and ejaculation (E) frequency of the rams upon exposure to estrous ewes. Behavioral responses and serum prolactin (PRL) concentrations were determined on a weekly basis before, during, and after the treatment period in each season. Treatment with bromocriptine caused a significant decrease in serum concentrations of PRL during both seasons (P < .01). Post-treatment period concentrations of PRL returned to pretreatment levels during the spring, whereas during the fall, post-treatment period PRL concentrations remained low (P < .05). The frequency of MA and M was lower during bromocriptine treatment relative to control rams in the spring (P < .05). The frequency of MA and M returned to pretreatment values after bromocriptine treatment was withdrawn. Ejaculation frequency tended to decrease during and after bromocriptine treatment relative to controls (P < .09). There was no effect of bromocriptine treatment on frequency of MA and M during the fall. During the fall, the frequency of E tended to decrease in bromocriptine-treated rams (P < .1). These data indicate that bromocriptine-induced hypoprolactinemia is associated with a significant diminution in expression of sexual behavior in rams. It is suggested that PRL modulates the intensity of expression of sexual behavior in rams, and this effect may be season-dependent.