Studying the Shape Variations of the Back the Neck and the Mandibular Angle of Horses Depending on Specific Feeding Postures Using Geometric Morphometrics

摘要

Many feeding devices such as hay nets are used to increase the time horses spend feeding on hay. However, when hay nets are used, the horse is often forced to keep unnatural feeding positions. Geometric morphometrics was applied to describe the shape variations of back and neck postures as well as the variations of the mandibular angle according to specific positions adopted during hay feeding: on the ground—control position (CP); neck held 15 ± 3° below withers height with low hay net position (LP); neck held 15 ± 3° above withers height with high hay net position (HP). Our results showed that the back and neck postures as well as the mandibular angle were different in HP compared to CP. Moreover, LP showed that the back posture more closely resembled the shape exhibited by horses feeding from CP; however, no similarity was recorded for neck posture and mandibular angle. Our findings suggest that more attention should be paid when horses keep an unnatural feeding position in comparison to when hay nets are used, since the back and neck postures as well as the mandibular angle can be altered especially when horses are forced to eat with a neck held at 15 ± 3° above the withers.