Impact of Forage Presentation on the Equine Brachiocephalicus Mechanical Nociceptive Threshold (MNT) and Forelimb Kinematics

Aims: This investigation aimed to specify whether haynet feeding or floor feeding causes different areas of sensitivity/tensions in the m. brachiocephalicus. The secondary aim was to elucidate whether specific areas of tension within the m. brachiocephalicus would affect the protraction and retraction of the forelimb. Methodology: Ten horses (seven geldings; three mares) were used in the study with an age range of 614. Horses were split into two groups of their already established feeding methods (five haynet feeders; five floor feeders). Each horse was assessed for points of sensitivity in the m. brachiocephalicus at its origin, insertion, and muscle belly, by the use of a pressure algometer. The horse was then walked past a camera for kinematic analysis. Motion analysis software was used to measure the protraction and retraction of each forelimb. Shapiro-Wilk tests were used to measure normal distribution. Data that was deemed normally distributed was analyzed using Independent T-Tests. Data that was not deemed normally distributed was analyzed using Mann-Whitney U tests. Results: The results of the study suggest that the use of haynet feeding has a negative impact on the muscular tensions of the m. brachiocephalicus, most significantly at its insertion. Additionally, haynet groups indicated increased levels of tension in both the muscle belly and origin. It was not significant the effect of the points of tension seen throughout the m. brachiocephalicus have over the kinematics of the forelimb. It can be concluded that haynet feeding increases m. brachiocephalicus sensitivity/tension, which could impact horse welfare and performance.