Effect of rostrocaudal mobility of the mandible on feed digestibility and fecal particle size in horses.

This study investigates whether the movement of a horse’s lower jaw (called rostrocaudal mobility or RCM) during extension and flexion impacts weight gain, how well horses digest their feed, and the size of particle in their feces. However, the experimental results from a trial involving 34 pregnant horses contradict commonly held beliefs, finding that jaw mobility had no impact on these three factors.

Study Aim and Methodology

• The research aimed to explore the influence of rostrocaudal mobility (RCM) of the horse’s lower jaw (also known as the mandible) during the extension and flexion of the atlanto-occipital joint on three parameters: weight gain, feed digestibility, and the particle size in feces.
• The research was devised as a randomized control trial involving 34 pregnant horses that were all kept in the same barn. The horses were divided randomly into either a treatment group or a control group, with 17 horses in each group.
• The key measurement taken was the distance between the front parts of the upper and lower incisor arcades (or teeth rows) during extension and flexion of the atlanto-occipital joint. The calculation of mandibular RCM was made by figuring out the difference between these values. In the case of the treatment group, these measurements were taken after a procedure known as dental floating.
• The body weight of the animals was taken a day before dental floating and at various intervals after the RCM measurement was taken, over 24 weeks. The feces of the horses were also collected during two 5-day periods during the trial.
• Various analyses were carried out on samples of the feed and feces to figure out the digestibility of the feed, and the drying and analysis of fecal samples was done to determine particle size.

Results

• The data derived from the trial showed that the RCM of the mandible had no impact on weight gain, feed digestibility, or fecal particle size with no breed-related variations observed. This held true even when variables like age and the count of dental lesions were taken into consideration.

Conclusion

• From these findings, the researchers concluded that the rostrocaudal mobility (RCM) of the horse’s mandible does not influence weight gain, feed digestibility, or fecal particle size. This challenges the existing assumption that dental abnormalities in horses might negatively impact digestion. Given these findings, the researchers suggest that further research should be aimed at revisiting this assumption.