To test the hypothesis that routine dental correction (removal only of shar
p hooks and points from molars and premolars) would improve digestion of a
hay/grain ration whereas performance 'floats' (rounding and smoothing of th
e dental arcades) would adversely affect digestion, 8 mature horses free fr
om dental correction for over a year were used. Five-day digestion trials w
ere conducted before and 2 and 4 weeks after correction in all horses. Alth
ough all horses had sharp points and minor premolar hooks, none had severe
dental abnormalities. There were no significant differences found in appare
nt digestion of dry matter, crude protein, neutral detergent fibre or acid
detergent fibre relative to precorrection data or controls (uncorrected hor
ses on same digestion trial), Apparent digestibility of crude protein and f
ibre, however, was reduced if the occlusal angle of premolar 307 was greate
r than 80 degrees relative to the vertical axis (flattened), It should be r
ecommended that regular dental correction be continued. However, if only sm
all points and hooks are present, correction will not significantly improve
digestion. Performance floating does not adversely affect digestion 2-4 we
eks after the procedure is performed. Alterations in molar occlusal surface
angle may affect digestibility of protein and fibre.