segregate horses into groups according to age, sex, and size where possible;
ensure newly formed groups are monitored frequently and have ample space
in muddy conditions, horses must, at a minimum. have access to a mud-free, well-drained area in the pasture/yard on which to stand or lie down
a good practice is to feed forage first
hack racks/feed troughs should provide 3.3ft of eating space per animal.
an extra feeding point (i.e. one more than the number of horses) can help reduce aggression