Which is the safest way to feed groups of yearlings turned out at pasture?
A study at Pennsylvania State University investigated how horses responded to three different feeding systems.
Over two years, two groups of yearlings (four fillies and four geldings each year, full siblings between years) had been kept together at pasture since weaning. They were normally fed in feeders constructed from a pair of large tractor tyres with a board between them. This gave a feeding area that could accommodate more than one horse at a time, with the food raised above the ground.
Investigator Susan Motch and her colleagues compared how the horses behaved when fed using this system, and when they were fed in individual tubs or in a manger with individual feeding stations.
The horses were fed twice daily. The scientists observed the horses during afternoon feedings from the moment food was placed in the feeder until it had been eaten up. Each different feeding system was used for 10 days, then changed, until each system had been used twice.
Horses often turned over the individual feeders, spilling the food on the ground. This often prompted them to move to another feeder.
When fed with the tyre system, the horses spent longer eating and showed less antagonist behaviour towards their fellows. Horses were most likely to show antagonistic behaviour when feeding from the manger system.
The fact that the horses had been used to being fed from the tyre feeders before the study began may account for why they spent more time eating and showed less aggressive behaviour when eating from them.
Motch also found that fillies were more likely than geldings to show aggressive behaviour. Fillies displayed three times the number of agonistic behaviours - such as biting, kicking, striking - or threatening to do so - than did geldings.
Overall there was a low occurrence of agonistic behaviour. However in this study the horses behaved best when fed with the tyre system. The horses showed most agonistic behaviours feeding from the manger. Because of the crowding there was a greater risk of injury with this system.
A note on yearling horse ingestive and agonistic behaviours in three concentrate feeding systems.
Susan Marie Motch, Harold William Harpster, Sarah Ralston, Nancy Ostiguy, Nancy Kate Diehl.
Applied Animal Behaviour Science (2007) 106, 167 - 172.