Two years ago, the Oklahoma City Zoo’s horticulture and behavioral departments teamed up to start an exciting process of silaging trees.
Silage is a process of fermenting high-moisture stored fodder, which can be fed to ruminants (animals that chew cud). It can also be made from field crops or, in our case, trees.
This process originated in the agricultural industry, but in zoos, we create our own silage process using trees that are grown on-grounds. Species include elm, mulberry, hackberry and others. Our animals especially enjoy the elm so this is the species we use most often.
Browse (leaves) is an important dietary component for many species, but until now, it was difficult and expensive to provide during colder months. While silaging is a time-consuming process, it is extremely important to our animal care program.
The process starts in June or July when the tree leaves are highly nutritious and before their chemical properties start changing to get the trees ready for cooler weather. Our horticulture department sustainably trims branches from species of trees that have been approved as safe and non-toxic.
The silage process starts out as a mountain of tree branches that need to be hand cut into large animal bite sized pieces and then distributed into 30-gallon barrels. Only the leaves and pencil thin branches are silaged. The tree material is stamped down to eliminate as much air as possible and sealed. The barrels are then stored for 4-6 months with us opening the first barrels in January. When opened, each barrel is inspected and approved for consumption by our veterinary nutritionist before the contents are fed to any animal. This process allows us to have properly processed browse material for our herbivores even in the cold winter months.
Every year, the browse silaging program relies on a team effort to ensure we have enough plant material to provide for our animals. Our horticulture team cuts the trees, then various other teams jump in to process the mound of foliage and branches into the storage barrels. This year, teams included the behavioral department, animal caretaker teams, guest experience, the education team and some amazing guest volunteer groups. I cannot tell you how important volunteer groups are to supporting many of our efforts including silage. It truly takes a village to silage enough trees to support the browsing animals during the winter.
Although our program is new and not quite grown to sustain all the browse eating animals completely thorough the winter, we can provide enough to supplement their specially designed diets until the growing season starts again. Zoo guests may even get the chance to offer some of our tasty silage browse if you visit our giraffe-feeding platform during warm winter days. Hope to see you there!
-Laura Bottaro, behavioral husbandry administrator