Yup, she was having a quiet laydown to digest her morning's foraging. She was quite happy to just lie there and look at me for several minutes. Her fawn bounded off up the hill and that must have made her nervous because then she got up and stood in back of a tree with just her head showing, and then finally most of her body came out from behind the tree.
As I stood there watching her watching me, she began to regurgitate and chew; it looked exactly like someone chewing gum, with the same sideways grinding motion. And then looking a little more closely at her as she was chewing I could see her swallow as a noticeable bolus of chewed wad quickly made its way down her esophagus, and just as quickly another bolus came up. The transit time couldn't have been more than 1/2 second, which surprised me because when we swallow food, it takes several seconds to get it down. The yellow line is where I saw all this activity in her neck (I colored it in to make it more obvious).
You might think this is really geeky, but I spent 4 years at the Univ of Minnesota using radiography to film turkeys swallowing their food and so comparisons with how other animals manipulate and swallow food is kind of interesting.
Ruminants (like cattle and sheep, but not horses) may take a long time to digest their food by chewing it over several times, but this makes them more efficient at digesting it, so they can get by with poorer quality forage, like what the deer will have to eat this winter when the leafy greens are all gone.
Ruminants (like cattle and sheep, but not horses) may take a long time to digest their food by chewing it over several times, but this makes them more efficient at digesting it, so they can get by with poorer quality forage, like what the deer will have to eat this winter when the leafy greens are all gone.
When I taught - I would always use that turkey feeding experiment we did in your phys. class to illustrate cephalic and gastric phase of digestion.
ReplyDeleteWe have had two fawns hang out from time to time in our back yard for the past several months. A similar story except there is no mom to teach them how to survive. We watched them loose their spots and turn dark in color as all deer do. Ours is just a stopping place for them but they seem comfortable, unbothered by us if we show up on the deck. A mile square wetlands is across the street and two lakes and nature preserve the opposite direction. We have an acre with about a third of it quite heavily wooded in back where they seem to come from. They have spent many mornings just lying in our backyard, grazing, lounging, chewing, always alert but seemingly never bothered by much. I have talked to them and walked within 25 feet and they just look at me. I hope they don't get too trusting. I also hope they will survive the winter without mom's help.
ReplyDeleteI would put out corn this to help but that would be wrong. I wish them well.
What a neat physiology lesson! I guess I never thought about the mechanics of how rumination actually happens. How does the esophagus push up the right wad-- the not chewed enough yet wad rather than the just chewed a second time wad?
ReplyDeleteGood question, and I wondered the same thing, especially since it happened so quickly. Perhaps it is the same wad plus some new material from the rumen that gets pushed back up, or perhaps there is a valve at the base of the esophagus that directs the up and down movements of the material. I do know that really well chewed stuff tends to sink to the bottom of the rumen and then pass into the next chamber, while the newly eaten material floats on top of the rumen contents and is more easily regurgitated to be re-chewed.
ReplyDelete