The Moos Room™

[music]
[cow moos]
Joe: Welcome to The Moos Room, everybody. We are doing our first episode that is by request. Someone sent in this topic wanted to know more, and I think we needed to cover it anyway because it is going to set the stage for future conversations that we have around calves and ruminant nutrition in general. We needed to cover this. We're going to try to make it as interesting as possible as we walk our way through the ruminant digestive system. Please enjoy the episode. Please continue to send us any scathing rebuttals, remarks, comments, anything you want to hear, suggestions out there that you have.
If you need information on this subject, if you want more or you want to dig in deeper, please visit extension.umn.edu. Thank you again for listening, enjoy this episode. Welcome to The Moos Room, everybody. We are here today to cover what I have been told is a incredibly boring subject by my co-hosts here today but we're going to do it. We're going to--
Bradley: Only, Emily said that. Only Emily said that. It's not boring at all.
Emily: I believe you agreed with me, Bradley.
Joe: Who knows? We're going to try to walk through it, go through some of the basics. It is the ruminant digestive system. We'll be highlighting ways it's different from a non-ruminant and we'll start by talking about calves. There's a lot of things to consider when you're raising a calf when you're trying to develop a ruminant because it's not where they start. They start as a non-ruminant animal when they hit the ground.
They're only drinking milk and that rumen, and I've looked for it when I've done necropsies and it's no bigger than a baseball when you start, it's so small. That's because they don't need it yet. When we're doing that, we have an esophageal groove, which funnels milk away from the rumen to the abomasum. That's how we bypass the rumen while we're on milk. We'll jump right into one of the topics that comes up all the time. How do you get that rumen developed? How do you get it bigger? How do you grow the papillae on the inside that are supposed to be there? Brad, what do you think?
Bradley: Grain. That's, the big way to get that rumen development. Now, obviously, some people are going to disagree with me, that's normal.
Emily: Well, Yes. This seems like a pretty controversial opinion coming from Mr. Grazing Systems himself here, Doctor Grazing Systems [unintelligible 00:02:59].
Bradley: [mumbles] [unintelligible 00:03:00]. I have done some work with the Waseca calf facility in Minnesota where they feed lots of calves, do lots of studies. We've looked at calf growth from birth until weaning. Really, the thing that really comes back to it all is grain. It's maybe not necessarily grain as much. I had a graduate student do a study, looked at metabolizable energy in the grain, and the more metabolizable energy that the calf gets through the grain, the rumen probably is developed more, they grow more and do a little bit better and have less health problems.
Joe: What we're really looking for is that rumen development so that that rumen is ready to go when we wean that calf. We can't leave them short on that and then expect them to perform when they can't get nutrients from their rumen like they're supposed to. The studies I see are great. The images are perfect, that's the most striking thing about some of these studies is that when they feed that calf milk only as a control, milk plus some type of forage, and then milk plus grain only, the pictures of those developing rumens are vastly different.
You see that the grain is truly the factor that grows those papillae and gets that rumen ready to use nutrients on its own without having to depend on milk as well. The most successful calf raisers I see don't even incorporate forage until after weaning or maybe start to incorporate it pretty late. Certainly not before six weeks, I don't think is really necessary. Are we on the same page there, Brad?
Bradley: Yes. That's probably one of the biggest debated things in the calf world, and it still happens today, is when should I feed hay? It's fun going to meetings because you'll have very differing opinions and some people will love to challenge each other on it. Some people think feeding hay at two to three weeks helps with rumen development along with grain.
Some people say wait till eight weeks or later to start feeding hay. In our research dairy, we don't start till about eight weeks of age to feed grain, sorry, hay.
Joe: Emily, do you remember what you did growing up?
Emily: We did grain.
Joe: Grain, and when did you start offering it?
Emily: Right away.
Joe: Right away. Perfect. This isn't a new concept that we're talking about, I don't think, but for whatever reason, there's plenty of arguments around it still.
Emily: Well, that's just because we like arguing about things.
Joe: That's true, I think that's part of it. The key is that it's time, it's all time-dependent and that rumen has to be ready to go if you're going to pull the milk. If it's not ready to go, that's where you see calves stumble. It takes a good five weeks minimum, five weeks minimum, to develop that rumen with consistent grain intake. If you don't offer grain right away, you're cutting yourself short, you're not giving yourself enough time especially if you're weaning early, you're doing something like that so feed grain.
Bradley: However, here's my--
Joe: Oh, here we go.
Bradley: Here we go. I did a study, me and my grad student, my first grad student, we did a study a long time ago looking at grass-fed dairy steers. We did this in dairy steers and we didn't feed calves any grain and they were actually eating hay at two to three weeks of age and they grew about 1.5 pounds per day. Now the ones that we've fed grain to, were doing about two pounds a day.
I think that some people equate with, "Oh, if you don't feed grain, you're going to have small calves and they're not going to grow." In my mind, getting 1.5 pounds a day off of milk and hay, I was pretty happy with that, I think.
Joe: I would be happy with that too, 1.5 is what we target to get the benefits that we see later in life from that average daily gain preweaning. I think that's good. I'm just more concerned about are they ready when you take the milk away, that would be my biggest concern if you're weaning at eight weeks, let's say. Is that rumen ready to support that entire calf without additional calories from milk?
Bradley: That's a good question because we face that now. A lot of dairy farmers are facing that when if we're feeding all this milk that all the researchers like me tell you, you should feed more milk, 8 liters, 12 liters, there's a lot of people doing ad lib stuff now. I think we've talked about that before, is that rumen developed enough? When they get weaned, do they have setbacks because they don't know what to do except to drink milk and now they're suffering because maybe that rumen isn't developed enough because they haven't eaten enough grain while they were on an ad lib situation?
It grows nice big calves but you see that maybe that rumen development suffers and they have a setback when they go to weaning.
Joe: To me, part of that has to be related to a microbiome issue in that rumen. When we switch rations, and I've been getting this question a lot on the beef side lately, people are stepping cattle back from high mega cow rations to try to slow them down. A lot of questions about what to do with ration changes. We know that the microbiome in that rumen takes 10 to 20 days or two to three weeks to fully change and if you're going from a high concentrate to a forage, it's completely different microbes that you need. If you're not developing that microbiome ahead of time and then all of a sudden you just switch on a dime, you're going to have an issue.
You have to because nothing's set up for success in that calf. I think that's a lot of it, and hopefully, we can learn more about that as we go. It's definitely an area of interest that is coming up more and more and people are looking into, more and more often. Let's get away from calves, we got to cover the rest of this digestive system and how it develops so we've got [unintelligible 00:09:50].
Emily: We're going to be rummaging through the rumen?
Joe: [chuckles] You could say that. You could say that.
Emily: Adventuring across the abomasum?
Joe: Yes, exactly.
Bradley: Wow. You're full [unintelligible 00:09:58] one.
Emily: Roving through the reticulum.
Joe: Roving through the reticulum. That's a good one. I like that one.
Emily: Meandering about the omasum.
Joe: That's good, that's good.
Bradley: Wow.
Joe: You got all sorts of stuff today.
Emily: Oh, yes. I'm full of tricks.
Joe: Let's start higher than that. Digestion in almost everything starts up top at the mouth. Cows, you got to get it in the mouth first but then-
Emily: Moving through the mouth.
Joe: -moving through the mouth. [laughs] You have to break down particle size, add saliva to the mix. There's enzymes in the saliva that add to the digestive process. Cows actually, saliva is hugely, hugely important. Hugely important as a buffering agent as well so it starts there. We go down the esophagus into the rumen, which I like to think of as a giant fermentation vessel.
Emily: Exiting through the esophagus. [laughs]
Joe: Exiting through the esophagus.
Emily: [unintelligible 00:11:05]. [laughs]
Joe: Exiting through the esophagus into the rumen, which is a giant fermentation vessel. It's huge in an adult cow. It's massive, it's massive. If you picture a 55-gallon drum, you're really not that far off, it's huge, it's big. It holds a lot of liquid and a lot of material in there. The main purpose is to ferment to get rumen, microbes and bacteria, protozoa, other microbes, yeast involved in the digestive process of the material that's in there. It's what makes a cow so special because they can use material that not a whole lot of other species can use including humans. They can use food sources that we cannot and turn it into something that we can use in the form of milk or beef and meat.
Bradley: What about pH? pH-
Joe: [unintelligible 00:12:03].
Bradley: -that's what we got to talk about all the time with the rumen, right?
Joe: The rumen, yes. The pH is important because the bugs that are in there are very sensitive to the correct pH. If you're at the wrong pH, you can create a proportion of microbes that's actually harmful to the cow. Rumen acidosis leads to a lot of bad things and sets up the first knocks down that first domino in a wave of all of these other things that can happen to create a sick animal.
Bradley: They make good sensors that measure room and pH too-
Joe: Really?
Bradley: -that you can put in, yes, precision technology. We need to talk about precision technology more. They got some boluses. We have some at Morris, of course. I have all the cool gadgets.
Joe: Is that the same smaXtec Bolus?
Bradley: Yes, smaXtec, yes.
Joe: SmaXtec, that's right.
Bradley: That will measure room and pH. If you get that bolus, it'll do that for you.
Emily: Is that a constant read or an alert when it changes?
Bradley: Yes, it reads constantly what the room and pH is. If it changes, then it will alert you that there's something wrong with this cow from a nutritional standpoint.
Joe: That's cool.
Bradley: It's cool. I know, technology in my mind is going to change the dairy industry, but that's a subject for another day.
Joe: That could be a whole podcast.
Bradley: Exactly.
Joe: We can get into it. We talked about--
Emily: That'll be a whole series of podcasts.
Bradley: That's right.
Joe: I don't know how much of the specifics we want to get into about where cows get their energy and protein, but it's the main function of the rumen is to allow the bacteria to do work on materials we provide, give us volatile fatty acids, which are the main source of our cow's energy, which are absorbed through the room and wall. We can probably leave it there, I don't think we need to go too far into that. I don't think anyone wants to get all the way back into the Krebs cycle and things like that.
Bradley: Oh, boy, I am not a nutritionist. I did not study nutrition in grad school so I--
Emily: When I took nutrition in undergrad and on one of our tests, we had to draw the Krebs cycle. I let that page blink.
Joe: It's a rough one. Now, I'm second-guessing myself to make sure I even said the right cycle. Is it the Krebs cycle or is it a different cycle from organic chem a long time ago?
Bradley: I don't know, you're the vet.
Joe: I don't know that stuff anymore. That was long time ago.
Bradley: What's the Krebs cycle?
Joe: It's how you make ATP, I hope. [laughs]
Emily: Oh, yes, that sounds right.
Joe: Yes, yes. I think I'm right, I think I'm right. We're going to call it [unintelligible 00:15:02].
Emily: I'm pretty sure you're right. We'll go with that.
Bradley: Group consensus, Joe's right.
Joe: Okay.
Bradley: Yes, it is ATP.
Joe: Okay, good, [unintelligible 00:15:10]-
Bradley: There's your science lesson for the day.
Joe: -remembered something. You'll have to memorize that sometime in school at some point and then you'll forget it as I did too. [laughs] The reticulum usually gets its own section. It's part of the rumen in my mind and I don't think of it as separate because it really is just a compartment of the rumen. It's always considered a separate compartment. It has some special functions and it really is different-looking than the rest of the rumen and that's why we treat it as a separate compartment. It's honeycomb shape.
If you've ever been able to cut open a rumen or had the chance to necropsy a cow, you will see that it looks like a little honeycomb. It's where everything falls because of gravity and the way that that compartment is situated and shaped, that's where you get all of your metal and anything else the cow's not supposed to eat, that's heavy, it ends up there. If you're giving a magnet, that's where it ends up. If you're looking for hardware disease or you're trying to find a wire that was poking through the diaphragm and tickling the heart, that's where you'll find it coming through the reticulum.
Bradley: That's the only time I ever think about the reticulum is when I think about hardware.
Joe: Absolutely.
Bradley: That's it, I don't know.
Joe: That's really all there is to say about it. It looks different than the rest of the room and it's just a separate compartment, but it's where everything heavy falls that they're not supposed to eat, that's where your magnet sits. The omasum is next. We go out of the rumen into the omasum is interesting. It's a big ball, it's like a basketball. It's usually pretty hard because it absorbs water, dries everything out and if you cut it open, it looks like the pages of a book.
It's just a drying chamber to prepare feed and everything else to go into the abomasum, which is our probably most troubling stomach or piece of the digestive system and the one we talk about the most on the dairy side just because it tends to move around and get in the wrong spot. That's the one that's just like most non-ruminant stomachs. It's just very similar to our stomach, similar anatomy, produces acid just like ours and everything else. That's the one that gets into the wrong spot and goes to the left, creates our left displaced abomasum, twists on the right, creates our right displaced abomasum. Let's talk about rumination. How often should that rumen contract? Every minute, Emily?
Emily: No idea.
Joe: No idea? I thought you were on a quiz bowl team at some point you could have answered that.
Emily: I was on the quiz bowl team quite some time ago, so my dairy trivia is not where it once was.
Bradley: They didn't teach you that in Le Sueur County?
Emily: No.
Joe: It's one to two times every minute. If you see your veterinarian out there listening to the rumen, what he is really checking for is contraction and the strength of that contraction and how often it's contracting. One to two times a minute, pretty strong, you should be able to actually visually see it contracting and coming out. That's rumen contractions. Also, part of rumination is cud chewing. You probably notice that a lot when you see cows, they're constantly chewing a piece of cud, mostly because it takes up about, what do you say, Brad? 30, 40, 50% another day, they're cud chewing and trying to ruminate.
Bradley: Yes, 50% of the day probably.
Joe: It's a big portion of that, that's bringing stuff back up from the rumen in to reach you. Break down some more, add saliva. As we said, saliva is a big piece of the digestive process with enzymes, but also to buffer the rumen and keep that pH where we want it. Who's got to a guess for how much saliva a cow produces every day?
Emily: 80 gallons.
Joe: Not quite right.
Bradley: 20 gallons, 20 gallons.
Joe: 20 gallons is closer, yes. It can be even higher than that depending on the diet and then that influences a lot. The higher forages, you'll produce more saliva because there's just more to chew. It could be as high as 50 gallons a day. If you think about--
Emily: I was close?
Joe: Yes, you were close. If you think about 45, 50 gallons, just think about, this is the part I love to tell people because it really makes it real, 10 5-gallon buckets of saliva, that's gross.
Bradley: That's nasty. That's nasty.
Emily: That sounds like something I would not be interested in. [laughs]
Joe: It's important and they produce a lot of it because it's that important. They need it to digest, they need it to buffer that rumen, that rumen needs to stay in that 6 to 7, 6.2 to 6.8 pH. That's where we want it to stay for most situations in most diets. Saliva's a big piece of that.
Bradley: We got sensors that can measure rumination.
Joe: The takeaway is to just always [unintelligible 00:20:36].
Bradley: Just use the sensor.
Joe: Just use the sensor. They'll tell you everything you need to know-
Emily: Or all the story.
Joe: -don't worry about the rest of this.
[laughter]
Bradley: That's what my life is, just put a sensor on and it's good enough. It's good enough.
Joe: Yes, it'll tell you when something's wrong. [laughs] That's perfect, perfect. What else do we got to do? Oh, we should talk about this troublesome abomasum a little more. It likes to float and go to the wrong spot.
Emily: That's rude.
Joe: I know, it's super rude and the cow doesn't appreciate it either. The most common one is that left displaced abomasum. You hear about that all the time. I'm sure if you have a dairy at some point on your dairy, it's going to happen regardless of how good a job you do and the vet's going to have to come out and fix it if you want to keep that cow around. You just had one, didn't you, Brad? I saw a post.
Bradley: We've had two DAs in the last--
Emily: What?
Bradley: Yes. That's like--
Emily: Brad, you're slacking.
Bradley: Exactly. Actually, that's two DAs in seven years. I don't know what was going on. Actually, it's interesting.
Joe: That is interesting.
Bradley: It was mom and daughter, both had a DA at the same time.
Joe: That's fine.
Bradley: That's who it was so it is genetics.
Emily: You pin it all in the family.
Bradley: It's genetics.
Joe: Definitely. Confirmation plays a part in it. Post-calving is our most common time to get a left displaced abomasum, an LDA. We think it has to do with just the lack of room and fill. That calf leaving, all of a sudden, there's lots of space, that abomasum doesn't actually have to get all the way across on its own to flip, just part of it does. When that part fills up with gas, it floats and it goes over to the left, which it shouldn't be there. Then you got to call someone like me to do surgery, which is fun, is one of the things I miss. I miss doing a DA mostly because it usually meant I had a designated time to talk to the farmer and catch up and hang out.
Bradley: It was interesting, the one cow that we had, you could tell everybody how you find a DA. Use a stethoscope and you ping on their side and this one had a nice [unintelligible 00:22:50] drum sound to it.
Emily: Whoo.
Bradley: It was there.
Joe: I haven't thought about pinging a cow for a while now, but yes, it becomes second nature. I actually have a callus on my finger from flicking cows so much.
Bradley: Oh, really?
Joe: Yes. [laughs] Bradley didn't like that, he thought it was gross. [laughs] It's right here, can you see it? See it? If people don't know, I think the most common way I can describe the sound that you're hearing is what you're doing is creating a sound wave in the cow. Because you have a air and gas under pressure, because that abomasum is really tight and full of gas and some liquid, it creates a high-pitched ping sound.
The only way I think you can recreate it in everyday life that people will know what you're talking about is if you leave a basketball out overnight and then the next morning you bounce it on the ground, you'll hear that noise. You'll hear that high-pitch ping noise. It looks really goofy when you're looking for one and you have your stethoscope just ran on the cow side and you're actually flicking it with your finger to create the sound wave and that--
Emily: That's what you went to school for eight years for, right?
Joe: I went to school for a long time to be able to do that, yes, but it can happen on the right as well. That abomasum likes to rotate, sorry, this way, rotate.
Emily: You know they can't see you, right?
Joe: Yes, I know, but you guys can. [chuckles] It rotates and causes issues, that right displaced abomasum is a big problem. It's an emergency, it cuts off blood flow, it can get really tight, that abomasum can actually die if you don't take care of it quickly enough. Big deal if it twists on the right.
Bradley: I learned how to do an LDA, a roll intact when I lived in California a long, long, long time ago. A lot of people like to do surgeries, but I don't know, many people don't do roll intacts to fix the DA anymore.
Joe: You still hear about it a lot because it is less expensive.
Bradley: Maybe if it's not so bad, that's easy to do.
Joe: It can be quicker too, yes, absolutely. My experience with it though is that-
Bradley: It just floats back up.
Joe: -it can float back up and you can tack the wrong thing. There can be a lot of complications. You need a decent amount of people to do it. If I'm by myself, which is a lot of the time when you're in practice, it's actually easier to just do the surgery. If it's a straightforward one and there's nothing complicated about it, I can sedate, clip, do the surgery, and from turning my truck off to then getting off the farm, it could be 40 minutes tops and you're gone. I can do it by myself.
I think that's why the surgery has just become the way to go and I can also see what's happening. I can feel what's going on, I can tell if it's adhered in a bad spot. I can tell if there's another issue that's causing it by feeling around, check on the liver while I'm in there, reach down and feel that reticulum and see if there's anything that's causing an issue down there as well. I can feel her uterus and make sure that's nothing wrong back there. There's a lot of things, a lot of value in that surgery. Just a shameless plug for veterinarians doing surgeries.
Bradley: [laughs] Expensive surgeries.
Joe: It's part of it.
Bradley: That's right, yes, I get it. I get it.
Emily: Well, it's got to eat.
Bradley: Exactly.
Joe: Girl got to eat so you got to get paid at some point. After the abomasum, even after the omasum, after we leave the omasum, so rumen, omasum, abomasum, it's all very similar to a non-ruminant GI tract at that point. You've got small intestine, the caecum is obviously different, large intestine and they all function very similar to humans or any other species in that regard. Small intestine is involved in further digestion and absorbing more nutrients. Caecum is further fermentation and possibly some more nutrients absorption and then large intestine is mainly getting as much water back as we can to make it efficient.
Let's talk about, and we covered this in Episode 4, cows need to burp a lot and they do it a ton. They have to because we are fermenting something in the rumen, and that produces gas so it has to go somewhere and it's usually easier to let that out the front than to push it all the way through that whole system and get it out the back.
Bradley: We got sensors that can measure that too.
Joe: There's also sensors for that. [laughs] We can measure all of that. Oh, my goodness. Well, we're going to have to do a series on all the different crazy complex equipment that will now become more and more and more affordable in changing industry.
Bradley: That's right. We'll have to cover new--
Emily: I have a question actually.
Joe: Let's do it.
Emily: It's probably a stupid question.
Joe: No.
Emily: When we think about the rumen and we know it's huge and it has this liquid in it, this microbiome, how does the microbiome get there? The liquid and the bugs and all of that, how does that end up there?
Joe: That's a really good question. Most of it is probably coming from the feed source itself. There's bacteria and everyone knows this, especially now, there's bacteria in the environment, they're everywhere. Some of this is just an evolutionary thing where cows were built to eat a certain thing and they've adapted to allow the microbes that are present on those things to help them do that. That would be my take on it.
I don't know if anybody could really 100% solve that question and say, "This is exactly where they come from." It's probably a combination of what's on the feed already, just exposure in the environment, and then creating a system in the room and then an environment in the room, and that promotes the growth of the correct bacteria. All right, let's wrap it there. There is an old but very good article on the extension website with very good information all about this topic. If you need more, dig into it a little deeper, go to extension.umn.edu. If you have questions, comments, suggestions for us, scathing rebuttals, we are starting to pick up traffic in our email, you can always reach us@themoosroomumn.edu.
Emily: That's T-H-E-M-O-O-S-R-O-O-M@umn.edu.
Joe: Good work.
Bradley: People are even listening to us in Australia.
Emily: Special shout out to my mate from down under, Jace. Thank you for listening from Australia and if you are listening from some other far-flung country, let us know, maybe we'll shout you out.
Joe: Exactly, exactly. Thanks, everybody. We'll catch you in the next episode.
[music]
Emily: Rummaging through the rumen, venturing across the abomasum, roving-
Bradley: [unintelligible 00:30:46] good one.
Emily: -through the reticulum, meandering about the omasum, moving through the mouth, exiting through the esophagus.
[laughter]
[music]
[cow moos]
[00:31:04] [END OF AUDIO]

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