(Dan) Hey folks, thanks for joining me on DocTalk today, I’m Dr. Dan Thomson here at Kansas State University. Today’s show is going to be talking about how the rumen works to digest different types of feedstuffs. My guest is Dr. Chris Reinhardt, who is a Professor and Feedlot Extension Specialist for the state of Kansas. Join me here after these messages.
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(Dan) Dr. Reinhardt, welcome to DocTalk. (Chris) It’s great to be here. (Dan) Folks, Dr. Chris Reinhardt. He is a Professor and he is our Feedlot Extension Specialist here for the state of Kansas. He is over in Animal Sciences and Industry and we are going to talk about how the rumen works. I think most of you understand what a ruminant animal is, it’s a cow or a goat, but understanding how that rumen works. Dr. Reinhardt’s a Ruminant Nutritionist so talk to me a little bit about what the rumen is and just in general. (Chris) Simply put the rumen is a huge fermentation vat. It’s made up of the four chambers, the rumen, reticulum, abomasum and omasum. They all have separate functions, but the one we really care about is the rumen. The rumen is where all of that fermentation happens. (Dan) When we have the rumen and it’s large, especially in some of these old brood cows and dairy cows and you can hold a lot of feed. So, talk to me then about what are some of the different things going on? You say fermentation, so I assume that means microbial fermentation? (Chris) Exactly. That’s what it’s all about. That cow was made to eat things we could never eat and survive on because it’s full of bacteria, protozoa and fungi. Those are the critters that are actually doing all the work. (Dan) Right. So, we feed the microbes first and then the microbes, the byproducts of microbial fermentation are what the cow lives on. (Chris) Exactly, without those microbes that cow would starve to death. (Dan) Thinking in general, talk to me a little bit about the difference between the purposes or roles or sizes or differences between bacteria, protozoa and fungi. (Chris) Relatively speaking the protozoa are really, really big compared to the bacteria, but they’re pretty small in number compared to the bacteria. (Dan) OK. Bacteria, what are some of the common species that we’re going to be talking about? And I think it’s important for people to understand, these aren’t species of bacteria or protozoa or fungi that cause infection. These are good bacteria, kind of like when you see the acidophilus commercials and lactobacillus commercials, this is a whole rumen vat full of these good bacteria. (Chris) I probably wouldn’t want to drink a glass full of them. (Dan) No. (Chris) But they sure do the cow a lot of good. (Dan) Right. But they aren’t causing infections. (Chris) Exactly. They are there and they’re there almost from birth. As soon as that calf is exposed to the environment, starts licking itself, licking it’s mother, suckling, etc. They’re taking in bacteria from the world and those bacteria begin to colonize in the rumen. (Dan) OK. Generally speaking, when a cow ingests something, how long is it going to take for the bacteria to digest it? (Chris) That is a really good question, and it totally depends on the quality of that feedstuff. If it’s a bite of corn it takes a matter of an hour to an hour and a half before there is some substantial fermentation going on. If it’s a bite of corn stalk, it could be hours and hours before that feed is mostly processed. (Dan) So, understanding that the rumen is a fermentation vat, that it has different types of good microbes such as bacteria, protozoa and fungi and also understanding that there are differences in the way that it can digest due to the quality of the feedstuff is vitally important. When we come back, we’re going to work with Dr. Reinhardt and we’re going to discuss the difference between soluble carbohydrates and structural carbohydrates in the rumen and digestion. More after these messages.
(Dan) Hey folks, welcome back to DocTalk. Dr. Dan Thomson and Dr. Chris Reinhardt, who is my friend and colleague from the Department of Animal Sciences and Industry and he is our state Feedlot Extension Specialist and Ruminant Nutritionist. What we’re talking about today is how the rumen works within the cow, that fermentation vat that’s full of bacteria and protozoa that is digesting the hay, digesting the starch to give the byproducts so that the cow can live off of those. Let’s talk about digestion or rumen digestibility. We have soluble carbohydrates and structural carbohydrates. Talk to me about the differences between those two. (Chris) Soluble carbohydrates, just like the name implies, they’re very digestible, very soluble, full of starch and sugars and things to that nature. Structural carbohydrates, just like the name implies, they’re there to hold the plant vertical and they’re very poorly digestible. (Dan) So, give me some examples of each. (Chris) The ultimate example on the soluble side would be grain that we use for, we can eat, monogastrics, pigs, chickens, cows and feedlot cattle do very well. The structural carbohydrates would be corn stalks, wheat straw, etc. Anything that’s designed to hold a plant vertical. (Dan) OK. So when we start to think about this the difference in the two main substrates, because both of them have copious amounts of glucose and so when we think about those, the difference between glucose in the structural carbohydrates versus glucose in a soluble carbohydrate is what? (Chris) It’s how those individual glucose units are linked together. (Dan) And one, like starch, they have the alpha 1,4 and the structural have the beta 1,4, you think that little, two little words makes a difference, double, triple, quadruples the energy availability of that feedstuff. (Chris) Exactly again, with the alpha 1,4 you and I can live on grain. But with the beta, we would starve to death. (Dan) We, as humans, do not have the enzymes to digest cellulose, the structural carbohydrates. So, we can’t go out and eat hay and survive. (Chris) Nor does the cow actually. It’s the bacteria and protozoa that they do have in the rumen that have that enzyme necessary to break down that beta linkage. (Dan) Horses don’t have a rumen but they have the hind gut, kind of like rabbits and horses have the hind gut fermentation. So, they have a fermentation vat too, full of microbes that are breaking down those linkages. It’s just that theirs are located in a different spot of the anatomy. (Chris) Exact same function, just a different part of the animal. (Dan) When we think about structural carbohydrates versus soluble, the main difference within the rumen is the byproducts given off. (Chris) Right. The byproducts and then the rate that those things are broken down. (Dan) Right. As we mentioned earlier, you can have a cow eat corn and within an hour or two you have peak fermentation. (Chris) Exactly and then on the far end you’ve got corn stalks or wheat straw that might take a day and a half. (Dan) Yep, so understanding soluble carbohydrates, structural carbohydrates, things that are hay, roughages, versus grains is important when you understand ruminant nutrition and how they break down. When we come back, we’re going to talk about different types of protein sources and what happens when those hit the rumen. You’re watching DocTalk. More after these messages.
(Dan) Hey folks, welcome back to DocTalk. Dr. Dan Thomson here with Dr. Chris Reinhardt. We’re at Kansas State University and Dr. Reinhardt is from the Department of Animal Sciences and Industry, where he is the Feedlot Extension Specialist for the state of Kansas and beyond. Ruminant Nutritionist extraordinaire, Dr. Chris Reinhardt, glad to have you on the show. We’ve talked about different things with rumen digestion. I don’t think people really understand how dynamic that rumen system is, but when a cow can go out and eat grass and then a storm comes and they can go bed down for three or four days before they have to go back out. It’s kind of like the evolution of being able to live on the prairie and withstand long periods of time because they have that continuous digestion creating nutrients from the microbes. Now we’re going to talk about crude protein. Crude protein, we have three main sources, right? (Chris) The soluble, which we’d normally find in urea, the degradable, a lot of people understand soybean meal, cottonseed meal, things of that nature, very degradable protein in the rumen. Then there’s bypass sources of protein, that really we mean escape. They go into the rumen but they’re not broken down and we call them undegradable protein sources. (Dan) Right. So, urea is 100 percent solubilized in the rumen. (Chris) Almost instantaneously. (Dan) Right and it’s another one of those things that without the microbes, we don’t use. (Chris) Exactly. That cow cannot utilize urea by herself. Those microbes take the nitrogen from the urea, bind it with the carbon and they make actual good quality protein. (Dan) Right. As microbial group protein, just the population of microbes exploding in microbial crude protein synthesis. The other thing that will happen is ammonia that’s not utilized will go across the rumen wall, go to the liver, slap together and we have circulating urea again. (Chris) Exactly and that’s another really critical function. You talk about that cow surviving on the hillside, she’s cycling back any nitrogen that doesn’t get bound up as protein, she gets a second chance at it. That’s another function that’s allowed her to survive all these years. (Dan) Absolutely. Then when we move away from the nonprotein nitrogen sources and the one urea rule that Dr. Pressen always taught me was never feed more than one percent of diet dry matter as urea. (Chris) That’s a really good rule and in cattle grazing really poor quality forage, we bring that way, way down even from there. (Dan) Right. Let’s just talk a little bit about urea, because I think that when we look at lick tanks, when we look at lick blocks and the amount of nonprotein nitrogen in those, supplementing those on low quality forage, sometimes may not be the best source. (Chris) I can feed urea, as long as I’ve fed some soluble carbohydrates with it. And the amount of soluble carbohydrates we talked about will dictate how much urea I can use. (Dan) Those soluble carbohydrates could come in the form of molasses, they could come in the form of corn, but it’s not going to be the low quality roughage. (Chris) Exactly. (Dan) OK. Folks, we’re going to take a break. When we come back, we’re going to stay on the topic of crude protein because we’ve still got to get into the natural protein sources when we talk about rumen degradable and bypass and what that means to supplementation in cows. You’re watching Doc Talk. Thanks for joining us.
(Dan) Hey folks, welcome back to DocTalk. Dr. Dan Thomson here with Dr. Chris Reinhardt. We did solve where my coffee mug went, didn’t we? (Chris) Yes, it was a mystery. It’s resolved. (Dan) It’s in South Africa. We had a visiting guest from South Africa on the set and he had sticky fingers and the coffee mug went to South Africa. So, Pete we’re coming after you and we’re going to get our coffee mug back! So anyway, when we talk about crude protein, we’ll get back on the subject, talk about crude protein we’re talking about bypass versus rumen degradable. Give me some sources of protein that are high in degradable or just give me an example, soybean meal, cottonseed meal, they’d be about what? (Chris) They’d be 70 to 80 percent degradable, highly available to the rumen microbes. (Dan) So, 20 to 30 percent of that crude protein would bypass or escape rumen digestion and wind up at the small intestine as the way it was ingested. (Chris) Exactly. (Dan) Now, what are some examples of more bypass? (Chris) Protein in corn typically is thought of as 50-60 percent escape or bypass protein as well as things like feather meal and some other protein sources, really designed to be fed so that it’s not available in the rumen but available down stream as true protein. (Dan) So when we’re feeding some of these byproduct feeds we should be seeing a lot of bypass protein. Now, when you start to think about, and I guess the real reason to understand this is when we have cattle, baby calves being weaned and they don’t have a functioning rumen yet, we’re looking for sources of that escape protein, correct? (Chris) In some cases, yes because we’re still feeding essentially a monogastric calf. (Dan) So when we’re looking at that, and I guess anything that would be fed when we don’t have a functioning rumen would be bypass, but really we’re looking to feed that baby calf when we wean them, more of a natural protein source, a bypass protein source for improved gain. (Chris) Exactly and something we’ve talked a lot about here on the show, are high-risk calves that have come in, maybe been on the road for a day or more on a little bit of low quality forage, their rumen is all but shut down and we have to, for a while think of those almost like a monogastric. (Dan) So, if I say urea natural protein or bypass, if I say one of these species, I want you to say which source you would prefer. Mama cow out on low quality roughage? (Chris) Natural protein. (Dan) OK. Newly weaned calf? (Chris) Natural protein as well as some bypass protein. (Dan) Right. Then a feedlot steer on a finish ration, lots of grain, show steer, 90 percent roughage? (Chris) Urea number one and a little bit of true protein in addition. (Dan) So understanding that, matching your carbohydrate source with your protein source, is vitally important. It’s been a great show and I appreciate you being here today. (Chris) Thanks for having me on again Doc. (Dan) Folks, Dr. Chris Reinhardt. Remember always work with your local nutritionist. I usually say veterinarian, but on this subject, work with your nutritionist. Start to think about what you want to do for matching protein and energy. If you want to know more about what we do on DocTalk, you can find us on the web at www.doctalktv.com. Thanks for watching DocTalk today folks, I’m Dan Thomson and I’ll see you down the road.
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