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cc >> Welcome everyone to Wednesday Nite at the Lab. I'm Tom Zinnen, I work here at the UW-Madison Biotechnology Center. I also work for UW Extension, Cooperative Extension. On behalf of those folks and other core organizers, Wisconsin Public Television, the Wisconsin Alumni Association and the UW Science Alliance, thanks again for coming to Wednesday Nite at the Lab. We do this every Wednesday Nite, 50 times a year. Tonight it's my pleasure to introduce to you Professor Dave Combs. He's with the dairy science department. He's going to be talking about a new way to assess the digestibility of cattle feed. One of the things I'd like to do is put this in perspective. Walt Disney famously said, when talking about Disneyland and Disney World, "Keep in mind this all began with a mouse." You could say a similar thing about the life sciences research at UW-Madison, at least much of the life science research here. It all began with the cows. Whether it's Stephen Babcock in 1890 and the milk fat test, or the single-grain feeding study with dairy cattle from 1907 to 1911 that led to the discovery of vitamins, or the work starting in the 1933 here on what became Warfarin, looking at defects in cattle feed or the whole idea of artificial insemination in dairy cattle. Some of the most significant contributions to life sciences research coming out of this university have come from looking at dairy cattle. Keep that in mind when you get to hear Dave's talk tonight. He grew up in Willmar, Minnesota, which is just down the road from Lake Wobegon, he says. He went to the University of Minnesota for his bachelors and his masters. He got his PhD here, and has been on the faculty here at UW-Madison since 1985. Please join me in welcoming Dave Combs to Wednesday Night at the Lab.

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>> Thank you. It's a pleasure to be here. I'm very proud of being part of the dairy science department. As Tom had indicated, you know, there's a long legacy of some pretty neat stuff that's happened here in animal nutrition over the years. Our department is about 13 faculty members, and I'm one of five that work on feeding dairy cows. We kind of think that that's a pretty important aspect of that. I don't know if the test that's I've recently developed is anywhere near the stature of the things the Stephen Babcock and some of others of my forefathers have discovered, but it's my baby. It's almost like showing you a picture of my first born kid in some ways, so you'll have to bear with me a bit as I go along. I'm going to give you just a very, very quick little background. Tom has done a nice job of already kind of starting up about why dairy is important to the state. If you're not familiar with some of the things, obviously livestock agriculture is a driver of our economy. There's about 15 million acres of farm land in Wisconsin, still. We have about 5.7 million people, but I think the thing that's really kind of fascinating as I work with this is that we have about 1.3 million dairy cows in Wisconsin. More cows than deer, I think. That will give you an idea there. And we have about 11,000 farms. If you do the math and you think through it, it's really, really a very small proportion of our population that generates this huge revenue of livestock production, and in particular, in dairy. Dairy generates about 75% of the cash receipts in Wisconsin. Dairy is the industry that kind of drives our agricultural industry. If you drive across Wisconsin in the spring and the summer, as you look out across the landscape, particularly in southern Wisconsin, you see all the alfalfa fields. We produce about three million acres of alfalfa. That's about ten or 11 million tons of alfalfa. I think the key thing that I like to point out here is that the average dairy cow and her replacement animal, the heifer that will come along, consume about eight tons of forage per year, each cow. Okay? So if you think about these farms and you see the big equipment and all of this, it's because these cows eat a lot of forage and a lot of fiber. It's about 11 million tons of forage. So if you look at that, okay, it kind of suggests that virtually all of our alfalfa production is really dedicated to diary cows. I'm going to talk about forage testing. That's an important link here. Alfalfa is one of our prime forages. Corn production, we're number one in the United States in terms of corn silage production. We're kind of north of the Corn Belt as most people would think about it. Most of our corn production, particularly in the mid- and northern parts of the state is chopped for silage, and most of that too is feed back to dairy cattle. A fair amount of our corn is raised for grain. A lot of that is feed back to dairy cows also. That's also tested. But it's kind of interesting here, one dynamic that's changing in Wisconsin a bit is that we used to export corn out of the state because we produced more than our cattle and pigs and everybody could eat. We're now a net importer because of ethanol production. About 40% of our corn crop now go to ethanol. But our dairy cattle play a very key roll in that line also, because much of the byproduct from the ethanol industry, distillers' grains, is fed back to dairy cattle. They become our disposal system for these ethanol production plants, in you will, in some ways. So there's a lot of things here that really kind of tie to cropping systems. All right, I'm a dairy nutritionist. One of the big things that any nutritionist talks about is the concept of digestibility. Digestibility is what disappears from the time an animal of human eats it to it excretes out the other end. Okay? This had been really a challenge to try to talk to dairy producers or people a little bit about the complexity of digestion, because it's oftentimes kind of hard to understand exactly, how do you measure this? When a cow eats something and defecates, okay, well there's an input and output. But what does that really mean? It's been kind of interesting. We have some very, very simple tools that we use. In this picture you see up here you actually see a kitchen strainer. The first lesson I learned is tell farmers, don't take your wife's kitchen strainer.

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Okay, go to a hardware store and buy one if you want to test this. You can simply take cow manure and, if you're looking at corn digestion which is mainly starch, you can wash the manure and the corn kernel particles will capture on the screen. You can see the bits of yellow in there. That's a pretty good visual tool that digestibility isn't very good. That corn passed all the way through and can't be utilized. Fiber is a little bit more difficult. The point I'm trying to make here is that, really, to get the most utilization of every feed we have to have as high a digestibility as possible. Cows are not like us humans where we probably could shunk a few extra calories off pretty easily if we could drop digestibility. Our high-producing dairy cows need-- A cow that's producing about 80 pound of milk, ten gallons, consumers about 40,000 calories a day. Just to kind of put that in perspective, you're diet would be about 2,000. So one average, run-of-mill cow in a dairy herd here eats as much energy as 20 humans in a day. Every time we can tweak that digestibility of fiber or grain we generate more energy for milk production, and basically, improve the efficiency of that cow. The variation in fiber digestibility-- I'm bouncing around here, but stay with me. The fiber digestibility is quite large. There's a huge amount of variation in different sources of forage, how that's fed to the cow, how it's handled, how it's processed. That affects how much fiber is actually digested. It can account for as much as five to seven pounds of milk production in a cow, just by variation in the digestibility of the fiber alone. But until now we didn't really have a vary good test to actually gauge that so we could accommodate that as we balanced our diets. Starch digestibility, in the picture that I'm showing you up here on the kitchen strainer after that stuff has been sieved out, that would raise red flags, all those little yellow flecks. A nutritionist would tell a farmer, or a veterinarian, your losing probably three to five pounds of milk production because of that corn that's come through. But you can't quite do that as easily with fiber as visual. That's really what this is trying to show here. Two examples, here's a sample of manure that was actually washed with a kitchen strainer again. It's relatively poor digestion on the left, on your left there. Less than 40% of the fiber was digested. Well, that's a number that's kind of out of the sky, but bear with me. If you look at the picture there's some fairly large pieces and things like that that may be an indication that things aren't happening as well as we would like. You all know that cows chew their cud. As they chew they grind up that fiber and they reduce it's particle size. But that only really makes it more available in the stomach of the cow for digestion. Sometimes big pieces coming through tell us that things aren't working quite the way they should. Excellent digestion is usually greater than 50% of the fiber digested, about ten percentage units difference. Well, you think about that. If I'm screening this sample, there's a big pile of fiber in either one of these. If it's 40% digested the pile is just a little bit bigger, but we don't weigh everything in. We don't know what it is. So visually looking at a screen like this it becomes very, very difficult to try to estimate fiber digestibility. We can do it with starch and we use that as a tool quite often. The key here is that the energy from fiber, once it's unlocked by the bacteria that are breaking down that fiber in the stomach, a unit of energy from fiber is the same as a unit of energy from starch. We know that about a two to three unit change in digestibility is equivalent to about a pound of milk production. So from 40 to 50, that's ten units, that's three or 3-1/2 pounds of milk production lost just due to the differences in fiber digestibility. That's the kind of sensitivity that we're trying to measure with our forage testing. All right, so what have I done? This is a project that actually started back in the late to mid-'90's. I actually had a graduate student and we actually started a project-- Our goal was to actually develop a test to measure what we call dry matter digestibility. Dry matter would be all the energy-yielding substrates in a feed. Could we actually just do a simple test to actually do that? The instrument we used was called near-infrared reflection spectroscopy, which is kind of a fancy term for an instrument that basically looks at the reflection of light and correlates that to the chemistry of that sample. We messed around for two years and we couldn't get anywhere. But my graduate student came in one day and he says, you know-- And this poor guy was on his PhD program. You like to get him out in three years. I've burned up two of them with this dumb idea that I had at the beginning. The poor guy is getting pretty desperate. He says, you know, there's something with fiber here that I can see. I can't see digestibility of dry matter, which is the protein and the starch and everything together. But I can see something that looks like with fiber. That kind of started us on our way with this. We've been kind of developing this process all the way along. Well, it's 15 years later. This is a project that I've kind of shoe-stringed, but I figure it's cost me probably a half million dollars out of bits and pieces here and there to try to fund this project as it's gone along. But I think we finally have come very close to a tool that actually has some practicality. I'm going to talk about it today. The test is called TTNDFD. What it stands for is total tracked-- That's from mouths to rear end. NDF, which is the term for fiber, and digestibility. What this test is is it's an in vitro test that we can do on a feed before we feed it to a cow. We can predict how much of the fiber will be digested in that lactating cow. I'm going to kind of go through a little bit of some of the intricacies of that. It caught the attention of WARF. We actually had to patent an in vitro digestibility procedure that we could actually do this test with. So we got a patent for that. We've actually got a licence. We've got a lab now that's using this test and I'm working very hard to get some others to kind of buy in on it. I'm going to just give you a very quick lesson on why this is such a complicated thing. I want to point out that digestion is very, very dynamic. It's time sensitive. The longer a cow can keep something in her stomach the more completely she'll digest that feed. But with our very, very high-producing cows, they eat a lot, which means food move through their digestive systems very, very quickly. So there's a balancing act here. There's a balance here of how much feed can I get this cow to eat, and at the same time, how completely can that cow digest that feed. You're trying to hit that fine line of just fine tuning here in trying to get the most calories out of that particular diet. Again, I kind of equate it a bit to a human and a couch potato. You know, we're constantly pushing a little bit more. But a good thing with a cow is that she's making milk, not getting fatter and fatter as she goes along by eating more. So we kind of do it. But this whole things starts with a very simple concept. There's two things that affect how fiber is digested a the cow. It's the plant and the characteristics of that plant, and it's the cow. In the plant the major drivers are the amount of fiber that's in that plant. As plants become more mature they get more fiber which makes it more difficult to digest. We harvest alfalfa early to lower the fiber levels so we gain energy on it. But there's also characteristics of that fiber. That's what this fiber test is working on. It's to try to figure out the digestibility of that fiber component. The importance here is that cows need fiber. Fiber is not bad. They need a certain amount of fiber to keep their stomach in there healthy. What we're trying to do is make sure that as much of that fiber that they consume is actually converted to energy. We're trying to get that balance. Fiber digestibility, we look at it-- And this is kind of a key thing that I've done a little differently. We look at what we call potentially digestible fiber. This is the fiber that if you left it in there long enough would completely digest. Not all fiber in that plant material will digest. And then we look at how fast the fiber digests. I'll get back to that a little bit later. Our test is really kind of one that's set up to integrate rates of fiber digestion and the amount of fiber that's digestible. The other part of this is that if you're thinking about running this to a commercial lab, they've got to put a number on a piece of paper. The other challenge you have is that, well, if cows eat a lot and that changes the digestibility you've got to figure out a way to make a number that kind of indexes that forage to another forage. That's what the nutritionist or the farmer is really looking at. How can I compare this to the feed that I'm currently feeding. We've taken into account here a little bit of math that kind of shows that you can calculate how fast feed will pass through the digestive system if you know something about the cow. Since I don't know anything about the cow I'm going to gear it up to a typical, high-producing Wisconsin Holstein so that the number that comes out on the report kind of fits for that typical cow that this thing is going to be fed through. I didn't mention-- Okay, forage testing. Really, again, the key thing here is to make a tool that's available to farmers. There are several labs in the state. There are three large labs that do a lot of forage testing in the state. One of them is our University Station at Marshfield, and there's a couple of commercial labs here. This is a big business. An average forage test costs about $15 to $30, depending on what you're doing with the sample. Remember there's about 11,000 dairy farms. There's probably about a quarter million samples analyzed a year of corn silage and alfalfa. So at $15 to $30 a sample that's a big business. So these are tools that are used quite routinely as we move along. All right, so what's the concept? Total track fiber digestibility, or TTNDFD, really is a model, an approach that we've taken to kind of simulate digestion in a typical, high-producing dairy cow. What we need on the front end of what that cow eats is the characteristics of the fiber that that cow is eating. That's what our forage test is really geared on, is the amount of fiber, how much of that fiber will digest if it's left in the rumen forever, that's what we call potentially digestible fiber, and then the rate of digestion. That's really the key thing that we've really developed in this test, is how fast does that fiber disappear. We tied that in to a cow. As I said, it's a typical, high-producing dairy cow in Wisconsin. This test is really not set up for beef cattle at this point. We could certainly change the cow and we could give that number on a report, but we're putting a number on a report. Then we measure an estimate here of how much fiber is actually disappearing out that. And as I said, a two to three unit change in fiber digestibility is equated to about a pound of milk, a half a liter of milk or so. How is this determined? The test has really been developed to do in a laboratory. A sample comes in, we use what we call artificial rumens. We collect rumen fluid from donor cows that we have in our cows on the campus here. We put bacteria that are growing in the rumens of these cows in with the feed. We incubate the feed for 24, 30 and 48 hours. We pull the samples out and we measure the fiber residue at each of those times. What we measure over time is how fast that fiber is disappearing. The longer it stays in that flask the more fiber is digested away. The change in the amount of fiber over time is the rate of digestion, how fast that fiber disappears. One of the things we've been able to demonstrate is what we measure in that test tube is a plant characteristic, and it happens in the cow just like it happens in a test tube. That's kind of the neat thing about this test. The other thing we measure is what we call INDF. We let this feed sit in this test tube for about 10 days. By that time anything that's potentially going to break down by the bacteria will have digested. We get those two plant characteristics, the indigestible and the rate of digestion we get out of that test. We plug that into our cartoon cow down in the corner, our reference animal to kind of get an index. We have a model. It's a very, very simple model that we've set up. Then we can calculate total track digestibility. That's kind of a complicated concept. I try to explain it to people that, you know, this isn't really any different than if you think of how far you can drive you're car. The mileage is your rate. That's how many miles per gallon that you can get. That doesn't really tell you how far you're going to get if you don't know how big the gas tank is, right? So if you've got a little small car with really great mileage but you've only got a five gallon gas tank, you may not get that much further than that bus over here with a 500 gallon gas tank with really poor mileage. You need to couple those two things together. That's really what we're doing with this test is we're saying, how much milk you're going to get out of that forage is driven by the energy. That's how far you're going to get. And what that really amounts to is how much of that fiber is potentially digestible, the size of the gas tank, and the mileage, or how fast that fiber digests. It's really integrating those two things together. The report, the TTNDFD value is the distance that you go, or is that extent of energy that's available in that feed as you kind of go through. So we've actually developed that test. I don't know if this is live. Actually, it's a forage test. It comes off as what we call TTNDFD. Again, it's indexed to a cow, and it's actually reported to producers. Now I've got a number. Okay? Well, what does that number mean? 42, what does that number mean? In this particular example, the feed is actually tested at 48. The number far to the right there is the average of feed samples that have been submitted to this lab over a period of time. So 48 says that's quite a bit higher than 42. That's about 6 units. That's a pretty good forage. That actually is probably one that has a fairly high fiber digestibility. That number is now being picked up by producers. But you need an index, you need a number that that person can kind of begin to get used to and work around. All right, so what are some typical values? Our data would suggest that the typical Wisconsin alfalfa has a fiber digestibility of about 42%. A good quality alfalfa will be about 40% fiber. 42% of that fiber is actually digested and utilized. Almost 60% of that fiber actually winds up being excreted by the cow. Corn silage is also about 42, okay. But one of the things that we've been able to discover with this new test is that they get to 42 by different mechanisms. Corn silage has more digestible fiber but it digests more slowly. It starts out with a bigger pile and the bacteria chew on that pile, and the break it down more slowly. Alfalfa has an almost half of that forage is undigested, indigestible, but what is digestible the bacteria scarf up and break down very, very quickly. They get to the same end point but they do it quite differently. As I'll kind of-- One of the things that I'm really intrigued about this is that's a tremendous amount of variability in corn silage and plants in terms of rates and how much is digestible. So this may be a tool that we could start re-looking at plant breeding programs, where we could start down and say, let's start looking at populations of corn silages that have very fast rates of digestion. Maybe they would be better utilized by cows. It might give us a different direction here in terms of plant breeding. All right, so it's a model, it's a concept. You can get a lot of mileage out of that, but eventually if you're building a model-- And it's one of the things I try to train my grad students. You start with a concept, you ought to back that concept up with published literature as much as you can. You try to take independent data and you try to build up and say, okay, in this case I'm going to bring up the point of what do the cows tell me, in terms of digestion? Then you build your model, okay? That's the easy part. You can get tons of publications out of building the model. The hard part is validating and really kind of validating that model. That's where we've spent a lot of time is trying to build a model that we're trying to validate so that we can have some confidence that what we're measuring is right. Also, when you validate you start figuring out what's not quite right about your model and how to fix it, and how to improve it. We're really kind of walking through a story here of how to do that. I start out with the literature. I consider, as I'm building a model for a high-producing dairy cow, they're the experts. So what do the experts say about fiber digestion? That's really done quite routinely in feeding studies. I mentioned there's five of 13 faculty here at Wisconsin that are nutritionists. Most other animal science and dairy sciences are also probably over loaded with nutritionists too. To make our pay we feed cows or we feed different animals and we measure digestibility of feeds. We measure in that digestibility, the fiber. There's a lot of data out there that's actually been measured of what it is of the digestibility of a wide variety of feeds from mouth to feces. We don't know how it happens, but we know what the difference is. The literature would suggest that, when we find published studies-- We went over a period of time and found 20 different studies that had been published, made through peer review, 64 treatments. That's a lot. There's hundreds of cows involved in these studies, because these are all replicated. We found that for alfalfa, as the main component of diets, that the fiber digestibility is about 47%. So 47% of the fiber that that cow eats is actually being digested. It was also interesting to look those publications that the range was around 30 to almost 66%. That's really important too, and that was really probably more important to me than anything else. It said it made a difference. There's a lot of variation in forages from plant to plant here. The cows are telling us that. So if I can pick that up, and remember I said two to three unit change in fiber digestibility is a pound of milk. There's 30 units for spread there. That's 15 pound of milk. That's a lot of milk. In today's economy that's seven dollars per cow in terms of what milk is priced right now. That's not peanuts to a dairy farm. We did the same thing with corn silage. On average we found about 25 trials that were published here that had corn silage as the main ingredient. The average digestibility there was about 40%. So 40% of the fiber that that cow ate was actually digested when corn silage was the main. And again, the range went from 20% to almost 60% digestibility. There was a huge range here. So if we can model this we felt that we really are talking about a big variation in the energy supply of that forage and how that forage is going to be utilized. All right, so we start with what the cows tell us. Okay? I've already kind of explained our model. We've kind of built that around this rate and extent thing. But now how do you validate it? That becomes a little trickier. I can't just simply feed it and measure between the mouth and the manure, I'm really interested in what goes on between the mouth and the manure. What we really have relied very heavily on are what we can rumen cannulated animals. If you've ever toured our dairy barn-- It's one of the hallmarks here at Wisconsin. We have hundreds of school kids that come through every year, and we show them the cows with the windows in the side. We always get asked, what do you use those cows for? Well, they donate the rumen fluid that we incubate feed in in the lab. We actually can measure directly within that cow that whole digestion process. It's really pretty fascinating and kind of neat, because you see the inside of a working, living animal organ as it's doing it's business. If you can get students past the smell and actually reach in you can actually feel some really neat dynamics going on. That's probably why I got into this business. I mean, I can't smell very well, that is actually a plus.

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But that whole thing of what's going on, and the hundreds of species of bacteria that grow and how these things change as diets change has been kind of fascinating. So anyway, I'm going to show you just very quickly three little tests that we've done to try to validate this approach and different tactics. As I set these experiments up, and again, I'm a very applied type of a scientist, I know I had to convince farmers this test is worth doing. Okay? Well, you have to kind of appreciate Wisconsin farming a bit. You have farmers that are graziers. Our graziers are very committed to grass. I don't talk much about grass, but grass is a major forage also. In their production systems grasses are very, very important. We're finding-- Some of our larger producers are finding that these grasses that we've kind of ignored in our confinement systems over the years have become more and more important. When we talk about cropping systems in Wisconsin, our cropping systems have to be sustainable long term. One of the things that grasses really add to the sustainability of a dairy production system is that they can take the nutrients from manure and recycle those though very well. You get these larger dairy units where we concentrate animals, one of the things they're looking at is forage crops that can take those nutrients and can be spread back on the soil and turned back into new plant material and be utilized. Nitrogen and phosphorus are those two environmental things that we have. And actually, incorporating grass back into dairy units is one tool that we can use to actually make farms a little bit more sustainable. So the wheels are turning here and okay, I can make graziers happy if I just feed grass. But what can I do to make conventional farmers recognize that there's also maybe a nutritional benefit to putting grass in the rations. Well, to make a long story short, one of the things that we've found in our larger dairies is that as they've added more cows in Wisconsin and our herd size keeps increasing. Tom mentioned I came here in 1985. The average farm size in Wisconsin in 1985 was 44 cows. I left the farm in Minnesota. We had one of the largest farms in the neighborhood at the time. We were milking 42. All right, the average herd size in Wisconsin today is over 200. I think over 30% of our milk is actually produced on farms with over 500 cows. So our cows have concentrated. We've lost farms, but our farms have gotten larger. One of the things that we find is that as farms get larger, land is expensive, so farmers don't necessarily always increase their land base in proportion to the cows that they've brought in. That means they have to get higher yields of feed from that. One of the highest yielding crops that we have is corn silage. They move away from alfalfa and plant more corn silage. Corn silage is a good forage, but it's not the perfect forage. We tend to find that we get upset stomachs and we get lameness in cattle if we push too much corn silage in diets. So looking at these producers we started asking the question, well, how about grass? If we brought some grass in maybe that would be a good way of making this diet a little bit healthier. We started one trial there. I'll explain that one. We also took another tact. Plant breeders have understood fiber digestibility. Here's actually plant breeding programs, and there's two genetic variants or mutations in corn that cause lignin not to form. Lignin is a source of fiber. It's not digestible. But it cross links and it make other fiber indigestible. So what we have is we have what we call BMR corn. There's two genetic variants of that. There's actually BMR corns and sorghums that are sold that have higher fiber digestibility. Anyway, we've known about that. The problem with BMRs is that lignin is the thing that gives plant structure. If you drop the lignin too much the plant falls over. That's what we call lodging. There's always been that kind of a challenge. So anyway, we know we've increased fiber digestibility. We've got data on that. But we thought, well, this is a good test for ours. We now have two known plants here. We have high-fiber and low-fiber digestibility corns that have been genetically altered. Will this test be able to detect some of that? So I'll talk a little about that. And then finally, as I mentioned, there's a little bit of, at the end of the day not all plants get to the same digestibility with the same mechanism. Alfalfa has less digestible fiber. More of it will pass through the cow, but what does digest digests very fast. Corn silage, as I said, more digestible fiber, but it digests so slow that a lot of that stuff that could digest if it's hung in the rumen long enough would digest but it doesn't stay there long enough, so it's fiber digestibility gets depressed. We thought, there's three different mechanisms here that we can start testing that could take a look at that. I'll talk a little bit about the grass study first. We know that, particularly, the cool season grasses that we grow in Wisconsin, things like Brome and Timothy and orchard grass, these are forage sources that have kind of fallen out of favor with our traditional dairy producers for quite a while. Largely they fell out of favor because they traditionally carried more fiber. There was always the concept that, fiber's hard to digest, why do I want to feed more of it? But when we moved to more and more corn silage and now we start getting upset stomachs because we're not feeding enough fiber. Nobody ever really started taking a look and said, hmm, maybe we could kind of use that grass to kind of settle that rumen down a little bit. At least that was kind of our concept. We said, okay, we know grasses are higher in total fiber than alfalfa or corn silage typically. That used to be considered a bad thing. Maybe it's not in certain circumstances. Maybe that could actually work to our advantage. The second thing is is that we know that grass fiber is more digestible. It's more easily digested than the fiber that's in corn silage or alfalfa. Maybe that's something. Again, if I can get an increase in fiber digestibility that means I'm getting more energy and maybe that will support more milk. The question came in, where would that fit? In Wisconsin that probably would not only fit somewhat for the graziers, but it also fits maybe for some of these more concentrated dairy operations where their raising a lot of corn silage because they need the tonnage and the yield of feed, and they can use this grass. I mentioned the system. The system starts to fit together because now I've got a place to get rid of some manure too. Alfalfa, it's difficult to get rid of manure on that, because it's a perennial crop. But with grasses you can apply manure more strategically and you can actually handle some of the nutrients. Which makes the whole system a little bit more fundamental. So we set up a little study to take a look at that. The study that we set up was-- This is just a quick example. The question that we asked is, what happens if we add grass fiber that has high TTNDFD, high fiber digestibility, or wheat straw. Now farmers use wheat straw as bedding. Okay, to let the cows lie on. Why is wheat straw not a very productive feed? It's because there's a lot of fiber in wheat straw, and it's not very digestible, but it is fiber. So what we did is we used that as kind of a negative control. Straw is bad. Our control is not so good. That's alfalfa and corn silage, but really, really high quality alfalfa and corn silage where we're really not getting enough fiber in that cow's diet. The question is, if we bring grass in here, can we kind of make things a little better for this cow? In this study what we did is we used corn silage and alfalfa silage as our primary. We used two different fescues. These were actually fescues that had been bred for high-fiber digestibility. We've actually had some breeders that have gotten the concept here that we can actually start breeding plants very specifically for fiber digestibility. What we did here is we took a third of the corn silage or the alfalfa out of the diet and we replaced it with either tall fescue or meadow fescue. So same proportion of forage in the diet, but now a third of that forage is coming from a grass instead of 25% from corn silage and 25 or 26% from alfalfa silage. With straw we added the same amount of fiber as we added from the grass. Straw has much higher fiber content. We tried to kind of balance that out. That's kind of what the diets look like. The concept here, control, we knew that was not a good diet. I tell farmers, that's why you pay taxes to the University of Wisconsin. I can feed cows and I can screw them up, okay? You'll eventually pay for it, but you're paying for it with the rest of the state. That's a negative control. Our question was, can we improve the diet by adding those highly digestible fiber sources from the fescues? Our negative control was what about just very indigestible fiber. We know that that's important to a cow because one of the things that keeps the rumen healthy in her chewing cud. When they chew their cud or regurgitate they're bringing up fiber and they're chewing it and chewing it. They produce saliva, and that saliva neutralizes acids in the stomach, kind of like an antacid. It helps keep the cow healthy. We were trying to look at separating that physical effect of fiber from the digestibility or the chemical effect of fiber in this particular trial. All right, so here's what happened. We went on our control. Our diet level of fiber was 24%. As I tell farmers, I don't like that diet. I would never recommend that they feed that. That's not enough fiber in that diet. We know that won't keep a cow healthy. We usually balance closer to 27% or 28%. But the reality is we run into -- all the time that are actually down at 24%, 25% NDF. So it's not unreal. It happens because our farmers have gotten so good at harvesting forage that the quality is almost becoming too good sometimes. So we added these fibers, the fescue, the tall fescue, the meadow fescue and the straw. As we added more fiber the fiber content of the diet went up. That was exactly what we had intended. We measured between the mouth and the manure what fiber digestibility had happened. We had only 25% fiber digestibility on that control diet. The rumen was very acid. I doesn't support the bacteria that like to digest fiber very well. It actually depressed fiber digestibility. I can tell that because milk fat percent on that diet when down to 2.9%. That's a very, very low milk fat test. For Wisconsin, farmers are not very happy with that. They get paid based on the milk components, the protein and the fat in that milk. 2.9% butterfat milk, milk plants don't like that because it doesn't make very good cheese. The cheese yields are very, very low on that. I'll skip way over to the straw. We increased the fiber to 29%. We know that's not very digestible, but if you look way over there, look what happened to fat tests. It went up to 3.2%. I'm interpreting that to mean the cow was chewing her cud more, she neutralized some of the acid, and she actually was able to support a little better fat test. If you look though, it didn't really affect her milk production. I apologize. These are in kilos. That's about 85 pound of milk a day, about 10 gallons of milk per cow per day as we were going across. But when we added the two highly digestible grasses look what happened to fat tests. We went up another two to three units. We up to 3.4%, which is actually a pretty acceptable level. So adding fiber that chemically could digest provided the precursors to make milk fat, which actually increases the value of the milk. So this is kind of interesting to our larger producers, who are sitting here saying, well, if I'm feeding corn silage and I want to get some components in that milk, maybe these highly-digestible grasses will work as a tool to kind of get me there. That was really the key of this particular study. All right, I'm going to talk a little bit about this BMR versus conventional. This is actually, I've actually done a feeding trial, but I've kind of thrown that out. But I want to show you something I think that's very interesting with our test. We've got a commercial lab that does this now. They've given me access to their database, and it's really kind of cool when you can apply a tool like this. You get farmers submitting samples in and you can watch the data kind of building on a test like that. This just happens to be several hundred corn silage samples that were submitted to a commercial lab. The red dots and the heavy longer line at the bottom there is corn silages that were only identified by the nutritionist or the farmer as corn silage. Usually when farmers sample from farms what the say is, corn silage from my south silo, or my bunker, or my bag. They know what it is, but we know nothing else. All I know is that this said, corn silage. I'm assuming those are conventional corn silages. They're not bred with this BMR gene. That's a big assumption. The blue line up above and all the blue dots are samples that, when they were submitted to the lab, they said BMR on the label. So somebody identified that as, this was a BMR corn that I raised and I put it into that. Okay? You notice the cloud of dots. Huge overlap. What that really says is that changes in fiber digestibility not only happen because of the genetics of the plant material, but it also is dependant on the growing conditions in the environment of that corn plant. What it really says is there's huge overlap. The lines are the regressions that say, on average, a BMR is about five units higher in fiber digestibility than conventional. And that's exactly what the published literature tells us. So our test reflected that when you compare isogenic materials where the BMR gene is the only thing that's different and the samples are grown in the same environment, there's about a five unit difference in fiber digestibility on average. That's exactly what we picked up. It's anecdotal, it's not really a good control experiment. But it kind of shows, I think, the power of the test. It also shows the value of having the test. Just because you have a BMR corn doesn't necessarily mean that it's going to be of superior digestibility. It may be grown in environments that are not ideal that depress that fiber digestibility. The producer needs to know that. All right, so why are BMR corn silages higher? I talked about it already. It's largely because there's two genetic mutations here that impair lignin synthesis. Lignin is the thing that cross links and depresses digestibility. We know, and our test has shown that BMR don't greatly change the rate of fiber digestion. They just change how much of the fiber is digestible. That's enough to kind of swing that value. And I'll bring that up. I think there's a real plant breeding opportunity in the future of taking a look at that other side on corn silage fiber. Can we make that fiber digest faster? I think we can improve fiber digestibility in corn even more. The last one I'm going to show you here, it was the most fun study that we've done, at least for me. When I first started here in 1985 everybody was tied up with his, what's the better forage? Is alfalfa better than corn silage or is corn silage better than alfalfa? Even when I was young and naive I thought that was really kind of a silly argument, but it really kind of carried and it kind of went through. We still have people. This was kind of a throw-back study. It's saying, okay, I think I understand now that corn silage and alfalfa fiber digest differently. Let's try different blends of corn silage and alfalfa and predict what should happen, then measure what the experts tell us, what the cows say, in terms of what happens in the rumens of these cows as we feed through. So alfalfa fiber, 40%-50% indigestible. It digests at a rate of about 5% to 6% per hour. We know that corn silage is about 20% to 30% indigestible. So it's more digestible than alfalfa, but its rate of digestion is only half of what alfalfa is. So the question comes in, if I feed 100% alfalfa I've got a big pool of indigestible material here. But what does digest digests away quickly. If I feed 100% corn silage I've got a big pool of potentially digestible, but it's this hard to digest, slow to digest thing. How does that affect the cow? That's kind of what we set up. So we set up an experiment. It's very simple, and this is where we used our cannulated cows, rumen from the cows with the windows. We set up four proportions. 100% corn silage and zero alfalfa as the forage, with grain and protein and everything else to balance the diet for that cow. Two-thirds corn silage, one-third alfalfa. One-third corn silage, two-thirds alfalfa. And then the far right there, zero corn silage and 100%. We just simply fed four ratios. Okay? I'm going to bop down to the two bottom lines. The predicted TTNDFD-- We ran these diets through our testing system before we ever fed them to the cow. What our predictions said was that when we fed 100% corn silage the total track fiber digestibility should be about 38%. As we added more alfalfa we're going to increase indigestible fiber, but we're also going to increase the rate. What it said on balance was that we should actually increase fiber digestibility, because that fiber digesting twice as fast from alfalfa more than compensates for the loss in indigestible pool. It's the gas tank thing again. The gas tank on that alfalfa is quite a bit bigger, isn't that much smaller, I should say, than the gas tank on that corn silage. I can push a little bit more milk out of it. It said that we should get about seven units difference in fiber digestibility as we came across the board. We actually ran the trail. These trials, what you have to do with these rumen cannulated cows to do these studies is you feed the cows all they want to eat and then we have to manually dump all the feed out of their stomachs. We reach in that little 4" window and we dump everything out. We weigh everything in there and we figure out how much fiber in is the rumen. From that we can figure out how fast it's turning over or passing out of the rumen. There's a whole bunch of math involved with it. But just to give you an appreciation, that window is this big, 4". You have to reach in a handful at a time to pull it out. We did this on eight cows, twice, every period for four periods. We have a sleeve here. Yeah, the faint at heart use sleeves. Those of us that can't smell anymore, we know these leak very quickly. We, by nature, probably use one, but we know that it really isn't going to help that much. I've learned a long time ago, I don't go to Hilldale after I've dumped a rumen.

laughter

Even if I've taken a shower people notice me. Not quite the way I want to be noticed. To make a long story short, we did two trials like this. To give you appreciation of how much work my grad students did, and I did come out and help them but not nearly as much as they did. It was about 20,000 pounds, about ten tons of rumen contents that were dumped out a handful at a time. We did this Saturday and Sunday mornings so they wouldn't have to miss class.

laughter

I did take the crew out for brunch after the last one.

laughter

They appreciated that. They're cheap labor that way. They're easily impressed. But the key is we calculate out whatever went on in the rumen, but we also did the total track digestibility. That's TTNDFD. What did the cows tell us? If you look at the observed TTNDFD in vivo, that means, okay, these diets, we ran them through and we predicted on the front end. When we fed them, the numbers came out almost exactly what we had predicted. That was-- I mean, that almost never happens. We predicted 38 on that 100% corn silage. We actually measured 38. We got up to 100% alfalfa silage, it was 44 versus 45. Lots of other things are very interesting to me about this trial. Probably not so much to you. But it really, I think, was a very clear test here that we thought this would happen after we analyzed the samples. And son-of-a-gun, the cows agreed with us. That's really kind of the neat thing to get you excited about doing the next test. You know, you've got to set up another one to run it. Those are some of the tests that we've used. We also have a model. I also want to point out that with a model you can actually start talking about, energy comes from the amounts that you digest. What I wanted to do here is I've got my model up above, but I wanted to kind of point out here the out puts. What I'm really telling you here is, okay, when we predicted this with our index cow, our standard cow, we predicted that there would have been about 2.7 kilos. That's about six and a half pounds of digested NDF coming from the in vitro test. Six and a half pounds of digested fiber, that's the source of energy for milk production from that component. What we actually measured was 2.6. We missed it be 100 grams. Considering that cows eat about 54 pounds a feed a day, we missed it by 100 grams. To me, that's almost unbelievable. If it wasn't my data I wouldn't believe it. That's what I'm worried about as we submit this. We actually measured total track, we predicted about three kilos of fiber digested total track in these animals. That's the second to the bottom line. We were off by 250 grams, half a pound. That's nothing in the realm of a cow. But it really kind of shows, again, that the model that we're using seems to be working pretty good. We're quite encouraged about that. Okay, I'm going to spend just-- How much have I got? A couple minutes? Okay. What can we do with this? I want to just show you some really life examples. This is actually a real herd that was up by Appleton, Wisconsin. Just after we had released this test, and we actually have this, we can scan samples with and NIR instrument now. I mentioned that earlier. It can actually very quickly predict fiber digestibility. That's a whole 'nother part of this story. We ran into a herd here, it was actually the fall of 2010. As farmers harvest silage in the fall usually what they do is they have enough silage to get them through to about November. Then they run out of that last years crop and then they start feeding the new crop of silage. I happened to be working with a consultant. This was about 400 cow dairy, so a lot of animals on this farm. Their primary forage was corn silage, and their 2009 crop corn silage actually looked pretty good. It had about 43% NDF which is pretty typical, a good quality corn silage. The red there is the TTNDFD. We didn't know that. This was actually done before we'd actually released the test. Since we'd scanned these samples with NIR we had the spectra in library. We can go back and look at them after the case. That's what we did in this case. But if you look at that, he was running around 76 to 78 pounds of milk a day on 400 cows. That was a pretty typical Wisconsin herd. But about the middle of November, or late November, third week in November, milk production dropped precipitously. He went from about 78 to about 69 pounds. Almost 8 pounds of milk production dropped. If you look at that graph, it happened over the coarse of about two days. It was when he went into the new bunker of silage. He ran out of the old and went into the new. The consultant that was working with him knew it was coming. He had already analyzed the forage. It actually was lower in fiber which he assumed means that it's a better quality forage. I can feed a little bit more of it. He pushed a little bit more silage in because he thought that there was less fiber and he was trying to feed to a certain level. And this thing just totally crashed. It took him until mid-January to get back to that level of production. It was kind of interesting because I've got all the formulations that were done. We've got the NIR scans. I can go back in and I can re-reference. The only thing that changed in this window of time when that milk production dropped was when we went back and looked at the samples the fiber digestibility of the corn silage that he had raised in 2009 was 48%. 42% is average, 48% is excellent fiber digestibility. It was one of the higher fiber digestibility silages I'd seen at that time. This nutritionist had tweaked that ration and was humming along very well this very high fiber digestibility, like high octane gas. You're car is just running along. The new crop, even though it was lower in total fiber which usually we would think means more fiber digestibility, it was only 32%. It was a 16 unit drop. Remember I said two to three units is a pound of milk? 16 unit drop is seven pounds drop in milk production. It happened right now. As he went over he started manipulating the diet, changing ingredients and things, and we have the analyses. What he was doing blind, this consultant, over three weeks or a month period of time here, was adding ingredients. When he finally got this thing back up, fiber digestibility was about the same as before it crashed. He started using different feed sources to kind of bring it in. It was a pretty powerful anecdotal tool here, to kind of suggest how this tool could work. Last year was a good example of how important fiber digestibility is. 2013 versus 2012, the green bars there are estimates of forage samples coming into this commercial lab being routinely analyzed. On average in 2012 we had super-quality fiber digestibility corn silages. The fiber digestibilites of about 47%. Last year, because of the growing conditions that we had last summer, fiber digestibilities dropped to 40%. That's just about what every nutritionist has told me. When they switched into 2013 they saw two to three pound drop in milk production and they had phone calls from these farmers that were not happy. What's going on? Why aren't you doing your job? What did you do to my diet? They were going though. So some of the tool that we use, okay. We have our lab reports. Here's an example of how I recommend we use these tools. We look at the amount of fiber. Still the amount of fiber is our first indicator of forage quality, the lower the better. But then I look at that TTNDFD, and I look at that number also. So I want low fiber and high fiber digestibility. Those two tools kind of work together. This is an example of a good quality corn silage in terms of the amount of fiber, 39%. That's pretty good corn silage, but that fiber digestibility is lower than average. That means that those cows are probably not going to eat that feed and produce as well on that as a more typical corn silage. We can do the same thing with comparing hays. I have an example here. I have a farmer that told me that this isn't his sample, but he actually had extra silage that he had raised and he had something very similar to this. Two forages, same amount of fiber. 42% NDF is good quality alfalfa. Last year we were short on forages. Farmer were looking for forage and were willing to buy from each other for that. This was testing out very well, but he had one that was about 50% TTNDFD and another one that was 44%. Guess which one he sold.

laughter

He sold the low fiber digestibility one, because he knew the other one was probably the better quality forage for his own. I think I'll skip a couple of these. I think that's going in. I want to talk a little bit about where I see this stuff going and the potentials, okay? I work a lot with my agronomy friends and I think there's some real potential of maybe changing plant breeding programs based on this test. I want to really point out how forages are grown here for farmers. Alfalfas, there are virtually new varieties alfalfa coming out every couple of years. There's tremendous competition in the industry for the next best forage, the bast yield. There's tremendous pressure in terms of breeding and genetics to make the best alfalfa for a dairy cow. The selection criteria on quality really is based on the amount of fiber at a certain stage of maturity. Then what they usually do to assess digestibility is they do what we can an in vitro 48 hour incubation. It's just a single time-point. I'm just going to point out that that's not a very good indicator of forage digestibility, but that's kind of the standard of the industry right now. That's really what's been going on. I'm going to propose, and we're actually working here at Wisconsin on the idea, that maybe we ought to be selecting on the amount of fiber at a stage of maturity, just like we always have, that's one genetic parameter we can select. But maybe we ought to be selecting for rate and the amount of digestible fiber. Those are more specific. I can actually calculate back what TTNDFD would actually be on that. I've been kind of interested looking at samples coming into the labs that we've analyzed. We know that there's more than a two-fold range in rates of digestion of corn silage and alfalfa. We have some alfalfas that digest very slow and most of them digest quite a bit faster. But we also have corn silages that do that. There's a lot of variation in rates of digestion. There's probably a genetic component in that that we could build and select. We could at least-- The beauty of NIR is the feed libraries are already here. If we have the spectra, we can scan and go back and start saying, is there family lines here that differ in these characteristics? And is there something that we could change in the directions of breeding programs? Same thing goes for indigestible NDF. I mentioned that BMRs were kind of caught by accident by lowering the lignin which made more fiber digestible, but it makes the plant fall over if you get the lignins too low. If you really do the math, what would really make corn silage awesome forage is if we could make it digest as fast as alfalfa. Then we'd have this huge amount of potentially digestible fiber and we'd have it, but it could break down really, really quickly. It's naive, but there's enough variation, I think we could capture that. The next question is, what does that do to resistance to plant disease and other things. But there would be opportunities, I think, to actually identify and maybe change the way we breed plants for forage production. I wanted to also point out that this whole concept of plant breeding has not gone unnoticed. There actually is a company right now that is marketing on fiber digestibility. It's grass breeder. I think that's the issue that's going. Corn silage and alfalfa, I think, will come very quickly. I think it will be one of these things that evolve and kind of move along. I guess the take-home message-- First of all, fiber digestibility to me is a big deal. A two to three unit change in fiber digestibility is easily attained and that has a significant impact on milk production in dairy cattle. The second thing is that this is really a test that at this point that was set up for lactating dairy cows. It's really kind of specific to these good dairy cows in Wisconsin. It's a test, I think, that really has application here for ration balancing and for evaluating diets. Our goals? I keep telling farmers, do you need a number? Okay, that took me a long time to figure out. As a researcher you don't market ideas, but 42. That's the-- I wish I was 42 again. 42 is the magic number. Anything over 42 is pretty good, anything under 42 starts to raise a flag in terms of fiber digestibility. It's a number that's really kind of catching on with producers. There's a lot of theory, there's a lot of complex stuff going behind, but you can distill it down to a very simple number. People can walk away from that, and I think have some comfort that they can reference and look at it and remember. I will thank you for my time. That's what I have.

applause