AoR 21: Don Llewellyn, Fetal Programming and its Implications for Range Cattle Nutrition

Epigenetics studies in beef cattle have revealed surprising long-term effects of cow nutrition on performance of offspring in muscle and fat development, calf survivability, growth, carcass characteristics, reproduction, and health. Don Llewellyn and Tip discuss research what is meant by fetal programming (the more familiar name for this branch of epigenetics) and some of the research from Nebraska and Kansas that has illuminated the relationship between the health of the mother and the subsequent health of the calf throughout its life. 


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>>Welcome to the Art of Range, a podcast focused on rangelands and the people who manage them. I'm your host, Tip Hudson, range and livestock specialist with Washington State University Extension. The goal of this podcast is education and conservation through conversation. Find us online at

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We have Don Llewellyn back on the show today to follow up on some of what we discussed last time. But before we get to Don, I want to thank Emmett Jordan [assumed spelling] a rancher in Briggsdale Colorado for writing in to suggest some further exploration on the topic of nutrition and ranch management and genetics. He points out that shifting the gestation period so that calving coincides with more favorable weather and more importantly, so that cow pick nutrient demand more closely matches what nature provides. At least in most of the Northern Hemisphere seems to make both biological and economic sense. And I would agree. He also suggested touching on the cost of protein, specifically the use of urea as a supplement and what that cost and discuss a little bit the balancing act between minimizing inputs and input cost and trying to help the herd you've got perform well enough to make a living. So, we will get to that before we end today. Emmett, I really appreciate you listening regularly and taking the time to write. Somebody who gets paid public money to think instead of produce food, I really appreciate people who produce real wealth, things that we eat and where as the old Alabama song says, "They keep this country turning around." Culture doesn't last long if it doesn't value farmers. So we will get to your questions before the end of the episode, Don Llewellyn, and for those who didn't listen to Episode 20 is the ruminant nutritionist who is a colleague of mine here at Washington State University Extension. Don, welcome back.

>> Thanks, Jeff. It's great to be here.

>> I've said before on the podcast that what attracted me to range land science was the integrated nature of the discipline. It is a science of relations and I think, nowhere do we see that so clearly that in animal nutrition, range animals are mostly dependent on what nature provides. And if we have to spend too much to make up the difference between what nature provides and what the animal needs, there's no profit left. For those who are just now tuning into the podcast, which we started last October, I would refer you to episode 4 with Fred Provenza where we discussed developing a herd or a flock of animals that are adapted to their environment, that are able to remain healthy and reproduce a year after year in the environment that you have available to you. I would also recommend listening to Jack Southworth. I can't remember which episode number that was. A rancher in Eastern Oregon, and he talks about flexing herd size and nutritional inputs to balance production and cost, recognizing that, you know, you can push match the animal to the environment to the point that you're a little too rough on your animals but you can also spend too much money. All right. Don, as we discussed last time has been involved for years with research on the use of low quality forages. And we noted in the last episode that if large ungulates were not able to digest low quality feed, they would not last long. Because in most parts of the world, where the natural plant community is grasses and shrubs, the protein value for much of the year and the available forage is below the 7% that's generally considered the necessary minimum for maintaining a mature female that's not lactating. Granted, that research on diet selection at the microscale both in livestock and in wildlife shows that animals select individual plants and plant parts that meet their requirements. And those plants and plant parts are typically higher in nutrition than the average of the plant community. So, if we went out and clipped 20 random samples and analyze that forage, it would be lower in forge test values, than if we collect what the animals were biting off and consuming. The animals are smart enough to go get what they need. But Don, you said that they're not just picking out good stuff, they're also getting more out of what looks like bad feed stuff because we're not actually feeding the cow directly. We're feeding the rumen microbes and they make that available. Is that right?

>> Yeah, that's absolutely right and, you know, your thoughts well take and when you talk about diet selection. We did some studies when I was at Kansas State University as a graduate student, we'd look at those [inaudible] versus the samples that we actually took out of the rumen. Then there was about all say, three percentage points increase in the crude protein content of those samples that came out of the rumen versus what was clipped. And so that-- there is a method to the way that these animals are out there grazing and selecting and looking for the advantages of that good forage.

>> In our last interview, you talked about how the action of the rumen microbes and I guess-- I'm not a nutritionist, but my understanding is that more specifically the enzymes that are produced by the microbes that are able to break down cellulose. When we take care of the rumen microbes, when we feed them properly, those enzymes break down fiber in what would otherwise below quality forages that would test really low in crude protein, and even low in total digestible nutrients, which is the-- what most people are familiar with as the forage test proxy for energy. And we briefly mentioned in the last episode, a concept called fetal programming, which is the idea that how mother cows are managed nutritionally during pregnancy affects the performance of their offspring not just immediately after calving but clearly through their life all the way out, you know, if we're talking about animals that follow a conventional pathway to entering the human food chain, you know, that could be 18 to 24 months. It's as if their bodies have been programmed in utero to behave in certain ways, or not behave in certain ways. I'm not a nutritionist, so I'm flying blind. But this is fascinating stuff, and it's been in the news for the past two or three years. What is fetal programming?

>> Well Tip, another term for it is epigenetics. And it's essentially how environment has an effect on how animals are able to express their genetic potential. And so, really, this all comes back to, we need to be looking at our production systems, actually just as that as a systems approach that-- so-- that's been so much in the agricultural news as opposed to looking at our management of our cows in a piece meal fashion. We have to look at the nutrition and the health and genetics and all of these things as one big package. And in doing so, fetal programming takes this a step further in looking back at what that mama cow is consuming at various stages during her gestation anytime after conception until that calf is born and how that affects the fetus. And in essence, what she does or what she consumes and what she's doing during the time of pregnancy is going to have an effect on the calf, early in life as well as throughout their life or it has the potential to be that anyway.

>> Right. You have written in an extension publication that you did with Sarah Smith and Mendu [assumed spelling] that a whole host of traits that are-- that we could measure in the mother cow's offspring are known to be affected very much long term towards the animal's life by the stimuli that the mother receives during pregnancy. Those include muscle and fat development, which is, you know, that's what people make money on in the cattle business, a calf survivability, growth, carcass characteristics, reproductive success, animal health. That sounds like pretty much everything. So that's why people are saying this fetal programming, epigenetics is a big deal.

>> Absolutely, and let's start out talking about it by first saying that we always want to consider that we're going to provide adequate nutrition and try meet the nutritional requirements. But as we talk about fetal programming, we're no way trying to make a point that we're going to try to overfeed these cows in order to get a response out of the fetus. That's not the point. But there are certain times during the-- during fetal development that are really important for the development of the calf.

>> Right. So does that work-- you mentioned not trying to overfeed. Does that work both directions? In other words, if we under feed do we provide poor nutrition to the mother that that can have a long term negative effect in, I guess, a corresponding way that good nutrition or adequate nutrition has a positive effect?

>> That's true, and they've even-- in some of the early studies in this area even looked at humans and followed humans that had-- whose mothers had had nutritional restrictions for whatever reason during pregnancy. And then they followed these children into adulthood and throughout their lives and found that there was, you know, differences in the health and heart disease and diabetes and all of these things because of-- or they had tied that back to stresses on the fetus. But let's talk just a little bit about fetal development of calves and at certain times during the fetal stages or during gestation and how that might affect later performance on these calves. So, for instance, in our fact sheet we have-- and you may want to link this to your podcast, but early in gestation there's an increase in the formation of muscle fibers. And of course, we understand that that muscle is what we're trying to produce on our feedlot steers and feedlot heifers or whatever. And so that's really important for the number of muscle fibers that are developed, OK. So, we got to have a number of muscle fibers in order to have adequate muscle in these cattle. As we move toward later stages in gestation, there's-- the muscle fibers can be affected by-- as they-- can increase in size, OK. Adequate nutrition will make it so that these muscle fibers adequately increase in size. Same thing toward the later-- the last trimester pregnancy formation of fat cells, how that ties back is, is that if you-- if we have more fat cells forming during later pregnancy because we have adequate nutrition, then that can translate later on into intramuscular fat which is obviously one of our factors along with maturity that determines quality grade in these cattle.

>> And those are all fixed. So, you're saying after the animal is born, you have no more development of new fat cells or new muscle fibers?

>> Yes, this is how these fibers-- we're talking either an increase in the numbers or increasing in size.

>> Say with muscle and fat, you're saying that muscle is developed in early gestation, fat cells are developed late gestation. I mentioned before, these are the things that pay the bills, we're raising meat animals, and the meat that we eat is skeletal muscle. And it's not worth eating unless there's some fat in it that affects both tenderness and flavor. And I can see how our traditional understanding of genetics will hardwire or, you know, put sideboards on the potential development of an animal. But how does the mother's nutrition affect the animals' ability to produce muscle and fat? What's the mechanism there?

>> If we go back to some of the earlier studies back in 2007, 2008, 2009, they showed that with adequate protein supplementation of beef cows, and these were in some Nebraska studies where some of the early ones. That those cows that were adequately supplemented third trimester, you know, with various protein cubes or some are more 42% cubes, some are 28% cubes. But what they saw later on down the road in-- is that the calves that were in utero at the time that the supplementation took place, they had increased weaning weights, hot carcass weights were increased, and of course, this all translates into saleable product. And then, more than one study showed both of those things. And then later on, some of those studies showed that there was an actually an increase in the marbling scores which also translates into higher quality grades as well. That, of course, paying on the-- pricing on the grid and so forth translates into more income for-- on a first year basis based on the grade.

>> So, let me make sure I understand what that research was. The mother cows had-- some had just whatever the available forage was. A different set of mother cows had supplement appropriate to make what they're getting matched up with what they need. And in the calves from those two different sets of mother cows were on the same feed and came up with different performance. Is that right?

>> Yes. So those calves were followed and the whole point of it is, is that all other things remain constant.

>> Yeah.

>> Tying it back to that mama cow's supplementation that had an effect on-- and the astounding part of it is when you think about the third trimester of gestation for a cow, then that calf is born, and so that's seven, eight months later, so then you're 10 or 11 months down the road. Then that calf may go into a background in or a stalker system so that puts you 13 or 14 months down the road. Ever since that cow was-- or that calf got the benefit of the supplementation in utero, and then that calf goes to the feed yard. And then you're looking-- at depending on how long, how heavy the calf was when they came in, and how long they were fed. You know, you're looking at 18 or more months after that small amount of protein supplementation was delivered to the mother cow to not to overfeed her, but to help her meet her protein requirements for the type of low quality forage she was on in the wintertime. And that had an appreciable effect on the performance of her calf and just tying it all back to just the supplementation of the cow. And, that's pretty incredible when you really think about it, that a small amount of protein just for helping the cow meet the requirements can have that effect so far later on down the road in life. And we can take that on the heifer side, on the breeding heifer side. There were some studies that showed that the pregnancy rates in those first calf heifers were increased by 13 or 14%. I think it was actually 13%. And so, when you consider the cost of development of-- or the cost of development of a replacement heifer, or the cost of purchasing a replacement heifer, if you can get another 13 calves into production out of every hundred and thinking about the cost you have invested in those cattle.

>> Those are big numbers.

>> Thirteen-- Those are big numbers when you can have that kind of impact.

>> Huh.

>> And so, it's not just the steers, it's on the female side as well.

>> Yeah. There are a lot of implications of that mechanism. What other aspects of animal performance are affected by the nutrition of the mother?

>> You know, I mentioned the protein supplementation of the-- and the fetal programming for reproduction with-- on the heifer side. Some of the early studies were a little more inconclusive on health. But there's some inkling at least in the-- in those studies that appropriate supplementation of the mother during gestation may help from the standpoint of resistance to disease later on. Like I say, that was a little bit more inconclusive. There were some studies that showed a difference, some studies that maybe didn't but it's sure something that bears more investigation for sure.

>> Hmm.

>> But-- I mean, when you think about BRD, being one of our biggest problems and our biggest cost. I mean, if we can appropriately feed that mother cow and a percentage of-- or there's a lower percentage of cattle that are treated for BRD, when they go to background in or in the feedlot or even at the cow calf level, you know, that can be a significant cost savings as well.

>> Yeah. So how would you recommend people manage cows to predispose their calves for optimum nutritional performance? Anything beyond just making sure the cow gets what she needs?

>> Like I say, if I'm going to make a recommendation, it's going to be relative to knowing what your cows need at various points of time in the production cycle. And, you know, everybody really needs to have their nutrient requirement tables at home and be looking at those, you know. We don't worry so much about these cows. It turn out, say April, May, June but later in the summer when those cows are-- especially in Eastern Washington when the grass is dry and everything's going dormant and so forth, our proteins and the amount of energy we can deliver of that low quality grass is it gets fairly limiting. And so, later in the summer, we need to start thinking about what those nutrient requirements are, and if we have requirement tables that we can look at, we could get a fairly good handle on what those cows need. The other thing, producers, I think, I always try to make the point is that we need to be able to estimate fairly well what those cattle are going to eat of a various types of forages, you know. We know that if it's a really low quality forage, like say wheat straw, there out pasture wheat straw or you're feeding wheat straw after harvest or whatever, they're going to eat less than 1%of their body weight and dry matter of that because it's just so low quality and highly lignified and has the anti quality components in it. And they just won't eat much and so-- then as our forages or harvested feeds get better, we know that there's different thresholds about how much these cattle are expected to eat. Because we can't tell what we're delivering unless we can make a fairly good estimate of what those cattle are actually consuming and so-- then we can compare what they're consuming with the requirement tables or get a pretty good handle on what we should be doing for supplementation.

>> Speaking of supplementation, we'll come back to the question from Eastern Colorado. Urea is something that's commonly been used for a protein supplement. Is that a good idea? Is it something that's unnatural for a ruminant? How does it work? How does that-- how's the cost compare with something like Alfalfa hay?

>> So urea is one of our sources of what we call non protein nitrogen, another one is called biuret. And it has its place in cattle rations. We want to be careful with urea if we're-- we can't feed as much if we're talking about a low quality forage, then we can and say, a higher energy diet like we'd have in a background in diet or a feedlot type diet. And the reason for that is, is because usually a little supplemental energy goes a long way in helping the rumen microbes to utilize urea. And essentially what urea is doing is it's just providing a source of nitrogen for the rumen microbes. You know, we talked in our last-- the last time I was on a podcast with you about that the rumen microbes have a nutrient requirement just like the cow does. And so, the-- they have a nutrient requirement for nitrogen and a lot of our forage digesters can use ammonia as their source of nitrogen in order to make protein into their bacterial cells. And then, of course, that becomes microbial protein for-- to be part of the protein requirement of the cow. And so, urea works pretty well as long as we use it as a tool and as long as we provide whatever we need along with it friends-- for it. For example, a little energy to help the microbes utilize it. Now, if we overload the rumen with urea, then we get too much ammonia in there, over and above what the microbes can utilize. And then it has to go to liver and be detoxified and we can run into some ammonia toxicity in that respect. So, like I said, the energy will help with that. Now, that said, a lot of our prepared supplements like molasses blocks and lick wheels and so forth like that, they have a significant amount of urea in them. And just by the nature of the carrier, they have a lot of sugars in there and that's the reason that they'd match those urea with those sugars because the sugars helped the-- you know, like in the form of molasses or whatever, they help the urea to be utilized. And so, typically rule of thumb, if you go back into the literature, you know, in the cow calf area, there's some data that came out, you know, like Kansas State, some was done when I was there. Was, you know, you can use upwards of 25, 30% of the degradable protein can come from urea, but it sure can't be all of it. You could use up to that 25, 30% without having an appreciable decrease in performance, you know, like body weight gains and body condition scores and so forth in the cows. You know, animals, they're on a higher energy diet. You can probably push that limit some, but we have to use it as a tool and it will help reduce the cost. In a lot of cases, of course, that's dynamic, it depends on the cost of urea and it depends on the cost of what you're comparing it to. You're on a protein for protein basis, whether you're talking about the price of canola meal in the Pacific Northwest, or whether we're talking about price of Alfalfa hay or whatever you'd like to use for your source of protein. So-- but there's times when you can save a bit of money, some of the old-- some of the older rules of thumb would be, you know, at the inclusion of, say 15% of the degradable protein in as urea could, you know, maybe save you in the neighborhood of 5 to 8% on the cost of the supplement. At a higher inclusion rate, that might be 10 to 12%. That-- But it just kind of depends on what the price of your natural protein source is compared with the price of urea.

>> Right. I'm guessing there may be some people listening whether ranchers or non-ranchers that have not used nutrient requirement tables before. I happen to have in the office a copy of the NRC manual, but I don't know how wide to those are available. Are there online nutrient requirement tables that you could recommend that folks can use?

>> Absolutely. If you just Google up nutrient requirements of beef cattle, there's a lot of extension fact sheets from various universities that contain excerpts from like the beef cattle NRC or the nutrient requirements of beef cattle, the government publication but there should be plenty of things out there. And then there's also if you Google nutrient requirements of beef cattle, you'll also get some hits for some nutrient requirement calculators. And those are really handy for producers because you can plug in what feeds you want to use and the class of livestock that you've got. And you can get outputs both from-- both as to if you're meeting those requirements. And if the costs of the-- of your ingredients are in your feed tables. It'll also give you a cost comparison. One of them is a classic one is the Oklahoma State University calculator, and it's a good one. The noble foundation from Oklahoma has a cow nutrition calculator for cow calf operators. And, of course, you know, you just have to make sure that the feeds that you're using are included in the feed table and some of them have the ability to add feeds to them. The Oklahoma State versions, they have there an Excel spreadsheet based calculator and so you can actually add feed-- [Inaudible].

>> Yes.

>> Yeah.

>> Yes, you can put your own feeds and own-- and update your prices and everything. And so those are really nice tools. And, of course, you and I as extension people, we're more than happy to help producers learn how to run them and help them become self-sufficient, help producers become self-sufficient on how to make those things work and how to make those decisions.

>> You bet. One more question. I was-- it was-- one possibility for evaluating nutrient needs is body condition score. You know, we can talk about book values and forage test values. But the final test is how the animal actually does, is body condition scoring a decent way of evaluating whether the animals are getting what they need or is the lag time too long between what you feed and how the animals do for that to be useful in real time?

>> No. I think that body condition scoring is definitely useful and it's something that is simple and producers can easily implement into their herds. Now that said, body condition scoring isn't necessarily tied to some absolute standard. And what I mean by that is that if you score your cows tip at-- and you have an average body condition score of 5.5 in your herd and then your neighbor down the road, scores theirs and they have a body condition score average in their herd of 6.2, it may just be that you look at them a little bit differently. OK. So, just because you think yours is five and the neighbor is a low six is not a problem. But what you need to do is you need to get the body condition scoring pictures and descriptions and so forth and do your best in getting a handle on what the body condition score that is that's going to be your goal. And we typically say a body condition score five on a one to nine scale is about optimum for cows that, you know, when they come around to calving time. Now that said, we don't typically feed cows to be a body condition score of five or better all year round because we know that our beef cows are resilient and they can cycle away, right? So, we expect that those cows are going to lose some weight as-- or lose-- I'm sorry, lose some body condition and the associated weight with the body condition as those calves drag them down into the late summer and early fall. But the silver lining in the whole thing is that we can get some really very efficient body condition score gains in the post weaning period before the weather gets tough in the winter. And so, we can get those cows to build that back up and still meet our goal of say, a five or a little better by calving time if we appropriately feed those cows and supplement them and so forth, and so. But, you know, it's been shown way back that there's a really solid link between body condition score and reproductive performance in those cows and when I'm thinking about body condition score. I'm thinking about dividing up cows, if it's possible, not every operation it's possible to do this, just based on facilities management and so forth. But if you've got cattle that are at risk for reproductive failure because they're on a-- little on the thin side, then it's good to handle those cattle a little differently with a little bit better nutrition than our all-- our mature middle aged cows that are pretty resilient. For example, our two and three year old cows, I think we talked about this the last time I was on the podcast with you. Our two and three year old cows are at the greatest risk for reproductive failure, right? Because they're still trying to grow, they're trying to nurse the calf, it all comes back to that biological priority for the nutrients, you know. The last thing to happen is reproduction and it's the first thing you lose because they're trying to grow and they're trying to nurse the calf and they're doing everything they can to make that calf grow. And so, it's those cattle that are at the greatest risk that probably need the extra groceries at those critical times and because, like we were talking earlier, you know, we get such a huge investment in these young cows before they ever have a calf. And so, every one of those that we can get into their fourth year or fifth year or whatever, to where that-- they're actually mature cows and really fit into the herd as mature, you know, that's a big deal because we don't want to have to call and lose that investment. I mean, we recover some of it when you have to call but you never quite get it all back, you know.

>> Yeah, that's interesting. I was in a conversation a few years ago with a wildlife biologist. And we were discussing the potential for the winter to be a bottleneck. And then my assumption was that winter was the primary bottleneck for the health of these-- we're talking about elk, elk populations, and he said, it's actually more whether we had a good summer that determines whether or not the animals do well and make it through the winter, both in terms of individual survival as well as, you know, calving success, that if the animals go into a really hard winter, in good condition following a summer that had favorable forage conditions, they generally do just fine. You know, conversely you could have a relatively mild winter, but if the animals go in with low body condition as a result of, you know, droughty conditions, or some other kind of stress through the year, that they tend to not do so well, and you have quite a lot of both mortality and morbidity and low reproductive success. But I-- you know, my assumption was that wintertime conditions, particularly cold weather and high snow cover where the animals can't eat much, or have less available to them during the winter would be their primary limiting factor. And that's not so much the case. It's primarily what body condition score they go into the winter with.

>> Yeah, I expect that's true, and it stands to reason. That's why we see when we have a good fall, we see the next spring a lot of our dear with twins and so forth, they probably are doing better, have a better ovulation and so forth, so.

>> We will post a few more key articles on epigenetics and fetal programming in the show notes. For those who have not been listening for a while, the show notes are accessible both on the SoundCloud website or the SoundCloud plugin on the website. With the show notes are maybe even more accessible inside of your podcasting app on an iPhone that would be on podcast, or in Stitcher. You can see the show notes in there and those links are all in there. I also want to mention that if you have questions or comments related to an episode, please email them to show at and we'll address them on the air. Don, thanks for tuning in again. Any final comments?

>> [Background Music] I just appreciate the opportunity to come on and visit with you and hopefully provide some something that's useful for our producers. And that's what it's all about, that we're here to serve, so. And I know you are too, so I just appreciate the opportunity.

>> Thanks again.

>> Thank you for listening to the Art of Range podcast. You can subscribe to and review the show through iTunes or your favorite podcasting app so you never miss an episode. Just search for Art of Range. If you have questions or comments for us to address in a future episode, send an email to For articles and links to resources mentioned in the podcast, please see the show notes at Listener feedback is important to the success of our mission, empowering the rangeland managers. Please take a moment to fill out a brief survey at This podcast is produced by Connors Communications in the College of Agricultural Human and Natural Resource Sciences at Washington State University. The project is supported by the University of Arizona and funded by the Western Center for Risk Management Education through the USDA National Institute of Food and Agriculture.

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