Fat, whole body energy and profit in Merino ewes

Thanks, Josh. I'm back again, unfortunately for you guys, but I'm presenting this on behalf of Professor Andrew Thompson, who can't be here today. This was his time slot, but for a variety of reasons he can't get here. I want to acknowledge the other people whose names are up there. Sarah Blumer has spoken here at Mumblebone before. Unfortunately she lost a battle with a brain tumour a couple of years ago, which was pretty tough on our team, so it's a pretty sad day really to be presenting much of her work. But it's a great bit of work for the industry, so it's well worth presenting.

Andrew Thompson supervised Sarah, so Thommo has picked up the work, and there's a range of work that's partially finished and ongoing. John Young is one of the smartest blokes in the universe, and he's done all the economic modelling. For any podcast listeners, there's a good podcast with Youngy. It's a team I've worked with a lot when I was in WA, and it's an honour to be presenting for that high-quality team. I also want to acknowledge AWI, who funded the project behind the back half of this talk.

That project underpins the results I'll be presenting, and I'll go through it as we get to it. It's not finished. There's about six to 12 months of analysis to go before we know all the answers, but it's certainly a foundational piece of work.

Why stocking rate matters

I want to take us back to what we know about the sheep industry and making money from sheep, as gross margin. We know that stocking rate is a really important part of performance, production and gross margin in sheep. As we get into these years where we're starting to make more money, it becomes even more important to drive stocking rate to maximise the opportunities of those good years.

So stocking rate remains a really important part of how you make money on your farm, and you'll understand why I'm talking about stocking rate at the start of a genetics talk in a minute. Remember that you don't make money unless you're running plenty of livestock. That's how the system works.

In terms of systems efficiency and how genetics works in with that, high stocking rate is important, and I've just covered that. High cost efficiency is important. High welfare: you've just heard from lots of people today talking about why welfare is important, and you know why welfare is important on your farms. Then for us it's about balancing that with per head production.

We don't go for the one animal, and Henry covered this a bit. It's not about making the best animal in the world and then multiplying that by ten thousand. It's about having a group of animals on your farm that are optimised for that farm. That's a different set of thinking that you have to get your head around, and we might not be that good at it in the industry. We often focus on jamming as much production into the animal as we can, but the individual animal has no value. The whole mob has the value, and we have to create an efficient mob. That's where our thinking comes from around genetics.

Fat is money

When we move that to fat, it's an integral part of it, because locking energy into fat is how we shift good times to bad times. If I had one answer to what we need to take away from this part of the talk, it's that fat is money. "Money in mud" is something people have said a lot in the last few years to make themselves feel better about the fact they're farming in mud. But there's definitely money in fat in lots of the places where we farm livestock.

What we're going to talk a lot about today is greater energy reserves, which we're calling whole body energy, or WBE. That's a term you're going to hear a lot over the next decade if you hang around people like us. Whole body energy is what we're trying to build. It's the actual storage. If you put a sheep through a mincer and calculated how much energy is in that sheep, that's what that number is.

We don't put them through mincers. Well, we have, but after they're euthanased, just to clarify. I did that in my PhD. But now you can put them through a DEXA, and there are different ways you can measure whole body energy without destroying the animal.

We know that fat is part of the buffering capacity. You've seen the variation in seasons all your farming lives, and fat is the thing that will take the good times into the bad. We've seen the links to reproduction, and I'll cover them again briefly. And then the real driver of profit is the ability to run a higher stocking rate, so the animal can maintain its condition when it's under some stocking rate pressure.

The main enemy of a sheep is another sheep, so we need to find sheep that actually go all right when they're put next to other sheep. Depending on where you are in the world and whether you're feeding supplements or not, animals that maintain their own condition require less supplement to hold that condition. You can stop feeding earlier or start feeding later in those animals, and we'll cover some of that science.

A few facts about fat. This is the amount of energy it takes to lay down a kilogram of fat, so it's really expensive to lay down. And this is how much energy it takes to lay down muscle. It's around 45 or 46 megajoules of energy to lay down one kilogram of fat in a ewe, or in a human, which is something I do a pretty good job of. Muscle has a lot less energetic cost to lay down that kilogram. But when you're actually using that tissue, fat gives you almost 30 megajoules back, whereas muscle gives you only four. So the efficiency of that cycle is 60 per cent for fat, where for muscle it's only 40 per cent.

You get less energy back from muscle compared to the cost of putting it down. Fat is expensive to put down but efficient to keep, and you get a lot of payback from having that fat laid down.

When is that tissue being laid down? When is the sheep getting fat? In the good times. Can you use all your grass in the good times? A sheep that can shift the good times into the bad times is what we're talking about here. We're laying down fat when feed is cheap, very cheap, in fact wasted if you don't use it. Then we're getting it back and getting good bang for buck when things aren't going so well.

So what seems inefficient is actually an efficient way to handle a pasture curve. We're not farming in chook sheds or pig sheds where we can feed everything the same amount every day. We're farming in a very variable season.

So, things about fat. It's expensive to get, but it's cheap to keep. It's really efficient at staying there. When you've got muscle tissue laid down, it's mobilising itself and laying itself down all the time. Its turnover is high, so it costs you a bit of energy just to have muscle on. Fat is pretty much metabolically inactive. It's just sitting there in various spots on our bodies that we don't need to point out, and it's not costing as much energy to maintain. And it's very efficient at recycling, so laying down fat and mobilising it is more efficient than laying down muscle and mobilising it.

Fat, reproduction and lamb survival

This is how it plays out in the animal. This is the residual feed intake of animals. When those sheep are in higher condition score, which the genetically fatter ones are, they require less energy to maintain that weight. It changes their metabolism. If you lock them in a pen and feed them exactly the same, they lose less weight under that condition. It's that efficiency of how that animal rolls, because she's got a bit more fat in the system.

Let's go through what that means, and these are some things you will have seen before. In terms of reproduction, this is the impact of fat on ewe lamb reproduction across the national database. I've used post-weaning fat in this example. Sorry, Thommo gave me these slides. It's post-weaning fat, positive versus negative. At any given liveweight, there's higher reproductive performance from the ewe lambs with positive fat.

That's mating your ewe lambs, and it would play out pretty similarly in maidens, depending on which weight you're mating them at. So there's more reproduction in those early-maturing ewes, and that's generally what fat is doing in that age class. We're getting a bit more reproduction from that positive fat.

This is my age-old graph from my PhD, on maintaining lamb birth weight in seasons where things aren't going so well. This is more genetic fat out here, and this is the birth weight of their lambs. The fat ewes are maintaining the birth weight of their lambs as if they had been fed at a higher condition score. That buffering capacity is part of what's going on.

I'll rattle through this part. The other thing you will have heard me talk about is what happens when you just put a sire with higher fat over your ewes. We see a lift in lamb survival at any given birth weight. We know that birth weight is driving lamb survival, but if we breed a bit more fat into those ewes, we get a lift in lamb survival again. That's about a 10 per cent lift in lamb survival, just from the sire you use. That lamb is getting up with a bit more go in it and going to the udder and getting a feed.

So there are lots of positives around fat that we've talked about at various times. The thing I want to talk about now is whole body energy, and what we're seeing in the industry from the work that Sarah started and Thommo is continuing.

Whole body energy in different sheep types

I'm pretty sure Sarah put this graph up here at Mumblebone, but it's worth remembering. These are two different genotypes of sheep. The red lines are what we would call a carcase-type animal. I don't really like silos. I'm with Howard on that: being black and white isn't that useful, and I think everything's a grey area. But these have been selected on carcase traits, fat, muscle and growth, for years. The black ones are sheep that have been selected more for fleece weight, chasing wool.

When we first saw this, it was pretty mind-blowing. They pulled these animals into the shed at the same weight, put them through the DEXA at the start of the project and measured the whole body energy, so how many megajoules are on board for the total animal. The carcase ones were ahead on that front, and you'd expect that, because they've been selected that way. Then they stuck them in a shed, fed them above maintenance and put liveweight on them, and they rescanned them after 42 days.

What had happened is the wool sheep didn't do anything. They put on weight, but they grew a bit more wool and their skin expanded a bit. They didn't actually store any of that good time. None of it turned into higher energy. So these were sheep that weren't able to lay down and store fat, versus the other animals, which added 100 megajoules of whole body energy.

So one has gone through a good time and is no better off, and the other went through a good time and has got a buffer. That's really why we're so passionate about building fat into our sheep. We need animals that, when times are good, lock it down, and are ready to reward their owner when times aren't so good.

This is about the variation we see in our sheep, and I'll show you some graphs in a minute about how much you can genetically increase the whole body energy of a sheep. You can increase it by about 15 per cent. This is the modelling that John Young has done on what having that higher fat animal on your farm means. If you go out to the full extreme, it's a big increase in profit per hectare. You're getting that through an improvement in stocking rate and a decrease in how much supplement you're feeding.

That seems like a massive number, and that's why the work is continuing, to try and work out exactly what that number is. But if it's right, it's the most important trait that's ever been part of a sheep selection strategy. So that's something we're really interested in finding out.

You only get the money from fat if you run them accordingly, and this is what we see in sire evaluation. We see animals entered that are genetically good for fat, and they're the ones that sit half a condition score heavier than their contemporaries. They're wasted in that system if they're running with sheep that need a lower stocking rate to maintain condition score, because that whole group of animals has to be maintained at a good condition score.

The ones that are high fat actually get penalised under that system, because that's not how you should run them. You should run them at higher stocking rates and make more money. So this is the same genetic increase in whole body energy. If you manage them to their optimum condition score profile, you get the proportional increase in profit. If you run them at the same stocking rate, you don't get any money. They're a better animal, but you just don't get the reward. That's always the case in genetics: if you're changing the animal, you have to change your management to maximise the value in those animals.

What the sire evaluation data shows

Let's go into the experiment that's been going on. These are industry sires, part of the Merino Lifetime Productivity project that AWI has been funding. There's been one in New South Wales, and these are examples in WA. Each of the lines on these next three graphs is an individual sire. They're not named on this graph. They're a really good cross-section of the industry. There are animals that have been selected for carcase, some that are very much wool-driven, fine wools, mediums, strongs, everything mixed up in there, and there's no real trend by type.

This is pretty interesting stuff, and I don't know if anyone would have expected it. You put animals in a pen and feed them all they want to eat, and some of them can't even be stuffed eating. These are sire groups, so the progeny of each sire. There are progeny groups that will eat 1.7 kilos when they can eat as much feed as they want, and there are other progeny groups that will eat half a kilo more. So some animals can't eat enough, and some haven't got the drive to eat. That's an interesting finding, and it will be included in the economics of how you run those animals.

One thing we always see is variation in the condition score of those animals. Under the same conditions, on ad-lib feed with everything available to them, some of them will run at condition score two and a half and some will run over condition score three. Every time I've done a sire evaluation, I find that result. Some animals just don't want to be in good condition, or just don't turn feed into fat, and they're the ones that are hard to run, or you've got to run them in really cruisy scenarios.

So there's big variation in condition score. And if we move on to whole body energy, or fat percentage, again there's massive variation across those sires. There's almost 10 per cent higher whole body fat in some of those sire lines versus others. We've got this massive variation in our industry to play with, and I think that's really exciting. As we learn more from this project, we'll learn exactly how to play that game and optimise the production system for those animals. This will become a key part of how we design our indexes going forward, making sure we're maximising the opportunity here.

I think this is a pretty cool graph. It's a risky graph to put up at this time of day. This is the intake of these sire groups as their energy intake increases, so they're being fed more. These are five different sire lines, and this is how much energy they actually retain from that feed. There are some sire groups that aren't retaining much energy when they're being fed a lot of energy, and others that are locking down a lot of that energy.

We need this animal. It's locking it down when times are good and we've got feed available. It's storing that energy internally, versus this group of animals, which isn't storing anywhere near as much energy. So there are some really interesting things going on in this space.

What the work is also doing is asking, well, maybe this is right. Maybe we're all wrong. I'm with Howard: we've got to keep an open mind and keep challenging ourselves. Maybe this is a really high production animal, and it doesn't matter that it's not storing any fat because it's so productive with that feed. That's not what we're finding, but as we go forward, that's the kind of thing we have to be open to. For now, the animals that are laying down a lot of fat seem to be the ones we would want on our farms.

If we look across those sire groups at what that means for other things, as whole body fat increased, there are a few things going on. This one's interesting: their maintenance requirement comes down as whole body fat increases. That's the cool one, because it saves us that supplementary feed, or means we're not feeding more to maintain that animal. So as we genetically increase whole body fat, we're reducing their maintenance requirement.

And maintenance is your big cost. Seventy per cent of what you feed to your ewes is just maintenance energy. Every year, 70 per cent of all the feed we provide is just maintaining that ewe. So if we can take a meg a day out of that maintenance requirement, that pays out big time in our production systems.

Then there's the energy value of gain. The fatter ones, the ones with high whole body fat, tend to lay down more fat too, so those sheep are good at gaining energy rather than just gaining weight. We used to think a sheep is a sheep is a sheep. But there are all these different variations of sheep and how they play their energy game, which is really interesting.

Then the most important one is probably what it means for whole farm profit. This is Youngy's modelling of all those sire groups. These are out of the Merino Lifetime Productivity project, so their daughters have been lambing, and all that data has gone in. They were kept on farm for a long time, so all the information known about these individual sire groups has gone into this graph. It asks, of those sire groups that were high in whole body fat, which ones made the most money? And you can see the general trend is that the fatter they are, the more money you make on farm, managing that animal to its optimum.

Yes, there's some variation around that, which is interesting, and this is not going to be the whole story. But that's a pretty good story: as we drive whole body fat into our sheep, we get a more profitable sheep enterprise. That, to me, is a big part of what we're all here about. That's a pretty cool fact to come from the work so far, and it will be improved over time as we get more modelling and more data, but that's where it's at at the moment.

Which traits go with whole body energy

So the question then is, how do we get that fat? These are the correlations they've found. Some of them make sense or are obvious, and others are maybe not so obvious, so we'll go through them.

There's a favourable correlation with liveweight. Bigger animals have more fat, so that works. Growth is a really important part of a sheep enterprise, and with positive yearling weight breeding values, or higher liveweight, the more whole body fat you have. Obviously the one we've been rattling on about for a fair while is the genetic measurement for fat. Rams out there have a yearling fat breeding value on them, and generally those with a higher yearling fat breeding value have more whole body energy. They've been out on the right-hand side of all the graphs I've been presenting. We know that muscle and fat go together, and both are favourably correlated with whole body fat.

Then there are a couple we probably didn't expect. Coefficient of variation of fibre diameter, or CV as we talk about it, is the most underrated trait in the industry, I reckon. It's favourably correlated with everything useful, and here it is correlated with whole body energy. It's actually one of the stronger correlations in the data set. Low CV sheep store more whole body energy.

I might have told this story before, but that doesn't normally stop me. In my PhD I put adrenaline down the jugular of sheep and tested what happened, for a purpose. The highest correlation with the response to adrenaline in the adipose tissue was CV. The low CV sheep mobilised less fat under that small adrenaline challenge. That's a sheep walking around the paddock and getting scared by a magpie. Some of them get a fright, the cortisol goes up and you get a slight release of fat. The cruisy ones are the low CV sheep. They don't have that stress response as high.

So CV is a really cool one. It's one of the cheapest measurements you can do on a sheep, because you get it for free with your micron test, and it's really favourably correlated with lots of stuff.

The other one, which we definitely didn't expect, was worm egg count breeding values. The sheep with low worm egg count breeding values were storing higher whole body energy. So there's a group of traits there, and our job now is obviously to use these. We already have them pretty heavily weighted in a lot of the work we do, but for us it's about what happens to whole body energy under our selection strategy.

Questions from the audience

Dr Mark Ferguson: That's just because of a scaling issue, so no, it's better than it looks. The breeding value is on a higher scale. You've got minus 100 to plus 100 in that breeding value, whereas these are only plus one to plus two, so the scale is having an impact there.

I'm going to leave it there. Andrew Thompson is the author of that work and was meant to be here presenting it, and I'm sure he'd appreciate any questions you've got.