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August 1, 2023

Mark Ferguson: Welcome back to Head Shepherd. We're changing gears to nutrition this week. Welcome, Charlotte Westwood. 

Charlotte Westwood: Thanks for the opportunity to come along and catch up.

Great to have you along. We obviously talk a fair bit about genetics on Head Shepherd, but it’s a good opportunity today to talk about the bigger part of making money on a farm, and that's how well you feed the animals. There's always that story that 90% of the breeding is what goes down their throat or whatever those different sayings are.

We could argue about that ratio for a long time! 

Exactly, both things are important. Genetics is a longer burn, whereas with nutrition, you can see the results almost immediately and you have lots of opportunities throughout the year to get it right or wrong. So, it is a key part of livestock production.

I thought we might start with your background. There’s a vet degree there at some point, and now you’re at PGG Wrightson Seeds. What are the years between those two?

Like most New Zealand vets, I started off at Massey. I did my vet degree and then started in the Waikato at a practice. I was there for a number of years and, then, like so many large animal vets, I wrecked my back. I had some not-so-successful back surgery and I was faced with the opportunity of going into small animal practice or working for an industry company or doing some postgrad work.

It must have been something about the Australians - I decided to go into a PhD at the University of Sydney for four years. That was looking at cattle reproduction as influenced by the interaction between nutrition and genetic merit. 

While I was there, I was approached by what was then Wrightson Seeds, wondering if I wanted to work for a seed company. I was a little bit like, "What? Why would a seed company want a vet and a nutritionist?” Long story, I returned to New Zealand and worked for them for three years, but it was quite product-focused. I learned a lot about the species and agronomics, but my passion was back on farm.

So, I left there and went farm consulting for eight years, initially in New Zealand and then back to Australia for three years around southern New South Wales, northern Victoria, and then bounced back again in 2009, and I've been here ever since. Initially, I worked with PGG Wrightson Rural Supplies and then I got back into the seeds business in 2011, and there I have remained. 

We were both at Cleardale Station a while back, you were talking there about intramuscular fat. I guess we were talking about the genetics of it but, obviously, nutrition is a really key part of that. Some of what you covered was about how early you can stuff that up and how important it is to get a lot right to actually get animals to marble. 

Again, it's that interaction, that interplay between genetics and all aspects of management. And remember, management is not related entirely to nutrition. We've got the sex effects, the age of the animal and their live weight as a percentage of mature weight, the time of slaughter, etc. And you can’t leave those other management aspects alone and look just at the aspects around nutrition.

Nutrition is not quite such a slow burn as genetics, but as far as setting animals up well to lay down intramuscular fat, like many aspects around meat quality (but also wool production etc.), we often think it's about the weeks or maybe the months before the animal is processed. But a lot of what is happening when the animal reaches its finished stage for processing has actually started while still inside mum's tum. And so the opportunity to improve IMF in the finishing animal actually starts inside mum's tum. 

There's a term that's framed as ‘the marbling window’. It sounds a bit magical, doesn't it? It seems to be that the nutrition of mum in that last trimester can actually influence both the number, but also the potential for future growth of fat cells, adipocytes, within the muscle itself.

So, if mum has a hard time during the last trimester of pregnancy, and we can all probably admit our beef cows do work a little hard heading into calving sometimes, well, that may influence the decision around stem cells. Whether they're going to turn themselves later into fat cells, muscle cells or fibre cells such as collagen-producing cells. So there's a bit of a drafting gate happening there. If we don't get it right inside of mum's tum, that can, in a small way, influence future IMF deposition in the progeny.


That is not limited to just inside mum's tum. There is some degree of plasticity around continuing to encourage more of those stem cells to end up as fat cells - up to about 250 days of age. So, it puts a bit of heat on us to say, yes, beef cows have to do what they have to do, but if we are sincerely looking for an end-to-end aspect around nutrition and IMF deposition, it does start inside mum's tum and continues for that critical first 250 days. 

It's really interesting. Any prenatal stuff is always intriguing, and it doesn't stop at birth. It's one of those aspects of farming where you have your eye on the ball 365 days a year. 

You do, right the way through. In fact, it's nothing we're going to do specifically for IMF. But it may be looking at improving cow condition at calving, keeping on top of that and not letting them strip too much off in that last trimester. Usually, those things will go hand in hand. Similarly, good condition, feeding well for good lactational performance, genetics and the nutrition side of it - all those things lead to better pre-weaning live weights and a lot of other outcomes of interest.

I wouldn't suggest we tip a system on its head just to chase more IMF cells being deposited within the muscle bundles; but it kicks a few goals along the way. We don't want to look at IMF in isolation from other aspects around productivity and profitability, for sure. 

Equally, we don't want to spend three or four grand more on a bull because of its IMF breeding value and then burn its progeny through late pregnancy and early lactation. 

Yeah, it’s like buying a Ferrari and putting 91 in it. 

That's right. This is probably happening out there, with people thinking that genetics is the silver bullet and that you don’t have to worry about nutrition. There are both ends of the spectrum, I suppose…. We have people on the other end of the spectrum that think nutrition is the only driving force.

The two work together. This is the key thing in terms of IMF predisposition. Genetics is certainly a strong attribute to part of it. It’s like putting a jigsaw puzzle together. If you've got half the jigsaw pieces missing, well, you're not going to get the complete picture and end product. 

It seems, if we are chasing a premium product, which is what high-marbled beef and lamb are, we have to get all aspects of a production system right. You don't get to produce a premium product by accident - it tends to be lots of the little one-percenters adding up to the whole. 

That's certainly the case with IMF. Part of the key with IMF is that as animals start to get older - once they get through that leggy teenage phase - they start to lay fat down, and it’s in a specific order. It's laid down from internal fat - your visceral fat - because that's the most important part. It's an energy source and stops internal organs from getting knocked around.

Then they'll move on to all of the subcutaneous fat around the body. When that starts to lay down, they'll move on to the fat that's laid down between the muscles. These help with the mobility of muscles so that muscle groups can slide over one another. And then the final stage of fattening is when the animal is through maturity or getting close to its mature live weight - then IMF gets laid down. That's roughly the order that we go. When we've got good levels of nutrition, we're heading in that direction.


If things come unstuck when animals hit stress for any reason, they'll start to mobilise fat. It may be a feed deficit, we hit a drought, we don't have a feed budget in place that's adequately conservative, rough weather, transport, mixing mobs or whatever, can be enough for them to go through a short period of negative energy balance. And they'll start to mobilise it out in the same order that it was laid down. 

So, the IMF that you've lovingly sculpted through a combination of genetics, that you’ve looked after since the calf was inside mum's tum, for the sake of a period of stress, the IMF is the first to peel out. So, if we see a loss of condition, heaven forbid, in our prime cattle, the IMF is probably long gone, and we're going to have to start that process again. 

It's pretty gutting to have that happen, particularly if it's something like the floods up north where you had your animals ready to roll and then, out of your hands, you get something dealt to you. 

Grain feeding is the typical way for getting IMF into pretty much mature animals, but in New Zealand, there's a greater focus on grass feeding. Is there any combination of species that produces a better volatile fatty acid (VFA) profile that results in IMF? 

Feed-lotting is not really the thing here, apart from our one large one out of Ashburton, so we do look for more opportunities on a forage basis.

If we go back to a bit of boring old biochemistry for a moment. All of the good overseas work shows that the intramuscular fat cells love their glucose and love to take that glucose and turn it into fat, versus the subcutaneous fat that tends to prefer making fat directly from some of the VFAs inside the rumen, which is mainly acetate, but also butyrate. 

When we feed a heap of good quality leafy green feed, what we're trying to do is improve the total amount of VFAs. So we're getting more of a special one called propionate, and propionate is used to make blood glucose, and it converts it in the liver and makes more blood glucose. Now, we know from overseas work, that the more blood glucose the better, because the IMF fat cells prefer glucose as the building block to deposit fat. Any diet that can increase blood glucose is good for us.

On the feed-lotting side of it, I guess we cheat. We take our good grains - maize or corn grain, steam-flaked sorghum - and use it to lift glucose in two ways. One is that when you feed a lot of grain, we get more of the VFA, propionate, in the rumen. That's one way we get more glucose, which supports IMF deposition. Then the other thing, with our starch-containing grains, is that we get some rumen bypass of that starch to the intestines, and that also drives up blood glucose. 

When we come to New Zealand pastures, we're predominantly all temperate pastures here. So C3 grasses and legumes, but also, we're seeing the use of more herbs, including chicory and plantain. Certainly, in the lamb side of things, chicory mixed with clovers has formed an important part of feed bases for improving IMF but, also, the accumulation of the polyunsaturated fatty acids, which are omega-3s, which give the big tick for a range of eating quality and human health reasons. 

We are seeing improved IMF on these forages, specifically chicory. But increasingly, from a farm systems desirability point of view, blending chicory in with white and red clovers makes a beautiful sward that, at the end of the summer growth period, when chicory is growing really well, you can stitch grass into that and carry it through.

We're not entirely sure how these chicory-rich pastures, as a forage, are working. It seems that chicory drives a higher dry matter intake as a percentage of liveweight, so they're eating a whole lot more, which means a whole lot more VFAs, which coincidentally brings more propionate. It's all a bit boring, this VFA stuff, but it's kind of cool because then we can start to say, is it all chicory? Might other forages do this as well? 

Chicory breaks down very fast in the rumen, and it squirts straight down the rest of the guts, so they can eat more. Chicory doesn't change the ratios of the volatile fatty acids, so it doesn’t seem to be driving more propionate at the expense of acetate (that takes out that as a cunning idea of what might be happening, Ferg, it doesn’t seem to be the case!). But certainly, in the lamb space, that is driving higher IMF baselines in New Zealand, perhaps two to two and a half percent to upwards of four percent, as a target in the lamb space. 

The cattle space hasn't been looked at as well in New Zealand. I've been very privileged to work alongside a colleague of mine, Holly Phillips, who's doing a part-time PhD. She's in the home straight of finishing that and she's looked at the effects of a range of different forages on both IMF but also omega-3 accumulation in sheep and in cattle. 


Hopefully, we'll have an answer for you as Holly moves through all the analysis and all the hard yards of a PhD. She's got some pretty exciting stuff looking at both lambs and cattle to see whether we can replicate the chicory effect in cattle.

We've also looked at whether we can replicate more IMF (as we expect with chicory) with other things such as brassicas. We've looked at raphanobrassica and there's some pretty cool stuff coming. But the jury's still out on that one. 

Maybe it is just us nerds, but that's really interesting how that's playing out. 

It might be a bit nerdy for listeners, but if we don't capture a little bit of biochemistry, we can't hypothesise what different forages might look like and what they might do. 

Exactly, it's intriguing stuff. 

If we swing back to your PhD on the effects of genetics vs nutrition on reproduction, what were the key take-homes?

This was at the University of Sydney, out at Camden. We had a whole lot of dairy cows and we set up what is called a Calan gate feeding facility; we had a two by two crossover design, feeding two different types of diet to high and low EBV dairy cows. The diet was ‘isonitrogenous’, which means the same amount of nitrogen or the same amount of crude protein, but differing in the degradability of protein.

We set one up that contained a huge amount of urea, trying to replicate a lot of rumen-degradable protein on temperate pastures, which we deal with in both New Zealand and southeastern parts of Australia and into Tassie. We hypothesised that feeding the highly rumen-degradable protein diet to cows of higher genetic merit would put them at the greatest risk of reproductive failure. 

We established that cattle of both high and low genetic merit did successfully get in calf in the presence of all of that urea. We had some cows eating over 200 grams of urea a day, once they were gradually adapted, which was a bit frightening. Once the cows were successfully adapted, we found that cows could tolerate very high levels of rumen-degradable protein, with accompanying high levels of blood and milk urea, provided they were on a rising plane of nutrition heading towards mating.

Our findings were that the protein itself didn't influence either resumption of cyclicity after calving or conception success, provided they were in a calculated positive energy balance. The high genetic merit cows weren't at greater risk of failure than the low genetic merit cows. They seemed to adapt, both at the level of the rumen and at the liver, to cope with exposure to higher levels of protein; but they must be gaining body condition.

We found body condition was a greater predictor of reproductive success in terms of change of body condition from calving through to mating. Liveweight dropped out on the multivariate analysis. It seems that any negativity around protein and conception success is driven by cows being in a concurrent state of negative energy balance.

There were take-homes that I believe are equally applicable to all of our ruminant species: just feed them and, if you're going to expose them to high levels of rumen-degradable protein, expose them early, preferably pre-calving.

When we look overseas, where perhaps cattle are housed all winter and then turned out in the spring, I think that sudden jump from a housed diet of concentrated/conserved feeds onto beautiful lush regrowth is probably going to cause concerns. But, here in southeastern Australia and New Zealand, chronic exposure to a lot of rumen-degradable protein allows them to adapt to a certain degree and, if we just feed them, we should be all good.

I do smile in the New Zealand dairy industry - there’s a lot of people diligently following their milk urea results from their milk processors and worrying about milk urea. But, based on four years of my life, just feed them and get them on a rising plane of nutrition.

There are a couple of things I would like to cover. One is you have, like me, spent time on both sides of the ditch. It would be interesting for you to contrast the farming systems - I often get asked that question, so I thought I would ask you that!

I had seven years in New South Wales predominantly, but into northern Victoria too. The timing was a bit unfortunate on those occasions, in that I dropped into Australia mid-drought on both occasions. I came from temperate farming in New Zealand and had a hell of a shock, I'll be honest. 

When I arrived at the University of Sydney, someone had rung wanting to know if they could feed shredded phone books to beef cattle, and we had to ponder that with the toxicity of the printer's ink. And I don't think you’d get asked about that in New Zealand.

I think for any younger listeners who want to get a stretch, I'd really recommend jumping out of New Zealand for a while. Because the diversity of environments in Australia, the types of forages and feeding systems, really took the blinkers off my New Zealand-focused approach. I have learnt to deal with drought feeding and the feeding of cattle and sheep in manners that we'd never normally encounter in New Zealand.

It's fascinating what byproducts and things the textbooks say “You should not do this!”, that, in fact, with careful ration design, management and animal management, we can actually get away with feeding crazy stuff that the textbooks say shouldn't work - including phone books (not recommending that one, though, with the toxicity risk). 

Well, if you want to be a rockstar, be a veterinary nutritionist in a drought, because everyone wants to know you at that time. 

We weren't short of work, that's for sure. But, again, as a New Zealander, I didn't realise the amount of mental health stress on producers, so I learned more than just nutrition. I learned a lot about how tough it can be through those years. On our farm visits, we would design a ration, and then we'd just sit there and talk about the pressures of the world. It was a tough old time for all of us, really. We certainly learned to get very creative with feeding. 

New Zealand is changing as well. The Hawkes Bay drought wasn't so long ago. I spent quite a bit of time with veterinary colleagues of mine and other people just trying to help out, providing feeding strategies in the drought.

So we are not immune to it here, and I value what farmers and colleagues in Australia taught me about drought feeding. Ensiling things that I never thought we could ensile. The feed quality of drought-affected cereals, for example - all these things that shouldn't be ensiled, actually can be ensiled quite successfully. So it was a double-edged sword.

One of the things about drought is it's actually easier on the animals than some of the experiences we have in New Zealand and southern Australia, where spring stays cold and wet, and the worm challenge is up. I grew up with 300mm of rainfall, so I dreamt of irrigation and high rainfall. But at least in a drought, you can get to the animals and you can feed them those rations. There are some tough times in a cold spring, too, aren't there? 

Very much so. Obviously, we're more experienced in New Zealand in that but, on both sides of the Tasman, that's going to be a real ongoing issue. We've got to really marry together the nutritional side of things and how we get through some of these wetter years, for those that aren't used to dealing with parasites, and looking at what we do with crops, what we do with nutrition, to keep the immunocompetency up on these animals.

I think the main thing is, whether we're at the drought end or in unusually wet conditions, reach out to all manner of people - your vet and us nutrition types, we don't bite! We are always open to try and help in any way we can. There are a lot of people that are always willing, under very stressful situations, to help out no matter what shirts we wear and who we work for.

If we turn our attention to the future, what are you investigating at the moment, or what are the things coming down the line that you're seeing as exciting from a nutrition point of view?

That's a really good question. I'm very fortunate in my role that I'm allowed to think creatively; but to be honest, most of the ideas that we come up with come from good farmers asking hard questions. 

Something we are looking at at the moment is recognising some of the pressures that are coming on to the dairy industry, whether that be heifers that aren't required, as well as the bobby calves that go for slaughter at a young age.

We're trying to think ahead. We’re working with a lot of other good people to provide a life worth living for a byproduct from the dairy industry with these calves. Particularly, if in the immediate or short-term future, we find that consumers no longer want bobby calves to reach their fate at a young age but rather to give them a life.

Within New Zealand, we've got a lot of good finishing country for cattle. But that finishing country is in competition with changes in land use - it may be arable, it may be areas that are not necessarily grazed by ruminants. I'm looking with a level of curiosity at country that may not be irrigated, that may not be particularly summer safe and looking for opportunities to bridge a feed gap. To take those 100-kilo live weight spring-born animals and feed them really well during their first summer of life, so we’re increasing the chances of finishing them before their second winter.

If we rely 100% on pasture in a non-summer-safe area, we can get some pretty grim pasture growth, both in terms of amount and quality, through that summer period. Something we have a toe in the water with at the moment is what we've framed up as the ‘Nine Month Brassica System’. It’s a bit random and out there!

We’ve taken, in North Canterbury, some (admittedly beautiful, genetically beautiful) Hereford cattle over Friesian cows, and we welcomed them onto our farm just before Christmas at about 110 kilos. After Christmas, we put them onto a raphanobrassica, which is a kale-radish cross, and they've spent 90 days chewing their way through that crop, along with some lucerne baleage. At the end of March, they jumped onto Cleancrop Firefly kale - and they didn't have to transition, they just jumped from this new Pallaton straight onto kale, so there's no transitional ruminal behaviour. They just kept on smiling and chewing their way through. 

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We're aiming to keep them on that right through to mid-September; essentially, nine months on brassicas. So far, they're doing really well. They're averaging 1 to 1.1 kilogram of live weight gain per head per day. Obviously, things change, and in the depths of a cold winter, they have greater maintenance requirements to keep warm; but we’re looking to take those through and jump them back onto grass and see where we're at come Christmas time - whether they are appropriate for store or whether we're getting them close to finishing. If we're going to finish them, we'll jump them back onto brassicas until they're finished in autumn next year. 

We are comparing this alongside a standard grass-based system. We've got a late-maturing tetraploid perennial ryegrass system where they're going to winter on grass right the way through. They'll never go on brassicas. Then we’ll see where we end up. 

We’re taking crops that are more resilient and higher quality, in more marginal areas of New Zealand, than what grasses are necessarily. That’s probably our latest crazy thing that we’re trying!

But on top of that, we're doing all sorts of things. We've got some work we're doing with Fonterra, looking at the quality of milk coming off either chicory or brassica-based systems through the summer. 

I'm really lucky. I have a very supportive range of colleagues and a manager who takes my harebrained schemes and allows us to have a wee play. But we're trying to future-proof ourselves in terms of climate change or whatever else is potentially going on there.

What I often see on farms is a small crop of turnips and a small crop of Italian etc. Every time we shift animals onto a different species, the rumen has got to change gears and we lose a bit of production - if we do that poorly, we lose quite a bit of time and production! It seems that if you haven’t got enough of any one type, it’s not worth having any?  

It’s a really good question and I'd agree - any dramatic change in feed type - that might be going from pasture to a forage brassica…or, indeed, lucerne (if we bring single lambs in off the hills and throw them straight on lucerne, they can check for a while, probably to do with that change in high levels of rumen-degradable protein). If you have a toe in the water with a different forage type to what you've previously used, there is sort of a scale-based effect that you do need, to make it worthwhile. If you're having a play agronomically with a forage type, maybe you haven't done a leafy turnip or you haven't done lucerne before, there is an argument to have enough of it to allow animals [to get the value of it].   

If we put your lambs into A’s, B’s and C’s. You've got A’s that are not far away from drafting out the gate and you have your B’s that are kind of mids and then you've got your tails, your C’s. Usually, when you're changing forage type, I'd rather that you split the allocation of those A’s, B’s and C's across different forages. 

For your A's, keep them on something that’s very similar to pasture; you might be able to sneak them onto a chicory and red/white clover mix, because you don't get much of a transition when you jump from grass to that, depending on what the grass quality's like. You might keep your tops (that are going to be drafted out in the next couple of weeks) on pasture or something very similar to pasture. 

And then the more dissimilar a crop type is to grass, you probably put your slow-burn animals - your C’s - on, because they're probably going to be with you for two or three months (worst case, if they’re really small). And, that way, if they need 10 or 14 days to adjust, you’re kind of diluting that period where they might stand still (or, heaven forbid, even lose a bit), you’re diluting that over a longer period of time.  

The roundabout way of answering it is, if agronomically you’re going to have a play with your rural retailer and have a look at a crop type you haven’t played with before, you might just want to put your bottom lambs on (the ones that are going to be with you for a longer time), so that transition period is diluted over a longer period of time. 

It is about really categorising your lambs - and anything that needs a major transition, bomb them onto the very high quality forages, because they will repay you in the long term. But your tops won’t, there’s no point - your tops are ready to go and then they go backwards for ten days, it’s a bit soul destroying.  

Which is probably counterintuitive, because you know you’ve got that rocket fuel there and you’ve got these animals that are close and you want to chuck them on there. But the reality is that’s not the best option.  

This is the fun thing about taking your crop types and your stock classes and, again, the jigsaw puzzle. You just shuffle them around on the table and decide who's going to go where and for how long and work backwards on the areas of crop that you need. 

That's been a fantastic chat, thanks, Charlotte. How do people find you if they want to get in touch? 

Google me, I'm pretty easy to find. For anyone that likes this nutrition stuff and, if Facebook's your thing, come and have a look at ‘The Rumen Room’ there. We have a podcast up and running, also called ‘The Rumen Room Podcast’, which you can find wherever you’re listening to this. There are about 30 topics in there, at the time I’m recording this with you. A lot of dairy stuff, but we've got sheep and beef stuff in there as well. It’s the basics of nutrition, reproductive performance, flushing ewes - there’s all sorts of things in there - jump in, if podcasts are your thing. 

Dr Mark Ferguson
Article by:
Dr Mark Ferguson

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