Thank you very much for joining us on this webinar. My name is Jenny Sharon and I'm gonna be talking to you about tackling bovine respiratory disease in calves. As a quick introduction to the webinar, we're gonna have a think about the importance and the impact of BRD.
Think about what KPIs we can use and data to utilisation in terms of how we can measure and monitor. Think about the methods that we're using for detection of VID on file, as well as then thinking about those risk factors and how we might measure and monitor them and things to consider when thinking about reducing those risks. In terms of the first question of is BRD common?
BRD's been reported to be one of the most common diseases in pre-weaning and weaned paths, and we can see this here whilst it's from US data from feedlots, we can see that BRD, which is this kind of dark blue, is a huge cause of morbidity of more than 80% and and accounts for a third of mortality. So it is really prevalent. In terms of what do we know in the UK, we have less of an idea in terms of prevalence and incidents, which we can come on to shortly as to possibly why.
But actually, in a study by Cat Baxter Smith, interviewing farmers and asking for how they felt about BRD, you can see that farmers overall in both kind of the dairy, beef and calfry sectors all found that they had experienced BRD. And actually, as well as that, we have significant numbers of farmers if we look at the overall, it's just showing 50% they've experienced mortality due to BID. So unsurprisingly it's a hugely relevant problem on our farms.
In terms of what impact is it having on our farms, what we need to think about is what is going on. And if we were to postmortem some of these animals, these are the images that we're gonna get. We get that long consolidation and with that areas that don't work and don't function and we're not doing their job.
What does it mean if they're not gonna be functioning and doing their job, or if we think about the normal function of the lungs, it's there to oxygenate the blood. The oxygenation is hugely important when we think about the fact that actually what we want is to use that oxygen to get anything out of the diet that we're feeding our cows. With speed being one of the major costs in the capital and rearing of our dairy farms, it's hugely important for us to be efficient and to get that maximum energy out.
If we have an animal that suffered from BRD. Then what happens is we have limited capacity of those lungs. That limited capacity reduces the amount of oxygenation we're getting with that blood and that reduces the amount of oxygen that's available for aerobic, .
Aerobic metabolism, sorry. What that then in turn leads to is this aerobic fermentation and with that we don't get as much energy out of the diet and therefore we've got an inefficiency. What does that then translate to?
Well, we know from a meta-analysis from Steven Brzezinski, that actually we get this decrease in daily life weight gain, we get a reduction in first life patient yield and a decrease in the the odds if they're surviving. If we look at that in a bit more detail. We can see here that actually we end up with a loss if we look at the, 5 different studies that have looked at this of just over 120 litres in milk.
What does that translate to? These are prices based on 36 pence per litre, which actually is lower than kind of the 4145 pence per litre we're currently getting in October 24 for farm gate milk price. But you can see that actually that's the equivalent of around 43, 44 pounds a heifer, so probably not far off 50 pounds with the current milk price.
Combine that overall the heifers and the farm, that can have a significant impact. What's probably even more significant is this survival, and this is the odds of removal before first carving. So therefore these are animals that haven't actually given us anything back in return for our investment economically, so they still owe us money.
And what's quite scary is we've got an odds of 2.3% removal. And this was shown by different studies, Alex Baxx showing that basically if you had in formal treatments for respiratory disease, in order to be leaving, you might as well flip a coin, and we have other studies which show similar results.
And then as we've discussed earlier, we've got this decrease in daily life weight gain. And here you see we have more studies over a wider range. And again, these are all predominantly focusing on that pre-weaning, but we do have some studies that are focusing on post-weaning.
And actually the impact whether it was between the first in that 1st 3 months of life or 3 to 6 months of life doesn't seem to have an matter as much. They all have this negative impact. And that is around 70 grammes per day.
And this is a dissimilar work that's coming out from the group with David Renard. It's actually showing in that 1st 77 days, one day of bovine respiratory disease results in a decrease in daily live weight gain of 180 grammes per day. So again, there's there's more work coming out on this, but whatever the answer is, we're definitely reducing that daily live weight gain, and we're also seeing it kind of on a longer term scale.
So what does that then mean? Currently we've been talking in a more dairy focus and actually if we look at that for that first sorry for a dairy heifer, what we can see is we've got various different costs along the way. And this is where from Bartram in 2017 that's estimating that lifetime total economic cost.
So we've got the immediate treatment costs. We've got this there for delay in weaning and due to decreased daily live weight gain. I'm struggling with that starter intake.
With that, we get a prolonged decreased daily live weight gain. We're gonna get an increased age at first carving. Alongside that we're gonna get a 4% and 8% reduction in 1st and 2nd lactation yield, and we're gonna get that decrease in that all important longevity.
So it's been estimated that it costs just over 770 pounds per case of clinical BID. This obviously doesn't take into account any cases of subclinical BRD which we know will also occur alongside animals with clinical BRD. And we have a look on the beef side and again, this is taken from Australia.
We're looking now at how much it costs in terms of beef. We can see that actually, again, in terms of costing clinical BID they're estimated at 176 pounds. You've got severe lung lesions, notice the abattoir, we've got 75 pounds.
Severe pleural lesions at 113, and that's subclinical they've estimated at 55, and it's really hard to put that cost on it. If you break it down, looking at that work further, oops sorry, looking at this work further, we can see here that actually where does that come from as we look at. Some of the different aspects that we look at in terms of costings for beef cattle.
As you can see here it's a decreased average daily life weight gain and ultimately that then impacts that carcass weight at the end. You can see him there enough of that impact of having had that treatment for BRD, but also interestingly we've got that other treatment cost. So with that, if we've had that case of BRD, we're more likely to have treatments for other aspects.
And again, the one above that we've got that increased feed cost per animal. So this is having a huge impact and not always one that we can see directly on the floor, but in terms of efficiency, it is an area to think about. And I think for the beef that's really important when we think of the work that's coming out of SRUC, that's looking very top level at that cattle trade system.
Basically what we're looking at in terms of losses in the UK, 55% of losses were due to poor daily life weight gain, and we can see here that respiratory disease played a large role in that. So thinking about this on farm and thinking what it means, it's thinking about how do we measure these KPIs and what can we look at. How are we utilising that data?
For a minute, I'd like to just take a step back and think about how other sectors are using it. The top two graphs, graphs of the first one being disease treatment, on the left and the top right being daily life weight gain of a bus of carbs. On the right.
This is the kind of data that we look at within the cattle industry, . It's good that we're looking at some data, but the thing I would always say is we're often looking at it after the horse has bolt it. We're looking for what happened historically and how do we stop that from happening again.
If we look at the bottom two, these are taken from my colleague Mike Clark, he's kindly shared them with me, and looking at what that looks like, what they would measure for, respiratory disease indicators in poultry. And you can see on the X axis, it's every day that the boilers are in the units. And we can see we're measuring in those houses at that population level, things like water consumption, and we can see on that yellow line that sudden decrease that correlated with a spike in disease.
These guys will spot this immediately on reacting to this. Similarly, CO2 is hugely important, and I can't remember what the level is. They don't want it to go above in terms of percentage, but that for them is a huge indicator.
But again, it's real-time measurements and they're responding to it immediately. So when we think about what KPIs we've got and and thinking about how that fits with something like the poultry industry. All of us are doing kind of, we've got an antimicrobial use.
So what's happening over time, how much are we using, which groups, those chronic treatments. We have some people using observational data, so there are lots of different class scoring systems, but things like the Wisconsin class scoring systems, thoracic ultrasound. Similarly to our partners in poultry.
To the ones we look at daily life weight gain and mortalities. But the other thing for us to think about, and it's that, what else could we measure, what could we look at, I think for me it's getting a bit smarter looking at some of those nutrition aspects of the conversion rate and also kind of water consumption. We have a lot of exits.
So if we do have animals going, what are those abattoir rejections? What do the lungs look like in abattoir? Are we seeing those areas of consolidation in animals that we're not necessarily picking up on the farm?
And with that, if we're culling animals, why, when, at what time? So we'll talk a bit more about KPIs and I think for me, one that is often underutilised is things like daily life weight gain. Daily live weight is a really nice one to get.
Obviously our gold standard is on a waist scale. But actually, even if the farms don't have the means or the desire to invest in a way scale, we can still start to get some data in way shapes. This is taken for a study that we did at Nottingham, and the table on the right shows you, the age between two ways in terms of days.
So that top row here would be 14 days, and therefore, the number of cars you would need to wean if you need to so we using a wave band if you were, weighing every 14 days. In order to get kind of this absolute error of less than 0.05 kilogrammes per day.
The key thing for me is this is a population tool, and actually you can see that we don't need to weigh every week, but actually if we weighed every 4 weeks, so if we think of a pre-weaning calf, if we did a birth, a midweight at 4 weeks and a weight around weaning, and we've got a population of 18 animals, we're gonna be really happy that actually we're very accurate. And the other aspect of it as well is it's making that we say sure the same person weighs because they count for about a third of the variation in the body weights. But it is data we can get.
And how are we gonna utilise that? Well, actually, we can start to see those trends over time. You can see here this is a farm and this graph that I'm waiting at first in 4 weeks, 4 to 6 weeks.
Weeks of weaning, and you wonder what's going on in about 4 to 6 weeks. Does this reflect women development? Does it reflect a change in temperature, the environment, or does it reflect something like respiratory disease?
Similarly with having body weight in that post-screening period, how many have hit our target, and the ones that haven't, these are ones that had the respiratory disease, why do we not have that uniformity within the group? We discussed feed conversion efficiency. Again, this is, it's probably easier than you think to do.
If we can work out how much, especially in the pre-weaning period, milk can concentrate those animals are on, and we know how much they grow in that period, so we can then work out that kind of pounds per kilo growth. And therefore we want to know how much does it cost for 1 kg on and you can see here when you plot on this left hander for every single car you get quite a variation. We always have outlays what where are the outliers where they come from, and that's in terms of.
And how much they are. But if we look over here at the same data as the fox, you can see that actually between that middle 50% of animals, which is the same box, there's a difference of 75 pence per day. Now this is data taken over an 8 week time period, so that's 42 pounds difference in my growth of my middle 50%.
Of animals, where does that come from? Like, yeah, it might not be respiratory disease, but it's something that we can use to point towards that direction and use to help with the farmer, communicate what that impact is depending on what is the thing that pushes their buttons to engage. The other thing we can look at is antimicrobial use, so that makes the PCU.
It's always gonna be quite small because the volumes that we're using in carbs are small. But we can see here, these are some different farms that are benchmarked. Personally, I have a real issue with benchmarking farms for spiritual disease because there's nothing to say that farms C and D are better than farm GNH.
It might be that farm C&B only spot them when the calf sounds like Thomas the Tank Engine and and can no longer really breathe and is really chronically ill. My farm GNH might pick up those early signs and treat once. The AMU can be useful, but just be careful when you're benchmarking because it depends upon how.
What signs they need and how they're detecting. If we've got good records, we can look for that incident over time. We can do that by looking at those number of cases and that number of at-risk animals.
Annual incidences can be helpful, but don't help us really find out when and where it's happening. We want to be looking for the patterns. There are annual incidents in this example is 47 cases per 100 cars per year.
But what we can see is we actually get better on this graph is we've got this really, really seasonal trend. In this graph we've got month on the X-axis. We've got the number of cars that most to be green and the number of cases of red, and no red off the left hand axis.
And then got this 3 month rolling average of cases per 100 cars per year as a purple line, and we can really see that we have issues in that springtime. It drops right down over the summer and we start to ramp it back up unsurprisingly in the autumn, showing that real seasonality and how the environment's impacting it. The only thing we can look at by plotting our denominator, so our number of cars at risk, is do things like stocking density impact it as well.
How are they having a role? But this only works if the data recorded on farm is of any use, and therefore we can't have farmer treatments in their heads. It needs to be.
At least on paper, ideally digitalized for your sake. And we also need to know who our at risk group are, so looking at it in terms of groups, so who's in those air spaces at those times. And we also need to know how they're detecting it, because otherwise we could be in the position of being under detection cases.
So, in terms of detection of BRD this is hugely important cos otherwise a farm can tell you that they don't have a problem when actually they do, they just don't spot it. What is early detection? So this animal for me that kind of we look at those early signs.
This pis probably had the disease for a little while. Apologies for judging around. We've got the ocular discharge, that increased respiratory rate and effort.
But actually, what other signs should we be looking for? We all think of pyrexia, which is great, and you shouldn't walk into a calf shed and have to take your own thermometer. The cal staff should be able to hand you one immediately, but there are other aspects for us to look at.
This includes feeding behaviour. So this is what we want to see in life carves up, Adam, drinking, tails going. But actually with that it's that cast that hangs back that doesn't get involved.
This is where actually milking machines are really helpful. It's great if you've got trained staff that know the cars well, but we can see this change in speed behaviour much more with the automated systems. This is a work by Melissa Canter back in 2022, and what we can see is here, these are 33 calves that have respiratory disease that were paired with 33 healthy carbs and compared in terms of their feeding.
They were group pals. The male sizes were up to 3 litres, and they were in groups of 3 to 9 carbs, total volume 10 litres by the day. And what they could see is that change in food behaviour as early as 4 days beforehand.
And we can see we get this decrease in milk intake and also a decrease in starter intake. This isn't surprising if we think of respiratory disease in ourselves, we get pyrexic, we feel rubbish, we change our eating and drinking habits. This is real life data from a farm that I work at following a calf, and you can see this calf generally tended to be pretty consistent on how many times they went up to the feeder and how many wasted visits they had.
And in that run up to the respiratory disease noted by the staff. We can see that this car starts to change its behaviour, and with that it also reduces the amount of volume that it's consumed. So again, cars are giving you some really early signs.
It takes a very good stockmen or women, or also technology to allow us to pick this up. We've obviously touched on some of the behavioural changes, and calves being baby toddlers. It's really good to think about other behaviours that they do.
Play behaviour being a big one, of course. This is work from again from the same study. This time these guys have 32 matched pairs, pairs of calves, and I should have said the BRD was diagnosed through calf scoring system and so long consolidation on thoracic ultrasound.
Again, 10 litres a little place for a day in a group. You can see this time if we look at the VID status we don't see anything statistically significant. There is this, suggested here and heading towards a potential trends that there might have been a change in acceleration activity which we would see as player behaviour.
This has been seen by another study that was conducted at the University of Nottingham looking at calves who were group cod. And these are calves that have been pahoused for the 1st 3 to 4 weeks of life and then have gone into groups of 12 to 16 calves afterwards. And what we saw was that actually these sick parts affected by respiratory disease.
Did things like lowered their food consumption, but also were less social. They didn't like socialising with other cars. They did still tend to socialise with the cars they've been paired with in the 1st 4 weeks, but they didn't tend to socialise with those other cars.
And With that, we kind of feel that I'm actually showing those types of behaviour or do they, are they avoiding those social interactions and equally are those healthy animals avoiding that sick animal or both. So we're not quite sure what it means, but what we do know is that calves behave differently when they're sick, and is there something there that we can start to look at and to utilise going forward. So in terms of early detection, we've obviously got that virus dominantly starting by and going secondary bacterial, but we've got that infection occurring fast.
And then we're gonna start to see those early clinical signs, which, currently we're thinking of things like feeding behaviour, social behaviours, and also, yrexia. At some point it's gonna go into a low respiratory tract and we're gonna start to get to see signs. Quite often, you know, we showed the postmortem pictures early on.
That, that's too late, that's too late. It's kind of think it's been there a long time. There's a large extensive damage.
The question is, now, can we pick it up when it's small damage and almost in that subclinical stage before kind of you can see it with the stethoscope or the scoring systems. I'm not gonna touch too much on this, but obviously thoracic ultrasound. Is something that's been a real interest and the graph here on the right is work from Vicky Rhodes where she was scanning cars at 2028 days.
This is intervals on spring block carving units over in Ireland. And what we can see is that actually, yes, we do have these cards using that TUS score, where we, you know, they, if they've got severe consolidation, they stay, but actually, it is also quite interchangeable. The other thing I would say with this is, the work from Bob Pardon, give back to there's also a large amount of user variation and ability to interpret.
So I think. It's good. It, it could be a tool.
Again, the horse has already bolted, we've already got it in the lungs. But we've got to remember that there's quite a lot of us, user variation. And also when we look at some of the studies that are coming from Europe and the States, these guys are scanning at very high frequencies.
So whether that's applicable to UK practise. So the next section I'd like to move on to is I'm thinking about these risk factors for BRD and what that means for our farms. So the first one I want to kind of focus on is the environment.
So again just going back to poultry, you look at the environmental monitoring that poultry shed has, and this is phenomenal. The amount of sensors that they have in there. Obviously it's a very controlled environment and therefore they they need that far more than we did in some respects, but equally they know what's going on in their sheds, which is something we don't necessarily know what's going on in the UK calf sheds.
Can we monitor the environment in UK calf sheds? This is something that we've been doing with some of our farmers and for instance, these two for Brexit, data loggers, these are the ones I like. Obviously different ones that are available, but these are great.
They're about 15 quid for a 2. They log data for 100. Days, and then start to wipe it as it goes through as it goes more than 100 days and you can get it on your phone, as you can see over here on the right hand side, it measures temperature and humidity and you get the data out for about 100 days in a few.
And we can have them on our beautiful piece of UK British time past height. They're relatively inexpensive live data coming through and also you can start to prove those points as to where we might be in terms of temperature and humidity, and we'll discuss how these can be useful shortly. Other aspects, again, if we look to the pig and poultry industry, these guys are really hot on measuring ammonia.
Ammonia isn't something we know mass is about in terms of respiratory disease. There was a systematic review done by John Dolan and his colleagues, and there are two studies here that investigated the ammonia concentrations and that combination respiratory disease. One showed it was protective, one showed it increased that risk.
So I think the answer is we don't know, and it depends on what levels they're, they're talking about. But I think for me, something to consider is that calves are more likely, are more likely to be more sensitive to environmental irritants such as humonia. And actually ammonia often is that concentration is gonna depend on that accumulation of urine and pieces.
Again, Whether it is going to be hugely applicable going forward, but these are the concentrations and targets that have been aimed for historically. But you can see again a broiler house is much lower than we're looking at for a car for adult housing. And, and that broiler house is in that enclosed environment.
So it might be something for us to think about and something in the future that we start to see being measured. But I think for the environmental measuring, we can start to do some basics and, and see what information it gets us. So going through those risk factors, if we start with that humidity is the first risk factor.
Relative humidity is basically that moisture content. It's in the atmosphere and it doesn't cause condensation. What's the impact of it on respiratory disease referred back to the systematic review by John.
There were 8 papers that were found. And again, we have conflicting evidence. 2 papers didn't didn't examine the association with BRD.
2 showed a weak association. 3 showed no relationship and one found lower relative humidity was associated with a higher frequency of BRD. So currently it's unknown.
However, I'd like to kind of show you a real life example, again, using my favourite little data loggers, hang them up in a shed, and I get a phone call to say that actually around Christmas time we've done a lot of respiratory disease treatments. We then plot the number of BRD treatments, which are the grey bars, which you can read off the right-hand axis and you can see we've got two big spikes around the 20th of December and the 31st of December. I also then plotted the average temperature, which is the blue line, against, again the right hand axis and the relative humidity, which is the left hand axis.
Interestingly, what we can see is before we have the big spike in treatment, we get an increase in that relative humidity up to 100%. So what's happening in that shed? This is the drain of doom, as far as I'm concerned.
It was a drain that was built in a building that has no fall. So basically this drain has to be manually emptied every day. If it's not manually emptied, it starts to look like the Battle of the Somme.
With that we get a buildup of urine and faeces and we get a buildup of milk. And we increase that relative humidity. So actually my environmental senses here told me that my environment had changed.
And then it involve more moisture and with that an increase in respiratory disease. Where does that come from? It's come from this strain.
Now whether it's the relative humidity or whether it is the increase in ammonia. On the general pathogen load, we don't know, but ultimately it came down to a block chain and how I could prove it was a block chain was through utilising these environmental monitors. Other things that we look at is ventilation.
So we talk about ventilation of the building a hell of a lot. And without meaning to make it kind of granny like teaching, what we're talking about here is moving air in and out of that space. So it gives us fresh air and removes kind of any scale contaminated air and makes sure that we have that high quality.
And that scale contamination isn't just, pathogens, and also dust and ammonia. And the other key thing as well is that it also doesn't put the calves under any thermal stress. Once again, it's really hard when we think of that critical temperature of calves, but under 3 weeks of age being between 15 and 20 degrees and, and again less than 10 degrees for calves over 3 weeks.
How are we gonna ventilate? Traditionally we've always thought about stat effects when we think about natural ventilation. Animal produces heat that rises the air up and leaves through to the top, and by doing so creates a vacuum and draws fresh, fresh air in along those long sides.
It really is those long sides, those gable ends, but the triangle ends do not count. That's great. And apart from the fact that it's not gonna work fast.
The reason being is that Heat is generated by the giant fermentation vat that is the rumen in adult chaos. Baby calves, we're gonna struggle to get that. So baby cal it's not gonna become kind of 95%.
And function of an adult to 6 months. So baby cars are incredibly good at losing heat, but they do not generate heat. It's really hard for them to naturally ventilate.
The things they would say they can naturally ventilate are hutches and igloos. So there you do need to be careful, and with some of the hutch designs, you need to make sure there is an outlet, because that's if you look, there is no outlet on the top. And that's where possibly drilling small holes in the top to let the air out is helpful.
You'll be able to see that because you'll get a lot of condensation within those patches and it's always very sweaty and horrible. So Natural ventilation will work in hutches, but it's not gonna work in our chests. So can we actually measure whether these environments are ventilating?
So there's only ever been one study that's really tried to look at that in the world of calves, and that was done by Largo back in 2006. And Quite often, so we talked about the poultry that they use CO2 concentration as a proxy. The idea being that if there's adequate air exchange going on, CO2 levels will remain low.
If we have got inadequate air exchange, it will go high. This is really hard. The the studies that have looked at it haven't really shown any detrimental effects of respiratory disease, but that might be due to the design of the sheds.
Going back to the Lago study in 2006, these guys looked at, bacterial counts within sheds. So these are. She's in Wisconsin, looking at how they ventilate.
And what you can see is that CFU per metre cubes can vary quite a lot. The different lines indicate different bedding materials, so those straws and sawdust. And solid planes are basically how solid the walls are between it.
And surprisingly, if you had more solid walls, you had less ventilation rates, so air changes per hour. And with that, the fewer air changes per hour have that increased. In any, in the bacterial present.
What we can also see is that we don't really know what it should be. These are estimations. So they've said that fully ventilated with a risk of bovine respiratory disease is greater than 1000 CFU per metre cubes, we haven't got to those levels there.
Well ventilated bones of 5000 to 30,000, so I mean that's 6 times different, that's a phenomenal variation. And there's a decreased risk of lung problems at less than 15,000, and actually if we look at less than 15,000, we struggle to get that. The one thing I would say is to put this into context, a UK human operating theatre will have to be less than 10.
So we're talking about high bacterial learn those bacteria aren't necessarily pathogenic, but they might still irritate the respiratory tracts and cause inflammation. And with that allow for that colonisation of other pathogens or improve the chances of causing clinical disease. In terms of what does it look like in the UK, so there's a Sophie by sorry, a study by Sophie Mahendra, which came out last year, and Sophy looked at, 10 different shared setups and looked at different environmental factors including bacterial numbers, she looked at all.
And we found that they were sat at kind of that 10 to 18,000 CSU per me to give, this is a picture of one of Sophie's by the way. And again, a shared system varies between 8 and 19. The only thing I would say for me is also that that range is hugely variable, so you're starting in the low 100s and are going up to 645,000.
And the sheds are going up to 70 to 3000. So that variation is massive. That's gonna depend upon the setup of how those sheds are done, but it's also going to depend on that day that it's happening.
That's the air speed when they last looked out, how many cars are there, have they got respiratory disease. So again, really interesting data that again very snapshotting and it and it's really hard for us to make a judgement on that. And again, something that is still staying very at the minute.
So why is it that we get obsessed with that ventilation, that number of air changes? We want to decrease that airborne pathogen concentration. They can still be high, as we've said, and most are non-pathogenic, but they are still able to elicit a response from the host and therefore compromise respiratory function.
We want to decrease airborne dust contamination because that's similar and the same and airborne and the toxin levels. We talk about maintaining an optimum humidity, we discussed earlier that the research wasn't necessarily there for that, but equally I think it is worth saying that. It is worth doing this and information on the bedding coming up we'll talk about in a minute.
But also there could still be a link. There's still not masses of information. Maintaining an optimum temperature like when it's twofold, so the literature around whether it impacts respiratory disease or not from that systematic review by John Donnel.
Suggests that warmer temperature can get an increase in BRD but equally they also similar in one study with a lower environmental temperature. The issue with a lower environmental temperature is the fact that we're gonna put those animals under cold stress and we're gonna compromise that immune system. That's why.
Environmental temperature, we increase the replication rate of our pathogens. We want to eliminate areas of stagnant air within the shed that's gonna that shed to ventilate all the way through, and we want to eliminate the noxious gases, so the Amona we discussed and eliminate draught, which we'll talk about shortly. How do we assess ventilation?
We've got the old smoke bombs, set them off, see where it goes. Smoke bombs come with pros and cons. They're quite good to engage a farmer, and that's always like making, Dramatic smoke flying around the shed.
But if it's really hard to assess. It's gonna change on your day to day, it depends on your wind direction, your wind speed coming in, how many animals you've got in there. Where you stand in the shed.
You know, if you do it 3 or 4 times in 1 day in the fridge, you'll often find the air moves in different places depending on where those animals are. We can look at how long it takes to leave the shed. And we can look for the circulation patterns, and we can look for if it does actually shed, where is it going, but it doesn't allow us to quantify it.
We do have the assessment calculation, there's the AHDB and have it great on there and there's also an Excel sheet you can download for it. It's really good and really useful, and quite easy to use. For me, this, this is always the starting point.
There is obviously the caveat that it's really hard when we've got baby calves in there. And the first one we start that is 100 kg again. It's having that heat to allow it to rise.
But it allows us to work out our inlets and outlets and and how we're gonna change that. And in terms of what it means and, and how, what impacts whether that shed ventilate. If we look at the shed itself, quite different.
And that's that height between the inlets and the floors, because that's going to impact that airflow and also that height floor in the outlet. So if we think about the hot air going up, if my shed's really tall, and we love to put carbs in our tractor sheds because we ran out of money and didn't buy, build the cars in my shed. On a grain shed, they've got a really high roofs and therefore as that any warm air goes up, it's gonna lose its heat, and as it loses its heat, it's gonna start to drop back down.
So if it's too high, it's just never gonna be able to reach. With that, the other aspect is that building width. So if we've got a really wide building and we're talking more than 10 metres, really hard to get the air to come all the way across, even if you've got adult cows and you're using, that stack effect.
It's getting it to come all the way into that middle and we talked about that fact that we want to make sure there's no stagnant air in any part of the building. If they have a wide building, it also then means we end up with a flat roof. That latter roof is a problem because as our hot air tries to escape, it's more likely to hit the roof than to hit the outlet, and that roof is always going to be colder than the air.
So the warmth from the air is gonna transport to the roof and then vice versa, the coldness of the roof is gonna transfer to the warmth of the air and therefore make that air cold and it's gonna drop back down. So we're seeing how much steeper pitches of roofs coming in, but with that you need that longer, narrower shed, so we also have that picture of roof. This again is really important because it's similar with the outlet design.
But if there's anything in the way, such as the cat ridge, that means that it's gonna hit the cat ridge and not the outlet as it tries to leave, get cold and drop back down. So kind of wide buildings that are really high with shallow roofs and anything constructing the outlet mean we are gonna end up with recirculating air. Inlet design again is really important.
So things like space boarding, depending on your width, tend to be around 16% void. So what that means is if if I have an inlet area of 100 metres squares, remembering that the inlet is only the long side, it's not the triangular glow. And it's space boarded, that would be the equivalent of 16 metres square of inlet.
Scalebreaker has more than 25%, but things like that tin with very small holes in, that's only about 5%. So sometimes actually simple things can be allowing more inlet and we want that and we say a minimum of 2 to 4 times the outlet, the more inlet you can get, the better. Obviously the cars are compromises it can create a draught and car height.
Building location is again really important, making sure that there's nothing blocking the way, whether that's trees and another building. We love to build a building that is kind of a concrete passageway whipped away from another building. So where possible, try not to block it.
And it's also worth when thinking about it, have a look at things like the direction. So the thing in the UK is our wind doesn't come from one direction all the time, and apologies for this, being quite busy, but we can start to see, we get an idea of where our winds coming from and you can see that 25% of the time we've got a southwesterly wind, which kind of 17% also from the south, and then another 17% from the the west. However, 10, more than 10% a year, we are gonna get a northwesterly wind.
So it shows that we cannot rely on the wind coming in to allow us to naturally ventilate shed. And there will also be days where we don't have any wind, and that's especially problematic in the summer, when we can then see heat stress, and heat stress is a factor that impacts both adults and baby calves. With that in mind, there's been a lot of talk around artificial ventilation and and positive pressure tubs or funds.
These can work really well, and the one thing I would say is that especially the positive pressure tubes, these are not a buy it off the shelf job, they, they need to be calculated specifically for that shed to enable it to do what we want it to do. Some of those considerations are, you know, depending on the width of your building, you might need more than one tube, so it's normally recommended that it's kind of 10 per 12 metres of width. In terms of length, we can't go over 76 metres, otherwise we don't end up with uniform air distribution.
And the tube diameter itself, it needs to be calculated based on the velocity of the air. Coming in, and with that it will also depend on the size of the fan that we need and kind of that's gonna depend on how long it may shed is and where the holes are located in that whole design. What we want to do is make sure that when we are pushing air down that tube, that we want that air to kind of come out, but, but not create a draught.
So it's still by the time it gets to 1.2 metres off the floor. So we need to therefore, work out what height that is gonna be.
And then the whole location is gonna depend on that height from the floor and how far wide you want to throw it. So I suppose for me the key thing is please don't let your farmers buy them off the shelf and get them calculated properly or they are going to run into problems, and also warn them to not hit them when they when they're mucking out of the yard. So I'm gonna ask that very quickly to touch on his wind speed and direction.
So we talk about draughts and actually again the systematic review from John really did show that draughts at a calf level appears to be positively associated with respiratory disease. The key thing is there hasn't been a cut-off that's been established. This is taken from the AHDB Knowledge library, and you can start to see that this is thinking about it in terms of, cold stress, and the animal's gonna have to start to use energy, to keep warm.
We're actually looking at 0.3 metres per second, so cold stress happens at a really low wind speed, and that is something we can measure with an ometer. Again, these handheld ones are cheap and easy to use.
It's snapshot data, but it gives you an idea if you can sit in the car, where the cars there. Laying down and standing and going things like going to eat it might put them off feeding, if it's really windy and to start to see that impact. Is it stuff like boards can be used to stop that draught from coming through?
Do we need to get a galebreaker? To reduce that airray coming in but still allowing us to. Other things to consider when it comes to the environment is bedding management.
So bacteria and parasites need moisture to reproduce and complete their life cycle. The other thing to consider is that actually our calves spent 80% of the time lying down, so it's really important that we get that bedding, right. And this work from Cheer suggests that these calves need up to 20 kg per head a week of straw bedding to make sure that it's dry.
It's it's a solid floor. And actually one of the big associations that was found in the systematic review is increasing wet pack deaths and decreasing nesting scores. So making it cold and wet in the areas where calves spend 80% of their time and surprisingly increases their risk of respiratory disease.
So again, something that's really important to talks on. And to assess when you're going around. In terms of thinking about that environment and how our groupings look, it's that airspace stocking density.
And An airspace documents is really hard to put a figure on because basically everything in that air space in that shed is in that same airspace. And if you've got a really high roof, you could end up with a really nice air space, Picasso's large, but actually if they're all crammed together it's a really high roof. Then it might not work, it, it's difficult to put a finger on that.
When you look at the spaces, ideal spaces required for cars, and the minimum under UK for for cars under 100 kg is 1.5 metre square floor space. If you look at the HDB recommendations, they go for 3.
And what's interesting is here, this is very slightly shifted over to the right, but you get the idea. You can see that actually for some of those we start to see a lower bacterial load with that floor space, we're pushing it out further. I think for me, the other thing to think about with that, airspace and stocking density is who's in that airspace.
We know older animals are at risk of, passing the disease on the is that reservoir. You know, we get very obsessed with, with the groups that are in the same pen together in terms of floor space ageing, but we also need to look at that, in respect to. Animals.
And if we think about COVID, we had a lot of little pods, working at the university, getting students back. They stayed in their little pods, and actually the fewer interactions they have and they stay in that same pod, the less likely they are to get respiratory disease and it's the same principle that we can apply across farms. The other ones to quickly touch on it and not get things like a new status.
So yet again, we're talking about passive transfer. If we look across the UK, you know, we've got work from Julie McFarlane. Andy Henderson recently did one as well, England, where about 1 in 4 animals with failure passive transfer.
Scotland look better in Ally Hegarty's study, but you can see it's still globally a huge problem. And with that we get variation between farms as well, and variation between batches of cars and farms. Why is it important?
You can see that actually increase that risk of BRD by times 1.75, the meta-analysis by Didi Ravison. And again, that really comes through in the work from Lombard and Sandra Godon, looking at those kind of, theorem IGT.
Levels and you actually have X of that blue line is far less likely to get disease and that includes bovine respiratory disease. In terms of those costings, you can see here that prevalence of failure passage transfer again from Didier Ravaissons. We can see that actually here that total cost of a case of failure passage transfer is about 50 pounds per case, but the BRD does really contribute to that as well.
The other ones set on vaccination status. What's going on, when are they vaccinating and things like that, running out of time on this webinar, and so I'm not going to touch on that today. And similarly with BVD, you know BVD status and make sure that they're checking regularly because although they may feel they're free, it can sneak in.
The last one I wanted to touch on in this webinar was management, you know, we often get, we have problems after discrediting, we have problems after weaning, and weaning is a big one of cars going back to us, and that can be subclinical and clinical respiratory disease. So when are people weaning carbs have been taken from a survey by 3100 in 2020 of UK farmers and and what were they making those decisions on, kind of age, weight, concentrate intake, some of nobody used for free. Some of them used a mixture.
But I think it's having that discussion and making sure that they're aware it needs to be on that concentrate intake and making sure that we're not putting those carbs under nutritional stress. Why is that important? Because actually dropping 2 litres of milk feed is an energy loss.
So if you think what we want to be aiming for if they're on a 6 litre a day, twice a day feeding schedule, which is probably the most common in the UK, they go to 4 litres to 2 litre feeds for a week, hold that for a week and then go to 1 feed of 2 litres for a week and hold that. That's be dropping that 2 litres of milk. Is the equivalent of just over 5.5 to 6 megajoules.
What does that look like? Actually, ultimately it's a 23 to 23% decrease in total nutrition intake. So we've nearly taken a quarter of their feed away.
What's that the equivalent of that equivalent of about 0.5 kg of cake that these guys need to eat more. So that's huge, you know, and we need to be careful about how we do that.
The other aspects to consider, and this is work taken from Bobby Highway factors impacting daily earth weight gain. Actually One of the other things that impacts the disease is housing. So yes, they love it is now, but we also see it in terms of social stresses.
So we've got management stresses of disbugging, weaning and things like that, but social stress is changing those group environments. And we really saw that going through in terms of housing, the daily life weight gain. Because actually for every extra 10 days which class stayed in that first pre-wing group and that social hierarchy, they grew better.
And actually again, research has shown that that's gonna be the same for respiratory disease. So thank you very much for sticking with me for the last hour. I appreciate there's a lot of information that has been thrown at you there, but I think for me, if I could kind of summarise my points.
Really think about the metrics that we're using, and if we don't have the best metrics for some, can we get some in other places? Think about whether we're underreporting, whether we're truly detecting that rate of respiratory disease. Is this just the tip of the iceberg there, much more, more milder cases happening on that farm?
What's the impact of the subclinical? Do we see that in future performance impacts? We didn't touch on it, but actually, can you see that in cohorts of fertile lactation animals in terms of yield or not getting back in calf or survival?
When we're talking about the underreporting that detection, think about how, why, who is doing that. Do you believe it? Is it a true prevalence?
Are we quick enough on that early detection? Something we didn't cover was, you know, early detection, early treatment. We've got much higher rate of, cure, so treatment success and also decreasing relapse rate, and we're decreasing that inflammation that's occurred.
And then in terms of investigating risk factors, think about how we get environmental measuring and monitoring on the farm, might be something that can be used as well to get your farmer brought into this. Where are those key risk factors and where are the early wins? These are gonna vary for each of your different farms.
But actually, and we don't have to tackle them all at once, but can we do 2 or 3 at a time? Can we combat that culture stress, any group changes? Can we get them to clouds and a pen for an extra week?
Can we, monitor that temperature? Can we put lots of shelters in so the animals can get out of the cold? Can we put boards up to stop those droughts?
All these different things that are hugely important and things to think about. I hope you've enjoyed the webinar and thank you for your attention.