Sam Flight Honours project seminar

so thank you everyone thanks join us and like Beth has stated my research was looking at milk urea concentration as a pasture management tool in the Tasmanian dairy industry so the Tasmanian dairy industry is unique in that it is largely pasture based and that gives the industry a competitive advantage and to highlight this I placed a graph there are of the average pasture and feed consumption over the last five years from the Tasmanian benchmarking program and so that data is a small representative of around ten percent of the industry and so talking about that pasture pasture based system to maintain that competitive competitive advantage and and relatively low costs farmers need to be feeding cows well and managing pastures and so that in involves things like your nitrogen application and with pasture being the basis for the diet it is difficult to analyse those components in the feed without our feed test yeah and so I I guess coming along the lines of what farmers are doing and it at different times the year there either can be in excess protein due to nitrogen applications or potential deficiency where fair gaps are replaced with low protein silages for example so normally it’s not until a problem occurs on farm or that yeah it is then tested and looked at or attended to so I guess this brings me to the fact that there is an opportunity that if finally we could use a different measure to be able to use fertilizer without under shooting or over shooting and so so what about milk urea I didn’t click on that um so this is something you receive daily or every second day we do pickup and milk urea nitrogen is ready to use in in places like the northern hemisphere but not here in Tasmania and so it’s throughout this presentation I will be using the term um so keep that in mind now here in front of you I’m showing you I guess trying to understand what is protein and why is it important so protein and energy are key nutritional requirements in a cow’s diet to achieve production potential protein proteins are in grass and other feet and it’s partly driven in pastures through nitrogen fertilization milk urea could be considered as an indicator of the amount of wasted nitrogen from the diet of the cow so if protein in the diet is low money is expected to be low and because there is not much into waste if protein the diet is high money’s expected to be high due to a lot of nitrogen wasted so continuing on the slide oh I want to highlight that pathway in red so crude protein comes into into the cow and into the rumen as rumen degradable protein and now that is converted to ammonia but that ammonia can be used by microbes to produce volatile fatty acids or micro crude protein which is is absorbed in the intestines but without ammonia in excess it is passed through blood into liver and excreted as urine but in addition is diffused into the milk and and saliva so that’s how it gets there now my hypotheses for my project there was four and I set out so I guess find out a bit more about these so they were MUN will not be affected by seasonal differences MUN who not vary between herds and therefore MUN might be useful pasture management tool and regional differences won’t be significant so that’s what I set out to do through rejecting or accepting these null hypotheses so going forward to the methodology while the study was there spaced and there were a lot of components from getting the herd test data consolidating

this through the selection of farmers to be suited a statistical analysis gaining human ethics and completing the surveys and analyzing these in in ruminate so the raw her test data it was received by Peter Nish from TasHerd I’d like to thank Peter and and the above sample you can see here highlights the components reported on in a herd test so these were your volume your fat your protein your lactose somatic cell count month freeze point depression along with the details that I identified the farm and the time of the third test so I received her test for three years these are 2014 2015 and 2016 and from these years there were 158 158 farms in total with 1200 for herd tests at an average of 290 cows per herd tests um to understand MUN in a bulk tank milk scenario I needed to calculate the weighted averages now this was done by dividing the factor by the sum of volume. Yeah talking about those um weighted averages I divided factor by the sum of the volume for each farms herd test and to ensure the data is reflective of what would be received in a bulk tank scenario I remove outliers that might reduce the accuracy of the results so these were things like the freeze point depression of below 400 as the closer to 0 this get some more chance of water contamination in the sample I also removed 0 values such as those of MUN as this is value not possible and not always calculated in Tasmania but in addition well I guess yeah also the somatic cell count for anything about seven and a half million be removed as that would indicate potentially um plentiful cases of mastitis that would not be not not be sent away in the milk now going further into the methodology Excel will use the calculating the weighted means test range on seasonal and and yearly means and out of the her test results farmers were selected for a for a farm survey now the statistical analysis I’d like to thank James Hills for he supported in this and it was done using our complete completed using the linear model as well as the anova function and the to take tests in the emmeans package now don’t lean further into talk about the farmer survey so the farmer survey was made up of 40 farms or sorry 40 farms were selected for this but unfortunately there was a proportion of those that were either unwilling or for some reason or another did not participate and so I ended up having 24 farms participating and the survey was sectioned to describe the farm system the cow diet and the food wise usage with the completion time ranging anywhere within an hour depending on the details farmers were able to provide keeping in mind they were thinking back a few a few seasons so for some that was more difficult than others now from surveilling information provide by farmers individual diets with them back calculated for given periods of time and this was done in ruminate which which is common in pasture based systems so the diet calculations were faith focused on the energy and the protein components so ruminate is a software application that’s available farmers and consultants for balancing of cow diets and ruminate uses Australian nutrition models fitted for pasture dominant dairy diets and calculates components such as metabolisable protein and now I’ve got that circle there in in red now if I click over you can also see that the the particular point that I looked at was excess protein so this was provided in in kind of a pop-out screen when you when you work your way through ruminate and so excess protein is the amount of protein in excess of demand that is absorbed through the rumen and therefore must be excreted now going on to my results so this is the exciting part results of MUN levels

across months showed a seasonal trend similar to that of crude protein in pastures across Tasmania as seen in research done by Peter Raedts which you can see there to the right of the screen now my my graph there shows months in numbers so you can imagine January’s one through two to December it is 12 now this month of monthly data showed statistically significant differences between January February November and December compared to the mill months highlighting that bell curve you can see and so taking a closer look at that seasonal difference it is evident that summer month is lower than spring with autumn and winter both being higher and therefore statistically different and so this is expected when you think about Tasmanian pastures and how they grow and the fertilizer usage on farm so in-stream there is much faster pasture growth hence diluting crude protein and lowering the levels in pastures but also in fertilizer is avoided in early spring when when it’s too wet to put on paddocks and with late spring some farmers reduce their end rates and yeah I guess this is due to that natural surplus of pasture that you get at that time of year and that that can lead to to skipping around a fertilizer and so so thinking regionally which relates back to one of my research questions regionally there were differences and in particular the difference between the far northwest and northeast in comparison to the other two regions with statistically significant in spring where pasture makes up most of the diet and and I guess yeah I didn’t really have time in this project to delve into that but I think it could be explored explored further so from the ruminate analysis and thinking about that excess protein excess protein correlated really well with MUN so with an r-squared value of 4.8 and this this gives me confidence in MUN as an indicator for excess protein in the diet now you can see I’ve placed two bars in red and these highlight what research and literature has indicated as thresholds for overshooting and undershooting the protein and the diet so below ten is known to to have production impacts and above 20 some research seeds as fertility implications and so it is evident the and you can see this that a lot of farms sit outside of those those bars and I in the previous graph I had earlier I also show over that 20 threshold and you can see that they see they sit above that so yeah you can and I think one of the interesting points here is that you can even see some of those negative results and there that’s a clear indication to me that month could be used as a warning sign that there’s not enough crude protein could be amended by essentially your supplements or or an addition of additives so at spoken about earlier the nitrogen fertilizer usage impacts the protein in pastures and the survey work looked at fertilizer usage to see how this impacted MUN levels so yes so the MUN levels in milk and crude protein from from the cows diet and I categorized this in my fertilizer and average fertilizer so below was 150 units and or below that and then the the average with a hundred fifty between hundred fifty and 350 units have been to the hectare now this showed a difference in Mun and crude protein with average fertilizer farms things slightly higher than low I think this warrants further exploration and and you can expect that even though a farmer might mow um depending on the timing of fertilize and this can be stopped my levels regardless

still indicates a result that yeah will that change in MUN and yeah being both influenced by fertilizing you see so in conclusion you can see there my hypotheses and I was able to reject all four null hypothesis so I can reject these and confirm that the MUN or milk urea nitrogen could be used as a useful tool to manage pastures and any fertilizer usage it’s evident then Tasmanian setting MUN is impacted by seasonal changes and MUN correlates extremely well with excess protein and if received on a regular basis we indicate I guess whether pastures are low in protein but also when perhaps nitrogen fertilizer is too high and is being wasted and and therefore farmers change things like their fertilizer usage or regime and this would not only have production and profitability impacts as nitrogen fertilizers cost money but also I guess in both extremes they can have detrimental production effects and and in addition positive environment for benefits so things like you know avoiding in making its way into rivers and streams and things like that so going forward I’d like to see some yeah development of extension act tools to facilitate the use of this in Tasmania and get on board yeah doing this like places like the north northern hemisphere already do so I’m really happy with my outcomes and yeah thank you everyone for the supports I like st. Peter Raedts to James Hills as my supervisors Mark Freeman also from his mentoring throughout Peter Nish for the TasHerd data as well I think the most important thanks goes for the farmers who who’ve been willing to participate in the survey so yep really appreciate it we do have a question from Simon Jones some said what was the reference to freeze point depression mean Yeah Simon so the freeze point depression is something that they is given with your who test and so it relates I guess it’s a it’s a way or a means of being able to know whether the the sample has been diluted in the sampling process by for some reason and in that case it’s not a true and representative sample and so that’s why they be removed as outliers so anything below so milks known to her to freeze at a certain level so I think anything below so I think that’s around 500 or so but I yeah so anything removed was negative yeah which was essentially from 400 to 0 yeah don’t answer the question hopefully I think you do yes did you have a question – I do say and Sam I just wondered and he says you know that you’re you want this to be expanded to farmers and what sort of what plans have you got to do that and and is this applicable also to farmers not some Tasmania’s so on the mainland for example yeah so definitely Beth I think from from my perspective working as an extension officer we’ve tear and in the dairy industry I I get phone calls from farmers we’ve got lots of random things but you know sometimes it is calling me to say that you know they can smell ammonia in the dairy or you know what should I be putting on fertilizer that’s my home and things like that the queries that I think having this as an indication of whether you’re doing things right or you know whether you need to to tweak things in the system I think it’s really helpful and so I think that that could be achieved potentially now I’m found out that that this does correlate and and it does make sense it indicates excess protein well not enough that that I could potentially put together like a almost like a flowchart of some description indicating farmers what decisions they should be making around the certain level so you know if you have a level at ten if you have a

level at thirty what are the things you should be stepping through so I can imagine that in some sort of flowchart and I do believe even on the making lands like I know I know some farms over there are using yes and with a next year through the milk company but I think I haven’t seen anything of the like you know produced as far as an extension to help you navigate your way around that know in case I question for you something you you mentioned that it’s already been used quite extensively in the northern hemisphere you think of any reasons why it might not have been used here so much in the early part of presentation but I guess that past the dominance yeah the fact that we are very pasture dominant here you’re an even on the mainland still very pasture dominant although I guess yeah it’s different levels and particularly here in Tassie but I think that is what makes it hard to think well you know for the fact that you can estimate what’s going in and you don’t know what the pasture quality is and less testing and things like that there’s a lot of unknowns and so I think the systems are probably set up better on in the yeah in places like the Netherlands than that to to do us and yeah I just I don’t really know why we’re behind in that sense but I think I’ve great answer I think that’s probably enough this Q&A but no really good job and look forward to see what happens next Thanks