Sunday, September 20, 2020

Measuring Sheep Methane Emission



Jinan Nova NS400 Handheld Multi Gas (CO2 and CH4) Detector.                     

Aug 2020.

Read some instructions first… always a good idea…

A wise man once told me, “there’s nothing new under the sun, whatever you’re doing, there’ll be someone, somewhere…..”

This isn’t a scientific discourse, so I’m allowed to put my citations, and resultant comment up front, which I hope will go some way to explaining the course/s of action I took in setting about this evaluation.

If you want to delve deeper, Google “” then in the search box, type in the citation code. There’s a little box to the right of the paper subject header that says “PMC Full Text” which in some instances you might need to click on to get the full paper.


A Review of Enteric Methane Emission Measurement Techniques in Ruminants

Zhao et al

RC (Respiration Chamber) – Animal in container full-time, regarded as ultimate because it collects total flux, (dung, farts, urine etc as well as respired), disadvantage said to be, its un-natural, not reliably reflecting animals emitting differently to what they might when outside.

Green Feed – Similar to above but outdoors with a bait station to lure the animal in, has high between day and animal variations, depending how long the cow stays in station.

Sniffer – Utilised on dairy cows feeding while milking, when they put their head into the feed-bin. Same infra-red CH4 detection as above two systems, but dosent measure total flux, only respiration, and is less accurate between animals because no control where cows head is relative to sensor. However, authors mention, respiration does provide PREDICTION values, so keep that in mind for NS400 implementation.

Ventilation hood or Face Mask – Both have a time/logistics problem as do RC and GF, either a hood/mask for every animal, or one you have to change from animal to animal, which would carry an additional problem of vacating the hood of gas residue from the previous subject.

LMD (Laser Methane Detector) – State of art laser beam from hand-held instrument measuring CH4 concentration via infra-red spectroscopy, again only measuring respired/eructed concentration.

Cheapest one I’ve seen, cost approx. $6000 USD, quote here in NZ, $10,000.

PAC (Portable Accumulation Chamber) – What we’re being offered locally by AgResearch for 84 animal x 3 week repeat survey service. PAC has advantage over RC in that animal confined for shorter time, up to one hour, but for the still not inconsiderable logistics involved, dosen’t include flux as comprehensively. Zhao et al further say the results don’t correlate at all well with RC, possibly due they say, “different aspects of genetic traits”.

 Values obtained by RC said to have the highest h2 of all systems.

IPCC, for GHG ruminant emission mitigation considerations, prefers the RC method, maintaining CH4 measurements are of little value without knowledge of feed intake, which can be best controlled in the RC system.

The authors conclude LMD and PAC have low cost simplicity, short term measurement in individuals under practical production conditions, offering potential opportunity for breeding lower emitting animals.


Genetic parameters of methane emissions determined using portable accumulation chambers in lambs and ewes grazing pasture and genetic correlations with emissions determined in respiration chambers

Included here for interest, Jonkers et al, including among the et al, Shackell, Dodds, Knowler, McEwan, this work likely contributing to the MO of the methane testing service currently offered local breeding industry. They put h2 at around 0.16 for PAC and 0.20 for RC.

 NS400- type handhelds offering a “breathalyser” approach, not included in the above survey, but following points pertain:

- Utilises the same infra-red technology, passing an inducted air stream via suction pump, past an infra-red sensor.

- Same small size utility as LMD, but better directional capability, intake nozzle can be held within 30mm of nostrils easily enough, with less background intrusion.

- Faster animal throughput at lower time and capital cost.

- With animals fresh off natural environment/pasture, given the above Sniffer comment, we can assume the predictive snapshot. This comment also supported in the following citation:


Assessment of methane emission traits in ewes using a laser methane detector: genetic parameters and impact on lamb weaning performance

Reintke et al

 CH4 readings partitioned into respired and eructed (belched), (see their Fig 1 graph for yourself, copyright prevents me from inclusion here).

Authors maintain a factor derived from either (respired or eructed), correlated well with ewe body wt (EBW), back fat thickness (BFT), body condition score (BCS), and lamb body wt (LBW).

Interestingly, this paper was not about GHG emissions, but focussed on feed conversion efficiency.

High levels of ewe CH4 emissions (representing energy losses) were significantly associated with lower LBW, EBW and BFT.

They say h2’s were small, (0.1), and not sure, but I think established via LBW on one generation of progeny. However, they say breeding on reduced CH4 emissions, (especially eructated), contributes to genetic improvement in that trait.

They used mini-peaks of respired and eructed CH4, and maintain such separation is reasonable physiologically.

Ewes with low CH4 during respiration reared heavier lambs, and simultaneously, were associated with higher EBW.

CH4 eructation represents larger CH4 emission than does respiration, but respired CH4 influences LBW and EBW significantly enough.

 NS400- I read this stuff after we’d done the first trial runs with the detector, carried out on 200 ram hgts.

The NS400 allows setting for recording interval and I had elected for average CH4 over 10 and 20 second intervals, instead of the 3 minutes as in the above trial, and assuming that an average of ppm values might suffice.

As the Reintke Fig1 graph shows, respiration CH4 levels are quite constant, and I found this to be so also, even given the shorter time interval I used.

Importantly, I did find significant difference in average respired CH4 levels between sheep with these shorter intervals, and such difference would be emphasised if the peak values as indicated by Reintke were used instead of average.

We struck a frequency of somewhere around 5% of the ram hgts where eructation occurred during the 20 seconds, which shot CH4 well over 1000 ppm, at times up to 3000 ppm.

Switch-off and re-boot of the detector was needed to clear the residual CH4, the 60 second boot-up process includes a 45 second pump activation while holding the instrument in “fresh” air.

 Consequently, I favour a shorter read interval (10 seconds) for the following reasons:

- faster throughput

- the longer the read time the greater risk of an eructation interruption

- the NS400 attains a steady “read” within the first few seconds

- WYS in a 10 second respiration pattern is fairly indicative of WYG subsequent

- sufficient between sheep difference achievable within this time

- shorter restraint time, better all round for both sheep and handler.

Incidentally, the 2 hour 200 sheep session only used 1/5 of battery life indicator.

Pictured here an NS400 sample 60 second CH4 graph, the 10 second peak to the left of the 15 sec vertical approx 127 ppm, and closing ppm 105.


 We thought we might encounter some taper off in CH4 with standing time in the yard, higher CH4 values were obtained in first hour.

So here are the scatters for the pasture and clover sessions: ppm CH4 up the side, and time across the bottom, in number of sheep, corresponding to 100=1 hour.


I suppose unsurprisingly, the CH4 settled fairly quickly for the clover, consistent with it being a better quality, more highly utilisable fodder, while off the rye pasture there was a longer tail.

The trend lines were more consistent than I thought they were going to be, but looking at both scatters, a half hour stand-time (=50) might be appropriate.

 Couple more citations worth a read:


Genetic and environmental variation in methane emissions of sheep at pasture


Animal board invited review: genetic possibilities to reduce enteric methane emissions from ruminants



200 ram hgts run through the Racewell squeeze, 100 per hour.

Holding sheep head with left hand, detector in right, assistant punching data to XR5000 indicator.

NS400 interface has 3 selectable modes,

Dual - showing both CO2 and CH4

Single – showing either or as pic below

Graph – as Page3. tracks readings over whatever gas and time period set.


I tried 5, 10, and 20 second timing periods, and used the final ppm indicated at period end. After some long-hand calculation I established this number was the ppm read at close of scan, not an average over the time period.

Any reading over 500ppm regarded as an eructation, and excluded from the summary. Readings I felt were influenced by an eructation in the previous sheep also excluded. While taking readings it is easy enough to tell if this is happening, and in future, will shut down/re-boot to clear the pump, if necessary.

However, would expect in future to avoid this with a short 10 sec read time.

To arrive at a usable CH4 factor for each sheep, I averaged the CH4 readings taken per sheep off both the rye pasture and the red clover, and rather than use a deviation from the total mean, I calculated a CH4 ratio based on the mean of each hour, a sort of cheap and dirty regression to account for standing time, (don’t laugh, it worked!)

I then compared CH4: between the top 25% LWT and HFW, and the bottom 25%.







Top 25%





Bottom 25%











There’s no adjustment in here for birth rank which might show lower emitters in better light, but I think the best I can say at this stage is, higher performing sheep are kinder on the environment.  High production, lower emission is a useful association, but limited by how big do we want our sheep to ultimately be. Efficiency at a fixed weight is a more ‘noble’ aspiration. My own genetic trend graphs, approx. 5kg LW12 and 0.2 kg FW12 in the last 8-year generation turn-over, equate a 1-2% per generation improvement in CH4 emission, based on production gain alone.

Looking at Dag Score, the small proportion of dirty sheep was hardly sufficient for robust comparison, but we noted a 4% CH4: advantage no dags vs any dags, (1.00 vs 1.04), and that the really daggy handful of score 4 and 5 were 1.51, ie. approx. 50% worse emitters/inefficient feed utilisers.


Sire Summary           CH4:               LWT                HFW           DagScore 










































Quite a difference between sires, but not necessarily production related except for Sire 2. When all factors affecting trait inheritance considered, individual intake or gut biome for instance, one can only speculate at this stage on heritability of energy conversion to bodily gains via this method of measurement. More data, over more time needed.



The NS400 can make a reliable contribution to the breeding tool-kit, given that all ways I’ve looked at the scenario, in what should be regarded as quite a small snapshot, still gave results consistent with themes in relevant literature.

This applicable also when considering the effect of different feed species illustrated here with the difference in emission profile between rye mix pasture and clover, and which could, by extrapolation, exist with other feed crops like chicory, plantain, and brassicas.

Incorporation of methane measurement into a breeding program would demonstrate a will to positively engage in GHG mitigation, and the contribution should ultimately be measurable. However, given the positive relationship between higher production and lower CH4 emission, performance driven flocks and herds have indirectly been doing the “right thing” by livestock GHG mitigation for at least 50 years, (here in NZ).

In a scenario where h2 is a low to moderate, 0.1 to 0.2, culling lower performers can lift the population mean quickly. Removing the bottom 10% of this trial sample improves the remainder mean CH4: by 8%.

For myself I’ll implement a worst CH4 performing 10% cull to my sale ram and replacement ewe hgts, in line with what I apply to all traits, and will be looking for the best male to retain as a stud keeper. I’ll be basing emission performance on two or more observations in the first 18 months of age.

As with all new technologies, the more you use them, the more uses become apparent, you can’t beat measuring stuff.

The NS400 fits that task for the practical breeder pretty well.


Thursday, July 9, 2020

Winter Shear

A fortuitous patch of warm weather for late June, too good a chance to miss for early winter shear.
Cover combs leave the sheep with a bit of wool left on so they can withstand any sort of adverse local weather after just a few days, plus we still have over 10 weeks till lambing starts. Due the drought we delayed putting the rams out by 2 weeks.
Got the wool weights back from the broker yesterday, the 2ths did 4.2kg for 11 months since last shear, the MA's did 2.8kg for 6 months.
Lot of dismay about current poor per kg returns for crossbred wool not being enough to cover cost of shearing. 
You can give up and say you're shearing sheep just for reason of their health, but we think we're keeping ahead of the costs by an extended time between shears, 8 monthly (3 times in 2 years, we got a bit out of phase this time due the lock-down), and keeping tabs on the genetics for fleece weight.
Waione sires continue to inhabit the national upper percentile for SIL's wool index. 
Airline and hospitality industry upholstery and carpeting have been the chief users of crossbred wool, but they've taken a hammering in these covid times, delaying any recovery in prices, for who knows how long.
Its a shame a natural, bio-friendly product should so languish.
NZ exports over 40,000 tons of this class of wool annually, we need an end product that captures the consumers imagination in a big enough way, and that is either competitive with synthetic materials, or inhabits an entirely separate market.

Tuesday, January 3, 2017

Book: Protecting Paradise

Real surprise here.
Fed Farmers promoted this book a while back on the weekly RamBull newsletter. Its a late 2016 print, so the Feds were right out of the blocks on it.
I got it because I thought, as a farmer, I had a responsibility to be as boned up on pest control as I could, seeing as we've had a career long involvement in keeping our cattle herds free of Tb, and introduced possum pest being cited as the chief disease vector. 
What I thought was going to be a rather dry dissertation on the pros and cons of 1080 use turned out to be more..., much, much more, in fact one of my most interesting reads of the last 12 months.
The author devotes the first chapters to a run-down on the state, or better described as, plight, of NZ's wildlife. We usually give cursory recognition to this state of affairs when mentioned in the Press, but here's page after page quietly ramming the point home. I couldn't say I'd do a definite number on my opinion and where it might have been swayed to, more it left me with a sadness about where we are right now.
So, what are we going to do about it.
Then there's a big section on 1080, the history of its use, about the extraordinary lengths DOC and researchers have had to go to satisfy a hostile public about its efficacy, and comparative toxicity, and the development of safest forms of deployment.
And here's where the book got really interesting, discussing the philosphy of disposition, argument, dissent, discontent... whatever, Hansford's done a great job of presenting how an argument looks from both sides, all sides actually, but really how difficult it is, with the best science behind your argument, how the opposition can use it against you without a shred of scientific research data of their own.
The proposition that we all argue an issue from the basis of our own perspective is well travelled in the book, and I have to say my own bias was tested when Hansford likened the 1080 debate to that of climate change. Like with disease and pest control, as a farmer I have to keep a weather eye on most things, climate change included. I'm probably classifiable in the "denier" side of fence-sitter on that, but I'd strongly disagree from my position of all-sectors polling rural realism, that climate deniers were as vociferous as the 1080 dissenters, in fact I'd give the climate bad-mouthing award to the climate activists.
However, Hansford should be pleased I'll henceforth side with DOC's use of aerial 1080 plans, and will join the plea for better funding for DOC by Govt.

For the last 5 years or so this farm has been part of a much larger district wide brodifacoum bait station program run by the regional council. Initially, I didnt like the signage at the gate that went with it, like the place was under quarantine, but I've relented big time.
Scenes like the plover family on the right are regular now. Year before last we had a family of 13 quail hatch, grow and disperse from under a hedge. Haven't seen a possum for 3 years, haven't had rats in my garage, stable, or around the dog kennels for a couple years either. Found a skink from under my front deck, haven't seen one since I was a kid. Tui's regularly gong away in the trees round the house.
I don't think the Predator Free NZ vision is at all nuts, even if only part achieved we'll see a big difference.

Dave Hansford's book is an extraordinarily well written exposition on what could have been a difficult subject. Heck, there's even a 30 page bibliography/citations.
I think its a triumph in the use of modern English.
Thankyou Dave, and thanks Fed Farmers for putting it on the reader list

Wednesday, December 7, 2016

1418 reporting for duty

Time for the bulls to go out, early Dec mating gives us an early Sep start to calving.
I've drifted off calving earlier, an extra month just gives that bit extra breathing space around the seasonal grass growth pattern. Having calves a month live-weight behind is a small price to pay for better herd well-being, and less stress on the Management.
The winter-saved calving paddocks, closed from Jun 1st till Sep 1st, give me time to finish a few more lambs beforehand, the block grows 5-6000 dm by Sep to put the cows on for calving. 
Meanwhile they've run out on the hills till end Jun, come off them before they do too much pug damage into the sidling wintering block, where they'll get balage if they need it, 2 months there, then into the calving block.

So here's 1418, home bred 2yo bull, introduced to his yearling consort. You'll see a flash of white on the heifers, that comes from a Hereford I used over 10 years ago, the odd white head and foot lingers. Apart from the Hereford, haven't used an outside blood bull in over 20 years.
The herd isn't on an official recording system, I keep my own records, and I think things are ticking along quite well.
Here's why.....
Nessa Carey's Junk DNA and The Epigenetics Revolution move one to the view that "what you see is what you get" performance, unadulterated by correction and heritability equations could in fact be the best thing for breeders to be chasing. That outlier corrected out of the hunt by BLUP, could in fact be the individual with the epigenetic modulation of RNA expression to take the flock or herd to the next level of production.
I've devised my own system of cow lifetime production measure, based on mean annual ratio of weight of calf weaned, with penalty of zero for barren, 0.5 for wet/dry, and 0.75 for calf died.
One thing sticks out like the proverbial....
If there's one selection criterion a commercial breeder can hang his hat on, I think its early calving. These cows inevitably have the heaviest calves, and will be the most likely to do it again next year.
I have a selection index for young stock that adds this dam performance to the mean weaning and yearling wt ratio.
Works great......
1418 was 124% for his wng/yrlg ratio, and his dam 114% lifetime calf prod, 238% index.

Sunday, November 20, 2016

Crops Away, and the new Walco Allspread 6.75 spreader

Direct drilled last Monday, the pasja's struck really well, only been six days!

First run with the new Walco 6.75 spreader.
Pleased to report it spread as accurately as the handbook settings said...., I was doing 40kg/ac DAP, 12 metre swath at 15 kmph.
A walk around the paddocks after showed distribution was happily satisfactory.
Got the same good result putting some urea on the paddock closed for Jan hay.
The bin will hold 1/2 ton no problem, but I had to work out a suitable driving technique, its not really wise to be doing turns at 15 kph with a load on the back, specially when I get up on the hills later on. Using the foot throttle solved the problem, slow down for the turns.
The handbook said work round and round for best spread, but with the GPS set on A to B, I prefer working in lands with a single run 12 metre headland across each end of the paddock.

Wasn't all sweetness and light however.
Real mission to mount on the tractor. I had to use outside extension pins to match the TYM's CatII linkage arms, and even then the width dosent match all my other CatII gear, so I'm going to have to frig round adjusting the shackles swapping between machinery, all this made worse by bugger all space between spreader bin and tractor, a frustrating squeeze for a bloke my size.

Bit of a bounce on my OD to fit the capital purchase in, but I got this idea, instead of one humungous annual fert bill, I'd do smaller one to three monthly bites of the cherry, as finances allow.
The 1/2 ton capacity allows for getting fert in Ravensdown's 1/2 ton bags, or, I can get bigger amounts in bulk, and load it with the old Same and bucket.