Validity of Heart-Girth Method of Weight Estimation of Hogs

[Double Naught Spy]

In a previous thread, Keg proclaimed that the heart-girth measurement for estimating the weight of hogs would not work with feral hogs because the article was based on finishing pigs, incorrectly noting that domestic finishing pigs and feral hogs were "like 2 different species."
http://thefiringline.com/forums/show...ht=heart+girth

The method and comparative data table can be found here...
http://www.thepigsite.com/articles/1...finishing-pigs

Keg further based his insight that the method would not work because the hogs don't look alike, specifically dealing with their fat and fitness issues and he would know that it doesn't work because he has killed so many hogs.

Whilst killing lots of hogs is quite admirable, it does nothing to actually invalidate a method not ever used by Keg.

I spoke with some hunters up this way and found that they have used the method with good results. Additional reading turns up that the method is used around the world and with the addition of 1-2 measurements depending on how much more refined the estimate needs to be and actually used on truly different species of pigs with good results.

So I have started putting the method to the test as well. So far, two hogs down. The first was a young sow that measured 27" and produced an estimated weight of 69 lbs. She came in between 66 and 67. The second was a good-sized boar. Heart-girth on this boar was 43.5". Looking at the chart, that would mean the boar should weigh about 237 lbs. Actual weight came in at 232.

So far based on documented, 3rd party, and direct experience, the heart-girth method of hog weight estimation works very well.

[Scorch]

Heart-girth measurements are used by wildlife professionals around the world for estimating animal weight on live captured or sedated animals. It is not exact, but yields a very usable number on everything from squirrels to rhinos. If it were not fairly accurate, they would not use it.

[Keg]

Now Brian.......I thought we had agreed U were wrong again......and moved on to bigger and better things.......oh well......I think that oldandslow had shot that out of the saddle months ago....U read his test???....guess not.......U just don't get it.................This method is for finishing pigs........Even your site says so.....U need to listen..........

Got this of one of those sites.......
The pigs should be on continuous feed and water to insure accurateresults. We have found heart girth measurements to be inaccurate if pigs have recently been transported or held off feed or water for a short period of time. Heart girth measuring can be useful for 4-H members and swine producers for estimating pig weight. In finishing pigs (domestic)............

Just let it be.......lol

[Double Naught Spy]

The pigs should be on continuous feed and water to insure accurateresults. We have found heart girth measurements to be inaccurate if pigs have recently been transported or held off feed or water for a short period of time. Heart girth measuring can be useful for 4-H members and swine producers for estimating pig weight. In finishing pigs (domestic)............

Just let it be.......lol

And yet as Scorch has noted and as the results I am finding so far indicate, the method works just fine beyond the controls which undoubtedly help provide better accuracy. Inaccurate is below the 95% confidence interval in the finishing pig study. That does not mean the method won't provide decent field estimates of weight, however.

Moreover, unlike domestic hogs which may be transported longer distances for show (4H) or sale or that may be deprived of food except at feeding times, feral hogs self regulate intake.

Gotta hand it to you. First you claim that the method won't work because there is a difference in domestic and feral hogs that will render it untenable for which you offered no valid insights to support and which turns out to be false. Now you are saying it won't work because the most accurate controls aren't in place. Good try, but you are still wrong, Keg.

In fact, the method is used by biologists in the field for assessing hogs.
http://research.myfwc.com/engine/dow...pe=publication

Mayer's abstract here indicates heart-girth to be excellent for estimating total body mass in wild hogs...http://www.wildpigconference.com/pdf/Program.pdf

However, if you can come up with some sort of harder evidence or biological studies that indicate heart-girth doesn't work, let us know.

[Keg]

...

[Scorch]

In general, these techniques yielded mean TBM estimates of sufficient accuracy to meet the aforementioned application needs. Although developed for use on the wild pigs found at the SRS, these techniques should be applicable to other populations of this species found in the United States.

That pretty much nails it right there.

[Keg]

...

[JohnKSa]

We are looking for weight not mass...

A meaningless distinction unless gravity is significantly different from earth normal where the weighing process takes place.

[Keg]

...

[JohnKSa]

What I'm trying to say is that weight and mass are the same thing for practical purposes unless the object under consideration is weighed where the gravity is significantly different from earth normal.

Mass is constant. Weight depends on gravity, but since gravity doesn't vary significantly on earth, mass and weight can be used interchangeably for the particular purpose at hand.

In addition, the paper isn't saying that gutted weight is equivalant to total body mass, he's saying that total body mass can be calculated from gutted weight just as it can be (though using a different formula) calculated from heart-girth measurement.

[Keg]

....

[JohnKSa]

If U have to weigh a gutted pig to find the mass..U have defeated the purpose of finding an easy way to estimate the weight of a feral pig...

The article doesn't say you have to weigh a gutted pig to find the total body mass. It only says that is one of the two most accurate methods for estimating the total body mass of a pig. The article states that the other is using the heart-girth measurement.

what I am sayin..is this is not the same equation as finding weight of a finished domestic pig (heart-girth).

Given that DNS is getting very accurate estimates from using the equation for a finished domestic pig on feral hogs (less than 5% error), and has favorable reports from others who are using it, it seems like proving that it won't work is going to be a tough row to hoe.

[Keg]

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[JohnKSa]

....not what I get out of it......

From the section of the article you quoted in your post:

"The most accurate estimates (i.e., r2 values of 0.97 to 0.99) were derived using gutted weight, body volume (i.e., heart girth x head-body length) and heart girth."

I did make an error. The article says the heart girth measurement is one of the THREE most accurate measurements they used to estimate total body mass, not one of the TWO most accurate as I said in my earlier post. The three measurements were: gutted weight, body volume and heart girth.

..but not accurate......my 2 cents

Again, given that so far it's providing estimation errors of less than 5% (about 2% and 4% in the two examples given) it's going to be pretty tough to argue that it's not accurate.

[Keg]

Last pig I got a couple of weeks ago was close enough to the truck that I could take it home and weigh, measure and clean it at the house. I have read about the chest measurement as the basis for a weight estimate so I did the measuring. Chest circumference of 38 inches, snout to rump measurement of 50 inches, and actual weight on my 500 pound scale of 120 pounds. If you use the chest measurement chart for the weight estimate then my pig should have weighed 181 pounds instead of the actual weight of 120 pounds. As the weight estimation chart says it was based on domestic pigs there may not be a correlation to wild pigs. I need to get some more pigs close by so I can take them home instead of field dressing them.

Actually I kind of like the chest circumference data- I can say the pig was 61 pounds heavier than it really was.

best wishes- oldandslow

What %??? Who's test to believe???

"The most accurate estimates (i.e., r2 values of 0.97 to 0.99) were derived using gutted weight, body volume (i.e., heart girth x head-body length) and heart girth."

Lets go back to square one.....
My apologies...I did not read the last heart girth....But I feel this is just quick field measurement.....Condition will be noted.....There is so much difference in pigs from southwest or from farm country..etc..etc....
After doing a lot of checking on the net..it seems there can be inacuracies..even in domestic pigs......Also off..by 1 inch of measurement can mean plus/minus 10 pounds.....hmmmm.....Lets also have feedback from those who have not been to horn hill range..to remove all bias....thanks....

[Double Naught Spy]

Well gee, Keg, scales can be off as well. It you don't tare your scale, it can be off. If you don't hoist your hog fully off the ground the measurement can be off. So if you don't actually do things right, you can be off, regardless of the method.

Scorch hasn't been to Horn Hill Range. The biological papers I cited are not by folks who have been there.

If you have some actual proof that it doesn't work other than your opinion, do let us know. So far, however, you haven't actually come up with anything.

http://www.jstor.org/pss/3798635
http://www.sciencedirect.com/science...1&searchtype=a

You have no basis to argue that heart girth is a poor method unless you can refute all the studies that have shown where it works and that have been doing so for the last several decades.

[Keg]

Well gee, Keg, scales can be off as well. It you don't tare your scale, it can be off. If you don't hoist your hog fully off the ground the measurement can be off. So if you don't actually do things right, you can be off, regardless of the method.

U don't say??? U figure that on your own??? U believe your scales but not someone elses.......


You hear only what U wanna hear.......I can go here and there..copy..paste..copy..paste......So far..U havent proven anything to me.....But this is really gettin old......Kinda bored with ya actually.......hahaa

[MLeake]

Keg, did you miss the part where DNS both measured and weighed his own hog kills?

And no, I have never been to Horn Hill Range.

[Keg]

Keg, did you miss the part where DNS both measured and weighed his own hog kills?

Seems like I read that......What about oldandslow??? hmmm...must have missed that.....

And no, I have never been to Horn Hill Range.

LOL.....I've been on these forums and witnessed..lots of kissin goin on..U know..It just makes ya sick.....:barf:

[JohnKSa]

Lets also have feedback from those who have not been to horn hill range..to remove all bias....thanks

I didn't learn the difference between mass and weight at Horn Hill, nor was that where I developed reading comprehension or learned the method for calculating percentage error.

And even if you believe that I'm biased (which is your prerogative, I suppose--a person is free to believe anything he chooses to), the nice thing about this kind of debate is that biases and opinions don't decide the outcome, facts do and facts aren't biased nor do they yield to any particular person's opinion.

I've been on these forums and witnessed..lots of kissin goin on..U know..It just makes ya sick.....

See if you can manage to debate this on the basis of facts, without all the innuendo.

[Keg]

I didn't learn the difference between mass and weight at Horn Hill, nor was that where I developed reading comprehension or learned the method for calculating percentage error.

And even if you believe that I'm biased (which is your prerogative, I suppose--a person is free to believe anything he chooses to), the nice thing about this kind of debate is that biases and opinions don't decide the outcome, facts do and facts aren't biased nor do they yield to any particular person's opinion.
Quote:

John....did not say ya did.....It just stands to reason......U may be more biased......The fact is..only DNS's tests are valid??? Why is that??? Mentioning facts...The fact is..someone ran this test months ago......Guess what??? I think U know.......

See if you can manage to debate this on the basis of facts, without all the innuendo.

See above......Please don't overlook the facts............I did not start this thread and bring someone elses name into it.......It could have been started without that.......Since U are not biased..I'm sure U agree......

[Keg]

Before my last post......I had decided to take the high road......To be more open to this method......
I had really never heard of this heart-girth method before and seemed foolish to me as far as getting a weight on feral pigs.....I still read here and there on the net that it can be off for finishing pigs that have gotten into poor condition......
I believe this is probably a good estimate on good healthy feral pigs.....
It would be good to use in the field..where there is no access to a scale.....
We generally have 50-100 killed off the 850 acre place I generally hunt.....Close to 500 on the whole ranch yearly.......I plan on using this method to see..for myself.......Like I said......I expect those in good condition to be fairly close......Oh well..we shall see.......

[Art Eatman]

Nuff fer now...