Cannibalism is a health risk. Eating your own kind, especially their brain matter, can cause something similar to Mad Cow disease in humans. It's been documented among aboriginal tribes who practice it.
So there's that, even if you want to ignore the moral and ethical taboos, as well as thinking murder is okay.
I'm not sure what you define as 'unnecessary'. Obviously supply and demand play a big part in how many animals, not just horses, are consumed.
Okay, so its for health reasons. The data you reference presumabley was collected from cultures that practice cannabalism. There are many people that are deemed "unfit" that are executed on a yearly basis around the globe, so no need for murder, however, since at least one culture is known to practice it (demand)...I will concede that it could lead to that (murder).
I personally define "unnecessary slaughter" as slaughtering a perfectly healthy horse.
Yes, supply and demand determines everything pretty much. But, as with transplant organs for which there is a huge demand, the supply is often regulated to protect all
of those involved.
I strongly feel undesirable horses should not be bred. I believe that if licensing were required and one had to simply identify what traits/abilities they sought in the "planned offspring", why, and why they felt the breeding of sire x to dam y would produce said traits - as well as be advised of the associated costs, longevity, and potential sale value, it would reduce the number of "undesirable" horses being "created". Even if NO license could be denied...it would raise awareness ten-fold.
In an economic downturn, be it on a national scale or individual, healthy undesirable (e.g., glaring confirmation defects or an untrained, grade adult horse) are the most likely candidates of the "healthy sort" to go to slaughter. I call it "unnecessary" since ordinarily a bit of effort goes into having a mare bred or keeping a stud... standing at stud...or not. Most breedings are not accidental....so breeding undesirable stock is easily
Registrations to a large degree already "self police", and for all intents and purposes achieve the same goal (i.e., to not produce undesirable horses) to the degree possible.
It would neither hinder people's "rights" nor stop slaughter. But, it would reduce
the number of horses that are "unnecessarily" slaughtered.
And, I am with herd, no animal should ever suffer at slaughter. I am also w PETA, keep it in the US so it can be regulated. As much as I wish it were not practiced, it is, and it cannot be stopped - but it can be regulated.