Maximum size of prey that a single male lion or tiger can kill

[Pckts]

Guategojira

I'll respond account by account

Your first account mentions scat samples which of course dont tell the whole tale.
It also mentions estimates of body weight and any carcass found was after death had already occurred.

2nd account
Maybe he did weigh them but they're still estimated based off meat already eaten. I'd also want to read the entire study to see actual kill data and means of obtaining it. Regardless again, kills are not witnessed here.
They also give a range of 500-1000kg for Gaur, again showing a major difference between a Bull and what I call an Alpha Bull.
You can see Bulls which are similar in size to Cows and you can see others which look surreal, they're so large.

In regards to horn length, the old bulls will have the largest horn length but that certainly doesn't mean they're in their prime.
Odin for instance, the old Bull Gaur that fought a Tiger all night long and lived to tell the tale would most likely have a massive horn length since it'll continue to grow over it's long life.

Finally I'll say this, I agree Tigers and Lions have killed Bulls of either species and my criteria for what an Alpha Bull is will be hard to explain to most.
It's just one of those things you have to see to get the gist I guess. 
I'll leave it at this, if I'm a betting man and you put a Lion or Tiger in a ring with a massive alpha Bull, my money would be one the Bull all things being even.
But as we know, the wild doesn't play by those rules and I fully acknowledge that anything I think is unlikely can easily be possible with the right conditions. Reply