For another anecdotal data point - I found that both the contrast between where money is spent and where the suffering happens, and the cumulative death count were highly effective emotionally (the dots animation less so).
However, for me personally, I'm not sure 'number of killed animals' is the best measurement for negative impact. I could imagine viewing an animal farming industry where the animals got to live free and happy lives until their sudden painless deaths as a pretty positive thing - animals in the wild generally live in far worse conditions and it seems unrealistic to expect humans to keep animals in a happy environment if there was no gain from it whatsoever.
This isn't something I'd thought about at all - I guess wild animal suffering is one of those things you just accept as unfortunate but inevitable.
Still I wouldn't say the absolute scale (# of suffering farm animals vs. # of suffering wild animals) makes much of a difference, rather the scale of what can be accomplished with a given resource investment. Suffering in factories seems like a much easier problem to solve, and I'd expect the amount of suffering reduced per dollar invested to be far higher.
Also, I would feel a lot more hesitant about large-scale interventions on wild animals, since they are part of complex ecosystems where I've been led to believe we don't have a good enough understanding to anticipate long-term consequences accurately. Farm animals are situated in a fairly simple living situation where I'd feel much more confident about the long-term suffering reduction of various interventions.
Maybe I'm missing some obvious high-impact interventions though? Or maybe the area is unexplored and there are big potential benefits from spending some effort figuring out if there are high-impact interventions?