I used to do this more often, back when I had a (dedicated) vegan blog.
The source of the photo is unknown to me, credited just to "Animal Rights Protest Photography".
In reality, too, there's only so much to see, and only so much to say. I wouldn't really want to make a hobby of this. Gary Francione has taken up ranting that undercover documentaries and photographs of farm conditions are "useless" because they don't show anything new, and won't change anything (etc.). Although I think he's wrong (really: dead wrong), I can imagine how he feels, as he will have seen thousands of similar images for so many years. And one more image seems like it won't make a difference.
But, as Stan Lee said (for decades), "every comic-book is someone's first comic-book". Every photo of this kind is someone's first exposure to the basic facts, questions and sentiments that vegans have become overly-familiar with.
By the same token, however, I wouldn't want my own web-presence to become as repetitive as Marvel Comics became (over during those same decades). :-/