Robert Kirkman appeared on the talk show Talking Dead last night and he confirmed that it was Otis who put Sophia in the barn before the rest of the group showed up at the farm.. He references the conversation Hershel had with Rick at the stream, when he explained that it was once Otis’ job to shepherd the walkers into the barn. Now, that doesn’t necessarily confirm that Hershel didn’t know Sophia was in there, but it seems like that’s a good possibility. Not that it lets Hershel off the hook for his delusional views on walkers or anything, but Shane's anger may be misdirected here. If anything, he should be mad at himself, considering the conversation about Sophia being in the barn is probably more likely to have come up had Otis not been eaten.