Refrigeration of a whole lamb isn't going to stop the guts from rotting. It will take a long time to cool the whole animal, particularly with the fleece on, so it sounds like that is what has contaminated the meat. What surprises me is that this hasn't happened before [member=29807]Mathewr[/member]
When we used to have ours slaughtered the fleece was removed and the guts almost immediately. I used to collect the fleeces a couple of hours after we delivered the lambs. The carcass was by then hung in a refrigerator and would be left there for 10 days before butchering.
I remember being told that if I shot a wild rabbit it had to be gutted immediately to avoid contamination of the meat- they have a similar diet to lambs I think, so their gut flora will react the same?