GM free isn't a direct alternative to Organic. The jury is still out on GM crops and their safety, but we know for sure that the chemicals used to produce crops under a 'conventional' system cause harm to the environment and to the consumer.
Although we keep our soil chemical free, we do use chemicals for our flock health where necessary, and we don't use organic feed - largely because it's not freely available. Our sheep mostly get grass grown without chemical applications, and hay cut from the same ground, by us. The proportion of manufactured feed used is low, but I think we're just being lazy by not investigating organic suppliers more thoroughly. So I will be interested in the results you get from this thread princesslayer.