Uninterested Border Collie

[Little Valley Farm]

I have a four year old border collie who was excellent help with cattle. He would round them up at feeding time, help me catch them when they got loose, and help me load them into trailers. I have recently switched from cattle to sheep, and he shows no interest in sheep besides giving them the eye when he first met them. I taught him not to herd chickens when he was a puppy, could this training have carried over to lambs?  Is there anyway to get him interested in sheep? I tried using another sheep dog in front of him, but he doesn't care. When I go out to bring the sheep back to their stalls, he doesn't even come along.