Wow what a fast game!! I love it ! it has a really great potential.
I think you could use a little more feedback, such as a little baby sheep sound when a new sheep is born, a sheep counter or even a "hurt by hunger" sound when we get hungry. It would help the player to keep track of its current state.
I must admit I had a lot of runs, it was a very fun game. In the first time I played, ALL MY SHEEP got infected HAHAHAH. The second time, they got infected again and I ate them, they were delicious.