that's part of being a cow dog, d - eating cow dung. I'm surprised Stryker hasn't turned green yet. And calf stuff is especially appealing to him. YUCK!! 
It is funny - in the spring I can't hardly keep him from it and wind up having to de-worm him of tapeworms about once every 4-6 weeks. I call the vet and they leave the wormer in a bag for me to pick up after hours.
Crescent Moon Ranch
Raising quality commercial calves