Calf in the Cottage

 is the 15 book in the Animal Ark book series, written by Lucy Daniels, which was first released in 1996.

Summary
Helping Mr Matthews on his dairy farm is a dream job for Mandy and James - especially at milking time - they love all kinds of animals and Mandy's parents run a veterinary surgery.

But one of the cows is in trouble. She's about to give birth early - to twins. Will her babies survive?