The offspring of two parents from different purebred strains is called a crossbreed or hybrid.

Here's why:

* Purebred: A purebred animal is one that comes from a long line of ancestors with the same breed characteristics. They are genetically similar.

* Crossbreed: When two animals from different purebred strains mate, their offspring inherit genetic material from both breeds, resulting in a mix of traits. This is a crossbreed or hybrid.

Examples:

* A Labrador Retriever (purebred) and a Golden Retriever (purebred) produce a Labrador Retriever/Golden Retriever mix (crossbreed).

* A German Shepherd (purebred) and a Husky (purebred) produce a German Shepherd/Husky mix (crossbreed).

Crossbreeds often exhibit traits from both parent breeds, making them unique and sometimes desirable.