* Size Difference: A full-sized cow weighs around 1,000-1,500 pounds, while a miniature bull breed is much smaller, typically weighing only 30-50 pounds. This huge size difference makes it physically impossible for a miniature bull breed to fully breed a cow.
* Reproductive Compatibility: Even if the size were somehow compatible, the reproductive systems of cows and miniature bull breeds are vastly different. Their anatomy and physiology are not designed to work together for breeding purposes.
It's important to note that breeding between species (like a bull and a cow) is already difficult and often results in infertile offspring. The size and reproductive system differences between a miniature bull breed and a cow make such breeding completely impossible.