Here's why:
* Horses are living animals: They are not objects that can be put into a bucket.
* Buckets have varying sizes: Even if you were talking about a bucket of *hay* or *grain* for a horse, the weight would depend on the size of the bucket.
To get a helpful answer, please clarify your question. For example:
* "How much does a 5-gallon bucket of horse feed weigh?"
* "How much does a typical bucket of grain for a horse weigh?"
Let me know, and I can help you!