"How to say donkey in English" is the question you've asked. In English, "donkey" is simply called "donkey".
If you're looking for other ways to refer to a donkey, there are a few different words that can be used depending on the context. For example, if you're talking about an animal specifically used for carrying heavy loads, you might use the word "mule", which is another term for a donkey used for this purpose. However, mules are generally smaller and more gentle than donkeys, so they may not be suitable for all tasks.
In general, "donkey" is the most common word to use when referring to this animal in English. If you need to know more specific information about donkeys, such as their diet or behavior, you could look up those topics in a guidebook or online resource.