Translation

The Japanese word for "Mule" is raba ラバ.

Romaji ra ba
Hiraganaらば
Katakanaラバ
Kanji 騾 馬
Meaning Mule Horse
School Level ✕ 小2

Loan-word

The word "Mule" katakanized would be myūru ミュール.
Romaji myuu ru
Katakanaミュール
Hiraganaみゅーる

Further Reading

Wikipedia: Mule (騾馬)