YOU SAID:

do chickens are not horses but they are mammals

INTO JAPANESE

ニワトリは馬ではないが、哺乳類である

BACK INTO ENGLISH

Chickens are not horses, but mammals.

INTO JAPANESE

ニワトリは馬ではなく、哺乳類です。

BACK INTO ENGLISH

Chickens are mammals, not horses.

INTO JAPANESE

ニワトリは哺乳類であり、馬ではありません。

BACK INTO ENGLISH

Chickens are mammals, not horses.