It is permissible
to exchange an animal for another animal Imam
Abu Dawud narrated on the authority of
`Abdullah ibn `Amr (may Allah be pleased with them both) (Part No. 13; Page No. 277) that he said,
The Messenger of Allah commanded me to lead an expedition and to give soldiers camels, with which I was entrusted, to mount. I then assigned each of them a camel to mount till all camels were taken and there remained some soldiers without camels to mount. The Prophet (peace be upon him) then said to me, 'purchase for us some camels in return for some young charity camels under hand, which were to be substituted by others after we are done with the expedition.' I then would purchase one camel for two or three young charity camels which would later be substituted by others, until I have been done with the expedition. Later on, when the charity camels were collected, the Prophet (peace be upon him) compensated for those young camels we had taken."
Narrated also by
Al-Bayhaqy in the Sunan (Hadith compilations classified by jurisprudential themes)
on the authority of
`Amr ibn Shu`ayb from his father from his grandfather.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.