Assignment of gender depends on the rules of the particular language utilized. The word Buffalo has been borrowed by several languages and is treated different in the context that it is found.
In English there is no gender derivative of the word and one must resort to the terms 'bull' and 'cow' after having established the spieces being discussed.
In latin based languages gender could be assigned by altering the terminal 'o' for male with an 'a' for female however I have never seen this done.
In Sino based languages gender could be assigned by adding inflection to some interior vowel : rising inflection for male /, falling inflection for female \.