It is preferable to use a shofar from a ram for tekiyas shofar. Since a ram was the sacrifice that was offered instead of Yitzchok Avinu, it serves as remembrance of the Akeidah. The ram should be at least a year old. If a shofar from a male is not available, one from a female is also acceptable. B’dieved, a shofar from any kosher animal is acceptable. If there is a choice, a shofar from a domesticated animal takes precedence over one from a wild animal. Preferably, the horn should come from an animal that had a kosher shechita. A shofar from a non-kosher animal is not acceptable. If that is the only one available, it should be blown without a brochah.
[שו"ע תקפ"ו, א ומשנ"ב א,ב,ג וח ביאורים ומוספים דרשו 1,2,ו7]