Groups of buffalo (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">groups of buffalo</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for herds that I've seen before include "Group of animals" , "Group of cattle or sheep" , "Groups of cattle" , "Groups of animals" .)