Asked May 26, 2016, 9:42 AM EDT
Pulaski County Kentucky
SInce I don't know what type of hey you have, I'll assume you have cool season grasses like fescue or orchardgrass. Go to the UK publication here: http://www2.ca.uky.edu/agcomm/pubs/agr/agr103/agr103.htm. Table 5 is probably what you need to reference.
If you need something different, please let me know.