Putting a word at each end of the text of a textfile in Unix -

i want know code in unix if had text.txt, example, , contains:

kerv kerv kerv kerv kerv kerv 

as output want add , @ each end of word follows:

kerv, kerv, kerv, kerv, kerv, kerv, 

try sed,

 sed 's/\(\w\+\)/&,/g'