Yes. Several customers have validated the use of rat type II collagen and bovine type II collagen in their experiments. The recommended protocol is: Keeping all of your reagents on ice: the tube, the antigen, Freund’s adjuvant and buffers, etc.  Add the reagents to the tube, and shake it for 60 sec. After shaking, put the tube back on ice for 3 minutes and shake it again.  Transfer it to syringes and place them on ice. Then immunize.