Another method you might try is taking the rodents out the morning of feed day. I usually take mine out before work and allow to thaw all day in room temp (12+ hours). Come feeding time I run some hot water through the tap and hold the rat's head under the hot water with my hemostats for roughly ten seconds just to heat up the head. Then I dry with paper towel and present to my BP. With the warm head, she is rather quick to go into feeding mode and usually strikes within the first ten seconds.