Can someone please explain me why do mayweather want a blood test?

the big fight is jeopardy because of this ****** blood test.pacquiao doesnt want his blood taken 48 hours before the fight because its going to interfere with his training but is willing to give blood in like january, february and immediately right after the fight and also he will give like how many urine tests they want.then how come mayweather is not accepting this one.its not like the other blood tests will not detect if pacquiao is on steroids or something.is this another antic of mayweather for ducking the fight or is there some other reason why he would not accept it?