IMO either none or only on off days. There is no point in doing cardio and training on the same day all you are doing is burning calories that you could be using to build muscle.
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"You've got to block out all distractions when you train. Your focus has to be 100% into the rep. You've got to get into a zone. You know you're in the zone when guys in the gym look you in the eye and then quickly turn away 'cause they see the fire. You've got to be all business." - Dorian Yates
I agree with this. If you want to do cardio during a bulking phase for health/heart/mood benefits, I'd limit it to 3 times a week for 20-30 minutes, keeping the heartrate low (as in under 130 should be good, or where you can talk without difficulty). Lower heartrates burn a greater proportion of fat. Prolonged higher heart rates (like high, as in 80% of max and above) trigger higher release of adrenalin and cortisol and can interfere with your gains.
i would always do cardio whilst bulking. bodybuilding isn't just about getting a good physique its about keeping healthy as well. keep the cardio low but still do some