You're reading about such differences in bulb wattages used because it depends on whether they're being brooded in the house (most keep thier homes around 70 degrees, so a lower wattage can be used) or in a shed/coop/barn, or what season they're being brooded...brooding in July vs brooding in Jan is a world apart temp-wise for most folks.
If they're in an unheated barn and your area gets fairly cold, you'll want a higher wattage heat bulb. But that also depends on how tight or open your brooder is (you don't want to cook them). If temps in your area are getting down to freezing, and they're kept in a barn, a regular bulb won't cut it, much less a floresc. You need a heat bulb - I'd say at least a 75 or 100 W heat bulb. You can get the red kind at pet shops in the reptile department. Make sure your lamp housing is rated for the bulb you choose. Remember, only the area beneath the lamp,not the entire brooder, needs to be nice and warm. If they're hovering under the lamp a lot, they need more heat. If they're under there a bit, then out a bit, they're good.