In 3.0 there wasn't an animal companion ability- It was a spell(Drd1/Rgr1)that let you gain up to your Caster level in animal companions or CLx2 if you don't adventure(basicly only NPCs)so a high level Druid NPC could/would have like-a pair of Tigers for Flanking(6HD each)an Owl/Hawk/Raven for scouting(1HD each) a Dire Bear for the fighting(12HD I think)
the Beastmaster was in Comp. Adventurer