Final answer:
The noisy animals in the menagerie always drowned out any protests.
Step-by-step explanation:
The animals that always drowned out any protests were the noisy animals in the menagerie.
For example, in the passage, it mentions the 'stink from the stalls, the animals' commotion at night, the pieces of raw meat dragged past him for the carnivorous beasts, and the roars at feeding time.' These sounds would drown out any protests.