How many letters does the top answer for “a animal that feeds on animal food.” have?

The most common answer is zooephagan (10 letters).

Crossword clue: a animal that feeds on animal food.

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

zooephagan 10 letters web-def

A animal that feeds on animal food.

zoophagan 9 letters web-def

A animal that feeds on animal food.

the killing of animals (as for food) 50% similar → slaughter