Variable substitution doesn't work inside a YAML block

en.yml

# Variable substitution works here
foo: "The quick brown %{ animal } jumped over the lazy dog"

# Variable substitution done not work here
# Instead, "%{ animal }" gets rendered
bar: |
  The quick
  brown %{ animal }
  jumped over
  the lazy dog

# What syntax should be used in the block for the substitution to work?