The intelligence of the animal isn’t a condition if your ethics are based on YHWH’s commands. As long as we’re NOT living in Eden-like conditions, we can eat certain animals (because otherwise, even animals will stop eating animals and become vegetarians, us included i.e. Genesis 1:29–30 and Isaiah 11:6–9;).
In the Garden:
Genesis 1:29–30 (NIV)
29 Then God said, “I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food. 30 And to all the beasts of the earth and all the birds in the sky and all the creatures that move along the ground—everything that has the breath of life in it—I give every green plant for food.” And it was so.
In the future:
Isaiah 11:6–9 (NIV)
6 The wolf will live with the lamb,
the leopard will lie down with the goat,
the calf and the lion and the yearling[a] together;
and a little child will lead them.
7 The cow will feed with the bear,
their young will lie down together,
and the lion will eat straw like the ox.
8 The infant will play near the cobra’s den,
and the young child will put its hand into the viper’s nest.
9 They will neither harm nor destroy
on all my holy mountain,
for the earth will be filled with the knowledge of the Lord
as the waters cover the sea.
Footnotes:
a. Isaiah 11:6 Hebrew; Septuagint lion will feed