in reality the house voted against requiring the government to add a clause into the EU Withdrawal Bill that would have then bound the government to include it as part of the EU withdrawal:
Clause 7, page 6, line 18, at end insert—
“(g) fail to pay full regard to the welfare requirements of animals as sentient beings.”
Member’s explanatory statement
This amendment holds Ministers to the animal welfare standards enshrined in Article 13 of the
Treaty on the Functioning of the European Union.
which isn't the same thing as "voting against animals feeling pain"
the government could still do this, just it isn't bound to
(the environment secretary has been on a bit of a roll recently, such as requiring CCTV in slaughterhouses, a total ban on bee-harming pesticides, and so on)