The animals can't manufacture the amino acid, lysine.
4 seconds sound clip from the Jurassic Park (1993) movie soundboard.
You can hear this line at 01:32:33 in the Blu-ray version of the movie.
Quote context
[...]
- Would we get the phones back?
- What about the lysine contingency? We could put that into effect. What's that?
- That is absolutely out of the question.
- The lysine contingency prevents the spread of animals, if they ever get off the island.
- Doctor Wu inserted a gene that creates a single faulty enzyme in protein metabolism.
- The animals can't manufacture the amino acid, lysine.
- Unless they're completely supplied with lysine by us, they slip into a coma and die.
- Will you please shut down the system?
- It's okay. Look, see that? It's on. It worked.
[...]