Verified answer

It's slang and it carries the idea of "Hang in there, things will be different.". Or "a new day will dawn", which is exactly what happens when the rooster crows.

Literally: "then another rooster will sing", but the real translation is:

"It would be different "

Si las gentes entendieran que tenemos tres mentes, otro gallo cantaría, posiblemente hasta se interesarían más por estos estudios. "It would be different if people understood that we have three minds, possibly they might even be more interested in these studies."

"things would now be very different".

Y si la Comisión hubiese hecho caso de las advertencias que venimos haciendo desde 1999, otro gallo cantaría. If the Commission had heeded the warnings that we have been giving since 1999,things would now be very different."

"It would be a very different matter."

Si las gentes entendieran que tenemos tres mentes, otro gallo cantaría. "If people understood that we have three minds, it would be a very different matter."

By the way, the correct expression is "Pues otro gallo cantaría", but in Mexico is used as "otro gallo cantara".

then another rooster will sing