This site says that cocks crowing say "cuc-a dudal-du", but that seems suspiciously like the English version, and is missing accents over the last two u's which would give the right sound:
http://ga.glosbe.com/en/ga/cockThere's a Daltaí discussion forum at
http://www.daltai.com/discus/messages/12465/11445.html?1045840880 which has two people offering
A Cháich, Éirigh! Éirigh!, as included in this list:
. A HORSE NEIGHS: NEIGH – NEIGH
Déanann capall seithreach: Né Né
2. A DONKEY BRAYS: HEE-HAW
Déanann asal grágáil: íá íá
3. A SHEEP BLEATS: BAA- BAA
Déanann caora méileach: bea bea
4. A DUCK QUACKS: QUACK-QUACK
Bíonn lacha ag gogalaigh: bheac bheac
5. A COW MOOS: MOO
Bíonn bó ag géimnigh: Mú Mú
6. A BEE BUZZES: BUZZ - BUZZ
Bíonn na beacha ag crónán: bis bis
7. A BIRD CHIRPS: CHIRP-CHIRP
Déanann éan bíogarnach: tsíp tsíp
8. A DOG BARKS: WOOF-WOOF
Déanann madra tafann: bhuf bhuf
9. A COCK CROWS: COOK-A-DOODLE-DOO
Scairteann coileach: A CHÁICH, ÉIRIGÍ! ÉIRIGÍ!
10. A HEN CLUCKS: CLUCK-CLUCK
Déanann cearc glágarnach: poc poc
11. A CAT MIAOWS: MIAOW
Déanann cat miamhlach: miao - miao
12. A PIG GRUNTS: OINK-OINK
Bíonn an mhuc ag gnúsach: áinc áinc
13. AN ELEPHANT TOOTS: TOO – TOO
Trúmpann an Eilifint: Tú Tú
14. A FROG CROAKS: REBBIT – REBBIT
Bíonn frog ag crónán: Ribid ribid