I think I've solved this one: Mods, please move this to Solved.
It appears that I did, in fact, conflate two movies. The breastfeeding of the baby in the end credits is from the Juzo Itami's Tampopo (1985). Breastfeeding in credits, check. But carnival music plays in the background.
The Thus Spake Zarathustra music in the end credits is from one of my favourite B(ee)-movies, Invasion of the Bee Girls (1973). As the music plays, the camera pulls back out of a window, and focuses on bees gathering pollen from flowers in the foreground.https://archive.org/details/InvasionOfTheBeeGirlsWidescreenQualityUpgrade