While looking for answers to another question about orcs on Quora, I read an answer that referred to Gollum killing and eating an orc child in the Hobbit, but I don't recall coming across that when I read the book (though to be honest I haven't ruled out repressing the memory)- did this actually happen in the book, and if so, where?
Gollum's last meal prior to when we meet him in The Hobbit is said to have been "a small goblin imp", and later described again as "young".
And still sometimes he put [the Ring] on, when he could not bear to be parted from it any longer, or when he was very, very, hungry, and tired of fish. Then he would creep along dark passages looking for stray goblins. He might even venture into places where the torches were lit and made his eyes blink and smart; for he would be safe. Oh yes, quite safe. No one would see him, no one would notice him, till he had his fingers on their throat. Only a few hours ago he had worn it, and caught a small goblin-imp. How it squeaked! He still had a bone or two left to gnaw, but he wanted something softer.
“My birthday-present! Curse it! How did we lose it, my precious? Yes, that’s it. When we came this way last, when we twisted that nassty young squeaker. That’s it. Curse it! It slipped from us, after all these ages and ages! It’s gone, gollum.”
The Hobbit - Chapter 5 - "Riddles in the Dark"
John Rateliff, in The History of the Hobbit, says that this is our only encounter with an Orc child in all of Tolkien's writings.
The ‘small goblin-imp’ captured, throttled, and eaten by Gollum is probably our only encounter in the legendarium with an orc-child. Again, see [the later passage] for Tolkien’s description of it as not just ‘little’ but ‘young’.
The History of the Hobbit - "The 1947 Hobbit" (i) - Text Note 13
In The Lord of the Rings it's perhaps further implied that Gollum specially eats children.
The Wood-elves tracked him first, an easy task for them, for his trail was still fresh then. Through Mirkwood and back again it led them, though they never caught him. The wood was full of the rumour of him, dreadful tales even among beasts and birds. The Woodmen said that there was some new terror abroad, a ghost that drank blood. It climbed trees to find nests; it crept into holes to find the young; it slipped through windows to find cradles.
The Lord of the Rings - Book I Chapter 2 - "The Shadow of the Past"
Yes, Gollum did kill and eat young orcs (goblins) for centuries when he lived beneath the Misty Mountains, but there is no mention of Gollum killing and eating an orc child in The Hobbit. The only reference to Gollum's cannibalism in The Hobbit is that he intended to eat Bilbo after the Riddles in the Dark.
Citations:  https://fictionhorizon.com/is-gollum-a-cannibal-and-does-he-eat-babies/  https://www.reddit.com/r/tolkienfans/comments/1kl17u/gollum_eats_babies/  https://en.wikipedia.org/wiki/Gollum