Single word for "Young of an animal"

In a conversation today I needed a word for "Young of an animal". Not animal-specific like "puppy" or "kitten".

The conversation went like this:

Me: 2 kittens to be precise!
Person: Kittens are cute!
Me: All [hesitation due to not knowing a word] youngs of animals are cute.

I would have said litter but I am not referring to a group of youngs. Also I want that word in singular.

Youngling can mean a young animal.

Merriam-Webster defines it as:

one that is young; especially : a young person or animal

Offspring and spawn are reasonable generic suggestions. The plural and singular forms of these words are identical.

There is no single word for this concept that is in common use; usually, the terms people use for the types of animal with which humans have the greatest involvement are fairly species-specific, as you have already implied.

However, the simple description 'young animal(s)' covers the idea quite well for the young of any animal that isn't conventionally thought of as a bug or a creepy-crawly.

Take a look at this Ngram (which I have set to display the maximum possible smoothing of 50) to compare the prevalence of some terms (most of which will be very familiar) for young animals in books published between 1800 and 2000. (I have excluded terms like 'kit' and 'fry', which would generate too many false positives because of their overlap with senses of the word that have nothing to do with animals.)

You will notice that youngling, which is very much a dialect term, always lies at the very bottom of the frequency distribution.

As long as the animal is carnivorous, it is a cub.