Ry

I feel weird that I’m been here long enough to remember the original context–OP is mocking this post:

the picture clearly looks like some sort of strawberry ice cream, so OP did a copypasta of the original text and replaced with picture with something even funnier.

(One thing before we start: I’m finding that with the phrasing, I’m torn between what’s scientifically correct, and what’s actually easy to comprehend for anyone starting off with no previous knowledge. I hope I found a sort of compromise that works for both.)

Let’s start with the Extension locus. The two possible alleles that can be present here are labelled E and e. E is dominant, while e is recessive. This means that a horse only needs one copy of E to be able to produce black pigment.

Here’s an example of how a chestnut foal can be born out of a pairing with two black parents:

The deposition of the black pigment is also influenced by the Agouti locus:

If we add the Agouti locus into the mix, things look a little more complicated. A is dominant, while a is recessive. If both A and E are present, the black pigment mainly shows up in the hair in the “points” (legs, mane, tail etc.), while the body remains red/brown. This creates the typical bay coat.

Here’s one more example of a possible pairing:

“Haunted and Hunted” by Lore on Twitter

On one hand, I've always heard the '20% of their weight' rule but on the other you have, for example, rather large adults who ride smallish horses seemingly without problems (like Icelandic horses) and Mongol ponies who can supposedly carry more than their own weight

If a horse has been trained to carry itself correct, the saddle fits and the rider sits properly can they safely carry much more than 20%? Does it depend on breed and conformation?

GV here.

It definitely varies from horse to horse. Fitness (of both horse and rider!), bone density, age, and height of the horse all matter. 20% is a general starting point, but may go up or down depending on the mentioned factors. A heavy rider that is good at riding and can balance well, is honestly easier for the horse to carry than a rider that is perhaps lighter weight but isn’t balanced or bounces all over the horse’s back. A 25 year old horse probably can’t carry the same weight that it carried as a 10 year old. A 17hh thoroughbred probably can’t carry the same amount of weight as a 17hh draft horse.

For example - take William Fox-Pitt. He is an Olympic level eventer, which is well regarded as one of the most physically difficult riding disciplines out there. He is 6′5″ and makes his horses look tiny. A healthy weight for someone of his height is about 190-230#, so we’ll assume he’s somewhere in there.