HGG Community Forums

What is happening?
The + and t alleles of agouti are being removed from the game.

When?
Probably around September but I am not positive on the exact date.

Why is this happening?
When HAJ was first created we did not have agouti variants. Then it became the internet consenses that + and t were real. After several years of this being the dogma, I added them to the game. There now is updated scientific evidence showing that the thinking from that period was incorrect. As far as we know A and a are the only alleles of the extension gene found in horses.

What is going to happen to wild bays?
I am going to create a new gene for the restriction of black points. It will work just like wild bay does now BUT instead of being on the agouti gene directly, it will be inherited separately. You will need to breed for agouti AND agouti promoter to get wild bay horses. Agouti promoter is going to be just as common as + is now and I will be turning horses with + in the game now into these promoter horses. The transition should be seamless for you. Other than having to watch out for both genes when breeding instead of just agouti status breeding wild bays won't be notably different.

The + allele will be removed completely in one swoop but your horses will not appear any different.

What is going to happen to brown?
Brown is more complex and will see more drastic changes. First, the t allele is going away NOT the brown phenotype. Brown will change to work like liver and chocolate palomino does now. A horse will need 4 or mark darkening conditions to have bay become brown in their color name. This is based on current scientific understanding showing that EE horses tend to be darker than Ee horses and that Aa horses tend to be darker than AA horses. (EE Aa horses tend to be brown.) This is combined with other darkening factors (represented as sooty in the game) to create the final shade of the horse's coat. E (extension) and A (agouti) status are not the only factors that decide if a horse is brown but they are contributing factors.

What is a darkening condition?
With our liver horses each copy of sooty and each copy of DP count as one darkening condition. This will be true with brown horses as well. In addition to sooty and DP being EE or Aa will also count as a darkening condition for brown horses.

EE = +1
Aa = +1
Sty/- = +1
Dp/- = +1
Sty/Sty = +2
Dp/DP =+ 2


Will my brown horses turn bay?
No. While I am totally eliminating all copies of the + allele the brown allele will stay in the game as a ghost allele. I will not be removing t from any horses. I will be making it so all t alleles look like normal A alleles but they will secretly be t. That way if your horse is brown now that won't change. However, they will not be able to pass on this t allele after the changeover. All foals they produce will get the normal A allele instead of t.

Will my brown lines turn bay?
Maybe. Absolutely some genetic combinations currently in the game called brown will be called bay after this change. Since most people who breed for brown also breed for heavy sooty and DP in their brown lines, most lines will be unaffected. This post is your multiple months in advance warning. If you breed for brown without sooty and DP you should start adding those to your line. Sty was already a requirement to get reliable brown horses in the game so this should not be difficult.

Exactly what genetic combos will be bay versus brown?
I have made a spreadsheet
https://docs.google.com/spreadsheets/d/1EHr5iP5D8NNHME1LWc-6tgpwupd_BdZpuMKeqNBnZuI/edit?usp=sharing

Will DP now be required for brown?
No, EE Aa StySty horses will brown even without the DP gene.

How can I guarantee brown foals every time?
EEAAStyStyDpDP is true-breeding and will produce a brown foal every single time if both parents have this genetic combo. Make sure your lines are heavy with Sty and Dp to guarantee brown foals. Keeping your brown line homozygous for black will also help a lot.



You are welcome to post any questions, concerns, or feedback. I am starting this conversation very early because I know this is going to be a scary change for some of you and I want to make this as smooth as possible for everyone. :)