South Korean babies born on December 31 become 2-year-olds the next day.

[csziggy]

4. Same for Quarter Horses

People try to bred the mares in late January or early February so the foals will be born as close to January 1 as possible. Average gestation in horses is about 340 days so if the mare is cycling appropriately, you can time the birth. Ocasionally a foal will be a few days early - and often those foals are not "discovered" in the fields until January 1.

I visited some horse farms in March and saw foals with very long tails and manes - obviously they were more than three or four months old. More like six or seven months in my opinion.

As a performance horse breeder, I did not have the pressure to produce foals that early, though the natural cycles favor conception in the spring. I did have a foal or two born in the fall, mostly when I had a mare with fertility problems that we turned out with our young stallion so she could teach him manners. He learned to be a gentleman when breeding and we got a lovely foal that we never expected!