Seems some of the folks here just jump right on criticizing people and don't really even read what is said.
The colt JUST turned 5 months old days ago and I will not go against my Vet's advice and geld him too soon. I don't think horses are people nor am I putting human emotion on them. I have been reading a lot about raising horses naturally and this is the information I have found. It has been PROVEN that abrupt weaning can/may cause loss of confidence and setbacks in training. Perhaps not with every horse but why would I take a chance?
My mare IS the reason I posted this. My concern is for her weight and how to keep it up while she weans her foal.
There are such judgmental people here.
Many of us have worked with broodies, many of them. We also have years and years of working with horses. And you have been told the mare will not keep weight on as long as foal is pulling off her, which is true. And also tells us that you are not feeding mare properly or she wouldn't be underweight in the first place.
And I've never seen anything in print that weaning early/abruptly causes behavior issues. If that were the case, it would be touted widely and followed by the big ranches/farms. Those horsemen spend time and money to turn out the best horses possible. If you have run across it, link or information on where you are reading it is needed.
As another said, what causes problems is people mishandling the foals by petting them and babying them. What is cute in a foal, ceases to be cute when that foal is 1000 pounds.
Horses take their confidence from the humans handling them. They don't dwell on their lives and need therapy to get over early weaning. They don't have problems in their training, with exception of someone spoiling them as foals, from being weaned too early, or too abruptly.
You've been given advice on what to do by people who have experience with this, who got that experience by actually doing it and working with a multitude of horses, not from a book they read on it.