suddenly spooky/starled horse

Question
Hi. This is a great forum on nutrition!  I'm hoping you may have some thoughts on a boarder's 3 yo TWH recent behavior change.

Has been under saddle since young 2yo.  Purchased from horsetrader in TN. Has usually been calm on trail but very jumpy in stall [24 x 24, no regualr turnout schedule]. EX: every day, when bucket w/supps is dumped into feeder, he jumps. He recently bucked off a child and the owner [very uncharacteristic].

DIET: ~16h, BCS 4-5
1 flake of alfalfa/grass mix 2x/d. Fed by flake, not weight. :-(    Eating time ~1 hour/day.  
Owner recently supplementing him w/multiple fats--Cocosoya oil, a rice bran product [do not know if it is balanced and stabilized for Ca: Phos] and another weight gain product. In your answer regarding Omega 6:3 ratio, I am wondering if all of this fat supplementation is throwing something off or reducing the absorption of vitamins or minerals from hay or other supps. A holistic vet saw him recently and thought he had been overvaccinated w/Flu/Rhino and had some herpes lingering in system, but owner did not agree or follow up.
I'm feeling sorry for this horse.  He is jumping at every slight move or noise.

Any thoughts welcome.

Answer
Hi Barbara,

I really enjoy writing this column as it is my passion.  I'm just a horse nutrition nerd that way:)

Before I put together an theory (and in true Canadian form) I'm going to answer a question with a question...or two, or three.

1.  Is the horse on any grain at all, if so what and how much?
2.  How much of the fat supplements is the horse getting (not sure if you'll have access to this)?
3.  What weight gain supplement is the horse on?
4.  Has the horse had any illness or been on medication (other than the vaccines) as of late?

I'm pretty sure I have a suggestion that will help but it would be a patch to something else going on and I'd like to see if we could get to the root of the problem.

Look forward to the information.

Thanks, Corlena