Feed for Energy????

I'd definately up her energy intake.  But seriously, you should consider giving her at least one full day off a week.  Where you don't ride her at all.  Sometimes horses get lazy because they don't like/get soured with doing the same thing all the time with no actual break.  Just a thought
You could also try taking a blood picture off her, she might be sickening for something, or her red cell count might be low.  When a horse's red cell count is low, they're not getting enough oxygen carried through their system and thus they become lethargic and tired easily.
Hope this helps

She gets a day or two off a week, our trail rides aren't too strenuous either at the moment bc hubby is going now and we generally stay at a walk.
 
Our scoop is a big metal one so a 1/4 of our scoop is probably half a scoop on the plastic ones.  I'm going to try upping her intake some more. She's not losing weight which is why I wasn't sure what was going on, so I'll try adding more.

In that case I'd definately advise you to take a blood off her.  I know this is expensive, but it might be worth it in the long run, even if just to rule out the possiblity.  You might find she has a low red cell count, and this is what could be making her lethargic.

1/2 scoop, 1/4 scoop........... You don't feed by the size of the scoop you feed by weight. If you are feeding a pre mixed feed start off by following the directions on the bag. It sounds like Tess is working a lot and running out of energy. She just may need more feed. Read the bag.

  Sound advise so far. 
 
  Uping the protein is counterproductive.  When she digests the protein, she will product heat and it's a poor source of energy.  She needs about 2# of protein a day and that will come from 20# of 10% grass hay.  She needs more concentrated energy.  1/2 a scoop is only 1 1/2 to 2# of feed.  I'd get her up to 5-6# for starters.  High fat diets (adding 2C veg oil) has been proven to provide long term energy without the heat build up (mostly used in endurance horses).  You won't go wrong by adding fat, you won't cause any inbalances (you probably would by adding corn), no sugars, can't make her hot...  Blood tests have run me $100 for starters.  You can buy alot of feed with that money.

Well I've been giving her more grain and upped the amount of veggie oil i'm adding in.  (2many, i saw an article on that , the veggie oil in race horses, I was just afraid to give her too much for fear of her getting the poops. ) Last night she had some pep in her step and it was 84 degrees out.. lol. SO I do believe she just needed more calories.
I didn't mean to sound like an inexperienced horse caretaker but I've never had one that had a lack of energy. Mostly mine have too much.
She is on grass hay/timothy all day long, we feed round bales and she's at one almost all day...[] and has grass to spare, the whole pasture has grass but they won't eat it.
 
I also got a mineral salt lick which has taken a beating so she must have been lacking something, which she's now getting.
Now if I can just keep them from pooping in the food dish... [:@]
 
 
Thanks for everyones replies!!!!!!!!

  If you start with about 1/2 C oil daily and add more at a reasonable rate, you won't have any problems.
 
  If she's eating off the round bale all day and isn't plump, that's a good indication that it's mature high fiber hay without much for calories.  It's an excellent hay to keep her busy and warm in the winter but not so good to put weight on and supply energy.  Look at the label on your mineral block.  Most are 98%+ salt.  They don't provide any macro minerals (Ca and P) just the trace minerals.  Look for a loose mineral product with at least 20% Ca (you feed straight grass so Ca levels should be marginal), 10% or so P (much less than the Ca, 2:1 Ca to P is ideal), no more than 20% salt (why pay a premium for salt?), 100,000 IU Vit A per # and some added Vit E.  Hang a bucket with a couple #s on the fence out in the pasture.  They will gobble down the first bucket and drop down to a few ounces per day.

Well she is plump, she is still gaining but is gaining quickly on the hay, that's why I wasn't sure what to do, weight wise she's great, she just had a lack of energy.
 
I did start her on strategy, which is working out well. I believe she just needed something with more to it since i'm asking so much of her, along with needing more in the way of food itself.  We had a 4 hour trail ride yesterday, ( with breaks. ) and she was still rarin to go when we got home.

I wish I had anything intellegent to offer.  I feed mine the best I can for the least amount of money.  Zag's a maniac. []