my mare with the tmj infection has dropped some weight these past couple weeks due to the heat. What can I add into her sr grain that’s easy to chew? She’s currently getting 8lb sr a day and 2 large cups alfalfa pellets

I loved Healthy Weight from Platinum, but my old guy had been on it so long (I think) he got to where he wouldn't eat all his food.  So I switched to rice bran, and I'm happy with it too.  

I love rice bran for weight gain. You can get max e glo almost anywhere and a bag goes a long way.  

Rice bran pellets and alfalfa. I've also had good luck with Triple Crown Sr.

I've had good luck with Purina Amplify.

GROUND FLAX!!!!!  Google it.  TONS of benefits.  One cup per day provides 2000 calories.  Anti-inflammatory qualities..... Most local feed stores can get it in.  Cold Milled Flax in a 50lb bag runs less than 30 dollars

For putting on a finishing touch of fat on one I like rice bran and and oil, or flax and oil.

For helping an underweight horse I like to cover all the fat bases and use flax, rice bran, oil, and I've started using cool calories to really pack some fat weight on.

I also starting using no-hull sunflower seeds this year. They are full of good fats and so many vitamins and minerals! All but my lactating broodie are fat and shiney (and the broodie is looking good - just no fat deposits anymore) and I'm thinking that I can cut out the oil from any feed not getting flax or cool calories. 

Alfalfa is great for topline gain but does not add much to the shoulder or rump fat.