I didn't mean Baxter IS the horse my friend rescued, I mean that how far underweight he is LOOKS like my friend's horse that she rescued.
Personally, I'd start feeding him alfalfa (more protein content than timothy or bermuda grass) and start with supplements or grain, as Superhorse suggested. I know my friend put Compton (the thoroughbred) on alfalfa twice a day, free-choice bermuda grass hay (via a hay net) and Purina Equine Senior in the evenings (can't remember exactly how much, but basically a big Folgers coffee can worth lol).
Now that I went back and looked at the pics of Compton when my friend got him, I have to say that Baxter is MUCH thinner.
Thoroughbreds are HARD keepers Heres what I do....
I have Thoroughbreds (don't know if your horse is a TB or not) but I've had a heck of a time keeping weight on mine. I got them and they were skinny VERY skinny.
First off like the other posters said, you have to check their teeth
Have them wormed. If the horse IS a TB check for ulcers.
Or YOU COULD JUST GET THE SMART PACK Ultra Digest or smart gut
You can also add oil to the feed for more fat.
I used to give mine olive oil but corn oil is ok too
Also just for reference mine get 4 coffee cans of concentrate feed
Split into 2 feedings with free choice grass hay and 1/4 bale of Alfalfa
Once daily. That's a LOT of feed to most ppl but the TBs eat a lot. They are 16.2 and 17HH and a horse that big is almost twice as big as most horses
So guess what? They eat twice as much LOL
Was this horse Skinny when you got him or has his condition gone downhill since buying him? No judgements It's happened to me too I was just wondering if he was in good condition when you bought him then you could call the previous owner and ask what she/he was giving him to eat. That could be your base line starting point. Otherwise I'd slowly start upping his feed to give him more to eat. If you find you have been giving him a lot more feed and he still looks skinny then try the smart digest smart packs
They worked really well for my skinny horses.
I didn't see the pictures, but I know that my daughters jumping mare is a thoroughbred and we have a heck of a time keeping weight on her. She gets grass and alfalfa hay. We were feeding her a special grain made by a local feed store, with rice bran oil and a product called Cool Calories, which did wonders. Is your horses coat rough looking? Worm and teeth, if that doesn't help you might opt for a simple blood culture to make sure there isn't underlying problems. :) I hope all works out. I know that sometimes things sound harsh on forums, but it sounds like you really care.
That horse is darling but I must agree, he's really underweight. When was the last time you dewormed him? I think you said you'd had him 6 months? If that's the case then go ahead and deworm him. You can get that at the local feed stores.
Next I would think about getting his teeth checked. You can do that at your next vet appointment if you have one scheduled or planned in the next few months. Is he up to date on all his shots?
Now, the hay may not be the issue but you can never go wrong with a good quality hay so if yours is mediocre you'll be surprised at what a difference a good quality hay will make.
I would probably go ahead and put him on a pelleted grain. My first horse was a good 250-300lbs underweight when I bought him. You could actually fit 2 fingers between his ribs and believe it or not, I had no idea just how thin he was. I even hauled him to a horse show. He had a hole in his face that was draining puss, you could see every bone in his body, his hooves were cracked, and he had starvation hairs on his belly and to me... He was perfect. Luckily there was a really nice older women at the showgrounds that asked if I would like a tour of the barn. While she took me on this tour she explained to me about each horses personal needs and discussed feeding schedules, she talked about worming and shoeing and shots... basically educating me without me realizing it.
I started out by feeding him just 50lbs of pelleted grain per week (he was fed twice a day) and he ate about a bale of hay a week. He was also on 30 acres of grass at the time. Within in 2 months he was amazing. Ribs were gone and man did that coat shine!
I've had rescued horses come in as thin as Baxter and worse. One thing that seems to work for me is Purina Omolene 400 and Ultium Competition. The 400 is designed to be a complete feed so that if the hay you're getting isn't the best quality the horse still gets the nutrition he needs. Depending on the size of the horse, I decide what weight he SHOULD be and I start feeding for that weight. For instance, a 15 hand horse with large bone should weigh approximately 1100 lbs when fit in light work, so I find the weight on the bag's feeding instructions and give that many pounds of feed. So on the 400 bag it says I should be feeding between 13 and 15 lbs of feed per horse per day. I would break that up into at least 3 feedings, preferably 4 so that he's not fed too much at once. I then add 1/4 lb of the Ultium to the feed per feeding for 1 week. Then after 2 weeks I add 1/2 lb per feeding and stay there until the horse has reached what I consider his ideal weight. I also free feed grass hay through out, I just make sure the horse eats his bucket first, then he can have all the hay he wants. I also put 1 oz of fine white salt on his feed twice a day and give lots of fresh, clean water for him to drink.
I've had a lot of success with this feeding regimen and gotten some skinny skinny horses back up to weight and shine with it. I also routinely De-worm with Ivermectin twice, 1 time now and then 1 again in a week, and then one month later I use a combination de-wormer to make sure I get anything left by the Ivermectin. I also have teeth checked and floated if necessary, and if any bad ones have them pulled. Sometimes the vet will want to wait on teeth until the horse is in better condition, that's ok, you can soak this mixture until it's nice an soft with no problems.
Looking forward to seeing pics of Baxter when he's fat, sassy and shiney! I've attached a picture of one of my horses, we call him Round Boy because he plumped up so well on this feed. He was very thin when I got him.
He's still in real good flesh, but he's not this fat anymore, he got a little tooooo healthy on this feed so I cut the amount a bit.