I've always had pretty easy keepers but recently acquired a lease horse who works quite hard and needs a lot more feed than I'm used to providing. I analyzed the diet he was on before he came to me and came up with one using my preferred brand of feeds that was better or comparable in every dimension except fat. For a couple months I fed him that diet (1.5 lbs of Triple Crown 30% and 3 lbs of Triple Crown Senior plus 1 lb of alfalfa cubes and free choice hay), thinking he might not need the same amount of fat with me riding him as with his owner, who is a professional trainer. When he started looking a little ribby, I researched the best ways to add fat back into his diet.
There are lots of options, including adding or increasing: an appropriate hard or complete feed, oil (vegetable, rice bran, cocosoya oil), rice bran, flax seed, black oil sunflower seeds, or calorie/fat supplements like Cool Calories. They have different nutritional profiles, pros/cons, and of course costs. More educated people than me have written about the nutritional profiles and pros/cons of these different options so I will not go into that in detail (see the always awesome Understanding Horse Nutrition to start), but what I will share is the cost analysis I performed for the options I considered.
It's easy to figure out how much these options cost per day but to compare apples to apples, you have to also consider how many of your desired nutrients each option provides. Therefore I calculated the cost of four different options per kilocalorie (1,000 calories or 1 Calorie), per gram of fat, and per gram of protein. The options I considered were increasing his TC Senior, adding Legends rice bran, adding canola oil, or adding Cool Calories (a powdered fat supplement). I also considered whether these options provided balanced nutrition or not. Here's what I came up with (click to enlarge if needed):
Red indicates highest costs per unit and green indicates lowest. Of course, costs vary by store and region but these were the costs pertinent to me in the Mid-Atlantic area. The canola oil price was from an online restaurant supply store that sold it for a better price than local stores, but I have heard that Costco is an excellent source too (I'm not a member).
I ultimately decided to try rice bran because 1) the horse had been on it before successfully, 2) oil is messy, 3) it adds protein as well as fat/calories, and 4) it checked the most boxes as far as cost. Since it's not a balanced feedstuff by itself, I checked his new diet in my old standby nutrition spreadsheet (pictured here) to make sure it would not throw off any mineral ratios or cause other disturbances. Good to go!