Most feeds (in the US) are in the 1500-1600 cal/lb range. There are a few “performance” feeds I know of, like Ultium Competition, which are higher (in the 1900 range) but also, there are some Sr feeds, like Triple Crown Sr Gold, in that range (around 1800).
There’s a lot of assumption that performance feeds are higher in calories, and “maintenance” feeds are lower. That’s really not the case, because see above - the vast majority are in the 1500-1600 range, whether it’s growth or sr or maintenance or performance. The details might vary - higher protein or higher fat. But in general, they’re all mostly in the same 1500/1600 range, with a few in the 1400 range and a few above 1600.
Same for sugars. This seems to be more about brands, than category of feed. Triple Crown feeds for example are all less than 21% NSC, with most < 20%, and the majority <16%, whether it’s competition or growth or sr. Purina? The Omelene series is almost all over 30%, including the growth feed. Omolene 100 is aimed at the “active pleasure” horse, but has an NSC over 30%. Then there’s the WellSolve line aimed at the EMS horse (regardless of calorie needs) Nutrena is mostly on the higher side, with some on the lower side.
There are a TON of feeds available for all ranges of horses. People just don’t choose properly, and sometimes that’s due to availability.
Want a practical, realistic feed for ordinary easy keepers? Ration balancer. Nearly every brand has one, and most stores who carry a brand carry the balancer. But even then, people don’t use it right. It’s an education problem Companies can’t make people understand. They can’t help that people need calories, but use a ration balancer, so feed 8lb of it instead of getting a more suitable feed. They can’t help that people don’t need the calories but get a 'regular" feed and just feed 1lb of it.
The feeds are out there. It’s buyer education that’s lacking.