I used to use 16+ mix on my old boy until he had trouble chewing, then i put him on high fibre cubes(soaked) and dodson and horrell's ultimate balancer.
Spillers Senior Conditioning Mix & Afla A - I have a cob who thinks she's a TB diet wise. Did try the Splliers Conditioning cubes to save a few bob, but she had a complete personality transpalnt til I changed back.
I don't as the high starch and protein worry me. I opt for a high fibre and oil diet for both my veterans. Alfa a Oil, topspec balancer and one of them has topspec conditioning flakes as he's a poor doer (they are very palatable). It also makes their feeds very easy to eat.
Was on D&H 16+, Alfa A, Sugar beet, Vits&Minerals, Codliver Oil, and Tripple Crown body building formula.
Now changed to TopSpec balancer, TopSpec Conditioning Flakes, Alfa A, Sugar beet for my 20yr old. Much easier.
I used to feed sixteen plus for my old boy but i have to agree with Kezza, had my knowledge of feed been what it is now i would have had him on topspec balancer and fibre with conditioning flakes (he was a TB)
I did find sixteen plus did the job thought but he was worked quite hard,