You need to compare pictures during the same season. Big difference in winter vs summer coats on a lot of them. I know my app I have now and the one I had as a kid had almost 2 sets of markings.
Those crack are just surface cracks. I could actually brush them out with a rasp. I did once because my daughter was giving me crap about making feet look pretty. Did it just to prove to her I can.
I wouldn't worry about it. Trotter is a nice feed. For an older one that has been around a long time it is fairly low starch. I fed it for over 20 yrs with no issues. And what I noticed in my own horses could very well be caused by reaching advanced old age. King colicked in the night and kinked a gut. It was too late when I found him. 35 yrs isn't ancient but it's respectable. He went the distance.
I'm so certain the last round of trotter I bought did mention the spent grain from the brewery. I forget how it worded. It shouldn't be a problem because fermentation used up most of the sugar and starch. The tag online is the one I saw year after year unchanged. I do read them periodically. I think now I'm going to save one from time to time. Write the date on them and tuck them away.
That picture is King taken just 2 days before he died. Not bad for an old man.
and King at 17ish. Trotter fed the whole time. It's just that sneaking, nagging suspicion something was different. It could even be just me still mourning his loss. I do so miss the big dopey muscle head and all the chaos that came with him.
I don't mean to worry you needlessly. If I go into town today I'll have to read a bag of trotter. It's really bugging me now.
Trotter is still a nice feed. Don't worry.