Fiona, I think the issue is that they are estimated starch and sugar levels and not guaranteed levels.   I read someone had them tested once and they were no where near the listed levels. The safe feeds list has foods with guaranteed levels of starch/sugar.
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Lesley Bludworth 
Phoenix, AZ   7/2022
Sophie TWH mare
https://ecir.groups.io/g/CaseHistory/files/SophieB%20Case%20History
https://ecir.groups.io/g/CaseHistory/album?id=277749