I do not weigh their feed and could not know how much she is eating as the two horses are together.  Midnight probably eats more than Stara as indicated by her body score of 7+ while Stara is a perfect 5.  But there is always hay left in the nets and they both rest in between eating... Midnight at least as much as Stara.  I think like people, some horses are just heavier.  They are full sisters, 2 years apart and could not be more different in most every way.  She's almost 21 years old and has never had laminitis.  My vet says she's less concerned about that but worries about lipomas, which is what got her mom when she was 27.  But I do agree that it would be great if I could give her less hay.
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Linda in CA  2020  Midnight and Ostara
https://ecir.groups.io/g/CaseHistory/files/Linda%20Midnight%20OStara