I'm hoping the feed gurus can help me make sense of what I'm learning about my mare's nutritional needs (first time owner, owned her for about 10 months). This is a bit long, so I can give all the details upfront...but here's my overarching question: In an older mare with light exercise on a diet of primarily average quality hay, is a hay belly just inevitable?
The basics about my horse:
She's a 900 lb, 19 year old Morgan mare. She's a pleasure horse- ridden about 4 times a week for 30-45 minutes at a time. She is turned out in a 2-4 acre pasture (pastures rotate every other day) every day from about 7am-7pm, and stalled with a run out paddock in the evenings. She doesn't do a ton of self-exercise in the pasture, but is already moving around a lot more now that the snow and ice have finally melted. She is on a regular deworming program.
The basics about her feed:
I feed the hay provided by the barn, a grass mix. She gets 2 flakes morning, 1 around noon (morning/noon rations are sort of hypothetical- flakes are put out in the field, and I suspect she actually eats more than this), 1 around 7pm in her stall, and then 2 overnight in a slow feeder net. Hay has been so-so quality all winter. Here's an analysis of the hay quality (green bars represent the hay):
She also gets 1.5 lbs of Poulin Grain's MVP morning and evening. The vet feels she needs some grain because of hay quality, or she would drop weight, and he likes the weight she's at now.
Finally, she gets a tbs of raspberry leaves each feeding (the equivalent of "mare magic") and 2 oz. Of ground flaxmeal each feeding.
Vet saw her today for spring shots and floating, and his overall assessment was that while her primary diet is primarily 1st cut hay, given her age, build, and activity level, she probably is just going to have a hay belly look to her (worms are not an issue at this time). He thinks the hay belly will go down as she a) gets more grass as the pasture recovers from the winter; and b) gets ridden more in the nicer weather.
I'm new to all this and trust the vet's opinion, but being new to all these feed decisions, it's just nagging at me that she shouldn't necessarily have such a swollen look to her abdomen. Do you all think it's just a given that with her living arrangements and feed, she's going to have a hay belly?
This is clearly not a confo shot, but shows her belly (as well as her weak topline, which is a different issue to work on, but also probably just a sign of her age):