Pretty unique premise and main character. Well-written and paced, and with an interesting scenario.
Looking good for a first chapter, in terms of quality and chapter length. Looking forward to a future update!

A FOE story from the author of The Book of Friendship? You have my attention, and the attention of anyone else who'll listen to me.

I like what you've done here. Characters are diverse and interesting. Dialogue feels natural. You do a good job of weaving subtle exposition into the narration without cluttering it (I especially like how you interspersed snippets of Scootaloo's message to the overmare throughout the narration; it makes the story accessible, even to those who haven't read FOE, by mentioning things like the war with the zebras, the bombs, Stable-tec, social experiments, etc.).

I like how your characters all have very obvious names. I see a lot of authors (myself included) putting a lot of time and effort into their characters' names, but it's really rather refreshing to see everyone be exactly what it says on the tin.

And I especially like how your narrative takes its time with setting up the story, but while still accomplishing the important things a first chapter should accomplish (namely: catching my attention, and introducing the main character(s)). A more hackneyed FOE story might have had a gang of raiders simply break into the stable halfway through the chapter...
Instead, we get time to see what the condition of the stable is like, and get a feel for how the ponies there make their lives. And, honestly, it seems pretty benign. Boss is a dick, but she's apparently the only pony in there who hates her job. There's freedom of expression, freedom of information, and though the overmare is strictly a dictator by definition of her role, she's ultimately a benevolent one, so it works out.

I'm eager to see what comes next.

Oh, you goofed and called it stable 55 in there somewhere, btw.

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Ohhh, dang it. I'll have to fix that up. Heh. I made a number of errors while writing it - couldn't remember if this was stable 51 or 52, hehe.

A few typos, but a good start otherwise.

I really like you've done with this story so far. Please keep going. (I'll be stalking following your progress on the Pony Fanfiction Thread)