[@Arawak]
The Dominion has Half a dozen standard battlefleets and two "Fleets of Recalcitrant Justice" which exist outside of Space Force hierarchy and whose sworn mission is crushing insurrection. The destruction of an antimatter world would probably be felt immediately within its local region of space as the nearby system depend on it for resupply, and the negative effects would slowly trickle into the rest of the Dominion. As time went on. While down an entire antimatter world the Dominion doesn't quite have enough production to meet total demand and while there is a hefty surplus it will still spark an energy crisis until another world can get converted(a process which takes a couple years).