Unless my math is wrong it seems like you would lose silver by using lamb meat to make good feed. It would be nice if the market prices adjusted to make good feed profitable.
A lot of craftable goods in the game are this way. Even something as big as a frigate, the selling price doesn't reflect what goes into making it.
I should mention, you can get multiples out of things like food crafts though the higher your cooking level, so cost can be offset.