Shrimp shells would be great for them - blitz them in the food processor to crush them into small enough pieces so that they can eat them easily.
They may eat the sprouts raw - my neighbour's chickens love raw cabbage. But mine won't touch raw cabbage or sprouts, they're only interested in it when it's cooked. Having said that, I've seen my flock's tastes change over time - maybe due to the influence of new additions, who are prepared to try things the old flock never showed an interest in.
How old is Violet? She may not be laying simply because of the stress of confinement in the garage, or due to the temperatures and lack of daylight (most chickens stop or slow down during the winter).
They may eat the sprouts raw - my neighbour's chickens love raw cabbage. But mine won't touch raw cabbage or sprouts, they're only interested in it when it's cooked. Having said that, I've seen my flock's tastes change over time - maybe due to the influence of new additions, who are prepared to try things the old flock never showed an interest in.
How old is Violet? She may not be laying simply because of the stress of confinement in the garage, or due to the temperatures and lack of daylight (most chickens stop or slow down during the winter).