There are two basic differences in chicken feed, calcium and protein. Hens that are laying need extra calcium for their egg shells. The chickens that are not laying don’t need that much calcium and the amount of calcium in Layer is dangerous for growing chicks. The broody hen does not need the calcium since she is not laying eggs. The chicks should not have it. So get a feed for them that is somewhere around 1% calcium, not around 4% like most Layer. Look at the analysis on the label.
You can get feed with around 1% calcium that has a protein level anywhere from 15% to 24% and maybe higher. A general recommendation is to feed them a relatively high protein feed, probably around 20% protein the first 4 to 8 weeks, whenever the bag runs out in that time frame. Then switch to a Grower that is probably around 16% until they start to lay. The higher protein level in Starter gets them feathered out faster and off to a good start, but after they are feathered out and have that start they simply don’t need the higher protein level. Other people like to feed a higher protein level. As long as you don’t get ridiculous about it a higher protein level won’t hurt them, but higher protein feed costs more. Since they don’t need it, I don’t feed it.
There is another side to this though. It’s not about what is in one bite, it’s about how much total calcium or protein they eat in the entire day. If the feed is only a small portion of what they eat and they get a lot of their food by foraging or from something else, then the make-up of the feed is less important. You have a lot of flexibility in what you feed them.
The chick needs to stay on the chick feed until it starts to lay if it is female. The calcium is the danger to a growing chick. There is a lot of debate on here as to how much the extra calcium in Layer might harm an adult chicken that is not shedding the excess calcium by putting it into egg shells. Some people think adult chickens can handle the extra calcium, some think it puts too much stress on the kidneys and liver to expel that extra calcium from their bodies. I avoid that debate by never offering a high calcium feed. I feed a grower or starter, depending on whether I have chicks with the flock or not, and offer oyster shell on the side. The ones that need the calcium for their eggs seem to instinctively know they need it while the ones that don’t need it don’t eat enough to harm themselves.
If the broody hen is raising them on the ground they will be eating dirt, small pebbles for grit, bits of vegetation, and anything she can catch for them or they can catch themselves, including worms. The key is that they will be eating some small pebbles to use in their gizzard to grind this stuff up. They don’t have teeth to chew with so they use what we call grit in their gizzard to substitute for teeth. I don’t know where you are located. If you are in the US, the stuff labelled “grit” at the feed store is what you are after, it’s crushed granite. Get the chick grit so it is small enough for them to use. If you are in the UK what I’m talking about is labeled “insoluble grit“. “Soluble grit” is oyster shell, which the chicks should not eat and is not what you want. If they are on the ground, they will find their own grit. In any case it never hurts to read the label and see what the contents are.
Broody hens have been hatching chicks with the flock and raising chicks free rage with the flock since there have been chickens. A lot of us let them do that. But a lot of us isolate the broody while she is hatching, some isolate the hen and chicks when she raises them. Some people take the chicks away from the broody hen and raise them themselves. There are different benefits and risks of each method. There is not one right way to do any of this where everything else is wrong. There are a lot of options. That’s part of the problem for new people unfamiliar with chickens, there are too many options that work.
I let my broody hens hatch and raise the chicks with the flock. The other chickens normally don’t bother the chicks, but if they do Mama politely and thoroughly kicks butt. Nobody threatens her babies! The dominant rooster is highly unlikely to harm a chick. He is much more likely to help Mama raise his kids (whether he is actually the father or not), though most dominant roosters just leave that up to Mama. Non-dominant roosters and especially young cockerels are likely to act more like the hens, not likely to cause a problem but if they do, Mama handles it.
One of the keys to this is how much room you have. Mama needs some room to work with. If she is shoehorned into a tiny area it makes it harder on her, but you’ll probably have problems trying to integrate Mama and the chick (I think you only have one) back with the flock if you isolate her and don’t have much room.
One thing I’ll mention since your post raised a red flag. While most of the time the rest of the flock doesn’t bother the chicks, they are still a threat. Most of the time does not mean always. If you try to isolate them, make sure the chick cannot get through the fence and away from mama’s protection. That’s one of the risks of isolating them, that the chicks can get away from Mama’s protection.
Edited by Ridgerunner - 1/30/16 at 7:00am