Guineas are 28 dayincubation. Give or take 2-3 days like other poultry. If you have any male guineas the eggs your hens lay should be fertile and if left alone long enough 1 or 2 will most likely set on a nest. Sometimes its a nest that ALL the hens layed in. Issue with guineas is they like to be alone for broodiness. On my 3rd and hoping 4th guinea brooder. Last year we didn't even know we had 2 hens sitting. Until I saw a white cloud follwing hen. Then went looking and found a 2nd broody guinea. They hatched great, not so well on rearing. I have 1 white already this year due really soon, sitting on a nest of about 48. Another went AWOL last week. My birds free range except birds kept in breeding pens for pure, experiments or SL reasons. Guineas are free to roam and they do roam everywhere.
As for the silkies brooding it depends on birds My BA just successfully hatched eggs in what I call the general layin house. There are chickens ducks and guineas in that coop. She never had issues. But other have the opposite in their flocks. Pecking order went thru a big change, she was the new "DON'T MESS WITH ME" bird. Even the Rouen drake that chases male guineas away stayed well away from her. I did move her and chicks today into a booding pen because her nest was 2-1/2 ft off the ground and the drake might have tried grab a chick. And the female rouen started laying in coop again today. SHe only fussed when she was put in pen w/o her chicks for about 2 minutes. Then she calmed right down with her babies.
