Sorry to her you lost some girls. Snakes usually will take a chick or eggs but a hen is rarer
Clearing debris piles and trimming long grass/weeds helps A LOT. Takes away hiding places. Depending on the snake (king snakes, rat snakes, Gofer snakes, non venomous water snakes) you may want to put them on the other side of those same woods alive, you want some around or you'll have an influx of rodent problems. Which can end up being a bigger problem than the snake. Venomous snakes should be handled by experienced persons and relocated to non people areas or killed if a continuous threat.
If they're getting inside to kill find out how. They can get thru chicken wire. Change it to half inch hardware cloth wire, fill any holes check for cracks in boards.
If they're getting attacked free ranging, its harder. Clearing the hiding spots is great. My aunt uses a garlic/leek spray (her excess she grows she mushes all together raw making a horribly strong tea and sprays that liquid) along her fence line to her woods and swears the snakes don't like it and he hasn't been bothered since.