Finding an egg in the nest box with blood on the shell can give any chicken keeper quite the scare… At least it did for me, my first time, a few years ago! Young hens and pullets coming into lay are most prone to laying blood-stained egg shells than older hens. However, it can happen at almost any age. So… how does it happen… and maybe more importantly, is it dangerous?
In Young Hens:
When a young hen begins to lay, her internal reproductive system is still adjusting to its new task (creating, moving, holding and expelling eggs). During the early stages of this process, some small blood vessels in the oviduct may rupture. This may occur a few times until the hen’s internal system stretches to the appropriate size and settles.
In Middle-aged or Older Hens (2-3+ years old):
A bloody egg layed by older/middle-aged hen can be the result of a sudden increase in egg size. This can cause a few blood vessels in the oviduct to rupture. Older/adult hens laying blood stained eggs can be caused by sudden increases in day-light. This is because hens’ egg laying cycles are controlled by daylight (as you can read about here: Comb & Wattle Seasonal Growth & Shrinkage). Since daylight controls chickens’ reproductive cycles, sudden increases in light can cause a hen’s body to think it needs to increase its egg production. Sudden increases in egg production can strain a hen’s reproductive system and result in ruptured blood vessels.
Picking & Bloody Egg Shells:
Sometimes blood on the outer surface of the egg can be a sign of picking. When chickens pick on each other, the soft down near the hent is often targeted. When there is blood near the vent, it can result in blood left on eggs layed by the abused hen. For this reason, it is often a good idea to check the vent area of the hen who layed the bloody egg. If you find blood and any abrasions on the external surface of the vent area, clean it gently with a soft, clean wash-cloth and apply a wound/skin care salve. Vetricyn or an over the counter anti-bacterial wound ointment (like NeoSporain) work well. Alternatively, you could use a DIY Honey Wound Salve. If excessive picking (i.e. picking that leads to feather-loss or injuries) occurs in your flock, than you may need to consider giving your chickens more space or keeping less chickens. Flock-blocks/seed-blocks and grass-clippings may help prevent picking by keeping chickens busy.
Lighting & Bloody Eggs
It is true that coop lighting can encourage hens to lay. However, non-natural lighting ing the coop must be used carefully… Since lighting abnormalities can alter hens’ reproductive cycles, artificial lighting in the coop is best used with caution. If you are using artificial lighting in the coop and start noticing egg shell quality issues (such as bloody eggs), doing some research on how and when to use it would be a good idea. You can read more about when and how to use artificial lighting in the coop here: Artificial Lighting: Why and How (The Chicken Chick).