The probability of hatching an equal number of hens and roosters when you set eggs in an incubator is about 50/50 with a slight edge towards hatching more males. Since most people are interested in hatching only female chicks, or at the very least, hatching predominantly more females, wouldn't it be nice if there were a way to hatch improve your odds of hatching hens and not roosters? Well there is!
While there are various ways to sex baby chicks after they hatch (including wing feather length, feather color differences, and vent sexing), some only work on certain breeds and some - like vent sexing - are best done by the professionals. There are also many old wives tales passed down generation to generation to determine if you have male or female chicks, but they're not proven nor produce consistently accurate results - and they all also require waiting for the egg to hatch.
And while researchers from the University of Leipzig in Germany are working on a spectroscope that will supposedly be able to do in-ovo testing three days into the incubation period to determine the sex of an egg before it hatches, the technology isn't on the market yet - and I assume will be pretty pricey once it is.
What about Egg Shape?
While many swear that it works, it's a myth that egg shape determines the sex of the chick. Some say that pointed eggs result in little roosters and rounder eggs hatch out little hens. However, it's not a reputable method either. Although I guess it can't hurt to set only rounded eggs - just in case.... and yes, while each hen generally lays the same shaped egg all the time, some hens do produce more female embryos, while others produce more males. But either way, it's not a surefire method.
But, there is a way to hatch a greater percentage of "female" eggs.
How to Hatch Hens Not Roosters
Apparently it's all about temperature. I've read that if you raise your incubator temperature just half a degree you're more likely to hatch out males; lower the temperature just half a degree and you will likely hatch out more females. Interestingly, if you hatch under a broody hen, it's thought you're more likely to hatch out more hens. I guess Mother Nature realizes that a flock needs more hens than roosters?
But the temperature at which you store your hatching eggs seems to play a role as well. Try storing the eggs you'll be hatching for several days at 40 degrees Fahrenheit to hatch out more females, instead of the higher, commonly recommended storing temperature of 60 degrees Fahrenheit. A study done in Australia actually bore out that conclusion.
Now, keep in mind that what you're doing is not changing the sex of the chick inside the egg - that's been predetermined - but for whatever reason, male embryos seem to be more sensitive to low temperatures and those eggs just won't hatch. So you'll likely have a lower overall hatch rate, but what you do hatch should be a higher percentage of females.
Regardless of your views on when life starts and all that, it's a sad fact that most roosters don't meet a good end in life. Even those people who keep roosters in their flock don't keep an even number of roosters and hens, not even close, so poor roosters are pretty much doomed from the start. It's clearly far more humane to just not even let the eggs hatch than hatch out unwanted roosters. And think of it this way, if you do have a rooster in your flock and eat your chickens' eggs, you're likely eating both hens- and roosters-to-be every day.
I really find this kind of information fascinating. Since I ordered my hatching eggs while the temperatures were still cold here in Maine, I wouldn't be surprised if they got down to around 40 degrees at some point during their journey. I also did lower the incubator temperature a bit for the first few days of the incubation period. I'll be interested to see what my male/female ratio ends up being out of the eight chicks I hatched - although all eight that I set did hatch, so unless they were all female eggs, I'm thinking either they weren't stored for long enough at a low enough temperature or the incubator temperature needs to be lowered for the entire incubation period. But I guess we'll see!
Has anyone else tried this method? If so, I would love to hear your results!
I would love for you to join me here...
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