2 of my hens lost their voice and stopped laying, the flock has lower, rougher voice

[Radhanuga]

They are 31 weeks old, a Wyandotte and a Brahma, the first started laying at 19 weeks and did daily until 3 weeks ago when we added 2 new chickens (which are both under her in the pecking order), the second (head of flock) started laying around 23 weeks and stopped 10 days ago, after acting strange for an entire day, in the nesting box but no eggs, making some really strange sounds, but normal looking comb and poop, she got better after a day, started acting her usual self, feeding normally, but has lost her voice and stopped laying.

All the others are healthy and laying fine, but they all (minus our Polish) are quiet now, I rarely hear any of them anymore, they voices seems rougher and not as loud. 7 hens total.

What in the world could cause all this?

 

[Eggcessive]

The new chickens should have been quarantined away from your other chickens for at least a month. They may have brought in respiratory disease. Symptoms of respiratory disease may be runny nose, eye drainage, sneeze or cough, rattles in the chest, and diarrhea. Most diseases create carriers of the flock. Antibiotics may help with a bacterial disease, or sometimes to prevent secondary infections in viruses. Here is a good link about the common diseases--infectious bronchitis, mycoplasma (MG,) coryza, ILT, and a disease from mold, aspergillosis: http://www.the-chicken-chick.com/2012/12/coccidiosis-what-backyard-chicken.html

 

[Radhanuga]

I have read many books about chicken diseases and pests. I did quarantine the new hens originally, a whole separate coop and run.

My two girls have absolutely no runny nose, eye drainage, sneeze or cough, rattles in the chest, and diarrhea. They are healthy, active, bright red combs, eating and drinking well.
I posted because I've been through the full symptom list and they have none. I look at them thoroughly, checked their throats, their eyes, noses, vents, legs, armpits... everything every day. They have no other symptoms other than not laying and a reduced voice. No mites, no lice.

The new hens lay daily so could have been carriers of something, but didn't have it themselves.

 

[Eggcessive]

I am not an expert, but chickens can stop laying for short periods because of so many reasons. Right now, many of mine are molting, so not laying, but yours would be way too young for that. Hot temperatures of summer, cold temps and short daylight periods in winter can affect laying. Worms can affect laying. Aspergillosis can affect voices, and is caused by mold which is easily found when there is wet conditions around feed and bedding. I would make sure that the coop has good ventilation, that there is dry bedding, no dust, mold, or ammonia odor. Then make sure they are on at least 16-20% protein layer feed plus oyster shell available. There can be very mild cases of infectious bronchitis which may not be noticeable that can cause a decrease in laying, and sometimes wrinkled shells may be noticed.

 

[Radhanuga]

Thank you!