dr sb if you look at the link below you will surely know what to do....thanks and all the best....

http://www2.ca.uky.edu/poultryprofitability/Production_manual/Chapter7_Ventilation_principles/Chapter7_air_exchange_for_moisture_control.html

 Hi Ommati, your answer is not explanatory.explain please from instrument you means what types of instrument?

by instruments i think he means simple ventillation system stuff like fans or airconditioner etc but easy way to increase humidity is if u put some buckets full of water inside shed it will increase humidity and if u put a nice exhaust and open all windows u can reduce humidity...i hope it helps...

thanks dr sb

Thanks Zahid Sahib for your kind information.

Hello

Also , visit link here will help you 

Good Luck 

http://www.ces.ncsu.edu/depts/poulsci/tech_manuals/hot_weather_management.html

http://msucares.com/poultry/reproductions/hatchmgt.htm

You can use spray or fog to increase humidity and using negative pressure ventilation for decrease it.

By the way, what is your purpose of increasing or decreasing the humidity? May I know if what is the actual humidity that you are having in the poultry now? 

In a usual open shed, if the temperature and the behavior of your chicken is right, then no need to increase or decrease, as long as they are eating and drinking properly. 

Install adjustable ventilation or curtain to control humidity in an open poultry shed.

Dear Melvin i want to work on japanese quail under heat stress for which humidity is  nescessary to control.during experiment it may increase or decrease.therefore its control at specific point is necessary.

open poulty shed control the humidity should have some difficult, you can spray or water on the floor.the most important is that what your purpose.

Maybe is better to stick with ventilation only. If you add humidity and have high temps,

you risk spreading of viruses and/or pathogens.

I think there is a possibility of changing the humidity level in an open poultry house using proper natural ventilation system.