Why Measuring Air Speed at Bird Level May Not Be Advisable
Published:October 14, 2016
Summary
Figure 1. Air speeds in fifteen locations across the cross-section of a 40' X 500' broiler house with market-age birds. Keeping market-age birds cool during hot weather is all about air speed. It’s quite simple. The greater the air speed in a house, the greater the amount of heat removed from the birds, the lower their body temperature, and the better weight gains and feed con...
The field results of this article are good and beneficial. It is expected to have a nonconstant air speed at the level of grown broiler or floor level, because of the total body volume covering the whole floor area. This works as a movable obestical which results in varying air speed. But the good thing about the article is quantifying this phenomenon in tunnel poultry house. My question: how much these variations in air speed would affect the meat gain of broiler? And why? Thanks, Dr Mohammed AL Derbi Saudi Arabia
Many poultry producers have adopted the tunnel ventilation in their poultry houses. But unfortunately, they do not master the knowledge of air speed. The extractors have one type of speed. There should be extractors which can have variable speed same as a domestic fan. With the sensors for temperature and humidity, the speed of air can be altered automatically. The disadvantage of the evaporating cooling pads is that the humidity increases with the moisture and this is a handicap in the cooling process of the birds.
Yes.
Tunnel ventilation is important issue in control poultry house and one must be clear about it. Bird level air speed will give us real feel temperature at birds level, one must known what the birds feels exectly
Dr. Derbi:
Measuring air speed in a tunnel house is not a precise science. What we are trying to do by measuring air speed a few feet above the floor is to get a relative idea of what the air speed is in the house so we can make comparisons between houses. In general it takes air speed differences of at 100 ft/min or more to result in a significant differences in bird cooling and therefore performance.
Muhammad Faeooq Qureshi
If a measurement at floor level is not accurate then in accurate conclusions will be drawn about the level of bird cooling in a house. By measuring the air speed accurately higher above the floor and realizing that air speed at bird level is around 100 ft/min lower that is better than taking a possible incorrect measurement at bird level.
Ismet Mamode
Air speed can be varied by simply changing the number of fans operating. This is far less expensive and simpler than installing variable speed exhaust fans.
Dear Dr Mike Czarick
Nice to see your response. We have introduced the tunnel ventilation system in our brioler farms in 2004 for the first time in Saudi Arabia. I had modified the system to get adapted to our environmental and climate conditions. The system works very well and help to have excellent birds performance. The farm results of last cycle which finished 3 days ago: FCR 1.48 mortality 2.46% average weight at 28 day 1469 grams per bird. By the way our market requires small weights not like American or other markets.
My regards
Thanks Mr. M. Aderbi, for sharing valuable knowledge. In Pakistan best result in tunnel ventilation system is around 2100 g weight, feed efficiency 1.6 and mortality around 3.5% at 33-35 days.
Mr M.Aderbi, that is a very good result you got there. Can you share with us about your air speed, humidity and temperature for different stage of production in broiler?
I do not fully agree that "it is ALL about air speed". I think you should also consider the temparature underneath the litter surface. When keeping the birds at high stocking density ventilation above the birds may not be effective in removing the heat developed by microbial acitivty in the litter (see Reiter and Bessei, 2000; loc. cit Bessei W, 2006. Welfare of broilers: a review. Worlds Poultry Science Journal, 62, 455-466)
Could not have agreed more, is not about air speed, the birds are capable of adapting to temperature but not the air quality. So the key is the air quality and humidity level.
As the density increases, the cooling effect decreases. Thus, the water intake of the broiler can severely affect the litter quality. Therefore regardless of how fast your air movement, if the litter is unable to dry up, is a waste effort cause it contributes to poor air quality.
The focus of air speed is to determine how to reduce water moisture from the coop due to enviromment and respiratory from the chicken.
I live in a tropical climate and the humidity is the main problem. Especially nights or rainy days.
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