The Importance of Placing 5 to 6 Anti-Migration Barriers per House: A Minimal Investment for Significant Returns.
Uneven distribution of birds in the house can economically penalize us.
Authors: Michael Czarick and Brian Fairchild.
Department of Poultry Science, University of Georgia, USA.
Although broilers often appear to be evenly distributed throughout the house, most of the time our eyes deceive us.
Photos 1 and 2 are of the tunnel fan area and the air inlet area of a 183 x 15 meter (600 x 50 feet) house with 20-day-old birds.
This house has two ultrasonic water meters installed, one for the tunnel air inlet half and another for the tunnel fan half (Photos 3 and 4).
In addition to measuring water consumption, these meters also show the percentage of water consumption between the two zones.
At first glance, the bird density seems quite uniform, but upon closer examination, it becomes evident that there are more birds in the tunnel air inlet area than in any other part of the house.
Key questions: Is this "slight" difference in bird density significant? Will it create problems in the future?
These meters are very useful for determining if the birds are evenly distributed between the two ends of the house, as water usage is a good indicator of bird density.
If the water meters indicate that birds are drinking more water at one end than at the other, it is very likely that there are more birds at one end than at the other.
When the poultry farmer realized this, he tried to move the birds from the tunnel air inlet half to the tunnel fan half but had only limited success.
Graph 1: Daily water consumption throughout the entire flock.
Despite spreading the birds throughout the house on day 9 and installing three migration fences on day 14, there was an approximate 60%/40% split in water usage between the tunnel air inlet half and the tunnel fan half.
Although the difference in water usage between the two ends of the house tended to decrease slightly towards the end of the flock, this was probably not due to the movement of birds between the two ends of the house.
The fact is that, since the density was significantly lower in the tunnel fan half, the birds had easier access to food and water than the birds in the denser tunnel air inlet half, resulting in greater weight gains.
This became evident when they weighed the birds at 58 days of age (Graph 2).
Graph 2: Average bird weight (Section 1 = Tunnel air inlet zone, Section 4 = Tunnel fan zone).
Even though air temperatures during the August/September flock were generally lower in the tunnel air inlet zone, birds in this zone weighed almost 340 grams (0.75 lbs) less than those in the warmer tunnel fan zone.
What economically penalized the poultry farmer more was that birds in the tunnel air inlet half weighed approximately 20% less than those in the tunnel fan half.
To ensure that bird density is as uniform as possible between all areas of the house, consider the following points:
Install at least two water meters
In longer houses (over 183 meters or 600 feet), consider dividing the drinking system into four sections and installing a water meter for each section.
Having four water measurements not only provides a more detailed view of bird density but also facilitates recognizing potential performance issues that may be occurring in different areas of the house.
Reception of 1-day-old birds throughout the house during warm weather
During warm weather, when bird migration tends to be higher and economically penalizes us more, consider placing 1-day-old birds throughout the house.
This way, anti-migration barriers can be installed to precisely control the number of chicks placed in each section.
In houses with a brooding chamber, install anti-migration barriers between three and five days after opening the birds throughout the house
This way, the older the birds, the more difficult it is to move them from one end of the house to the other.
In houses over 152 meters (500 feet), consider installing four or more anti-migration barriers
Placing an additional barrier 15 meters (50 feet) from the tunnel fan wall will help ensure there are enough birds in this zone of the house to properly activate the feed control pans.
Place an "additional" anti-migration barrier
Doing this 30 meters (100 feet) from the tunnel fan wall can help ensure that bird density is minimized in this area where airspeed tends to be minimal.
In total, it is recommended to install 5 to 6 barriers.
