Broiler Management 1
If I didn't get good body weight in the 1st week, what can I do in later to improve my flock?
Achieving good first week body weight is very important; otherwise it will lead to a compromised flock performance that often cannot be fixed later. We should place more emphasis on improving brooding practices for future flocks by making sure we have our 5 basic factors of feed, water, temperature, ventilation and lighting working in optimal conditions. I would prefer to take some time to investigate what is causing the flock to not achieve their first week body weight target so this can be fixed for future flocks.
Nevertheless, if we are already presented with the situation of not achieving good first week body weight, we may need to consider culling selected extra small chicks by 7-14 days as it’s difficult to recover those extra small chicks by then. This will hopefully improve uniformity besides looking into maximizing feed intake for the flock after that. For your future flocks, the extra effort during brooding phase will definitely be rewarded in the final flock performance.
We are harvesting right now at 33 days average. What is the maximum allowable bird population for a 450ft x 52ft building?
A tunnel ventilated house with evaporative cooling, an air velocity of about 600fpm and a minimum of at least R10 insulation in the ceiling should perform well at about 35kg/m². If the speed and insulation are poor with many air leaks, you will have to significantly drop the stocking density. It is important to check with local regulations for stocking density as this may vary from region to region. Bird health and welfare are also important factors and must be considered.
Can we completely eliminate panting in a hot climate area by evaporative cooling?
No. Even if the bird is close to its thermal neutral zone it will still use natural evaporative cooling – panting, to release the metabolic heat. When the evaporative cooling pad is being used, the relative humidity in the house will always be close to 85%. Under these high humidity conditions, its ability to remove heat through evaporation will be very inefficient, so in my opinion you will always see a significant portion of the birds panting. As stocking density increases, this will be even more obvious.
Broiler Management 2
Is heat stress index useful to be measured during brooding?
I don't recommend using it. What we prefer to do is monitor cloacal temperatures and observation. See details in the Cobb Broiler Guide.
Can we add disinfectants such as Virkon-S to the running water which goes to cooling pad?
It’s very important not to use any products that would increase the pH above 7.5, as a high pH will soften the pads and they will collapse. Do not use products which are Peroxygen compounds – containing hydrogen peroxide. As far as I am aware, Virkon S will fall into this category. Never apply chlorine-based products directly onto the pads. Quaternary ammonium compounds are generally ok for use on pads, but please take advice from the pad supplier before use. Most reputable suppliers publish literature online listing approved chemicals.
For a house 120 m long, what is the maximum temperature difference (in Celsius) required between the front and end pens?
In the hottest conditions with market aged broilers under high stocking density, the absolute maximum difference between pens is 2.8°C. This number is used as a benchmark for calculating the fan capacity needed in a new house to remove the heat from the birds and the heat entering the house through all the surfaces. In my experience if you have very good ceiling/roof insulation, it should be easily achieved – in a 120m house this should be less than 2°C if you have high air speeds and good insulation. Always ventilate your house for the hottest part – if you can use the temperature sensors at the fan end of the house to manage your tunnel ventilation.
Broiler Management 3
We run all of our fans but still we can't control the relative humidity inside the house, what option do we have?
Unfortunately, you cannot reduce humidity. What humidity you have outside the house and the humidity added from the evaporative cooling system is something you can only manage in terms of bird comfort. That’s why in tropical countries it’s very important to have air velocity to remove heat from the birds.
What is the recommended temperature and humidity from 26 days to 32 days until harvesting?
We don’t have any specific temperature and humidity guides post 14 days. Keep in mind controlling humidity early in cold climates is for litter moisture control. Unfortunately, you cannot control humidity. If you are faced with high temperatures and humidity, after 25 days you will definitely be using evaporative cooling, pushing humidity in the house to 85%. Your target temperature in the last week before harvest is going to depend on stocking density. As a general rule, once the birds reach 25 – 28 days and temperatures are high, they will be very comfortable with air speeds of around 600fpm or 3m/s. If the birds show signs of discomfort, move your target temperature down – it’s not necessarily about ambient temperature, but how the bird feels or the sensation of wind chill. Don’t be scared to run as much ventilation capacity as you can in the last week, especially at night when humidity outside can reach nearly 100%.
In case of open house system, how could we control temperature, humidity and ventilation?
Controlling temperature in an open house is possible to some degree. The most important is to have a well-insulated roof and sealed curtains to maintain target temperatures during brooding. During the grow-out stage, stirring fans used in conjunction with foggers will provide cooling. We have a section on open house ventilation in our broiler guide.
Broiler Management 4
Which is effective, roof insulation or ceiling insulation?
Roof insulation simply refers to an integrated type of roof sheet which is insulated. A good example would be a good quality metal sided sandwich panel. Ceiling insulation refers to a drop ceiling which can be made of corrugated metal sheets (this would be my preference as opposed to plastic) with a plastic vapor barrier and a blanket type of insulation on top of it. It is simply personal preference. In most cases with a drop ceiling design you are guaranteed a smooth ceiling which is very important for air flow during perimeter ventilation (minimum & transition) stages. Many open truss ceilings have purlins which can obstruct incoming air from the perimeter inlets
If the temperature is 27°C but the humidity is almost 90%, should the wind velocity be increased?
If the birds are in the last week, you can definitely increase the air velocity, especially when humidity is so high. Their evaporative cooling function starts to diminish very significantly after 85% RH.
What is the expected percentage of broiler mortality in colonies in hot weather?
Generally, the mortality in the broiler colony system is lower than the floor system. A good mortality if the health status is good and without an aggressive vaccination program should be about 3%. As long as the stocking density is correct and ventilation capacity of the house is good, performance in the colony systems is better than the floor system.
Broiler Management 5
What is the best light program we can consider for broilers?
At Cobb we have a number of light program options depending on your bird size, growth rates and nutrition. Please see our broiler guide for some more detailed options.
What is the ideal air speed for baby chick and on/off time of Evaporative cooling system?
We don’t have any specific speeds since it’s going to depend a lot on the outside temperatures. In my experience in the 1st week with air temperatures close to the chicks’ body temperatures, they will happily tolerate 100 – 150fpm (2 or 3 tunnel fans). In the 2nd week this speed can be increased. Be aware when house temperatures are dropped a few degrees by the cooling system they will respond very differently if speeds are too high. The amount of on time is really going to depend on the evaporative cooling pump and the header pipe hole size and water column height. You certainly don’t want to risk completely saturating the pads. The latest turnkey systems have the pumps calibrated specifically for use with small chicks. If your supplier is not able to help, I would run some experiments to see what run time is needed to achieve sufficient wetting of the pads and also the off time. Most growers usually run about 10 – 15s on a 20min cycle to start off with – just enough time to ensure some wetting of the pad over its full length and the water to reach the end of the distribution pipe. This will drop incoming air temperatures from the 36°C + to about 32/33°C. Don’t allow the house temperature to drop too low.
What is the minimum and maximum air speed across the inlets from the maximum and minimum ventilation?
Referring to a tunnel house without perimeter inlets, the speed should be the same in theory. When using perimeter inlet ventilation, the pressure drop across the opening will depend on how far you want the cold air to travel. We have a table in our broiler guide.
No matter if using a perimeter or tunnel inlet, an accurate air speed reading is going to be difficult. I would always open the inlet based on pressure.
If you are using a tunnel inlet in full tunnel mode, the curtain or door needs to be open enough to achieve a good turn to minimize the dead zone. When using doors, the opening needs to be adjusted to achieve a good return to the side walls. If the inlet is sized correctly, you would never open it 100%. There is no exact number in terms of pressure or speed, but keep in mind in tunnel mode pressure increases over the length of the house.
Broiler Management 6
How can humidity be reduced in the inlet area post brooding to help prevent chronic respiratory disease?
Unfortunately, if humidity of the air outside the house is high you cannot change the situation. In cold climates with low outside temperatures and high humidity, increasing the temperature of the fresh air entering with heaters will decrease humidity. I don’t believe this is the reason for your respiratory disease.
Regarding wind-chill effect on birds can we have some estimated standard like RH%, velocity, etc.?
We don’t advise any specific wind chill. There are some controllers with software to “predict” wind-chill based on RH, speed, and temperature. Be aware that bird age and feather cover, house structure, insulation and stocking density are also very important. My advice is to use observation first.
Is there any modern technology to control humidity in the shed except increasing ventilation?
No, but the sensors used to monitor humidity are becoming more reliable. There are controllers on the market which have software capable of adjusting minimum ventilation rates based on humidity – primarily to keep the litter dry and used extensively in colder climates. Furthermore, in hot weather these controllers will use humidity to predict heat index – they adjust air velocity based on a wind chill factor.
If the temperature rises to 34 degrees Celsius and humidity is more than 85 %, what can be done to decrease temperature? Should I also stop EC system?
When you run the EC system, if the house insulation is good, very few leaks, and your EC system is well maintained, the system should drop house temperature to 28-29°C and increase house humidity to about 85%. There is nothing you can do to change this. So, under high humidity conditions you have to have good air velocity. The birds need to use more sensible heat loss because its evaporative function is diminished with high humidity. I believe it’s going to be very unusual to have 34°C and 85% humidity outside; just before or after a thunderstorm it’s possible.
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