THE EFFECTS OF POOR BROODING: The brooding period is a critical time in the life of commercial exotic poultry and thus determines largely the success of the poultry enterprise in general and broiler management in particular. For example, when broiler chicks are subjected to poor brooding environment during the first two weeks of life, reduced growth rate and increased fed conversion ratio that follows may not be fully regained before market age.

Immuno-depression and increased incidence of ascites have been associated with exposure of chicks to low brooding temperatures and high ammonia concentrations in the brooder pen. Since the ability to regulate body temperature is not yet fully developed in newly hatched chicks, failure to provide adequate brooding environment can indeed introduce great loses to the operator.

As air temperature decreases, the internal body temperature of the chick s also decreases. In order to function optimally, the entire body metabolism of chicks depends on the maintenance of the right body temperature. Excessive cold exposure in the first few days can therefore seriously threaten the bird’s survival. During the first two weeks of life, the chick’s digestive system along with other body functions gradually matures. Thereafter, feather development, competent nervous system, and increased body mass help the chick to maintain its optimal body temperature as it grows within a reasonable range of ambient temperatures.

Low temperatures also influence the feeding habit of chicks. They respond to excessive cold by huddling together to conserve warmth and are therefore unable to get to the feed and water. The maturing and functional digestive and immune systems will in the first few days of life depend on the nutrients and antibodies provided in the yolk sac, and thereafter on nutrients derived from feed. When chicks are unable to get enough feed and water at this early stage, mortalities occur. Furthermore, surviving chicks may develop mal-functional digestive and immune systems, which may consequently limit their growth and disease resistance potentials.

During cold stress, most of the energy derived from the feed the chick manages to consume is utilized in body heat maintenance, at the expense of muscle development and weight gain. If the cold stress persists, the chick in its bid to survive mobilizes stored carbohydrates and fats for body heat maintenance.

It is important to understand that during the brooding period warm conditions are a necessity for chicks. To humans, 80 o F feels warm, but chicks may feel cold at that temperature. Studies have shown that 90 o F is ideal for brooding especially at the early stages. Temperatures are then graduated downwards as the birds mature.

Abnormally low brooding temperatures have been shown to increase the incidence of ascites, or “water belly” among broiler flocks. Incidence of ascites may reach as high as 11% in broiler flocks raised under abnormally cold brooding environment.

 TEMPERATURE MANAGEMENT: Since chicks require temperatures of about 90 o F, supplemental heat is needed in the brooding pen for good flock performance even during warm weather, and especially during the night. Forced-air furnaces and brooders, (pancake style or radiant), are the two basic methods of pro-viding heat to chicks. Both methods are effective when managed properly.

Forced-air furnaces: Furnaces produce heat in the form of hot air. Hot air however rises toward the ceiling. As a result, the floor temperature will normally be much lower than the ceiling temperature. To achieve optimum temperature at bird level without burning excess fuel, the operator must device means of re-circulating the warm air. Air-mixing fans mounted under the ceiling have been found to work well in reducing air stratification. Paddle fans, or axial vane fans that blow air horizontally, can be used to achieve this purpose. Some studies have shown that provision ceiling fans increased floor temperature by 5 o F, and resulted in approximately 30% less energy use during brooding phase.

Field experience has also shown that minimum ventilation using static pressure controlled sidewall or ceiling air inlets or vent boxes can help to break up temperature stratification in the brooding pen. When the ventilation system is running, cool outside air is brought in uniformly through the inlets, thrown along the ceiling toward the center of the house thereby pushing the hot air produced from furnaces or brooders toward the floor. This action equally results in lowered energy consumption. Operators should however note that using static pressure controlled inlets successfully requires a reasonably air tight house. A useful test of house tightness is to close all doors and air inlets, and thereafter turn on a 48-inch or two 36-inch fans and measure the resulting in-house static pressure. A sufficiently tight house will register about 0.15 inches pressure on a photohelic gauge. If the static pressure is lower than this, improvements could be made by installing curtain flaps and making sure fan shutters and doors are shut and sealed properly.

Pancake And Radiant Brooders: Both pancake and radiant brooders provide most of their heat in the form of infrared light. Infrared light radiates heat to objects instead of heating the air. Thus, floor temperature under the brooder will be higher than the surrounding air temperature. The effect is that heat is delivered were it is most needed, and it is not necessary to fully heat the entire house in order to provide the right temperature at chick level.

The difference between pancake and radiant brooders is that pancakes are designed to provide a relatively uniform “comfort zone” directly under the brooder, while radiant brooders are larger and designed to create circular bands of temperatures, the warmest portion being directly under the brooder. Compared with furnaces, brooders reduce the likelihood of cold drafts and chills. Brooders usually require more maintenance and management effort than furnaces. Fuel consumption will usually be higher in a house that is furnace brooded. Successful use of brooders requires the right equipment, which unfortunately may be lacking in many farms in the country.

Temperature Sensors: Improper location of temperature sensors or setting of minimum ventilation rate can also lead to a poor environment for the young chick. If temperature sensors are placed too close to the brooders, it can be difficult to obtain optimum floor temperature. If radiant brooders are placed down the middle of the house, the temperature sensors should be placed between the feed and water lines. Which is about 9 to 10 feet from the brooders. The temperature sensors should also be placed about 3 to 4 inches above the floor.

In automated systems, the minimum ventilation timer must be set properly for the age of the birds, and the ventilation temperature thermostat must be set above the needed floor temperature so that chicks are not chilled as result of the thermostat overriding the minimum ventilation timer and turning ventilation fans on when they are not needed.

 CONTROLLING AMMONIA BUILD-UP: In addition to maintaining optimum floor temperature, providing the chick with high quality air is also important. Ammonia build-up is the most commonly observed air quality problem during brooding. Concentrations more than 25 ppm during brooding is known to decrease flock performance, reduce resistance to infections and increase condemnations. Studies have shown that feed conversion ratio in broilers increases in direct proportion to ammonia content of the pen’s atmosphere. It is important to understand that litter generates ammonia and that it is the first few inches above the litter that usually contain harmful concentrations of the gas.

High ammonia levels will compromise flock performance well before the operator smells the problem and before symptoms such as bird blindness manifests. Litter treatments to inhibit ammonia formation are now used widely in the advanced countries. Practical management practices like providing adequate ventilation and eliminating all moisture routes to the litter will minimize ammonia problem even in low scale operations. Ammonia production in the litter increases as litter moisture content increases. Proper ventilation is essential to take this moisture out of the litter and out of the pen.

Broilers consume about 1.5 to 2 times more water than feed, but retain only about 20% of the water, while the other 80% is excreted. Poultry operators should in addition understand that what constitutes appropriate ventilation to remove this moisture is dependent on the age and size of birds.