Brooding is generally the first 10-14 days in the house when the chicks are "started". Special house and feed conditions are used in this period to ensure that the chicks have an environment suited to their special temperature, management and nutrition needs.
The early brooding period is the first 4 days after hatch. Since the chick is not fully developed at hatch, conditions during this time determine the field performance of the flock. Problems during this time create non-compensatory performance losses.
Chicks are not just small broilers. Chicks differ from broilers in gastrointestinal tract anatomy and physiology therefore their nutrient digestion and absorption is limited at the time when the chicks have low feed consumption and fast development potential. Chicks also have immature thermoregulatory ability and immune system development.
Since the 7-day chick weight is directly correlated to the final body weight of the flock, the goal of the early brooding period is to uniformly meet the 7-day body weight goal. The 7-day chick weight is dependent on the environmental conditions during the early brooding period. Low body temperature at placement creates mortality and low body weights at 7 days.
A good start does not guarantee good performance later on, but a good start is necessary for good overall performance. A good start is measured by body weight and one week mortality.
Since altrical birds have a higher growth rate, genetic selection for the modern broiler means that birds have become more altrical than precocial. Altrical birds require more parental feeding after hatch; have a higher growth rate and a less mature gastrointestinal tract. Altrical chicks require a simple diet that does not require body resources to digest and absorb. This leaves more resources for somatic growth.
Gastrointestinal Tract Development
Birds hatch with an immature gastrointestinal tract. They do not utilize dietary carbohydrates and amino acids well. The chick undergoes rapid physical and functional development of the gastrointestinal tract to effectively digest feed and absorb nutrients. After hatch, the chick must make the transition from an endogenous yolk nutrient based diet to an exogenous carbohydrate based diet. Several days pre and post hatch are critical for development and survival of commercial chicks and poults.
Intestinal growth begins 24 hours after first ingesting food (when nutrients become available). At this time rapid development of the intestinal tract begins. The absorptive surface area increases by increasing the size of the villi. The mass of the small intestine increases by 600% in the first 7 days of the chick''''s life. (Noy et al., 2005)
Villi Changes with Age (Adapted from Viola, Penz, and Ribeiro)
Days 1 7 14 21
Number Villi per Quadrant 13.0 12.9 11.9 10.9
Villi Height, µm 514 1340 1448 1657
Crypt Depth, µm 54 86 114 101
The effect of water restriction on feed consumption, weight gain, feed conversion and intestine weight of chicks at 7 days of age (Ribeiro et al., 2005)
The most important management impact on performance of the baby chick is to ensure that they consume enough food and water.
Thermoregulatory System Development
Chicks undergo a gradual change from poikilotherm to homeotherm. During the first days of life, the chick is still poikilotherm. They are dependent on outside conditions; there is no correction mechanism available to the chick.
When chicks have a low body temperature, they huddle to decrease heat loss. When chicks huddle, they decrease feed and water intake. With high body temperature, chicks move away from the heat source. Water and feed intake decreases because the chicks are not near the feed and water and they eat less to decrease metabolic heat production. When feed and water intake decreases, there is less energy available for development and growth.
The thermal comfort zone is the temperature at which the metabolic rate is minimal and maintained at minimal energy cost. This means that there is the maximum amount of net energy available for development and growth. The rectal temperature of chicks in the thermal comfort zone is 104-105 °F, 40-40.6 ° C. . To measure rectal temperature in chicks, any veterinary probe that has a fast response can be used. It is important that the probe be ed approximately 2.5 centimeters, or 1 inch, inside the chick. I find that the Microlife VT1831 probe works well.
Chicks from young breeder flocks have less thermoregulatory development at hatch than chicks from prime and older breeder flocks (Weytjens et al. 1999). Chicks from young breeder flocks require higher environmental temperatures to maintain them in their thermal comfort zone.
The floor is a crucial influence on the body temperature of the chick. If the floor is too cold, chicks will lose body heat to the floor when they sit down. The air and the floor temperature must be balanced to maintain both standing and sitting chicks in the thermal comfort zone.
When chick rectal temperatures are low at placement, one-week mortality increases, uniformity decreases and 7-day weights are decreased.
Immune System Development
The intestinal tract is the largest lymphoid organ in the body. Development of the intestinal tract impacts the immune system function. Fasting impacts intestinal tract development and releases corticosteroid when delays the immune system development.
The yolk contains maternal immunoglobulin, which is essential to protect the bird against pathogens during the first few days of life. Residual lipids in the yolk are the essential components of cell membranes. Amino acids and energy should be supplied by the feed. The yolk sac contents should not be used to supply amino acids and energy. The yolk contents are not adequate to initiate growth (Nir and Levanon, 1993).
Musculoskeletal System Development
Feed consumption immediately after hatch is necessary to support early muscle development, which will ultimately affect meat yield. Muscle satellite activity in turkeys begins at 25 days of incubation, peaks at hatch, and decreases significantly by 7 days post hatch (Moore et al., 2005).
Mozdziak (et al. 2002) showed that feed deprivation 2 days post hatch (energy deprivation) decreases mitotic cell activity in the early phase and decreased meat yield at market age.
"Poor Chick Quality"
When energy is limited, the embryo will use energy for maintenance instead of growth. When energy is limited, the chick will lose weight and restrict growth of critical tissues, i.e. the musculoskeletal system, the gastrointestinal tract, and the immune system. In practical conditions, when availability of feed is limited in this early brooding period, hatchlings that have limited body reserves may not survive this critical period. Those that do survive will exhibit decreased body weight, high feed conversion ratio, decreased disease resistance, and decreased meat yield.
New Technology Solution: HatchBrood
HatchBrood is designed specifically to meet the early brooding needs of the modern yield broiler from all ages of parent stock.
In HatchBrood, all chicks are in their thermal comfort zone. Uniform airflow transfers heat to the chicks that need warmth. Uniform airflow removes heat from chicks that need heat cooling.
Time from hatch to placement is minimized so the gastrointestinal tract development begins at the earliest time possible in all chicks.
All chicks have immediate access to food and water in their thermal comfort zone. This creates uniform growth and development. There are no non-starters.
Since all chicks, from parent stock of all ages, are in their thermal comfort zone and have feed and water available, energy is not limited. Energy consumed is used to complete the chick development process in all chicks. There are no non-starters. It is not "difficult" to brood chicks from young breeder flocks. At the end of 4 days, they are equipped to perform competitively in the field with chicks from older breeder flocks.
An example of the impact of the impact on brooding young breeder flocks is shown in the following field data. In this field results, the body weight gain in 96 hours is the same in the young and the prime breeder flock. Both groups have a higher body weight gain than the traditional house brooding comparison.
Chicks with food and water in the thermal comfort zone use the yolk sac for maternal antibody stimulation and development of the immune system.
When chicks are provided with the right environment for efficient development in this very crucial early brooding period, the foundation is built for predictable and least cost field performance.
References
Maiorka, A., E. Santin, F. Dahlke, and I.C. Boleili, 2003. Post hatching water and feed deprivation affect the gastrointestinal tract and intestinal mucosa development of broiler chicks. Journal of Applied Poultry Research 12(4): 483-492.
Moore, D. T., Ferket, P. R. and Mozdziak, P.E. (2005) Muscle development in the late embryonic and early post-hatch poult, International Journal of Poultry Science 4(3): 138-142.
Mozdiak, P.E., T. J. Walsh, and D. W. McCoy, 2002. The effect of early post hatch nutrition on satellite cell mitotic activity. Comparative Biochemistry and Physiology-B Biochemistry and Molecular Biology 133(2): 221-226.
Nir, I. and M. Levanon. (1993) Effect of post hatch holding time on performance and residual yolk and liver composition. Poultry Science 72: 1994-1997.
Noy, Y., A. Geyra, and D. Sklan, (2001). The effect of early feeding on growth and small intestine development in the post hatch poult. Poultry Science 80:912-919.
Viola, T. H., A. M. Penz, Jr., and A. M. L. Ribeiro. The water restriction influence on broiler performance and organ development of broilers from 1 to 21 days of age. Journal of Applied Research (submitted for publication).
Weytjens, S., R. Meijerhof, J. Buyuse, and E. Decuypere. Thermoregulation in chicks originating from breeder flocks of two different ages. Journal of Applied Poultry Research, 1999, 8:139-145. 123