Hy-Line selection programs, in common with most primary breeders involve coordinated evaluation of strains on research farms, molecular biology laboratory, egg quality laboratory and field progeny tests. The objective of our genetics program is to achieve continuous improvement in all traits. Genetic progress must be measured annually applying a variety of techniques. These include field tests of sire-coded crossbred daughters held under commercial conditions in multiple bird cages in representative areas of the U.S. and other countries. Both field production data and egg quality assays are used in evaluation. Research farms evaluate pedigree pure line daughters under strictly controlled conditions on one location in single bird cages. Performance and quality are evaluated and are subjected to computer analysis to develop Breeding Value Estimates.

Consistent with commercial demands we and other primary breeders are aware of the importance of behavior as it impacts livability and production. Hy-Line is constantly striving to produce commercial strains which are compatible with emerging demands for sustainability. This implies improved feed conversion efficiency and low volume of solid and liquid waste from flocks. Pullets and hens must now be adaptable to floor production systems in addition to cages. This has implications for the inherent drive for dominance, the use of nest systems and retention of feather cover.

Behavioral issues in floor flocks

The significant problems encountered in floor systems include:

  • Fear - External stimuli and inter-flock interaction results in secretion of stress hormones which detract from optimal production by initiation of behaviors which impact feed and water intake and the use of nests and perches.
  • Elevated Mortality – This may be due to trauma such as vent peck or chronic stress which may depress the immune response and render flocks susceptible to infections which would otherwise elicit an antibody response.
  • Broody Behavior – A transitory cessation in egg production, associated with the secretion of prolactin. Affected hens sit in nests or on floor nests and are recognized by fluffed plumage and characteristic vocalization. The problem is generally initiated by overcrowding especially with high ambient temperature.

Reducing stress for flocks

The key to preventing many behavioral issues lies in appropriate housing and management and achieving socialization within flocks. It is an unfortunate consequence of generally lower mortality attributable to improve breeding, vaccination and housing, that many flocks have insufficient contact with humans. Wider use of controlled environment systems also limits contact with caretakers. Young flocks are frequently not habituated to stress factors associated with climatic change, noise, and exposure to unfamiliar equipment and placement of feed and water lines at the time of transfer from pullet rearing to laying units.

House design should incorporate full light control which allows bright illumination during the brooding period and when flocks are inspected at intervals during the day. Low levels of light should be selected during the mid to late growing period.

Partial litter houses allow pullets to peck which is a natural behavior. Rearing pullets on stretch wire or slats will result in displacement pecking which can take the form of feather pecking of the neck at the time of maturity.

Perches are essential to develop the musculo-skeletal system of pullets since this encourages the use of their leg and flight muscles. Either A-frame or suspended perches can be installed with allowances as shown in the table.


Pullets which are to be transferred to aviaries with multi-tier perching, feeding and watering must be reared in a compatible system so that they adapt quickly to the three dimensions of the aviary house at the time of transfer.

Training of pullet flocks by constantly walking, briskly with a light level of 25 to 30 foot candles is essential to socialize birds to humans. Walking should be spaced through the working day. Constant low light level will lead to fear, hence the need to increase the level of illumination when walking and inspecting flocks. Light intensity (not duration) should be increased in increments so that at the time of transfer light level in the pullet house corresponds to the laying unit.

Beak treatment can be carried out at the hatchery using infra-red equipment or by trained and supervised operators over a 7 to 10-day age span, using a hot blade trimmer with an appropriate sized template. A second touch-up trim can be carried out at 12 weeks if required or if this procedure is a routine component of the production system. Early trim may adversely affect skeletal development which is generally complete by 12 weeks. Excessive trimming will delay maturity and detect from total eggs produced per hen housed. Generally hens which have been effectively trimmed show less aggression and fear than flocks with intact beaks.

Management of laying flocks

Appropriate design of laying houses can contribute to optimal behavior and production.

  • Light intensity in the house should be the lowest at the point of entry to the nests.
  • Air flow should be even through the house. Nests must be free of drafts.
  • Perches over slats are beneficial and promote use of the vertical space in the house Perches allow low-peck order hens to find sanctuary.
  • Nipples should be spaced at 12 inch centers. This permits birds to drink without fear from adjacent hens.
  • The time of transfer is a critical period of adjustment for pullets and will markedly influence the socialization and performance of flocks.
  • The house should be sufficiently bright so that hens can explore their environment. Excessive light levels will be reflected in nervous (“flighty”) flocks.
  • Nest boxes should be opened at the time birds are delivered. Approximately every third flap should be taped open to encourage exploration.
  • Nest light can be operated one hour before house lights and then turned off for the remainder of the day. Generally nest lights are only required during the first six weeks after transfer.
  • It is essential to walk the flock at least four times daily. The program should commence on the day of transfer and should continue through 26 weeks of age.
  • Placement of feeders and water lines should not obstruct entry to the nest.
  • Flock should be “walked” from the perimeter of the house towards the nests.

If behavioral problems occur, attempt to analyze the cause. These may include:

  • Improper socialization
  • Incorrect light level or uneven pattern of light

The bottom line

Behavioral problems and losses can be avoided by:

  • appropriate design of pullet and laying housing,
  • adjusting levels of illumination,
  • acclimating pullets to human contact and facilitating socialization by frequent walking,
  • installing perches to encourage musculo-skeletal development.

Fearful and poorly socialized flocks show displacement behaviors which reduce production and increase mortality. Despite advances in genetics, molecular biology, nutrition and disease control, it is only by application of good stockmanship that flocks attain their genetic potential.