Stress in

breeders and layers

Hens and chickens are fearful animals,

very sensitive to stress.

They are creatures of habit.

Causes of

stress

Cold or heat

Vaccinations

Changes in environment

Changes in feed

Excessive or irregular handling

Noise

Overcrowding

Defective ventilation

Disease

Consequences of stress:

1) Worse livability and poorer body condition

Specially influenced by environmental conditions

(temperature, caging system).

2) Changes in the morphology of internal organs.

Liver status, bone resistance

to breakage, etc.

Consequences of stress:

3) Endocrinal and blood changes.

Decreased Ca2+ transport

in blood.

Water and sodium retention.

Hormonal changes.

Egg shell defects

Consequences of stress:

4) Changes in feed intake and use.

Reduction of feed intake.

Worse feed use

Metabolic changes in digestive system that favor the onset of

infections.

Consequences of stress:

5) Worse immunity.

Immune system is depressed,

showing fewer circulating lymphocytes

and less antibody response.

Consequences of stress:

6) Effects on reproduction and egg quality.

-Cessation or reduction of laying,

-Atrophic follicles.

- Decreased oviduct weight.

- Higher percentage of defective eggs

(cracked, weak or dirty).