10. At any one time there are approximately six million broiler breeder hens in the UK producing the fertile eggs to provide a supply of chicks (as hatched - i.e. approximately 50% male and 50% female) required by those producing table poultry. Well over 90% of the birds originate from two UK primary breeding companies who between them also supply a significant proportion of the world demand for broiler breeding stock. Both have pedigree stock in this country and carry out the complete selection and breeding programme for their national and international operations, typically through four generations:
11. By continual selection over the last 30 years the primary breeding companies have developed a genotype which is dramatically different from that which was farmed in the 1960s. Initially, progress concentrated on improving growth rate, feed conversion and conformation. Latterly more sophisticated methods of selection have enabled a much wider range of traits (currently in the region of 40) to be taken into consideration.
12. All genetic selection is undertaken within the pedigree flock and, because of the number of generations involved, any change at the pedigree level will take 4-5 years to reach the commercial broiler stage. Examples of selection traits are:
Age at sexual maturity
Body conformation/meat yield/fat deposition
Cardio-vascular health
Feathering
Feed conversion
Foot and leg health
Growth rate/weight for age
Health/resistance to disease
Reproductive performance (e.g., egg numbers, fertility, hatchability, egg size, sperm count, mating behaviour)
Social behaviour (e.g., aggression, docility)
13. Breeding birds are largely in the hands of some ten integrated companies with their own hatcheries and parent flocks which provide a constant supply of hatching eggs. These birds are normally reared from day-old to 18 weeks of age on premises which are separate from the laying farm. At that age, point-of-lay pullets and the appropriate number of cockerels (approximately 10%) are transferred to the laying farm. To about 60 weeks of age each female parent will produce some 120 broiler chicks. Based on a 47 week cycle (42 in lay and a five week turn around period between flocks) this represents about 2.5 chicks per female per week. Some 780 million broiler chicks are currently placed annually in the UK.