The poultry industry is vertically integrated, which means the industry has a tremendous amount of control of their products. It is distinctly different from many other animal industries. In that egg producers own and manage nearly every aspect of their business (e.g., rearing of birds, feeding, housing, husbandry, and marketing of their product) and are capable of meticulously monitoring the entire process. Poultry producers usually do not own the primary breeding stock (i.e., the parent lines supplying their operation), these birds are purchased from primary breeders.
Raising Layers (Leghorns)
The purpose of this section is to provide a general overview of a typical layer cycle in terms of chick placement, vaccination schedules, lighting, heating/cooling, feeding, molting, and removal of layers. Keep in mind, there are a number of ways to rear laying hens. It would be very unlikely that any two companies rear layers exactly the same way. However, all companies use a slight variation of the typical rearing program detailed in this section. Management differences for rearing layers may be accounted for by economics (breed selected, vaccination package and decision when to molt), producer preference (breed and strain selected), and/or geography (breed selected and vaccination package).
Hatching and Placement
Egg producers purchase their layer stock (i.e., day old leghorn chick) from an egg-type hatchery. Hatcheries deliver chicks to the producer within one to two days of hatching. At arrival, chicks are either placed in typical layer pens or reared in a pullet house. At the hatchery, chicks are vaccinated according to the producer’s specifications. For details regarding a typical vaccination schedule see Table 1.
Lighting and Temperature
Lighting and temperature conditions for a typical layer production period are shown in Tables 2, and 3 respectively. For those chicks reared in layer cages, a biodegradable mat is generally placed in the pen. The mat allows chicks to better locate feed while also providing time for the chicks to slowly adjust to the wire mesh floor. Within a week, the biodegradable mat is removed or degrades into the litter pit. A single layer cage may occupy as many as fifty chicks, but as they mature, cage density is lessened.
Chicks placed in pullet houses are reared on a floor covered with absorbent materials, such as pine shavings. During the first week, pullet chicks are usually beak trimmed. Pullets started on the floor remain there for approximately 10 to 15 weeks and then move to a layer facility. In either case, from chick placement through approximately 16 weeks of life, the pullets are fed according to body weight gain and/or age.
The goal is to raise a strong and healthy bird that can support egg production. As noted in Table 2, daily light exposure (photoperiod) begins to increase at Week 16. This increase in light exposure triggers hens to begin laying eggs. If the laying hen has not reached proper body weight (usually 3 lbs.) by Week 18, egg production will cease very quickly, following the onset of the laying period. Hence, it is important for the young laying hen (pullet) to attain the proper body weight that will support egg production. In tandem with light manipulation, the diet is also altered in order to support egg production.
It is assumed that layers, unlike birds raised specifically for meat, regulate their feed intake. Layers are generally reared on full feed (ad libitum). The feed is offered to birds via the chain system. The chain system transports feed into the metal feeder at precise times during the day. In general, 2 inches of feeder space is allotted per pullet and 2.5 inches or more for each adult laying hen (Animal Care Series, California Poultry Workshop, 1998).
Table 4 illustrates the dietary protein and energy recommendations based on age in of typical layer. Young birds are fed a high protein diet (20 percent) during the first few weeks of life. This level continuously decreases until it reaches approximately 12 to 15 percent protein during egg production. In addition to monitoring dietary protein, producers must closely examine other ingredients. During the laying phase, lysine, methionine, calcium, and phosphorus are precisely monitored to support maximum egg production.
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