Egg Production Cycle

Birds usually start to lay at around five months (20-21 weeks) of age and continue to lay for 12 months (52 weeks) on average, laying fewer eggs as they near the moulting period.

The typical production cycle lasts about 17 months (72 weeks) and involves three distinct phases, as follows.

· Phase 1: Small chicks or brooders. This phase lasts from 0 to 2 months (0-8 weeks) during which time small chicks are kept in facilities (brooder houses) separate from laying birds.

· Phase 2: Growers. This phase lasts about 3 months, from the ninth to the twentieth week of age. Growers may be either housed separately from small chicks or continue to be reared in brooder-cum-grower houses. It is important to provide appropriate care to the growers particularly between their seventeenth and twentieth week of age as their reproductive organs develop during this period.

· Phase 3: Layers. Growers are transferred from the grower house to the layer house when they are 18 weeks old to prepare for the laying cycle. Birds typically lay for a twelve-month period starting when they are about 21 weeks old and lasting until they are about 72 weeks old.

Production planning

On average a bird produces one egg per day. Furthermore, not all birds start to lay exactly when they are 21 weeks old. Planning is therefore required for egg production to be constant so as to meet market demand. A schedule similar to the one shown in Table 2, which indicates on average satisfactory levels of production for a flock of birds, can be used.

In areas where the climate is hot and humid, commercial hybrid laying birds produce on average between 180 and 200 eggs per year. In more temperate climates birds can produce on average between 250 and 300 eggs per year. The table below illustrates a typical production schedule in a hot and humid climate.

In Table 2 the age of the flock is shown in the first column and the percentage of birds that actually lay during that week of age is shown in the second column. Usually at 21 weeks of age only 5 percent of the flock lay.

As shown in the third column, for 100 birds at 21 weeks of age only five would actually be laying. In the fourth column the actual number of eggs produced is shown. On average a bird produces 208 eggs over a twelve-month period, which is a weekly production rate of four eggs per bird. At 21 weeks of age 20 eggs are produced (five birds produce four eggs each) and at 22 weeks 40 eggs are produced, etc.

The graph in Figure 3 shows the actual percentage of productive laying flock over a period of time, and the graph in Figure 4 shows the number of eggs produced over a period of time for 100 birds. Egg production rises rapidly and then starts to fall after 31 weeks of age. When less than 65 percent of the flock are laying eggs (71 weeks of age), it may become uneconomical to retain birds. Feed costs and sales of culled birds for meat must be considered as well as prices for eggs. In some instances when egg prices are high it may be viable to delay culling birds until only 45 percent of the flock is still laying eggs (78 weeks of age).

Table 2
Production schedule in temperate climate (100 birds)

Age of flock (in weeks)% of flock layingNo. of birds layingNo. of eggs produced per week
32 – 398888352
40 – 478383332
48 – 597777308
60 – 647373292
65 – 707070280

Clearly, egg production requires planning for costs as well as for profit generation and for meeting market demand. Planning involves not only the number of eggs laid by the flock over a period of time, but also when to hatch chicks to replace birds with diminishing laying capacity.

If production is to be kept constant, a simple chart as shown in Table 3, for example, will be needed to plan when new chicks must be hatched so that they can be introduced to laying in time to pick up on diminishing egg production.

Table 3
Production planning

Layer flocks01121314151617181
(……………………. time in weeks……………………..)
1st layersBornLay
2nd layersBornLay
3rd layersBornLay

As indicated on the chart, the first layer flock was hatched at 0 weeks to become productive after 21 weeks. The second flock of layers was hatched at the 21st week to be ready to lay after the 41st week, as the first layer flock starts to diminish production. This type of production entails having flocks of birds of different age groups.

Clean and hygienic living quarters and surroundings are essential to control disease. There should be no more than three or four different flock age groups present at one time. The mortality rate on average is between 20 and 25 percent. This means that if one wants 100 birds to lay, it may be necessary to buy between 120 and 125 small chicks.