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Enhancing Early Egg Size and Maintaining Shell Quality in Layers

by 5m Editor
5 June 2006, at 12:00am

By the Alberta Government - Underweight pullets are one of the most common causes for small early eggs. It is known that underweight pullets produce more small eggs early in the production cycle.

Enhancing Early Egg Size and Maintaining Shell Quality in Layers - By the Alberta Government - Underweight pullets are one of the most common causes for small early eggs. It is known that underweight pullets produce more small eggs early in the production cycle.

Achieving the proper pullet body weight is the first step in maintaining good early egg size

For every additional 45 grams in body weight at 18 weeks of age, the egg size increases 0.5 grams. In addition, underweight pullets usually do not have the skeletal frame necessary to maintain good egg shell quality after 40 weeks of age. Underweight pullets tend to be underweight as layers. The pullet body weight is affected by nutrition, disease, lighting, space allotment and beak trimming.

It is important to weigh pullets regularly to monitor their growth. A good weight monitoring program begins at four weeks and every two weeks thereafter, 100 pullets are weighed. Cages should be selected representing different locations within the pullet house. All birds in the cage should be weighed. Weighing the same cages increases the accuracy of the information. The weights of birds on the return side of the feeder line should be compared with the supply side to ensure that pullets are being fed frequently enough. By weighing every two weeks it is easier to identify the factors responsible for slowed growth. Weighing should coincide with changes in feed. If flocks are not at the target body weight for their age, the feed change should be delayed to give the underweight birds a chance to catch up. The variability of the body weights is as important as the average body weight. The goal for uniformity is that 90% of the birds should be within 10% of the average body weight.

A pullet will grow at its maximum rate between 9 and 14 weeks of age. This is the time at which the skeletal structure of the bird reaches its adult size and the oviduct matures and prepares for the onset of egg production. Stressful events during this time can have profound effects on body weight gain. If possible, stressful management practices such as moving or handling birds for vaccinations or beak trimming should be avoided during this period. Beak trimming is best completed prior to six weeks of age. The most appropriate time for the first beak trimming is seven to ten days of age, with the second beak trimming, if necessary, done at six weeks. Birds will recover more quickly and suffer less growth suppression from an early beak trimming.

Move pullets to the lay house early to avoid overcrowding pullets

Moving pullets into the laying unit late (18 or 19 weeks of age) can be harmful because pullets may become overcrowded for the final two weeks prior to moving. This can result in restricted feed and water consumption for some birds. Late overcrowding of pullets can be avoided by moving at 15 to 17 weeks of age.

Lighting programs to achieve good early egg size

One way to improve pullet body weights at the onset of egg production is to delay sexual maturity. Genetic selection has been advancing the rate of sexual maturity by about one day per year. Early maturity can be a valuable trait, provided the necessary body weight has been attained. However, if at least the standard body weight is not present at 18 weeks, the light stimulation of the flock should be delayed until the standard body weight is attained. Larger early egg weight is often the result of birds being heavier at sexual maturity. Encouraging more feed consumption early in the laying period will also promote larger early egg size. Management practices such as increasing the frequency of feeding or lowering house temperature can increase feed consumption. Sexual maturity can be delayed by using a lighting program that "steps down" the amount of light given to the pullet flock during the growing period after nine weeks. An example of a step down lighting program designed to delay sexual maturity is shown below:



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Source: Alberta Government - May 2006