The dangers of laying hens prematurely

There are three stages of laying hens

Laying hens can be divided into three stages according to their production cycle: brooding period (0-6 weeks old), rearing period (7-20 weeks old) and laying period (21-72 weeks old). Among them, the breeding period is the period when the sexual organs of the laying hens mature. The weight and light of the hens during this period have a significant impact on the sexual maturity of the laying hens (early and late production), especially the light.

Natural light on laying hens

In some places, professional chicken farmers use open chicken coops, and most of them use natural lighting. Using this method, if the chicks are introduced in spring and summer (April 15 to the end of August), they are in the period when the sunlight is getting shorter or shorter during the breeding period, and the natural light can be fully utilized, and the sexual maturity and production period are ideal.

On the contrary, if the chicks are introduced in autumn and winter (September 1st to April 14th of the following year), they will be in the growing period of sunshine or a longer period of time when they reach the breeding period. If natural light is still fully utilized and no other measures are taken, then It will stimulate the acceleration of the development of the sex organs of the mother chick, making it precocious puberty, early labor, laying small eggs and premature aging. This is the fundamental reason why the batches of laying hens introduced by some farmers in winter started laying early and laid small eggs.

Light has a great impact on the reproductive function of chickens.

Increasing light can stimulate the secretion of sex hormones, enhance the activity of ovaries and fallopian tubes, promote the formation of eggs and accelerate ovulation. Light control during the growing period is very critical.

In the breeding period, when the mother chick grows to 10 weeks of age, the prolonged light time will stimulate the rapid development of its sexual organs, resulting in premature sexual maturity, which is not conducive to future egg production. Therefore, the principle of light management at this stage is: the light time cannot be gradually extended, and the light intensity should be weak.

The time of illumination varies in different areas

However, the light time in nature is not constant. In different regions and different seasons, the light time has periodic annual changes. China is located in the northern hemisphere, and most of the regions are located between latitudes 20 and 45 north. In a year, the winter solstice has the shortest sunshine time, and the summer solstice the longest sunshine time; the sunshine time from the winter solstice to the summer solstice gradually increases, and the difference between the summer solstice and the winter solstice gradually shortens. The higher the latitude, the more obvious this trend is. Judging from the map, our local area is just on the line of 36 north latitude, which belongs to a typical warm temperate monsoon climate zone, with four distinct seasons and great annual changes in sunshine time.

In order to prevent laying hens from laying too early, artificial supplementary light should be used for chicks hatched from September 1 to April 14 of the following year to change the natural light pattern during the breeding period, so as to avoid precocious puberty caused by the gradual extension of light time.

There are two specific methods:

  1. Constant light in the brooding period, and gradually increase in light in the laying period. According to the local time of sunrise and sunset, from the day of hatching, the longest sunshine hours of the flock to the age of 20 weeks were found out as the constant lighting time. Except for 24 hours of continuous light per day within 4 to 7 days of age, the above constant lighting time was maintained at 8 to 140 days of age, and artificial supplementation was used when the sunshine time was insufficient. From 21 weeks of age, increase by 0.5 hours per week until 16 hours per day. This method is simple and easy to implement, but the effect of controlling sexual maturation is not good.
  2. The light is gradually reduced during the brooding period, and the light is gradually increased during the egg-laying period. 24 hours of continuous light per day for 4 to 7 days of age. The lighting plan for 8 to 140 days old is: find out the sunshine time of the chickens at 20 weeks of age, then add 7 hours as the lighting time from 8 days to 2 weeks old, and artificially supplement the light when the natural light is insufficient; Beginning at 3 weeks of age, reduce by 23 minutes per week, and subtract 7 hours at 20 weeks of age, which is exactly the number of natural light hours; at 21 weeks of age, increase by 0.5 hours per week until it increases to 16 hours per day. This method is not very convenient to implement in production, but the effect of controlling sexual maturation is better.Of course, practice has shown that the method of controlling sexual maturity simply by controlling the weight of chickens is not completely effective according to the requirements of feeding restrictions. Therefore, it is best to combine restricted feeding and light management according to the standard weight of laying hens, so as to start production in a timely manner.

    In particular, it should be pointed out that some modern high-yield supporting hybrid laying hens have the ability to start production early, and appropriate early light stimulation can make the production time of new hens appropriately advanced, which is conducive to reducing the cost of feeding. Therefore, the above two methods must be used flexibly in combination with the characteristics of the species.