The harm of premature laying of laying hens

According to the production cycle, laying hens can be divided into three stages: rearing 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 of sexual organ development and maturity of laying hens. During this period, the weight and light of hens have a great influence on the sexual maturity of laying hens, especially the light.

In some places, professional chicken farmers use open chicken sheds and mostly use natural light. By using this method, if the chicks introduced in spring and summer (from April 15 to the end of August), the sunshine is getting shorter or shorter in the breeding period, and the natural light can be fully utilized, and the sexual maturity and the first laying period are ideal. On the contrary, if the chicks introduced in autumn and winter (September 1 to April 14 of the following year) happen to be in a longer or longer period of sunshine, if they still make full use of natural light and do not take other measures, it will stimulate the sexual organ development of the mother chicks to accelerate, so that they have precocious puberty, early laying, laying eggs and premature senility. This is the root cause of the early laying and laying of the layers introduced by some farmers in winter.

Light has a great influence on the reproductive function of chickens. Increasing light can stimulate the secretion of sex hormones, enhance the activity function of ovaries and fallopian tubes, promote egg formation and accelerate ovulation, which has a great impact on the sexual maturity, body maturity, egg production and age of laying hens, so it is very important to control the light during the breeding period.

In the breeding period, when the female chicks grow to 10 weeks old, the prolongation of light time will stimulate the rapid development of their sexual organs, resulting in premature sexual maturity, which is disadvantageous to egg laying in the future. Therefore, the principle of light management at this stage is that the light time can not be extended gradually, and the light intensity should be weak.

However, the light time in nature is not constant, and it has periodic annual changes in different regions and seasons. China is located in the Northern Hemisphere, and most of the areas are located between 20 and 45 latitudes. In a year, the sunshine time of the Winter Solstice is the shortest and that of the Summer Solstice is the longest; the sunshine time from the Winter Solstice to the Summer Solstice is gradually extended, while the difference from the Summer Solstice to the Winter Solstice is gradually shortened, and the higher the latitude is, 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 variation of sunshine time.

In order to prevent laying hens from starting too early, the chicks that came out of their shells from September 1 to April 14 of the following year should use artificial supplementary light to change the law of natural light during the breeding period, so as to avoid precocious puberty caused by the gradual extension of light time. There are two specific methods:

The main results are as follows: 1. Constant light during the brooding period and gradually increasing light during the laying period. According to the fact that there is no time in the local sunrise day, from the date of hatching, the longest sunshine hours before the age of 20 weeks are found as the constant sunshine time. Except for continuous light 24 hours a day at the age of 4 to 7 days, the above constant light time was maintained at the age of 8 to 140 days, and artificial supplement was used when the sunshine time was insufficient. From the age of 21 weeks, it increased by 0.5 hours per week to 16 hours per day. The method is simple and easy, but the effect of controlled maturation is not good.

2. the light decreased gradually in the period of brooding, and increased gradually in the period of laying. The light was illuminated continuously for 24 hours every day at the age of 4-7 days. The illumination scheme of 8 to 140 days of age is to find out the sunshine time of the flock at the age of 20 weeks, and then add 7 hours as the illumination time from 8 days to 2 weeks of age, and replenish the light artificially when the natural light is insufficient; from the 3rd week, it decreases by 23 minutes per week, and subtracts 7 hours from the age of 20 weeks, which is exactly reduced to the number of natural light hours; from the age of 21 weeks, it increases by 0.5 hours per week until 16 hours a day. The method is not convenient to implement in production, but the effect of controlled maturity is better.

Of course, the practice shows that according to the feed restriction requirements, the method of controlling sexual maturity simply by controlling the weight of chickens can not be completely effective. Therefore, it is best to combine restricted feeding with light management according to the standard weight of laying hens, so as to start production at the right time.

In particular, it should be pointed out that some modern high-yield hybrid laying hens already have the ability to start production earlier, and appropriate light stimulation in advance to advance the starting time of new hens is helpful to reduce the feeding cost. Therefore, the above two methods must be used flexibly according to the characteristics of varieties.