Prevention and treatment of the decrease of laying rate of laying hens

At present, more than 30 batches of more than 60,000 laying hens have been investigated for epidemiological history, clinical symptom analysis, pathological examination and therapeutic effect observation.

??? First, the reasons:

? 1. Chicken flocks are stunted and their evenness is too poor.

The main manifestations are as follows: the length of ① bone is not enough. Tibia length is one of the most important indicators of whether laying hens meet the production requirements, but many chicken farmers do not know this index in the process of feeding, and do not feed qualified full-price feed in accordance with the requirements because of too much emphasis on cost, resulting in substandard feed nutrition; ignoring the management of the rearing period, the shank length of chicks before 8 weeks of age (82mm of 8 weeks old required by brown shell layers) is not up to standard. In some breeding households, the area of the chicken house during the breeding period is too small, resulting in excessive density, resulting in the length of the tibia can not reach the standard. The patella bone length of 8-week-old laying hens is very important, and it is said that 8-week-old laying hens will be born for 8 weeks. Due to the above factors, a considerable number of chicken tibia length in the flock is less than lOOmm: the normal tibia length of brown shell laying hens should reach 105mm,}, or even less than 90mm. The body weight of ② is not up to standard and its evenness is too poor. For chickens with poor evenness, the egg laying peak is often delayed for 2: 3 weeks to 9: 10 weeks after the beginning of laying. Practice has proved that for every 3% increase or decrease in chicken evenness, the average number of eggs per chicken per year increases or decreases correspondingly. Compared with 90% and 70% evenness flocks, there is only a difference of more than 20 eggs. According to current prices, the difference in income per chicken is 8: 10 yuan, and the mortality and disability rate of chickens with poor uniformity are high. The peak of egg production is not ideal, the maintenance time is short, and the overall benefit is poor. The sexual maturity of ③ is poor. Due to the inconsistency of sexual maturity, there are different individual production patterns in the group, and the egg production peak of individual chickens in the group is different, so the egg production peak is not prominent, and the maintenance time is short, and the egg production rate curve is smooth.

Chickens with the above conditions have pale crowns, light weight, lack of glossy feathers and malnutrition; some are "chubby" bodies. The laying of chickens was postponed, the number of soft-shell eggs, white-shell eggs and deformed eggs increased at the initial stage of laying, and the number of eggs rose slowly, and there were many prolapsed chickens. The autopsy showed that the internal organs were narrow, the elasticity was decreased, the development of follicles was slow, and there was no unique internal constitution of high-yielding chickens.

? 2. Sequelae of renal transmission

Chicks with renal infectious bronchitis within 3 weeks will cause a significant increase in the number of "pot-bellied chickens" in adulthood. Because the development of its follicles was not affected, the mature follicles could not be produced normally and fell into the abdominal cavity, which caused serious yolk peritonitis and reflex androgen secretion, resulting in ruddy and thick crowns of chickens, resulting in a large number of "fake hens" with low production and serious economic losses. The renal branch sequelae of chicks who had received renal branch vaccine or those who had been sick for more than 3 weeks were significantly better than those who had not used the vaccine and those who had developed the disease within 3 weeks, that is, the sequelae of renal branch were directly related to whether they were immunized or not and the age of onset of the disease. Practice has proved that if renal transmission occurs at the age of 1-3 weeks, causing damage to the fallopian tube and forming a high proportion of "fake hens", the laying rate of hens will be reduced by 10%-20%; if renal transmission occurs at 4-week-old and 0 weeks old, the number of "fake hens" will be reduced, which can reduce the egg production of chickens by 7%-8%; if kidney transmission occurs at 12-15 weeks, the laying rate of chickens will be reduced by about 5%. Mass KIB of laying hens will also cause a decline in egg production, but generally no more than 10%, and after the disease can be restored to close to the original egg level, and rarely form "fake hens."

Autopsy: the fallopian tube was narrow, ruptured and edema. Some of the pipes are dilated, with more than 1200g of stagnant water, becoming "pot-bellied chickens". Eventually, he died of yolk peritonitis.

Influence of infectious rhinitis and oncosis

The laying time of chickens with chronic infectious rhinitis before laying was obviously delayed and the peak of egg production rose slowly. the author once encountered the case of chickens with chronic infectious rhinitis who had not laid eggs at the age of 30 weeks. Chickens with tumor disease (Marek's disease, chicken leukemia, reticuloendotheliosis) will appear crown pallor, wrinkle, emaciation, long-term diarrhea, internal organ tumors and other symptoms, resulting in a decline in the physique of chickens, unable to start laying on schedule or unable to reach the peak of egg production.

Use of low-quality feed and long-term drug abuse

Some chicken farmers think that the backup chicken is a "shelf", as long as the chicken can be fed, often do not pay attention to feed quality, feeding density and so on, resulting in the stunted development of the reserve chicken flock. Some chicken farmers overuse or abuse drugs for a long time, and even use drugs that inhibit ovarian development or seriously affect the production of laying hens, such as aminopyrine, analgin, dexamethasone, prednisone and so on.

5. the quality of chicks

Due to the problems of stage diseases of breeder chickens or other reasons, commercial chicks are congenitally deficient, chicken flocks are stunted, and their egg laying performance is poor in adulthood.

6. Other factors

Management factors such as 3 hens per cage and 4 hens per cage, unreasonable beak or irregular beak, unreasonable light, low nipple water supply pressure, poor ventilation and other management factors can cause laying hens to delay the start of laying or fail to meet the requirements of laying peak.

? II. Prevention and control measures

Scientific management, full-price nutrition

In order to make the flock reach or approach the standard body weight, the chickens were generally fed with high nutritional feed at the age of 1-42 days (some breeders used full-price broiler pellets at the age of 14 days and egg grains at the age of 15-42 days). The tibia length and weight were measured regularly, and the final feeding time was determined according to the tibia length and body weight of broilers. The normal development of chicken flock will be affected when chicks are stressed by vaccination, beak amputation, herd conversion, disease and so on. It is suggested that the weight of chicken population is slightly higher than the recommended standard. In the daily feeding process, it is necessary to adjust the group in time combined with vaccination and weighing, and strengthen the feeding of lagging chickens to ensure good weight and evenness. The body indexes of chicks at the age of 8 weeks basically determine the production level of adulthood, which is the top priority in the whole feeding process.

Advocate high temperature brooding, reduce the temperature difference between day and night, and put an end to the occurrence of renal infectious bronchitis.