In recent years, although the vaccine immune density of broilers and laying hens has been continuously increasing, the protection rate and clinical cure rate of the epidemic have been getting lower and lower, the production performance has been declining year by year, the stress response has been increasing, and the rate of dead scouring has increased year by year. , Respiratory and intestinal diseases are permanently cured. Everyone is constantly thinking, what is the problem? Practice has shown that immunosuppression and mycotoxin contamination are two important invisible killers that cause the above-mentioned phenomena in poultry.
1Immune inhibition and immunosuppression
1.1 phenomenon
1.1.1 There is a stress reaction. When the chicken is under normal epidemic prevention, the body cannot produce a proper immune response, and the antibody uniformity is poor. When the respiratory vaccine is vaccinated, there is a strong reaction. If there is no respiratory symptom when inoculated, one or two days after the inoculation, respiratory symptoms such as swish, throwing nose and coughing will appear. Eggs were inoculated with oil seedlings, and egg production decreased.
1.1.2 Reduced production performance. Such as poor growth and development of broilers, uneven weight, poor feather development, there are some "stiff chicken", especially in young chicks as the most important; poor performance, such as the ratio of high meat and poultry meat, laying hens, low egg production, egg production peak The period remains short.
1.1.3 Reduced resistance. There are multiple diseases and more serious conditions such as mycoplasma, Escherichia coli, and coccidiosis are caused by infection.
1.2 substance
The immune organs, tissues, and cells of chickens are damaged, causing the immune system to function abnormally. It has low response to external "antigen" stimuli, and the resistance to infection by foreign pathogens is reduced, that is, the body has undergone immunosuppression. Immunosuppression diseases mainly affect the body's immune system and can cause non-transient and difficult-to-repair immunosuppression.
1.3 reasons
In recent years, there have been clinically significant variations in the viral strains of disease-causing strains and an increase in infectious power. The current state of multiple diseases and the difficulty in controlling new diseases has become increasingly apparent. In order to ensure the success of breeding, the farms must respond to the prevention and control of disease by increasing the number and dose of immunization. Take the bird flu epidemic prevention as an example, the original does not require epidemic prevention, and now generally chicken farms do two immunizations for H9, H5 do four immunizations, and in some areas to ensure the immune effect, artificially increase the immunization dose, plus The prevention of other normal diseases and the prevention of new diseases have transformed the chicken's immune response system from a normal working state to a long-term overload state, and the body has experienced "immune suppression."
At present, the main immunosuppressive diseases in chickens are: reovirus, reticuloendotheliosis, Bursitis disease, Marek's disease, J-subgroup leukemia, infectious anemia, and fungal infection.
1.4 Control
1.4.1 Strengthen feeding and management and strengthen bio-security defense measures. Use full-priced nutritious feed to minimize or avoid the impact of stress factors such as wind, light, cold, heat, humidity, and noise on the flock; establish a good biosecurity system to protect the flock against or less affected by exogenous pathogens Microbial attack. The reserve chickens and laying hens should be raised separately, the structure should be adjusted, and further division of labor should be carried out;
1.4.2 The correct use of drugs. According to the condition, use drugs rationally. When using drugs, the course of treatment should be appropriate to avoid long-term use; strictly follow the scope of use of glucocorticoids (adrenocorticotropic hormone), try to avoid the use of thiamphenicol and other drugs with strong immunosuppressive effects to prevent immune failure. Before or during immunization, appropriate use of immune enhancers such as levamisole can improve immune function and avoid immunosuppression. Many Chinese herbs can also increase the body's antibody levels and immunity. For example, replenishing Chinese medicines mostly have polysaccharides, such as ginseng polysaccharides, astragalus polysaccharides, Codonopsis pilosula polysaccharides, etc., which can improve the immune function of the body; Qingrejiedu traditional Chinese medicines such as Banlangen, Houttuynia, Coptis, Astragalus, Phellodendron, Andrographis, etc. also have enhanced chickens. The role of the body's immune function, these drugs can also effectively inhibit the reproduction of pathogens, can be used for the prevention and treatment of infectious diseases.
1.4.3 The correct choice of vaccines and biological products. Strengthen the immunization of breeder fowl viral immunosuppressive disease, provide maternal antibodies to offspring, passively protect offspring chickens at low age, prevent early immunosuppressive infections in chickens, and effectively prevent diseases. .
However, during the immunization, reasonable immunization procedures should be established according to the specific conditions of the farm to strengthen antibody monitoring. In the case of avian leukosis and reticuloendotheliosis virus, in the absence of effective vaccine prevention and control at the moment, positive chickens can only be detected after sensitive chickens are diagnosed. Therefore, it is necessary to strengthen diagnosis and investigation of the epidemic. Early detection, early elimination of infected chickens, purification of the population.
When using attenuated vaccines, we must pay attention to the source of raw materials for chicken embryos from manufacturers, strictly prohibit the use of non-SPF-derived attenuated vaccines, and prevent human-caused infections due to vaccine contamination. The SPF chicken embryos used in the manufacture of poultry vaccines must be tested against 17 pathogens (13 viral diseases, 2 bacterial diseases, and 2 mycoplasma) and the results are negative. Because non-SPF chick embryos contain antibodies in eggs, they inhibit viral proliferation, resulting in insufficient vaccine antigens. Chicken embryos used in the production of vaccines contaminate exogenous pathogens, especially the pathogens of egg transmission, and contaminate foreign pathogens in live vaccines for chickens. Vaccines contaminated with the pathogens transmitted by these eggs may cause immunosuppression or immune failure with the use of the vaccine, or cause the disease to develop in immunized chickens, and artificially cause the spread of the disease.
2 Mycotoxin contamination
2.1 phenomenon
2.1.1 broilers. In recent years, the growth of broilers has been slow, and there have been many cases of chronic gastritis and glandular gastritis in clinical practice. The symptoms of diarrhea have been severe, and the recurrence of coccidiosis has increased the susceptibility to E. coli. The farmers have not dared to discontinue the drug and increased drug costs. Seriously affect the feed remuneration and normal growth; there has been serious immunosuppression, after the immunization of the vaccine, the antibodies in the chicken can not reach the desired titer, and the susceptibility of atypical Newcastle disease, bird flu and other viral diseases is greatly enhanced in the late period of rearing. The risk of aquaculture is increasing.
2.1.2 breeder chickens. Egg production, fertilization rate, dead embryo rate, hatching rate decreased, eggshell quality decreased, and immunosuppression disease was high.
2.1.3 laying hens. The decrease in egg production and eggshell quality has severely affected the production performance of layer chickens.
2.2 Substance
There are many types of mycotoxins, including aflatoxin, echprotoxin, zearalenone, vomitomycin and T-2 toxin. Among them, aflatoxin mainly causes toxic hepatitis, ochratoxin mainly causes hepatocyte necrosis and nephropathy, zearalenone causes fetal (embryo) malformation, reproductive function decline, vomitoxin-induced immune dysfunction and nephropathy, T-2 Toxins cause stillbirth and abnormal reproductive function. Each mycotoxin may have multiple target organs or multiple types of cells. A variety of mycotoxins work together in the body, and their degree of harm is not simply added and often increases exponentially.
2.3 reasons
2.3.1 feed raw materials mold deterioration. Maize, soybean meal, fish meal and other moldy deterioration in feed ingredients are the direct cause of chicken mycotoxin contamination and even poisoning. The global climate change provides good conditions for the growth and reproduction of mold. In the harvest season, corn has too much rain. Before the harvest, it may have become moldy in the field, and it cannot dry in time after harvest, resulting in moldy deterioration. The toxins produced by moldy corn include Aspergillus flavus, zearalenone, and vomitomycin. Soybean meal and fishmeal also contaminate molds and produce mycotoxins during storage.
2.3.2 The impact of rising feed raw material prices on mycotoxin poisoning. Protein feed ingredients such as rapeseed meal, cottonseed meal, peanut cake, sunflower kernel cake, coconut powder and palm kernel powder are more likely to contaminate mycotoxins than traditional protein feed ingredients such as soybean meal. When the price of traditional feed ingredients rises, feed manufacturers will choose to use soybean meal substitutes, which increases the chance of mycotoxin poisoning. Similarly, rising corn prices will force feed processing companies to look for alternatives to other energy feed ingredients, including rice bran and wheat bran by-products; the use of by-products and feed ingredient substitutes will increase, although it will reduce feed costs, but it will also lead to the introduction of pollution. The chance of mycotoxin's raw materials has greatly increased.
2.3.3 Litter contamination. Ground litter for chickens mainly includes peanut shells, rice hulls, wheat straw, wood chips, etc. These litters are easy to mold under high temperature and high humidity conditions. Feeding litter or feed on the litter in culture can cause fungal infections or feed on mycotoxins.
2.4 Control
2.4.1 do a good job of feeding and management, eliminate mildew factors as much as possible, avoid the use of moldy feed or feed ingredients, and do a good job in the storage of feed and feed ingredients. Strengthen the disinfection of the shed to prevent moldy bedding and replace moldy litter.
2.4.2 Frequently use traditional Chinese medicines with adsorbed mycotoxins and intestines; try copper sulfate, iodine, gentian violet, try nystatin and other drugs; add mold or mycotoxins . Broilers were treated with a course of bacteriostatic and mycotoxin-reducing medications at intervals of 15 days; cats or breeders were used 5 days a month; layers or breeders used a course of treatment every 30-45 days, even in 3- At the age of 5 days, it started to prevent vertical transmission of mold and its toxins.
2.4.3 young chicks have low resistance, so we must ensure the quality of material No. 1. The adequate nutrient supply for early growth is the biggest key to raising good chickens. 15 days of age to the peak of egg production is a sensitive period, must not use mold contaminated feed.
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