I. Introduction
At present, the general environment of broiler breeding has changed, the stocking density is too high, the pursuit of feed conversion rate and the uneven quality of breeders have put more pressure on the relatively fragile physique of broilers.
At present, it seems that the use of antibiotics in broiler breeding is necessary. Practically speaking, without the use of antibiotics, the chances of successful broiler farming are currently very low. But how to rationally use antibiotics in the current breeding mode and use as little antibiotics as possible; how to save the cost of medication on the one hand, and how to ensure the normal growth of chickens and ensure benefits on the other; health considerations. Therefore, it is of great significance to seek the correct use of antibiotics and seek new ways to reduce the use of antibiotics.
After practical research, we found that drugs alone are not enough to solve the problem of the abuse of antibiotics in broilers and the success of breeding. One of the main treatment directions of antibiotics is colibacillosis, and the problem of Escherichia coli has always been an unavoidable topic of broiler breeding until the age of 30 or even 20 days. directly related.
Therefore, how to summarize suitable breeding models and theories, and how to re-examine the key points in the breeding process are of great significance to human health, to promoting the development of the industry, and to improving economic benefits.
2. The original feeding mode and the changes in recent years
(1) Normal feeding procedures.
In the normal 38-50 days of breeding, it is divided by week. From the first week to the fifth week (1-35 days old) is the key to breeding. As long as there is no problem in the fifth week, the basic breeding is successful. . Next, we will describe a commonly used immunization medication procedure.
In the first week (1-7 days of age), use quinolones once, commonly known as "opening drugs", at this time mainly to purify Salmonella.
The 7th-day-old was immunized by using the chicken new-branch double vaccine eye drop and nasal injection + Xinliu oil injection. (immune methods cannot be mixed)
The second week (7-14 days old) is the blank period of immunity, at this time antiviral drugs can be used, and drugs that enhance immunity can be selected. At the same time, use enteritis drugs or coccidial drugs once according to the actual situation.
14-day-old bursal vaccine.
In the third week (14-21 days of age), if necessary, use a preventive Escherichia coli and intestinal drugs according to the situation. At this time, attention should be paid to the prevention and treatment of coccidiosis or mycoplasma.
21-day-old immunization against Newcastle disease.
In the later stage, attention should be paid to the prevention and treatment of respiratory tract, enteritis, and colibacillosis.
However, it has been recently found that this program is difficult to raise successfully, and due to the frequent occurrence of colibacillosis, the dosage of later drugs is getting larger and larger, even to the point of damaging the liver and kidney. So everyone started looking for change.
(2) Problems that have arisen and current corrections
In recent years, the quality of chickens has declined. The original vertical transmission was mainly Salmonella. Now, after my many actual investigations, Clostridium and Mycoplasma also have vertical transmission, and quinolones basically have no good control over Salmonella. Therefore, other drugs can be considered for "opening drugs", such as the combination of florfenicol + doxycycline, which can control Mycoplasma, Escherichia coli, and Salmonella at the same time, but this program must be used to control the dosage. If the dosage is too large, immunity and growth will occur adverse consequences of inhibition.
Because the amount of drugs used increases, the internal organs of the body have been in a state of depression. In order to effectively kill pathogens, the dosage of drugs used in practice is pursuing a limit dosage. At the same time, some compatibility that was contraindicated in the past is also being tried. The kidneys of broilers are relatively fragile, so the situation of kidney necrosis and liver poisoning caused by such drugs is still relatively high. Many. Summarizing the usage, dosage, methods, and compatibility of each antibiotic to improve the ability of disease diagnosis is what grassroots veterinarians need to continuously learn and improve.
In recent years, mycotoxins in feed have become more common. Some viruses and pathogens together with mycotoxins and adenoviruses have caused the occurrence of glandular gastritis. The existence of this disease has disrupted the original normal medication and epidemic prevention procedures, and has become an important factor for many breeding failures. factor.
Immunosuppressive disease is the main problem now. Escherichia coli is a very "harmless" bacteria (except for a few highly infectious strains), but it occurs frequently in farming. This is not because Escherichia coli is highly infectious and virulent, but It expresses a state of extremely poor constitution and immunity.
I think the key point is immunization, because many breeding failures start from immunization. Many farms have abandoned the 14-day-old bursa vaccination and the 21-day-old Newcastle disease secondary immunization. Some programs have chosen 1 The bursa is practiced at the age of 14, and the vaccine is not given at the age of 14. There are also plans to carry out the second immunity of Newcastle disease until the age of 18. And many manufacturers have also launched products to replace vaccines. The main reason is that immediately after the immunization, respiratory symptoms, feed reduction, and the condition of the chickens deteriorated rapidly, just like being infected with Newcastle disease, and even the whole batch of chickens failed to raise, which is very likely to happen. If the chickens are not immunized, the non-specific antibody levels of the chickens will not rise, so in the last two weeks of raising, they are often accompanied by a large number of colibacillosis and enterotoxic syndrome.
In recent years, there has also been a problem of bronchial blockage. A long embolism is formed at the trachea and bronchial bifurcation, causing chickens to suffocate and die. This is a disease caused by the combination of extremely low immunity and poor breeding environment. On the one hand, this disease reflects that the vertically transmitted mycoplasma has not been purified in time, and the blockage begins to appear before the age of 15 days; , and eventually lead to the formation of bronchial blockage. After the disease, the comprehensive use of large doses of antibiotics and antibacterial drugs caused the abuse of drugs, and also caused the destruction of liver and kidney and further loss of immunity, which became a vicious circle.
3. New means
Through the process of breeding practice and actual diagnosis and treatment, I believe that we should follow the management of immunity as the main line, and use medication to assist to achieve the three-in-one approach. The problem of how to immunize mainly focuses on the two immunizations on the 14th and 21st days. Coincidentally, many of the revolutionary immunization processes I know have achieved successful breeding.
Because the only way to reduce the use of antibiotics in the later stage is to immunize in place. After the immunization is in place, the antibody level of the body will be relatively high, and most pathogens can be resisted by the body, so there will be no bad state of using antibiotics in large doses due to the rampant use of various pathogens in the later stage. Therefore, the continuous occurrence of chicken casualties and a large number of drug use in the later period has a lot to do with the second immunization of Newcastle disease. In addition, the immunity obtained by using some interferons and transfer factors is not self-contained, and the maintenance time is short, and it is not strong. This has been proved by many practices.
The 14-day-old and 21-day-old immunizations are all live vaccines. After our actual test, this immunization is not only for the production of bursal and Newcastle disease antibodies, but also for the rapid production of an interferon and Antibodies, which are used as an interfering agent, are the same as the emergency vaccination with the Newcastle disease vaccine as an interfering agent for fowl pox. The role of these two immunizations is not only the production of antibodies against bursa and Newcastle disease, but also the actual improvement of physical fitness and the production of a non-specific antibody; and if these two immunizations are not carried out, Immunity itself cannot be raised, and then suffers from H9 and adenovirus, and there is also damage to the liver and kidneys and other internal organs caused by excessive medication. The imbalance of the body in the later stage is the culprit that leads to colibacillosis.
The task of our research is to provide a reasonable way of immunization: we have done a lot of practical experiments and research on this. We believe that the timing and method of vaccine use should follow the following principles. After our experiments over the past few years, the success rate of immunization is now reached more than 95%.
At present, the principles of broiler immunity are as follows:
Not immune when antibody levels are high.
Not immune in the presence of mycoplasma.
When the internal organs such as liver and kidney are damaged, high-dose immunization cannot be given.
Not immune to Clostridium and enteritis.
Not immune to coccidia.
When the thymus gland atrophies and cannot produce an immune response, it cannot be immune.
If the weather is bad and the breeding environment is poor, it will not be immune.
Explanation: When infected with viral diseases such as atypical Newcastle disease, the antibody level is high at this time. If the epidemic is prevented at this time, it will be manifested as the strong combination of antibodies and antigens, resulting in immune failure, similar to infection with Newcastle disease or bursal disease. The important point of this principle is how to judge the level of antibodies. In breeding practice, it is possible to decide whether or not to be immune according to the status of the flock. If the judgment is not clear, you can experiment with hundreds of chickens, which is also an effective method.
Taking the above principles into consideration, we propose a way of taking immunity as the main line and the combination of drugs, so that the drugs can be used less or even stopped. Now let's reorganize the breeding program:
(1) Within 1-7 days of age, select high-quality chicks, and carefully observe which pathogens are vertically transmitted. According to the actual situation, purify various pathogens (such as Mycoplasma, Clostridium, Salmonella, Escherichia coli) to avoid occurrence of Within 15 days of age, there will be bronchial blockage, air sac inflammation and other conditions, which will affect the later procedures.
(2) 7-day-old normal immunity.
(3) 7-14 days old is the blank period of immunity. At this time, antiviral drugs can be used once. The main thing is to prepare for the 14-day-old bursa, and to remove pathogens that may hinder immunity according to the 7 principles of immunity.
(4) Bursa immunization at 14 days old. If there are inappropriate conditions such as high antibody levels, the immunization can be delayed for 2-3 days. The vaccine should be fresh. If you are not sure, you can do the test.
(5) After the bursa immunization is over, if there is no material reduction and respiratory symptoms, it is a success. At this time because the bursa vaccine will stimulate the intestinal tract. Can adjust the intestines. The later stage is to prepare for the second immunity of Newcastle disease.
(6) Practical proof. In many cases, the second immunization for Newcastle disease can be delayed to 24-28 days of age for better results. The antibody level is appropriate at this time. Or prepare for the epidemic prevention as described in step (4). If the epidemic prevention fails, you should continue to adjust the state of the body and make a supplementary exemption.
(7) If the immunization is successful. The efficacy of antibiotics will be obvious after 4-8 weeks. Antibiotics may also be used sparingly or not. Healthy chickens with strong immunity can raise for a few more days and wait for the chickens to be released when the price is right, so that they have the initiative.
Can I still be immunized if I have respiratory symptoms? Practice has proved that as long as the respiratory symptoms are not caused by viral diseases, after the use of antibiotics for respiratory infections, especially mycoplasma infections, immunization can be performed as long as the conditions are met, and it is very necessary.
4. Results and discussion
In a word, the normal use of vaccines is an effective way to reduce the abuse of antibiotics, and it is of great significance to continue research on the methods and methods of vaccine use and specific quantification.