Technical inquiries Report 2022 week 45

Review period: 07/11/2022 to 11/11/2022


  • Using immunological techniques to evaluate health programs on farms.

Many poultry diseases decrease the productive parameters in the farms. Poultry farms can use immunological techniques, like serological testing, to evaluate their health status programs, including a good vaccination response. The first step to control diseases like, Newcastle Disease, Infectious Bronchitis, Marek and Gumboro is to respect the recommended vaccination days and to take advantage of the bird’s immune windows at each stage. Also, to control Salmonella, Clostridium, and mycoplasmas, among other pathogens, is necessary to achieve a good immune status of the farm. Knowing the immune protection status through the dosage of antibodies is a management strategy that can be incorporated easily, since it is a simple practice for veterinary diagnostic laboratories.

The determinations are made from blood samples serum or in some cases from egg yolk. 3 ml of blood can be up to 1 ml of serum, which is enough for the diagnosis.

Sampling at the very entry day of the broilers to the farm allows to know the level of maternal immunity and to determine next vaccination dates. The next sampling is at 6th or 7th day, to know the immune level reached. Also, different strains of the viruses can be checked of the present diseases. Laying hens can be sample once or twice in rearing and up to 3 times in production stage. The sampling number to obtain will depend on the presence of animals with clinical signs, and the size of the batch.

The diagnostic techniques used are based in antigen-antibody reactions to determine the type of pathogen present and the concentration of antibody reached. Depending on the sensitivity and specificity of the technique used, false negatives and false positives may be obtained in the results. This will be advised by the laboratory that carries out the technique.

There are many immunological diagnostic techniques, the most used are:

  1. Rapid plate agglutination: when mixing a drop of serum and antigen, the appearance of different size lumps represents the antigen-antibody union. Blood or serum is used. It has been one of the first diagnostic tests used in poultry diseases control of Infections caused by Mycoplasma gallisepticum, Mycoplasma synoviae, Salmonella pullorum, Salmonella enteritidis, Salmonella typhimurium and Mycoplasma meleagridis. After 2 minutes of mixing, the reading result is ready. The result is positive if there are lumps. As it is a non-specific test, positive and negative control serum must be used, to have greater reading accuracy.
  2. Hemagglutination inhibition: Many avian viruses, such as Newcastle, Influenza, Bronchitis, and Adenovirus, and some bacteria and mycoplasmas are capable of agglutinating erythrocytes. The inhibition of hemagglutination by specific antibodies is the basis of the technique. The most widely used technique is that of a constant antigen and serum diluted with a known number of erythrocytes in microplates. 96-well microtiter plates (8 rows and 12 columns) are used in which 8 sera can be analyzed (one for each row) that are serially diluted along the 12 columns. The same amounts of PBS, antigen, and red blood cells have been added to each well. The antigen used must have between 4 and 8 hemagglutinating units (HAU). The title is the column or well. The serum titer will be of the dilution of the last well in which there is complete inhibition of haemagglutination.
  3. ELISA (enzyme linked immunosorbent assay): It is a widely used technique. Most diseases can be diagnosed by this technique. Different variations of the technique, depending on the marked antibodies and enzymes, are used. The reading of the results is carried out by the spectrophotometer that measures the absorbance of the sample using different filters. Final colors vary by kit manufacturer. The reader transforms the optical densities into values, expressed in units, which are grouped into groups to facilitate viewing the result. The classification in groups and units is different between the ELISA kit manufacturers and even within the different pathologies analyzed by the same manufacturer. Some manufacturers indicate the levels of antibodies produced by certain vaccinations, in this way you can compare and decide if they are within normal limits or not. It is recommended that each farm collect data to record the level of immunity achieved. Serological results from different laboratories are shown below for reference:

This are results suggested by the ELISA kit manufactures, but laboratories may have different parameters.

  • Broiler farm with mortality peaks. North of Africa.

Mortality peaks in a broiler farm is reported at day 31st of the cycle. The fattening cycle lasts between 35 to 38 days. They indicate the presence of whitish diarrhea and respiratory disease symptoms. At necropsy they found hepatomegaly, splenomegaly, and accumulation of uric acid in kidneys.

Respiratory and gastrointestinal diseases are very frequent to find in poultry farming. As well as the appearance of secondary diseases.

The symptoms described may be compatible with Infectious Bronchitis, complicated by other secondary diseases. Infectious Bronchitis is caused by a coronavirus and is highly contagious. It mainly affects the upper respiratory tract and lungs, with the presence of mucus. Other organs such as the liver and kidney can be affected. The presence of urates is frequent to find. There is a nephrotoxic strain of the Infectious Bronchitis virus that decreases the kidneys’ ability to eliminate uric acid, which is deposited in different viscera like the kidneys, in urate forms.

A differential diagnosis with Adenovirus (Avian Splenomegaly) and Inclusion Body Hepatitis should be carry out. Also, a mycotoxin concentration diagnosis in the feed can be performed. The presence of mycotoxins may be causing injuries as well.

  • Sodium humate use in feed. Southeast Asian

The need to keep raw materials and animal feed free of pathogens such as bacteria and fungi leads to the use of different compounds, including sodium humate. This compound comes from humic acid, which is found in humus, an organic matter in the soil. It is widely used as a crop fertilizer due to its effectiveness and its natural origin. One of the advantages is that it absorbs water and maintains soil moisture. It has also been used in animal feed combined with organic acids and essential oils. Its use as a mycotoxin binder have been tried but the administration dose and efficacy are not yet standardized or proven.

Alternatives such as Alquermold Natural, can be use. It’s a long-term feed preservative and it has intestinal biocidal effects against bacteria and fungi. Its efficacy has been tested and it is widely used on all continents. Alquerfeed Antitox is a mycotoxin binder that can be combined with Alquermold Natural. It is also a natural product with a broad spectrum of action. A combination of both products controls pathogens and mycotoxins that are transmitted by contaminated feed.

  • Wet litter in a poultry farm, dysbacteriosis. Microbiological analysis of a feed sample. Latin America

In a broiler farm, wet litter appears because of dysbacteriosis. This can happen due to enteritis, where more watery feces are produced. A microbiological analysis of the feed consumed was carried out. Presence of coliform bacteria (E. coli) and aerobic mesophilic bacteria (Salmonella, Staphylococcus, among others) were detected. These bacteria have a subclinical presentation that is evidenced by more watery feces or diarrhea. They also predispose fungi and other bacteria proliferation in the litter which, through ingestion, can cause serious secondary diseases. Contaminated feed has less nutritional value, causing a decrease in the productive performance of birds. The use of Alquermold Natural is recommended as a preservative in feed and as a treatment in drinking water to control pathogenic flora in birds. Alquermold Natural is an intestinal biocide, which replaces the use of antibiotics. It is from natural origin and does not require a withdrawal period.


  • Goodwin & Whittlestone scoring tables use for evaluating farms health programs.   

Lung lesions are a very common finding in slaughterhouses. The Goodwin & Whittlestone scoring tables are based on awarding points to the lesions present in the pigs’ lungs according to their location in the different lung lobes. This system was created to evaluate the lesions of Mycoplasma hyopneumoniae, the responsable of Enzootic Pneumonia. This disease is difficult to eradicate, and predispose to secondary diseases. This evaluation must be carried out routinely and programmed, with large batches, from 100 to 200 animals. This allows a deeper analysis of the herd health status. At the time of the injury’s evaluation, a roomy space should be available to examine and palpate each lung, with good lighting and extra staff to collect the information. The scoring system assigns points based on where the lesions are located: ten points for each apical or cardiac lobe, five points for the intermediate lobe, and five for the tips and each leading edge of the diaphragmatic lobes. The maximum score is given if the tissue is totally injured: 55 points, which is not usual in enzootic pneumonia.

  • A gestating sows farm presents lower reproductive parameters. Latin America.

A farm with gestating sows reports reproductive problems compared to the previous year. The farm has a history of Porcine Reproductive and Respiratory Syndrome (PRRS):

Some factors that can affect reproductive parameters are:

1. Management:

• Feeding: The feeding during pregnancy depends on the body condition of the sow. Overfeeding causes uterine weakness during farrow, increases the number of stillborn and generates smaller herd size due to embryonic loss.

• Temperature: The length of the photoperiod and high temperatures negatively affect sow productivity parameters.

• Lactation length: early weaning decreases the embryonic survival rate in sows.

2. Infectious or toxic causes:

• Porcine Reproductive and Respiratory Syndrome (PRRS): clinical signs are highly variable depending on the strain. North American strains can be clinically more severe. After a primary viremia, the disease becomes chronic, with animals that have the virus but don´t show any clinical signs. The decrease in productive parameters is a consequence. Some chronic signs are: abortions at a lower rate (2 to 5%), mummies, stillborn, weak piglets, premature farrowings, return to heat, and agalactia.

• Parvoviral Infection: Parvovirus is highly contagious and many times there are no signs even if the animal is sick. The most common symptoms are evident in sows, usually in gilts. Some of them are: Fewer pigs per litter, mummies, stillbirth, and neonatal mortality. Sporadic cases are seen in individual females who are infected for the first time.  

Brucella Suis and Leptospira spp.: Both bacteria affect many organs but can cause abortions in pregnant sows. When illness appears, lesions in other organs may indicate their presence. The diagnosis is based on the bacteria culture and the presence of clinical signs and serologic testing

• Mycotoxins: Zeralenone is a mycotoxin that belongs to the Lactonic chemical group. It is produced by the fungi Fusarium tricinctum, Fusarium roseum and Graminearum. In Latin America feed contamination risk with ZEA is 40%. The lesions caused by zearalenone usually occur in the reproductive tract of both females and males, due to its estrogenic nature. Since gonads have receptors in which the metabolites of this mycotoxin can act.

For an accurate diagnosis, it is recommended necropsy to determine compatible lesions with infectious disease and feed mycotoxin analysis.

To boost sows’ productivity, the use of Alquernat Inmuplus in the feed is recommended. Alquernat Inmuplus is a natural product that stimulates the specific and non-specific sows’ immune system. Improves the vaccine response. It doesn´t need withdrawal period and it can be used throughout the entire productive pig’s cycle. For gestating sows, its implementation is recommended until the weaning phase.


  • Milk control techniques to prevent mastitis in dairy cattle.

Many bacteria, mycoplasmas, fungi, yeasts and even some viruses can cause mastitis in cows. Mastitis is an infection in the mammary gland that affects productive performance and produce economic losses. Staphylococcus, Streptococcus and Corynebacterium bacteria are the most prevalent. The disease can have a subclinical or clinical presentation. Sometimes, lesions are macroscopic, signs of udder swelling, and milk macroscopic alterations can occur. It is a multifactorial disease due to infectious causes, environmental conditions, handling and individual susceptibility.

To reduce the occurrence of mastitis a combination of control practices are being use. Also, this help to clean the herd: to remove cows that are chronically ill or with more individual susceptibility to get ill.

Mastitis control techniques are:

1. Herd examination (medical history) and health status diagnosis

2. Review milking parlour and milking routine, hygiene, water quality, and facilities

3. Set corrective measures in facilities and management when necessary

4. Set maintenance procedures for the milking system

5. Establish the correct milking procedure and equipment sanitizing

6. Establish a cow milking order. For the best mastitis control:

– First, cows negative for CMT (California Test) are milked.

– Second, cows with mild subclinical mastitis (traces and one cross to the CMT)

– Third, cows with high-risk subclinical mastitis (2 and 3 crosses to the CMT)

– Fourth, place the cows with clinical mastitis. It is preferable that these cows are milked separately with a milking unit or in a special milking parlour.

7. Eliminate problem cows:

– Cows with 3 or more occurrence of clinical mastitis in the same campaign

– Old cows with persistent results of 2 to 3 crosses in the CMT (or high SCC)

– Cows with persistent bacteriological culture (3 cultures 7 to 15 days apart)

8. Establish a treatment program for clinical cases

9. Set drying system and drying treatment

10. Parameters registration, statistics and permanent monitoring of the control program is needed.

The CMT Test should normally be performed every 30 days. When dairy cattle with mastitis problems, it is usually necessary to carry out the CMT every 15 days, for establishing a milking order.

Bacteria culture should be included: periodic tank milk sampling, samples from quarters with clinical mastitis, periodic samples from quarters with a history of infection with Staphylococcus aureus.

• Feedlot feeding considerations in dairy cattle.

The feedlot sector represents an intensive production system to boost dairy cattle productivity. Feedlots are totally dependent upon harvested feed ingredients. The feed use consists of a feed formulated with the nutritional requirements of dairy cows and a forage supplement. The quality of the milk depends, among many factors, on the diet received, since the volatile fatty acids produced by the fermentation of the rumen bacteria are responsible for varying the milk percentage of fats, sugars, and proteins. The adequate volume of forage intake is necessary to stimulate rumination. In the rumination process, saliva is produced, and it regulates the rumen pH. The cereals fermentation tends to lower the pH. It is necessary that the rumen pH does not decrease below 5 since an acidosis process begins, which is difficult to reverse. For this reason, it is necessary to know the raw materials nutritional composition in which the diet is formulated. This can vary according to weather conditions, soil, and microbiological quality.


  • “PROGRAMA ZOOTÉCNICO EN BROILERS” realizado por Biovet S.A.
  • “Some experiments relating to artificial immunity in enzootic pneumonia of pigs” BY R. F. W. GOODWIN, RUTH G. HODGSON, P. WHITTLESTONE AND ROSEMARY L. WOODHAMS. School of Veterinary Medicine, University of Cambridge (Received 9 January 1969)