What factors cause or predispose to respiratory disease in poultry?

What factors cause or predispose to respiratory disease in poultryRespiratory physiology of poultry is unique. Unlike human respiratory anatomy the avian lungs do not expand or contract on breathing. The direction of the flow of gases is unidirectional in the lungs making it more efficient in gas exchange.  The air sacs associated with the poultry respiration form a very important component for air storage during inhalation or exhalation.  The air sacs also regulate body temperature by diverting air flow to pneumatic bones for effective heat exchange.

All etiologies for respiratory disease in poultry have an aerosol mediated entry point. The contact of these agents with the capillary system associated with the lungs is brief as they are diverted to the air sac for temporary storage. Air sacculitis forms a major finding for respiratory related mortalities on post mortem examinations. Keeping these facts in mind we can list factors affecting respiratory disease as;

Environmental stress affecting breathing of the birds

a) Heat/cold stress

b) Handling stress

Immunisation failures

a) Vaccine component failure

b) Immunodeficiency

Inflammatory agents affecting respiratory system

a) Microbial etiology in bio-aerosols

b) Irritant gases and particulates

Nutritional deficiencies

a) Hypovitaminosis ( A & B 12)

b) Amino acid deficiencies

Respiratory Disease In Poultry

Respiratory Disease In PoultryImagine a flock of 1000 chickens or may be a few backyard chickens. In both the case you can encounter major challenge in controlling respiratory diseases, when trying to maintain a healthy flock. So what are the most common signs you see in your flock. These could be- sneezing, discharge around the nostrils and eyes, open mouthed breathing, ruffled feathers, head shaking and wheezy breathing sounds.

The most common causes are described in brief below:

Newcastle Disease (ND), also known as pneumoencephilitis, is highly contagious and that attacks the internal organs (viscerotropic). All birds of wide age groups are susceptible to ND. Humans and other mammals are also affected by ND. ND occurs in three forms, lentogenic (mildly pathogenic), mesogenic (moderately pathogenic) and velogenic (highly pathogenic). It is characterized by a sudden onset of clinical signs including hoarse chirps (in chicks), watery discharge from nostrils, labored breathing (gasping), facial swelling, and paralysis, trembling and twisting of the neck. In laying birds, show symptoms such as decreased feed and water intake and a substantial drop in egg production. Newcastle virus can be transmitted by the air borne route or wild birds, contaminated footwear, workers, visitors, and dirty equipment. Newcastle virus is also transmitted in the egg and the infected embryos die before hatching.

In live birds, the virus is shed in body fluids, secretion, excreta and breath. There is no specific treatment for ND. Antibiotics can be given for 3-5 days to prevent two bacterial infections. However, prevention programs should include good sanitation, vaccination and implementation of a comprehensive biosecurity programme.

Infectious Bronchitis, also known as bronchitis or cold. It is found only in chickens. Similar disease occurs in quail caused by a different virus. The severity of infection is influenced by the age and immune status of the flock, by environmental conditions and by the presence of other diseases. Breathing noises are evident with a watery discharge from the eyes and nostrils. Feed and water consumption declines. Egg production drops dramatically. The IBV infects many tissues of the body, including the reproductive tract. It is known to spread by air, infected dead birds, infected houses and rodent. No specific treatment is available. But it can be prevented by enforcing a bio-security program. Vaccinations are also available.

Infectious coryza mostly affects chickens, pheasants and guinea fowl. It shows swelling around the face, foul smelling, thick, sticky discharge from the nostrils and eyes, labored breathing and rates. The birds may have diarrhea and growing birds may become stunted. Mortality is usually low. Transmission is primarily by direct bird-to-bird contact. This can be from infected birds brought into the flock as well as from birds which recover from the disease. Sulfadimethoxine is the preferred treatment antibiotic. Others such as erythromycin, sulfamethazine, and tetracycline can be used as alternative can be used as alternative treatment. Good management and sanitation are the best ways to avoid infectious coryza.

Avian influenza can occur in most, if not all, species of birds. AI is categorized as mild form which produces loss of appetite, listlessness, diarrhea, respiratory distress, dramatic drops in egg production and low mortality. The highly pathogenic form produces blue comb, facial swelling, wattles and dehydration with respiratory distress. Egg production and hatch ability decreases. There can be an increase in production of soft-shelled and shell-less eggs. AI virus can remain viable for long period of time at moderate temperatures. It can spread through shoes, clothing, crates and other equipment. Insects and rodents may mechanically carry the virus from infected to susceptible poultry. Broad spectrum antibiotics may reduce losses from secondary infections with proper nutrition, good husbandry. A vaccination program used in conjunction with a strict quarantine has been used to control mild form of the disease. With the more lethal form, strict quarantine and rapid destruction of all infected flocks remains the only effective method of stopping an avian influenza outbreak.

Infectious Bursal disease, also known as infectious bursitis mostly affects chickens. In affected chickens greater than three weeks of age, there is usually a rapid onset of the disease with a significant drop in feed and water consumption, watery droppings leading to soiling of feathers around the vent, and vent pecking. The virus is spread easily by infected bird contact, as well as by contact with contaminated people and equipment. The virus is also shed in the bird droppings and can be spread by air through dust particles. Dead birds are good source of the virus which should be incinerated. Antibiotics, sulfonamides and nitro-furans have little or no effect. Vitamin-electrolyte therapy is seldom effective. High levels of tetracycline are contaminated because they tie up calcium, thereby producing rickets. A vaccine is commercially available.

Fowl pox, also known as bird pox, sore head, avian diphtheria, chicken pox (not to be confused with chicken pox in humans). It affects mostly poultry, turkey, quail, duck; chickens- of all ages are susceptible. The clinical signs occur in two forms. The dry form characterised by raised wart-like lesions on un-feathered areas (head, legs, vent, etc). The lesions heal in about two weeks. In laying hens, infection result in a transient decline in egg production. The wet form shows presence of canker-like lesions in the mouth, trachea, pharynx, and larynx. It may cause respiratory distress by obstructing the upper air passages. Mosquitoes are the primary reservoir and spreaders of fowl pox on poultry ranges. Mosquitoes are infected by feeding on birds with fowl pox in their blood stream. Fowl pox can also be transmitted through direct contact with infected to susceptible birds. Currently, no treatment is available; however, fowl pox outbreaks can be controlled by killing mosquitoes. If fowl pox is endemic in the area, vaccination is recommended.

All the above diseases depict the significance of bio-security that is required in the farm. To help maintain a healthy poultry flock, farmers should buy birds from a reliable source, maintain a clean pen, feed an appropriate diet and protect the birds from disease and predators through proper biosecurity. Small flock owners should seek guidance from veterinary doctors if they have queries about the healthy and management of their flocks. In addition to improving animal welfare, economy, occupational health and consumer protection, future-oriented sustainable farm animal production should enhance standards aimed at preventing or reducing the respiratory diseases through air.

How can litter amendment systems be of help to the environment?

How can litter amendment systems be of help to the environmentLitter amendment refers to the treatment of the poultry litter with chemical, herbal or biological remedies to reduce ammonia emissions, microbial contamination and insect infestations on farms. The poultry litter is an excellent source of nitrogen rich nutrition for plants, thus many farmers sell the same as manure for significant revenue. The treatment of such manure is necessary owing to the high level of bacterial and fungal contamination’s coming from the poultry gut.

As amino acids and undigested nutrients form a big chunk of excreta of broilers or layers, this medium is enriched further for aerobic and anaerobic growth. The urea and uric acid deposited on the litter is converted into ammonia by a number of bacteria and fungi. This conversion is not only deleterious for the environment as pollutants, but also is harmful for the birds as the gas predisposes them to a respiratory etiology. As the nitrogen depletes from the litter and leaches into the environment it reduces the quality of poultry litter to be used as manure. Use of litter amendment systems with antimicrobial properties which is also safe for application with the birds present on the litter is essential.

These natural or chemical substances should be also targeting the urease and uricase positive bacteria and thus also reduce nitrogen depletion from litter as well as concurrently also affecting the ammonia formation in the poultry house. In the advent of complete environmentally controlled houses another important reason to use litter amendment systems is to reduce the litter moisture and thus also help control the humidity in the house. The dessicatory effects of such products also help in cooling the house more efficiently and curb ammonia emissions from the litter. As more concentration of good air exchange occurs between the house and the environment, the effect of ammonia on the environment can be curbed. A complete litter amendment system should possess all these qualities combined with the ease of application and preferably being a solution of natural origin for easy bio-degradation.

Litter Amendment System

Litter Amendment System

As the litter goes, so goes the flock! This aphorism holds a strong meaning as it associates with management of the litter and its effect on air quality.Most of the time,litter quality often reflects how well one has managed these systems. This article deals with the litter treatments which are critical in management of the farm and control the spread of the pathogens. Hopefully, the following piece of information will aid in a better knowledge of some important management concepts with built up litter.

The most prevalent obnoxious gas in poultry housing is ammonia, among others producing irritation to the eyes and reducing resistance to infection in poultry. Ammonia is a colourless gas produced from the evolution of uric acid decomposition in chicken manure. Microbial decomposition converts uric acid to ammonia and carbon dioxide which is volatilise into the atmosphere. Many factors influence the growth of these uric acid degrading microorganisms (bacteria and fungi) present in the litter such as temperature, moisture content and pH. The limiting ammonia concentration in poultry houses is recommended to be less than 25 ppm. Blake and Hess, in their report state about continuous exposure to ammonia concentrations of 10 ppm damaging bird’s respiratory system, making them susceptible to opportunistic infectious diseases.

Using litter amendments could be one of the solutions to the above problem. Litter amendment system can acts as an ammonia binder which help in improving the exposure of ammonia to the birds and reduces release of this greenhouse gas into the environment. Litter amendment systems also having disinfectant properties may be used as bio security enhancers in the poultry house. They also reduce the energy consumption by reducing ventilation required during winter season.Moore et al. have reported that the application of alum in broiler houses considerably reduced ammonia levels within three weeks. It stated better poultry performance due to lower ammonia levels in the early growth stage. Furthermore, it lowered the electric bills, as little ventilation was not required to reduce ammonia. Overall, the benefits of using alum were approximately double the cost of investment (To read morehttp://www.ars.usda.gov/SP2UserFiles/Program/212/LivestockGRACEnet/AlumPoultryLitter.pdf).Similar results were obtained when poultry guard was used as a litter amendment, reported by McWard and Taylor. In addition, it also reduces darkling beetle populations and salmonella levels in the litter (To read more McWard, G. W., and D. R. Taylor. 2000. Acidified clay litter amendment. J. Appl. Poult. Res. 9:518-529).

The litter amendment product, USM-98, marketed by UAP Southwest of Pittsburg, Texas, uses a combination of beneficial microbes and enzymes. The manufacturers of these products claim that such treatments allow microbes to work in sub optimal conditions in the litter or improve the conditions in the litter to enhance performance of the microbes. Venting the produced ammonia during layout will result in lower ammonia levels when the chicks are placed in the house later. This result in reduction of ammonia concentration, reduced mortality rate, and improved the bird performance. P.S. the above product is not published in any scientific journals. Also, venting ammonia into the atmosphere pollutes the environment.

Using amendments may offer other economic and environmental benefits: 
• Reducing ammonia loss will increase the nutrient value of the litter while improving air quality.
• Reducing ammonia production may reduce ventilation needs and, hence, energy costs in houses that have inadequate ventilation.
• Odor complaints from neighbours may be reduced.
• Pathogen and pest levels in the house may be reduced.
• Water quality may improve because the use of alum can reduce the loss of soluble phosphorus and heavy metals in the runoff from land-applied poultry litter.

Chemicals are also added to the litter to either reduce microbial growth or inhibit the mode of action, there by slowing the decomposition of uric acid. For instance, Phenyl phosphorodiamidate inhibits urease activity, reducing conversion of urea into ammonia. The main disadvantage is that inhibitors are currently not economically feasible to growers.A natural clay mineral, clinoptilolite (a type of zeolite) along with peat tend to adsorb ammonia. However, it has received mix reviews. One report states fair reductions in ammonia, while other study reports large increase in ammonia levels.Alkaline materials such as agricultural lime (CaCO3), hydrated or slaked lime (Ca(OH)2), or burnt lime (CaO) increase litter alkalinity and convert more of the ammonium in the litter into ammonia gas.However, this method releases lot of ammonia into the atmosphere, diminishing the fertiliser value of the litter, giving negative impact on the environment. Furthermore, if the alkaline material is not completely utilised during the layout period between flocks, ammonia levels in the house may increase when fresh manure is added to the litter.

To limit ammonia production, litter moisture below 30%;the litter pH should be below 7.0; and temperature at the level of the broiler’s satisfaction. Acidifies reduce ammonia levels in the poultry house and improve in-house air quality.This not only improves bird performance and health but also may positively impact worker health. Acidifies may decrease microbial loads in the litter, as well as pathogen dissemination to processing plants through the birds, thus becoming a useful bio-security control in the overall Hazard Analysis and Critical Control Point (HACCP) plan. Further acidifies also decrease darkling beetle populations at higher application rates. Finally, a well balanced fertiliser (high N/P ratio) will meet to the requirements of most crops. Overall, acidifiers are the most effective and widely used type of poultry litter amendment.

Currently, there is a growing interest in regulating ammonia emissions from animal facilities at each levels of the poultry industry. Many research studies has shown that litter amendments reduce ammonia levels in the poultry house and improve bird performance and health along with other economic and environmental benefits as well. In brief, the way in which we control built up litter will continue to modify as we are challenged with developing poultry production, welfare,food safety and environmental concerns.