Fowl Cholera in poultry

Fowl Cholera in poultry Published on: 4/15/2016 Author/s : Yosef Huberman and Horacio Terzolo. Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Balcarce (INTA EEA Balcarce). Argentina (Images provided by the authors) Introduction Fowl cholera is an infectious disease caused by the bacterium Pasteurella multocida. This species is named “multocida”, which may be interpreted as a bacterium that "kills" (cida) "many" (multo). In 1879, Pasteur was able to cultivate this bacterium; this was the first time that disease-causing bacteria were grown in culture media, outside the animal host. Pasteur inadvertently found that hens were protected from P. multocida challenge by inoculating an old broth cultures that have been attenuated. These were the first documented trials that were carried out with bacterial vaccines. 
Production losses Fowl cholera causes very high economic losses in chicken and turkey breeders, especially in broiler breeders, due to high mortality, low production of hatching eggs and reduction of fertility. Furthermore, fowl cholera was also described in broilers, turkeys and layers. Cases of complicated infectious coryza (Avibacterium paragallinarum) mainly associated with simultaneous infections of P. multocida have been described in chicken egg layer farms. 
Pasteurella multocida Pasteurella multocida is a Gram negative, very short characteristic cocobacillus; it also may form a few long strands of which coccoid forms dissociate free from its ends and are arranged into short chains (photo No. 1). Furthermore, in fresh smears or tissue imprints, stained with methylene blue, bacilli with a typical bipolar staining may be observed. In slide smears of bacterial suspensions, carried out with the addition of Chinese ink, the presence of negatively stained bacilli, due to the presence of polysaccharide capsules, are frequently observed in most P. multocida strains. Four subspecies, which differ by sugar fermentation tests, are recognized as follows: gallicida, septica, multocida and tigris. The subspecies gallicida is recognized as the causative agent of fowl cholera but has also been isolated from cattle. The subspecies septica has been isolated from dogs, cats, birds and humans. The subspecies multocida causes various diseases of importance in different species of domestic animals and humans. The subspecies tigris has only been described in human wounds caused by tiger bites. 
Photo N°1 This photo shows a Gram-Hucker stained smear obtained from a pure culture in Columbia blood agar plate after incubation for 24 hours at 37°C. At 1000X it can be seen that Pasteurella multocida is a Gram negative bacterium (stained red) with pleomorphic forms, coccobacilli or coccoid of 0.2-2 microns, grouped loose, in pairs or in few short chains with some filaments (arrows). Lipopolysaccharides and somatic serotyping The specificity of the somatic serotypes is determined by the type of lipopolysaccharide (LPS). The Heddleston precipitin test uses antisera prepared in chickens and thermostable antigens extracted from saline suspensions of formalinized bacteria. To date, 16 somatic serotypes have been isolated from poultry, cattle, pigs and humans. LPS combined with the carrier protein elicit the production of antibodies that protect birds against fowl cholera. Unlike other bacteria, in P. multocida there are two LPS, designated A and B, which are very similar and only show minor differences in their internal structure. LPS A is responsible for the pathophysiological properties of endotoxins. Furthermore, some strains of P. multocida produce a third LPS, designated C. It is believed that this simultaneous expression of several LPS improves survival of P. multocida in the bird. Capsular typing Capsules are highly hydrated polysaccharides, externally located and adherent to the bacterial cell wall. Many P. multocida strains express a capsule on their surfaces. The ability of P. multocida to invade and reproduce in the host is increased by the presence of the capsule. By passive hemagglutination test, which is performed using sensitized glutaraldehyde-fixed sheep erythrocytes, 5 capsular types (A, B, D, E and F) have been described. Currently, PCR tests are available to determine these capsular types. Capsule A mainly consists of hyaluronic acid, capsule D of heparin and capsule F of chondroitin whereas the exact chemical structure of the polysaccharide of types B and E capsules are not yet elucidated. The capsule is related to the pathogenesis and host predilection: strains with type A capsule are related to the majority of fowl cholera outbreaks, type B and E to bovine haemorrhagic septicaemia and type D to porcine atrophic rhinitis. Strains of P. multocida causing fowl cholera outbreaks Outbreaks of fowl cholera are usually associated with strains of P. multocida of serotype 1, 3 and 4. Many of these strains belong to the subspecies gallicida or multocida and belong to capsular type A. Some outbreaks in turkeys are associated with capsular type F. Virulence factors of Pasteurella multocida The mechanisms by which these bacteria invade the mucosa, evade innate immunity and cause systemic disease are slowly being elucidated. As P. multocida may be part of the microbiota in the upper respiratory tract , it may behave as a primary invasive pathogen or as a secondary pathogen , according to how virulence factors are expressed and act, counteracting the immune response of the host. Furthermore, some virulence factors are critical in determining the pathogenicity of certain strains in some hosts but not in others. Among the virulence factors it may be worth mentioning the lipopolysaccharide capsule, the iron acquisition system and some adhesins. The capsule is clearly involved in bacterial avoidance of phagocytosis and resistance to complement, while complete lipopolysaccharide is critical for bacterial survival in the host. The protean toxins of P. multocida strains occur in capsular type A and D. It is believed that the type A capsule, composed of hyaluronic acid, might serve as a mask against the immune system since the hyaluronic acid structure is indistinguishable from the one that constitutes the tissue structure of the bird. Reservoirs of infection Poultry,domestic and wild birds, including seabirds, may become infected and ill or even die from fowl cholera. All kinds of animals including humans may maintain the infection as carriers for a long period of time. Furthermore, this bacterium is able to survive for a long period of time in the environment. Pathogenicity differences between strains Certain strains are fully adapted to produce a specific disease in a given animal species but the same strains may be incapable of infecting a different animal species. Poultry are affected with different degrees of morbidity and mortality, which may vary according to the species of bird, health status, environmental factors or management as well as pathogenic differences between P. multocida strains. Some strains, very virulent in primo-isolation, often lose their virulence when they are successively cultivated in artificial media (in vitro passages attenuation). On the other hand, successive passages in susceptible birds (in vivo) make these same strains reacquire their initial pathogenicity. Susceptibility of poultry The relationship between birds and fowl cholera is complex and variable, depending on the type of bird, variations of each strain or individual variations of birds within the flock. Adult birds are more susceptible to suffer acute cholera as compared to very young poultry birds that are protected by trans-ovo maternal immunity. Furthermore, the diversity of conditions that have the different production systems, the quantity and density of birds in each house and the variable application of biosecurity measures should also be considered. Due to the stress caused by the high performance demands of the poultry industry, birds are raised in intensive production systems. Consequently, these birds are very sensitive and often suffer infections that require the use of an appropriate health management. Generally, the reduction of associated risk factors may reduce pathogen multiplication and dissemination. Routes of infection and persistence of the pathogen on farms The disease is spread by ingestion through drinking water, food or litter contaminated with droppings from sick or carrier birds. The respiratory route is another common way of infection, either directly by sneezing among birds or by indirectly inhaling contaminated dust. Wounds or skin lesions may also be a source of infection. Symptoms and lesions Fowl cholera has three clinical presentations: hyperacute, acute and chronic. The hyperacute form appears with the sudden death of birds without expressing the slightest symptom or detectable pathognomonic injury. The acute presentation course lasts for 1-2 days, during which the birds show anorexia, fever, intense thirst, sleepiness (photo No. 2A), prostration, profuse diarrhoea and sometimes bloody stained faeces, respiratory distress with abundant mucus and violet colour of the combs and wattles (photo No. 2B) due to intense cyanosis. During the acute course of fowl cholera the lesions have the characteristic signs of a haemorrhagic septicaemia with petechiae and generalized haemorrhages in organs and skin, hepatomegaly and hepatic congestion (photo No. 3), oedematous lungs which sometimes have small purulent grey areas, and a congestive spleen but without showing evident splenomegaly. The chronically diseased birds usually survive for a long time and become cachectic; commonly these birds have noticeable swelling of the combs and wattles, which is more evident in male breeders. The incision of the combs and wattles shows a purulent content or yellowing caseous lesions from which oozes a purulent fluid (photo No. 4), sometimes these lesions may spread as subcutaneous abscesses. Yellowish cheesy-like caseum may be found, either in small pieces or big masses, which may be located in the air sacs (photo No. 3) and / or peritoneum (photo No. 5). Petechiae may be found in the heart and gizzard. Hepatomegaly and congestion of the liver is frequently found, with or without white spots of necrosis. Cardiac dilation and arthritis may also be found in a few birds of the flock. In the last phase of the disease, septicaemia occurs and P. multocida freely multiplies in the blood stream affecting the entire circulatory system. As has been mentioned above, mortality and morbidity are variable. Hyperacute forms are infrequent in industrial poultry thanks to the implementation of immunization plans, as well as the use of strict application of good management and biosecurity measures. Therefore, most acute cases evolve into chronic. On the other hand, if the outbreak occurs in an unimmunized poultry flock, high mortality may be reached, as frequently happens in small scale or family poultry farms. Photo N°2 This photo shows two chickens suffering from an acute case of fowl cholera. The rooster on the left is depressed and sleepy (A). The hen on the right shows cyanotic comb and wattles (B). Photo N°3 The picture on the left shows a broiler breeder liver with remarkable congestion and hepatomegaly, collection of fibrin over the Glisson’s capsule and a haemorrhagic organ at the right side edge. In the picture on the right it is shown another chicken with evident hepatomegaly, collection of fibrin over the Glisson’s capsule and a great cheesy-like bright yellow caseum mass over one of the air sacs. 
 
Photo N°4 This photo shows a chronic clinical case of fowl cholera in a rooster. Note the severe swelling of the comb and both wattles. The incision of the wattles displays abundant yellow caseum material from which oozes a purulent fluid. This fluid may be sampled with a cotton swab directly cultured onto an agar plate. 
Photo N°5 Two lumps of yellow caseum material are found in the peritoneal omentum. 
PhotoN°6 In an outbreak of fowl cholera, the weakened sick birds are usually hidden under the nests to protect themselves from pecking . These birds, dying or recently dead, are suitable for sampling and culturing of Pasteurella multocida. Isolation of Pasteurella multocida Isolation is very important, not only for aetiological diagnosis but also to obtain strains from the farms. These strains may be useful for further development of inactivated vaccines (bacterins) that include local or regional antigens. These updated bacterins may be used to immunize future batches of birds. Also, by vaccinating a diseased flock with strains isolated from the same affected flock it is possible to prevent fowl cholera in those birds that have not yet become sick. Isolation of P. multocida is more difficult in chronic cases and selection of birds in affected poultry houses must be done with great care. Recently dead birds and infected birds showing clinical signs and lesions compatible with fowl cholera should be selected for samplings. Ideally, birds with congested, swollen, warm wattles should be selected. If dead or sick birds are not found, as often happens in subclinical cases, very weak birds, drowsy or cachectic, which are usually hidden in corners or under the nest boxes should be looked for (Photo 6). According to the pathological lesions the following samples may be cultivated: congested livers, spleens and lungs and/or with purulent or necrotic lesions; free caseous masses in the peritoneum or air sacs; synovial content or caseous material from the interior of affected joints; and indurated caseum or purulent contents within swollen wattles. P. multocida grows in rich culture media, such as agar base plus 0.1% decomplemented equine serum, dextrose starch agar, brain-heart agar or Columbia blood agar. Plates are incubated for 18 to 24 hours at 37°C. In acute cases, non-haemolytic colonies growing onto Columbia blood agar are smaller than 2-3 mm in diameter, grey and only sometimes adherent to the medium. In contrast, in acute cases the colonies grow larger and are mucoid (Photo7A). The aforementioned agar base with serum allows easy differentiation of typical P. multocida colonies from contaminants when transverse oblique illumination from a lamp is applied; when obliquely illuminated, the translucent colonies of P. multocida take on a bluish or iridescent hue, while colonies of other contaminating bacterial species are opaque, yellowish or whitish (photo No. 7B). Simultaneous plating of samples onto agars with and without blood, allows easy isolation from organs, fluids or swabs obtained from sick birds. Final identification is performed using pure cross sub-culturing of individual colonies from both agars. To prevent loss of immune-protective antigens of the selected strains, intended for the production of bacterins, primo-isolates should be kept frozen immediately after isolation. Photo N°7 A pure culture of Pasteurella multocida colonies colonies grown onto Columbia agar with the addition of 7% desfibrinated bovine whole blood (A). A contaminated culture of Pasteurella multocida developed onto agar base with the addition of 0.1% decomplemented horse serum (B). Note the bluish translucent colonies of Pasteurella multocida (arrows 1) in the last strokes of the plate mingled with contaminant colonies, which are opaque and yellowish (arrow 2). 
Prophylaxis and vaccination Management measures and disinfection, along with vaccination are practical to prevent and control both acute and chronic fowl cholera. Effective bacterins must contain virulent strains of avian origin. Antigenicity and protective power should be experimentally demonstrated by challenge trials. On the other hand, vaccines should be prepared from primo-isolates cultures, using a new aliquot each time the vaccine is prepared. The diversity of strains belonging to each geographical region requires adaptation and formulation of bacterins in order to contain representative strains that reflect epidemiological situation at the time of vaccination. In our experience, the best adjuvant is aluminium hydroxide gel; oily adjuvants should be carefully selected as some may cause severe necrotic side-effects in the application site due to the synergy of P. multocida antigens with the oils. It is desirable to vaccinate before 20 weeks of age, administering two doses of bacterin separated by a 3 to 4 week interval. In areas that are very exposed to the disease, it is advisable to apply the first dose from the 5th week of life onwards. Bacterins may be administered subcutaneously behind the neck or intramuscularly into the breast. In infected flocks, exposed to severe P. multocida challenge, revaccination should be carried out every 6 months. The live vaccine based on the attenuated strain of the University of Clemenson is available for oral vaccination of turkeys before 14 weeks of age and intradermal vaccination of 6 to 12 weeks old chickens by introducing a lancet into the skin of the alar fold. Vaccination of older birds is contraindicated because this strain retains some virulence. In Australia commercial vaccines have been developed based on auxotrophic mutants ring-A designated pMP1 (serotype 1) and pMP3 (serotype 3). Recently, it has been shown that turkeys reach adequate protection through the administration of inactivated vaccines based on a peptide (rFB2). Furthermore, chickens can be protected using a novel vaccine based on DNA encoding outer membrane proteins genes OmpH and OmpA. Despite vaccines provide good protection, outbreaks are often reported in vaccinated flocks. The lack of protection could be explained by the absence of cross-protection between various strains and serotypes acting on a farm, the constant evolution of indigenous strains in the same farm or other factors related to biosecurity measures, health condition of the flock or other causes. The pathogenicity of P. multocida is very variable as it quickly adapts to environmental changes and to the poultry host. Therefore, it is advisable that the vaccines should include regional or local strains. These strains should carry antigens of the acting serotypes and should be selected considering other factors such as capsular type, virulence genes, pattern of antibiotic resistance and / or phylogenetic characterization. Antibiotic treatment It must be considered that all birds in an infected flock are lifelong carriers of P. multocida. In these chronically infected flocks it is common to administer treatments with antibiotics and, although mortality may be temporarily stopped, the flock continues to be infected. Treatments usually give variable results, depending mainly on the drug used and the virulence of the acting strain in the outbreak. P. multocida often develops resistance to antibiotics that are commonly used. Regardless of its therapeutic action, the inappropriate use of antibiotics is of concern, on one hand, due to the residues in meat and eggs and, on the other hand, by an increase in resistance to antibiotics or chemotherapeutic agents and the danger that these resistance gens be transmitted to humans. Globally, there are more and more prohibitions to the preventive routine use of antibiotics at sub-therapeutic doses. These restrictions significantly reduce the available tools to treat the birds. Therefore, it is best to apply preventive immunization of poultry and limit to a minimum the use of antibiotics. Whenever possible, it is recommended to perform sensitivity tests (susceptibility) before treatment. However, sometimes it is necessary to act very fast and immediately treat the birds with antibiotics while waiting for the laboratory results to be ready. In these cases, the rapid treatment of choice could be made using florfenicol, trimethoprim-sulfamethoxazole or tetracycline. Secondly, depending on availability, ampicillin, kanamycin, colistin and enrofloxacin may be used. Generally, it is not advisable to administer streptomycin, gentamicin or neomycin. Article published on Albéitar 192 (January/February 2016), pages 34-37 and on Albéitar PV.

Potential biomarkers of broiler gut health identified

Potential biomarkers of broiler gut health identified US researchers from Novus International and the University of Arkansas have used coccidiosis over-vaccination to trigger a gut health challenge in broiler chickens fed a wheat–barley–rye diet. Alternative grains, such as wheat, barley and rye which are high in non-starch polysaccharides (NSP), can have a substantial negative impact on monogastric digestion and animal performance. Major economic implications Chickens have little or no intrinsic enzymes capable of hydrolyzing these NSP, leading to restricted digestibility of feed ingredients and significant reductions in growth. Undigested feed ingredients in the gut provide nutrients for bacteria overgrowth in the hind gut, which can lead to dysbacteriosis. High NSP diets have also been associated with bacterial diseases that have major economic implications in broiler chickens. The recent research study entitled "Identification of potential biomarkers for gut barrier failure in broiler chickens," published in Frontiers in Veterinary Sciences, showed that the overall growth performance and feed efficiency were severely reduced by this gut barrier failure (GBF) model. These results are in agreement with previous studies that concluded high NSP diets compromised growth performance in chickens. Biomarkers useful for monitoring poultry health The purpose of the study was not to determine the individual effects of diet ingredients or coccidia challenge, but rather to determine potential biomarkers that may be used to define GBF in future studies. Biomarkers could be useful to monitor poultry health and understand disease mechanisms. "This research demonstrates Novus's commitment to the understanding of basic physiological and metabolic processes in poultry," commented Jeffery Escobar, executive manager of Physiology Research at Novus. "The results of this study will allow scientists at Novus, academia, and other poultry researchers to perform better evaluations of gut health parameters and enhance the ability to test solutions, which can translate into safer poultry products for human consumption." By ROSIE BURGIN Aug 4, 2015 ( Word Poultry )

Phytobiotics: an Alternative to Antibiotic Growth Promoters The use of antibiotic growth promoters (AGPs) in animal production began half a century ago, when Stokstad and Jukes added residues of chlortetracycline production to chicken feed. They were added with the objective to serve as a source of vitamin B12, but they caused a growth stimulation that was far too large to be explained only as a vitamin effect. The almost obvious cause lays in the antibiotic activity of the residues. This observation was quickly extended to other antibiotics and to other animal species, leading to widespread adoption of AGP inclusion in feeds. Antibiotics have been used for treatment and prevention of diseases, improvement of feed efficiency in conventional livestock and poultry industries. The first use of antibiotics in these industries was a way to meet the increasing demand of food as antibiotics given to pigs were estimated to save as much as 20% of feed per pound because of the weight gain. Similar results have been reported in poultry industries also. Immense and extensive use of antibiotics has created a strong selective pressure, which resulted in the survival and spread of resistant bacteria providing best example of survival for the fittest or natural selection theory of Darwin. Quick concerns have been arisen about the development of resistant pathogens associated with human and animal diseases, as well as increase in the resistance gene pool in bacteria, but all these risks were outweighed by the benefits of reduced cost to the industry. At present we are confronting a major issue of antibiotic resistance in both human and animals resulting into severe health issues. A lot of debates are going on all over the world and recently European Union and Canada has banned the use of antibiotics in the animal feed industries. In China certain antibiotics have been banned and others are under observation. In United States, also discussions are going on about the uses of antibiotics and it is expected have big measures in the nearest future. In Mexico still animal feed industries are using extensively the antibiotics, ignoring the health issues and focusing on the commercials benefits of the respective companies. But it’s not too far when the strong legal measures will be implemented in Mexico also. From personal point of view, it’s a demand of the time, to take care of the health interests of consumers and prepare ourselves to look for other alternatives of the antibiotics as growth promoters. These alternatives might have similar effects in food producing animals. Studies to find the alternatives have resulted into probiotics, prebiotics, symbiotics, enzymes, organic acids and phytobiotics. Despite of initial and then often justified distrust of these alternatives by nutritionists and veterinarians, they are becoming rightly accepted after the debates going on all over the globe about the use of the antibiotics and related health concerns. The change in European Union feed additive legislation has also contributed to create enough space for these alternatives. Among the mentioned alternatives, phytobiotics have drawn a lot of attentions because of being natural, non toxic and residue free. Phytobiotics are defined as plant-derived products added to the feed in order to improve performance of agricultural livestock. With respect to biological origin, formulation, chemical description and purity, phytobiotics comprise a very wide range of substances and four subgroups may be classified: 1) Herbs -product from flowering, non-woody and non-persistent plants 2) Botanicals -entire or processed parts of a plant, e.g., root, leaves, bark 3) Essential oils- hydro distilled extracts of volatile plant compounds and 4) Oleoresins- extracts based on non-aqueous solvents Positive effects of the phytobiotics on the growth performance and animal health have been attributed to their antimicrobial activity and immune enhancement and immune modulation properties. In diseased chicken (infected with avian mycoplasma or Eimeria tenella) it has been demonstrated that plant and their extracts could improve the growth performance, reduce the coliforms and improve both cellular and humoral immune responses of chickens. A common feature of phytobiotics is that they are a very complex mixture of bioactive components as a result exerts multiple functions in the animal body. Different studies have reported growth enhancement through the use of phytobiotics probably by synergetic effects among complex active molecules existing in the phytobiotics. However, the exact growth enhancement mechanisms of the phytobiotics in chicken are not very well understood and further investigations are required to better understand the mechanism at molecular level. Among Phytobiotics, essentials oils have drawn a lot of attention as an effective alternative to the antibiotic growth promoter and have been applied into chicken feed in Europe, USA and many Asian countries. In Mexico, till date negligible research has been conducted to see the effect of essential oils in animal feed. However the results are still controversial as some research report no essential oil effects on the performance of the bird and some demonstrate similar to or even better than an antibiotic treatment. It´s very important to mention that while comparing the effects of essential oils on chicken performance one should always keep in mind that the quality as well as the quantity of the oil determines the response. Additionally, efficacy of essential oils in feeds is affected by intrinsic and extrinsic factors such as nutritional status of animals, infection, diet composition and environment. Till now research has been conducted with the essentials oils of Ginger, Cinnamon, Capsicum, Garlic, Thyme and Oregano among others, in different parts of the world. The results are really interesting and show positive effects on the performance of the birds. As mentioned above environment plays an important role in determining the effect of the essential oils, it is highly recommendable to conduct in field study in Mexico before launching the products in the market. Conclusions Because of the increasing concerns about the use of antibiotics as growth promoters in poultry industries, the animal feed industry is in search of other alternatives with good cost benefits. The phytobiotics, especially the essential oils are opening new opportunities and possibilities as a replacement of antibiotics. But the cost is an issue which is restricting the animal feed industries to accept these products as the cost of antibiotics is cheaper than other alternatives. But if we give close look to the authorization to new antibiotics by Food and Drug Administration (FDA), in year 2008-2009 only one antibiotic was approved. FDA is also releasing new guidelines for the use of antibiotics. All these strong measures will definitely help to answer the cost issue and force the consumers to accept alternative like Phytobiotics as essentials oils. REFERENCES. 1. Cromwell, G.L. (2002) Why and how antibiotics are used in swine production. Anim. Biotechnol. 13, 7–27 2. Guo, F.C., et al. (2004c) Effects of mushroom and herb polysaccharides on cellular and humoral immune responses of Eimeria tenella-infected chickens. Poultry Science 83: 1124-1132

Chicken Anemia Virus and Immunosuppression: Impact on Marek´s Disease Vaccine ProtectionSummary Subclinical immunosuppression caused by chicken infectious anemia virus (CIAV) is an important contributing factor to Marek’s disease (MD) vaccine breaks. Infection with CIAV results in reduced T helper and cytotoxic T lymphocyte activity affecting antibody and cell-mediated immune responses. CIAV infection is controlled by the development of virus-neutralizing antibodies, which can be compromised by poorly controlled infectious bursal disease virus (IBDV) infection. MD virus (MDV), especially the very virulent (vv+) strains, is also highly immunosuppressive. When field strains of MDV infect properly vaccinated birds or reactivate from latency, memory CTL will be activated to control virus replication. These CTL are also dividing thus providing target cells for CIAV replication. In conclusion, when CIAV is actively replicating during infection with or reactivation of MDV, CTL responses are suboptimal and MDV infection is poorly controlled leading to vaccine breaks. INTRODUCTION Although MD is in general well controlled by vaccination in ovo or at one d of age, MD remains a concern for several reasons. First of all, vaccination practices are often suboptimal resulting in some vaccine breaks. Proper use of standard operating procedures at the hatchery remains essential for optimal protection and has been the topic of many presentations. The short-term financial gain by using vaccines diluted beyond the recommendations by the manufacturer results in suboptimal protection when very virulent (vv) or vv+ strains of MDV are present (4). The second reason is the continuous evolution of MDV. Over the last 100 years MDV has increased significantly in virulence (10). The first increase in virulence occurred in the mid 1950’s when the poultry industry changed from a rather extensive to a more intensive production system. Subsequent increases in virulence are, at least in part, caused by the fact that none of the vaccines prevent infection with field strains thus allowing for the development of escape mutants (1). In addition, Atkins et al. (1) suggested that the reduction in age of broilers to processing also favors an increase in virulence. Unfortunately, there are no good options to change these developments. Without vaccination, losses would be staggering in breeder and layer flocks and in many countries in broilers as well. Thorough cleaning of broiler houses after each cycle may alleviate the need to vaccinate as is the case in some countries, but this will be impractical in the USA and Mexico. A third important factor is immunosuppression especially by chicken infectious anemia virus (CIAV), which is difficult to control in commercial production systems. In this review I will briefly discuss the pathogenesis of CIAV and its impact on immune responses, MD vaccine-induced immune responses, and how CIAV can influence MD vaccine-induced immune responses. With few exceptions only references for book chapters and review papers are used for these three sections. PATHOGENESIS OF CHICKEN INFECTIOUS ANEMIA VIRUS CIAV, currently the only member of the Gyrovirinae of the Circoviridae, is characterized by its small size (±25 nm), single-stranded, circular, covalently closed, negative sense DNA genome of 2,298 nt, and very important from a practical point of view the extreme resistance of CIAV to many commercial disinfectants (7, 9). The genome codes for only three proteins: VP1 (the capsid protein), VP2 (essential for the proper folding of VP1) and VP3, which is also known as apoptin. VP3 is essential for virus replication and mutation of the start codon will prevent virus replication. VP3 is also important because it causes apoptosis of infected cells. The replication of the viral genome requires the formation of double-stranded (ds)DNA, which resembles in some respects a mini-chromosome or a bacterial plasmid. Because CIAV does not code for the necessary enzymes to generate new DNA, and thus infectious virus particles, it needs to infect dividing cells using the cellular enzymes to generate viral DNA. The dividing cells which are susceptible to infection with CIAV are the hemocytoblasts, the precursor cells for erythrocytes, heterophils and thrombocytes, in the bone marrow, thymocytes and T cells. Destruction of the hemocytoblasts by CIAV results in lower hematocrit values, decreased phagocytosis of bacteria by a lack of heterophils and thrombocytes, and increased hemorrhages. Infection of the thymocyte series results in a loss of thymocytes (thymus atrophy), T helper (Th) and cytotoxic T lymphocytes (CTL). The loss of Th lymphocytes and CTL impacts negatively the antibody and cell-mediated immune responses. Virus-neutralizing (VN) antibodies develop within six wk post infection (pi) eliminating virus replication. However, CIAV can remain present in gonads and lymphocytes probably as dsDNA fulfilling the characteristics of latency (7). Latent CIAV can be transmitted vertically and be reactivated. Infection with CIAV only causes clinical disease if infection occurs during the first one to ten d of age in maternal antibody-negative chickens. However older chickens can develop clinical disease when humoral antibody responses are severely compromised for example after infection with vv infectious bursal disease virus (IBDV). Control of vvIBDV using appropriate vaccines without causing damage to the bursa of Fabricius is therefore an important component for the control of CIAV infections. MAREK’S DISEASE VACCINE-INDUCED IMMUNITY Infection of naïve chickens with MDV causes first a lytic infection of B lymphocytes followed by a lytic infection of mostly CD4+ T cells. The lytic phase of infection can cause severe atrophy of the thymus and bursa of Fabricius resulting in immunosuppression. Latent infections are established in CD4+ T cells starting around seven d pi but infection with vv+ strains may cause permanent damage to the primary lymphoid organs and early mortality. Latency can be permanent or temporarily depending on the genetic resistance and immunocompetence of the birds and the virulence of the MDV strain. Ultimately, MDV-positive CD4+ cells may transform in which case tumors develop. To protect against MD, chickens are vaccinated in the USA at 18 d of embryonation (broilers) or directly after hatching (layers and breeders). The latter two groups of birds receive sometimes a second vaccination between 1 – 14 d of age. If a second vaccination is given, it has to be done within the first one to two d of age before chickens are exposed to field virus. Vaccination induces both innate and acquired immune responses. The former include the production of nitric oxide and interferons as well as the activation of natural killer cells which are important to reduce early MDV infections. Innate responses are short-lived, lack memory, and are therefore only important during the first 7 – 10 d pi. However, innate responses are of crucial importance for the development of acquired immunity. Antibodies play only a minor role in protective immunity because MDV infection is strictly cell-associated. In contrast to antibodies, CTL responses are a key component of vaccine-induced acquired immunity. Protective immunity is primarily antiviral reducing but not preventing replication of field virus. The importance of antitumor immunity is controversial and immune responses to tumor cells may be directed to viral antigens rather than true tumor antigens. (8). IMPACT OF CIAV INFECTION ON MAREK’S DISEASE CIAV infection in maternal antibody-positive chickens typically occurs once maternal antibodies have weaned and flocks typically seroconvert between 4 – 10 wk of age. During this time birds may also become infected with MDV field strains. CTL responses are the key component to control virus replication and memory CTL against MDV antigens will be rapidly activated and start dividing thus presenting target cells for CIAV replication. MD vaccine breaks have been linked directly or indirectly to the presence of CIAV infection in several instances (2, 3). Similarly, CIAV infection has also been implicated in infectious bronchitis breaks (5). The effect of CIAV on CTL was clearly shown by Markowski-Grimsrud and Schat (6) using reticuloendotheliosis virus (REV) as a model. Chickens hatched from antibody-positive and -negative hens were infected at four wk of age with CIAV with or without exposure to REV at the same time. At seven d pi CIAV replication was measured by quantitative (q)PCR and qRT-PCR and CTL responses to REV-transformed lymphocytes was measured by chromium release assays (CRA). In the case of maternal antibody-positive chickens, qPCR and qRT-PCR showed lack of CIAV replication and a strong CTL response to REV. Residual maternal antibodies were apparently still present at four wk of age, even while the Iddex ELISA was negative. In contrast, maternal antibody-negative chicks showed high levels of CIAV DNA and RNA, the latter indicating active virus replication. The CTL response to REV was significantly reduced in these birds. CONCLUSIONS CIAV is an important pathogen causing subclinical immunosuppression and can be an important co-factor in vaccine breaks against MD and may other diseases. Development of vaccines to protect chickens to CIAV infection early in life will be an important addition to disease control programs. REFERENCES 1. Atkins, K. E., A. F. Read, N. J. Savill, K. G. Renz, A. F. Islam, S. W. Walkden-Brown, and M. E. Woolhouse. Vaccination and reduced cohort duration can drive virulence evolution: Marek's disease virus and industrialized agriculture. Evolution 67:851-860. 2013. 2. Davidson, I., M. Kedem, H. Borochovitz, N. Kass, G. Ayali, E. Hamzani, B. Perelman, B. Smith, and S. Perk. Chicken infectious anemia virus infection in Israeli commercial flocks: virus amplification, clinical signs, performance, and antibody status. Avian Dis. 48:108–118. 2004. 3. Fehler, F., and C. Winter. CAV infection in older chickens, an apathogenic infection? In: II. International Symposium on infectious bursal disease and chicken infectious anaemia. Institut fur Geflugelkrankheiten, Justus Liebig University, Giessen, Germany, Rauischholzhausen. pp 391-394. 2001. 4. Gimeno, I. M., A. L. Cortes, E. R. Montiel, S. Lemiere, and A. K. R. Pandiri. Effect of diluting Marek's disease vaccines on the outcomes of Marek's disease virus infection when challenged with highly virulent Marek's disease viruses. Avian Dis. 55:263-272. 2011. 5. Hoerr, F. J. Clinical aspects of immunosuppression in poultry. Avian Dis. 54:2-15. 2010. 6. Markowski-Grimsrud, C. J., and K. A. Schat. Infection with chicken anaemia virus impairs the generation of pathogen-specific cytotoxic T lymphocytes. Immunology 109:283-294. 2003. 7. Schat, K. A. Chicken anemia virus. Curr. Top. Microbiol. Immunol. 331:151-184. 2009. 8. Schat, K. A., and V. Nair. Marek's disease. In: Diseases of Poultry, 13 ed. D. E. Swayne, J. R. Glisson, L. R. McDougald, J. V. Nolan, D. L. Suarez and V. Nair, eds. Wiley-Blackwell, Ames, IA. pp 515-552. 2013. 9. Schat, K. A., and V. L. van Santen. Chicken infectious anemia. In: Diseases of Poultry, 13 ed. D. E. Swayne, J. R. Glisson, L. R. McDougald, J. V. Nolan, D. L. Suarez and V. Nair, eds. Wiley-Blackwell, Ames. IA. pp 248-264 and 276-284. 2013. 10. Witter, R. L. Increased virulence of Marek's disease virus field isolates. Avian Dis. 41:149-163. 1997. This paper was presented at the 63rd Western Poultry Disease Conference and XXXIX Convención Anual ANECA, Puerto Vallarta, Jalisco, Mexico, April 2014

Development of an Acid Scrubber for Reducing Ammonia Emissions from Animal Rearing Facilities

Development of an Acid Scrubber for Reducing Ammonia Emissions from Animal Rearing Facilities Author/s : Philip A. Moore, Jr. (University of Arkansas), Rory Maguire (Virginia Tech), Mark Reiter (Virginia Tech), Jactone Ogejo (Virginia Tech),Robert Burns (University of Tennessee), Hong Li (University of Delaware) Dana Miles, USDA/ARS Michael Buser, Oklahoma State University Abstract Recent research has shown that over half of nitrogen excreted by chickens is lost into the atmosphere via ammonia volatilization before the litter is removed from poultry houses. Large quantities of particulate matter and volatile organic compounds (VOCs) are also emitted from animal rearing facilities. During the past decade we have developed and patented an acid scrubber for capturing ammonia, VOCs and dust from air exhausted from poultry and swine barns. The objectives of this project were; (1) to re-design the scrubber to improve the ammonia removal efficacy, (2) conduct full-scale testing of the scrubber under controlled conditions at various ventilation rates, (3) evaluate the cost, practicality and efficacy of various acids for scrubbing ammonia, and (4) install scrubbers on exhaust fans of poultry houses located in Virginia and Arkansas and measure the efficiency of ammonia removal from the exhaust air. The efficiency of ammonia removal by the scrubber varied from 55-95%, depending on the type of acid used, air flow rate, and the internal scrubber configuration. This technology could potentially result in the capture of a large fraction of the N lost from AFOs, while simultaneously reducing emissions of bacteria, dust, and odors, which would improve the social, economic, and environmental sustainability of poultry and swine production. Purpose The objectives of this project were; (1) to re-design our ammonia scrubber to improve the ammonia removal efficacy, (2) conduct full-scale testing of the scrubber under controlled conditions at various ventilation rates, and (3) evaluate the cost, practicality and efficacy of various acids for scrubbing ammonia. What Did We Do? During the first year of this project the main task of our team was to re-design the ammonia scrubber developed and patented by Moore (2007). A full scale prototype was constructed of wood and a series of tests were conducted to evaluate various configurations on air flow and static pressure drop in tests conducted in a machine shop. The scrubber was connected to a 48” variable speed poultry fan. Air flow was measured using a fan assessment numeration system (FANS unit). Static pressure difference was measured using a Setra 2601MS1 differential pressure sensor. The effects of slat angle, number and arrangement of slats, and thickness of cool cell material were evaluated. Following the initial testing a fiberglass mold was made and six scrubbers were constructed. One of these was used to evaluate the effectiveness of water, strong acids, acid salts, and a neutral salt on scrubbing ammonia. Anhydrous ammonia was metered out into a distribution system located within the fan at a sufficient rate to result in 25 ppm NH3 in the plenum between the fan and the dust scrubber. Evaluations of each acid were made with the variable speed fan set at 60 and 40 Hz, which corresponded to air flows of approximately 8,000 and 5,000 cfm, respectively. A stainless steel star sampler was used to take air samples from the plenum and from the air exhausted from the scrubber. Ammonia concentrations were measured using a photoaccustic multigas analyzer (Innova 1412). All personal involved in this testing wore respirators equipped with NH3 cartridges. Three 2-hour trials were conducted with solutions of the following acids at both 40 and 60 Hz: alum, aluminum chloride, ferric sulfate, ferric chloride, sodium bisulfate, sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid. The effects of water and calcium chloride were also evaluated. For these trials the amount of each acid added was equivalent to 2 liters of concentrated sulfuric acid. In addition to measuring inflow and outflow ammonia levels, the mass accumulation of ammonia in both the dust and acid scrubber reservoirs was determined by analyzing the contents for ammonium using an auto-analyzer. Twenty ml aliquots of the scrubber solution were taken at times 0, 1 and 2 hours for ammonia and pH measurements. These data were used to validate that the difference in inlet and outlet ammonia were, in fact, due to accumulation of NH3 in the scrubber. Notes were also taken on each chemical’s ease of use and potential for problems. For example, some dry acids did not readily dissolve and some strong acids, like sulfuric acid, had very strong exothermic reactions. Salts of aluminum and iron become aluminum and iron hydroxides at high pH which have the potential to clog cool cell material. Another performance issue that was monitored was the loss of fine droplets (mist) from the scrubber. When dealing with high air volumes and small droplet sizes, there is a potential for mist to exit the system, resulting in not only the loss of N, but of the acid used to scrub NH3. In order to measure mist loss, five 12.5 cm Whatman 42 filters were attached on a wire cage on the exhaust of the scrubber. These filters were placed in a 50 ml centrifuge tub at the end of each trial and shaken with 25 ml of DDI water, which was analyzed for ammonium, along with sulfate, chloride, nitrate, or phosphate, depending on the acid used. What Have We Learned? Early on in this research we learned that two scrubbers (a dust scrubber and an acid scrubber) were needed rather than one. If the dust isn’t removed from the exhaust air of poultry houses, then a large amount of the acid will be wasted neutralizing the dust. We found that the relationship between slat angle and pressure drop was exponential and the angle that would maximize particle collisions on a wet surface while minimizing pressure drop was 45o. We also found that as the number of rows of slats increased the effect on pressure drop was linear. The final configuration chosen was eight rows of slats in the dust scrubber and three rows of slats in the chemical scrubber, followed by one or two 6” thick layers of cool cell material. The pressure drop using this configuration was about 0.1” of water at 5,000 cfm and 0.3” of water at 8,000 cfm. All of the acids scrubbed ammonium from air, whereas water and calcium chloride only worked for a very short period of time. The iron (Fe) and aluminum (Al) compounds tended to work a little better than the other acid salts or the strong acids. We believe this is due to Fe and Al compounds coating the cool cell material. Although no difference was observed in the static pressure during these short tests, we believe Al and Fe hydroxides would eventually form and may clog the cool cells. Due to the inherit danger in dealing with strong acids, we concluded that an acid salt that did not contain Al and Fe, such as sodium bisulfate, would be used for our research in the future. This product is sold under the tradename PLT for a poultry litter treatment and is readily available to poultry growers. Future Plans Four NH3 scrubbers will be attached to sidewall fans of a commercial broiler house located in Madison County, Arkansas. The efficacy of these scrubbers for reducing ammonia, volatile organic compounds (VOCs), and particulate matter will be evaluated. We will also measure the amount of sodium bisulfate, water and electricity used by the scrubbers, as well as the mass of nitrogen captured. A cost-benefit analysis will be performed based on this data. Data on the efficacy to scrub ammonia will also be conducted on farms in DE, VA, and PA. Acknowledgements This research was funding by USDA/ARS and by grants from USDA/NRCS and the National Wildlife Foundation. The authors would like to thank the hard work and great ideas supplied by Scott Becton and Jerry Martin, without which this scrubber could not have been built.

Treating Poultry Litter with Aluminum Sulfate (Alum)

Treating Poultry Litter with Aluminum Sulfate (Alum) Published on: 07/30/2012 Rating: Author : Philip Moore (USDA- ARS) Definition: Aluminum sulfate (alum) is added to poultry litter in the poultry house to reduce ammonia volatilization. Purpose: Over half of the nitrogen excreted by chickens is lost to the atmosphere as ammonia before the litter is removed from poultry houses. Research has shown that alum additions to poultry litter greatly reduces ammonia emissions. Lower ammonia levels in poultry houses due to alum additions result in heavier birds, better feed conversion and lower mortality. Alum additions to poultry litter also precipitates phosphorus into a form which is not water soluble. This greatly reduces phosphorus runoff from fields fertilized with poultry litter, as well as phosphorus leaching. Alum additions also reduce the number of pathogens in litter. How Does This Practice Work: Alum should be applied to poultry litter at a rate equivalent to 5-1 0% by weight (alum/manure). For typical broiler operations growing six week old birds, this is equivalent to adding 0.1 to 0.2 lbs alum per bird or 1 -2 tons of alum per house per flock if 20,000 birds are in each house. The reduction in ammonia emissions is due to the acid produced when alum is added to the litter. This acid converts ammonia to ammonium; which is not subject to volatilization. The reduction in litter pH also causes pathogen numbers to decrease. Aluminum from alum reacts with phosphorus to form an insoluble aluminum phosphate compound that is far less susceptible to runoff or leaching. Where This Practice Applies and Its Limitations: This practice applies to all poultry operations that have dry litter (broiler, breeder and turkey houses). There are no known limitations of this practice. Effectiveness: Alum additions result in less nitrogen being lost due to ammonia volatilization. Ammonia fluxes from alum-treated litter have been shown to be 70% lower than normal litter (Moore et al., 2000). This results in a higher nitrogen content of the litter, which boosts crop yields. Lower ammonia levels in the rearing facilities also improve poultry production and make the environment safer for agricultural workers. Reducing atmospheric ammonia emissions will also result in less air pollution, such as fine particulate matter (ammonia is a precursor to fine particulate matter), acid precipitation, and atmospheric nitrogen deposition. Treating poultry litter with alum is also one of the most effective methods of reducing phosphorus runoff from fields fertilized with litter. Alum applications to poultry litter have been shown to reduce phosphorus runoff by 87% from small plots (Shreve et al., 1 995) and by 75% from small watersheds (Moore and Edwards, 2007). The long-term effects of applying alumtreated litter to land have indicated that this practice is sustainable (Moore and Edwards, 2005; 2007). Soluble phosphorus levels in soils fertilized with alum-treated litter are significantly lower than that in soils fertilized with normal litter. Hence, there is less phosphorus leaching with alum-treated litter (Moore and Edwards, 2007). Longterm studies conducted by Moore and Edwards (2005) showed that exchangeable aluminum levels in soils fertilized with normal and alum-treated litter are low (less than 1 mg Al/kg soil) and are not significantly different, whereas plots fertilized with the same amount of nitrogen from ammonium nitrate have very high exchangeable aluminum (up to 1 00 mg Al/kg soil). Moore and Edwards (2005) also showed that tall fescue yields from long-term studies were highest with alum-treated litter, followed by normal litter and lowest with ammonium nitrate. Cost of Establishing and Putting Practice in Place: Treating poultry litter with alum is a cost effective best management practice, due to the economic returns from improved poultry production and reduced energy costs. Alum costs about $250/ton. As mentioned earlier two tons of alum should be applied to a typical broiler house after each flock. Moore et al. (2000) showed that the economic returns from this practice were $308 for the grower and $632 for the integrator (company), for a combined return of $940. This is almost twice the cost ($500) to treat the house, resulting in a benefit/cost ratio approaching 2. Operation and Maintenance: Alum is normally applied between each flock of birds. Dry alum can be applied with a number of different spreaders, such as de-caking machines, fertilizer spreaders, manure spreaders or drop spreaders. Applicators should always wear goggles for eye protection and a dust mask to avoid breathing alum dust. Gloves should also be worn to prevent skin irritation. To insure the chickens do not consume the granules of alum, it is best to till the product into the litter. This can be done with a litter de-caker or with any other device that physically mixes the alum into the litter. Liquid alum is normally only applied by a certified professional applicator. There are two types of liquid alum - normal liquid alum (48.5% alum) and acid alum (36.5% alum). Acid alum is preferred in situations where the litter is very dry, since it activates quickly. To add the equivalent of one ton of dry alum, 370 gallons of liquid alum or 51 2 gallons of acid alum is needed. References: Moore, P.A., Jr., S. Watkins, D.C. Carmen, and P.B. DeLaune. 2004 Treating poultry litter with alum. University ofArkansas Cooperative Extension Fact Sheet (FSA8003-PD-1 -04N). Moore, P.A., Jr, T.C. Daniel and D.R. Edwards. 2000. Reducing phosphorus runoff and inhibiting ammonia loss from poultry manure with aluminum sulfate. J. Environ. Qual. 29:37-49. Moore, P.A, Jr., and D.R. Edwards. 2005. Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on aluminum availability in soils. J. Environ. Qual. 34:21 04-2111 . Moore, P.A, Jr., and D.R. Edwards. 2007. Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on phosphorus availability in soils. J. Environ. Qual. 36:1 63-1 74. Shreve, B.R., P.A. Moore, T.C. Daniel, D.R. Edwards and D.M. Miller. 1 995. Reduction of phosphorus runoff from field-applied poultry litter using chemical amendments. J. Environ. Qual. 24:1 06-111 .

Treating Poultry Litter with Aluminum Sulfate (Alum)

Treating Poultry Litter with Aluminum Sulfate (Alum) Published on: 07/30/2012 Rating: Author : Philip Moore (USDA- ARS) Definition: Aluminum sulfate (alum) is added to poultry litter in the poultry house to reduce ammonia volatilization. Purpose: Over half of the nitrogen excreted by chickens is lost to the atmosphere as ammonia before the litter is removed from poultry houses. Research has shown that alum additions to poultry litter greatly reduces ammonia emissions. Lower ammonia levels in poultry houses due to alum additions result in heavier birds, better feed conversion and lower mortality. Alum additions to poultry litter also precipitates phosphorus into a form which is not water soluble. This greatly reduces phosphorus runoff from fields fertilized with poultry litter, as well as phosphorus leaching. Alum additions also reduce the number of pathogens in litter. How Does This Practice Work: Alum should be applied to poultry litter at a rate equivalent to 5-1 0% by weight (alum/manure). For typical broiler operations growing six week old birds, this is equivalent to adding 0.1 to 0.2 lbs alum per bird or 1 -2 tons of alum per house per flock if 20,000 birds are in each house. The reduction in ammonia emissions is due to the acid produced when alum is added to the litter. This acid converts ammonia to ammonium; which is not subject to volatilization. The reduction in litter pH also causes pathogen numbers to decrease. Aluminum from alum reacts with phosphorus to form an insoluble aluminum phosphate compound that is far less susceptible to runoff or leaching. Where This Practice Applies and Its Limitations: This practice applies to all poultry operations that have dry litter (broiler, breeder and turkey houses). There are no known limitations of this practice. Effectiveness: Alum additions result in less nitrogen being lost due to ammonia volatilization. Ammonia fluxes from alum-treated litter have been shown to be 70% lower than normal litter (Moore et al., 2000). This results in a higher nitrogen content of the litter, which boosts crop yields. Lower ammonia levels in the rearing facilities also improve poultry production and make the environment safer for agricultural workers. Reducing atmospheric ammonia emissions will also result in less air pollution, such as fine particulate matter (ammonia is a precursor to fine particulate matter), acid precipitation, and atmospheric nitrogen deposition. Treating poultry litter with alum is also one of the most effective methods of reducing phosphorus runoff from fields fertilized with litter. Alum applications to poultry litter have been shown to reduce phosphorus runoff by 87% from small plots (Shreve et al., 1 995) and by 75% from small watersheds (Moore and Edwards, 2007). The long-term effects of applying alumtreated litter to land have indicated that this practice is sustainable (Moore and Edwards, 2005; 2007). Soluble phosphorus levels in soils fertilized with alum-treated litter are significantly lower than that in soils fertilized with normal litter. Hence, there is less phosphorus leaching with alum-treated litter (Moore and Edwards, 2007). Longterm studies conducted by Moore and Edwards (2005) showed that exchangeable aluminum levels in soils fertilized with normal and alum-treated litter are low (less than 1 mg Al/kg soil) and are not significantly different, whereas plots fertilized with the same amount of nitrogen from ammonium nitrate have very high exchangeable aluminum (up to 1 00 mg Al/kg soil). Moore and Edwards (2005) also showed that tall fescue yields from long-term studies were highest with alum-treated litter, followed by normal litter and lowest with ammonium nitrate. Cost of Establishing and Putting Practice in Place: Treating poultry litter with alum is a cost effective best management practice, due to the economic returns from improved poultry production and reduced energy costs. Alum costs about $250/ton. As mentioned earlier two tons of alum should be applied to a typical broiler house after each flock. Moore et al. (2000) showed that the economic returns from this practice were $308 for the grower and $632 for the integrator (company), for a combined return of $940. This is almost twice the cost ($500) to treat the house, resulting in a benefit/cost ratio approaching 2. Operation and Maintenance: Alum is normally applied between each flock of birds. Dry alum can be applied with a number of different spreaders, such as de-caking machines, fertilizer spreaders, manure spreaders or drop spreaders. Applicators should always wear goggles for eye protection and a dust mask to avoid breathing alum dust. Gloves should also be worn to prevent skin irritation. To insure the chickens do not consume the granules of alum, it is best to till the product into the litter. This can be done with a litter de-caker or with any other device that physically mixes the alum into the litter. Liquid alum is normally only applied by a certified professional applicator. There are two types of liquid alum - normal liquid alum (48.5% alum) and acid alum (36.5% alum). Acid alum is preferred in situations where the litter is very dry, since it activates quickly. To add the equivalent of one ton of dry alum, 370 gallons of liquid alum or 51 2 gallons of acid alum is needed. References: Moore, P.A., Jr., S. Watkins, D.C. Carmen, and P.B. DeLaune. 2004 Treating poultry litter with alum. University ofArkansas Cooperative Extension Fact Sheet (FSA8003-PD-1 -04N). Moore, P.A., Jr, T.C. Daniel and D.R. Edwards. 2000. Reducing phosphorus runoff and inhibiting ammonia loss from poultry manure with aluminum sulfate. J. Environ. Qual. 29:37-49. Moore, P.A, Jr., and D.R. Edwards. 2005. Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on aluminum availability in soils. J. Environ. Qual. 34:21 04-2111 . Moore, P.A, Jr., and D.R. Edwards. 2007. Long-term effects of poultry litter, alum-treated litter, and ammonium nitrate on phosphorus availability in soils. J. Environ. Qual. 36:1 63-1 74. Shreve, B.R., P.A. Moore, T.C. Daniel, D.R. Edwards and D.M. Miller. 1 995. Reduction of phosphorus runoff from field-applied poultry litter using chemical amendments. J. Environ. Qual. 24:1 06-111 .