Figure 6. Hemorrhages in the chicken breast due to overstunning
During processing, poultry carcasses are often inspected for signs of disease or fecal contamination. In some cases, the presence of a disease or fecal contamination may result in a condemnation. When a carcass is condemned by USDA-FSIS, the carcass must be placed into a yellow trash receptacle and the meat must be denatured using a colored dye (usually red) so that humans will never consume the meat. The reasons for carcass condemnations vary greatly and differ from country to country.
Diseases leading to condemnationThere are several diseases that can lead an inspector to condemn a carcass, including:
Septicemia refers to the presence of bacteria in the bloodstream of a chicken. The infection has then resulted in a disease state that causes systemic changes within the bird. These changes are generally visualized by viewing the whole carcass as opposed to specific disease in certain areas. When chickens become septicemic, their organs begin to malfunction and the cells within the body deteriorate. Occasionally, septicemia will cause the bird to die prior to processing. However, in other cases, the immune system of the bird will overcome the disease and the bird is able to recover. It is important to note the bird is only septic for a brief period and then recovers or dies. If the bird has septicemia when it is processed, then the following may be visualized: petechial (pinpoint) hemorrhages on the heart, liver, kidneys, muscles and membranes; the liver, spleen and kidneys are often swollen and hyperemic; and carcasses show signs of generalized vascular degeneration with multiple petechial to ecchymotic hemorrhages.
Very few birds with septicemia survive catching and transportation to make to the processing plant alive. If the bird prior to catching has had a septicemia event, often the muscles have wasted away and have broken down because of changes in muscle metabolism. Some of these birds may eventually be culled in the field. However, even though the infection has subsided, these carcasses are not aesthetically desirable and should be condemned. Historically, septicemia and toxemia were the terms used by inspection staff to report not only carcasses affected with septicemia, but also those with nonspecific generalized or multiple localized conditions. The septicemia/toxemia category was the catchall for carcasses the plant did not find economically feasible to process, such as those with lesions of airsacculitis and inflammatory process. septicemia/toxemia chickens may not be a total loss because any unaffected portions of the carcass may be salvaged.
In chicken houses that are poorly ventilated and contain high levels of ammonia, the air sacs of the birds may become inflamed. The cilia in the respiratory system become paralyzed by ammonia and are unable to clear contaminants from the lungs. When this condition occurs, opportunistic viral or mycoplasmic infections may occur. This can lead to a secondary infection with E. coli, commonly found in high numbers in the poultry growout environment. The E. coli generally do not cause infection, but become opportunistic and infect the air sacs. This leads to the formation of a fibrinous lesion. These lesions can develop within 24 hours. Because birds are not able to produce the enzymes necessary to liquefy the fibrinous lesion, the lesion can persist for several weeks even though the infection has been resolved. If the infection becomes generalized, the bird usually succumbs quickly and dies or will be condemned as septicemia/toxemia. If birds are removed from the processing line for airsacculitis and the exudate is confined to the chest and kidney regions, then the entire carcass should be vacuumed to remove all exudate and the kidneys should also be removed if adjacent air sac membranes show evidence of airsacculitis. If the membranes are cloudy, but there is no exudate, this condition is related to an irritation that can be caused by several factors, including stress, heat and panting (Figure 1).
Inflammatory process is caused by scratches and usually involves the flank region. Inflammatory process in this area can be removed by quartering the carcass. Occasionally, the breast tissue is involved and at times can be quite extensive. In some cases, it may not be possible to salvage all unaffected portions, although any unaffected portions would be eligible for salvage. When necessary, affected carcasses may be vatted until appropriate measures are taken to remove OCPs as long as time and temperature guidelines are followed. If contamination is present, carcasses should be washed prior to vatting.
Cellulitis or inflammatory process
Cellulitis or inflammatory process refers to inflammation of connective tissue with severe inflammation of the dermal and subcutaneous layers of the skin. When birds pile up in a chicken house because of inequalities in temperature or because something scares them, they can scratch each other by jumping on each other’s backs. When this occurs, an opening in the skin allows normal bacteria to form an infection, resulting in cellulitis (Figure 2). When necessary, affected carcasses may be vatted until appropriate measures are taken to remove the lesions as long as time and temperature guidelines are followed. If contamination is present, carcasses should be washed and sanitized prior to vatting.
Synovitis and Tenosynovitis
Synovitis describes inflammation of the synovial membrane, which lines specific joints that possess cavities, known as synovial joints. In chickens, the hock area is often the joint affected by this condition. The hock joint usually swells because of the collection of synovial fluid. Once fluid accumulates, the tendon and/or joint becomes swollen and inflamed. It is recommended that all affected tissue be removed from the carcass. The drumsticks should not be trimmed when there is:
Liver tumors and disease
Marek’s disease and other viral diseases such as avian leukosis may cause tumors to form on the liver. Currently, the USDA-FSIS requires that carcasses affected with tumors caused by leukosis must be condemned. (See Figure 3.)
Keratoacanthoma (squamous cell carcinomas) is usually discovered when the birds are slaughtered. The skin is described as ulcerative, noduloulcerative or nodular. Carcasses with multiple lesions are always condemned for human consumption under the category of tumor. These lesions are only found in the feather tracts, indicating they originate from the feather follicle epithelium. The lesions form in the feather follicle and then heal, leaving a dermal scar. They are considered a common, low-grade skin tumor (Figure 4).
Ascites is a term that refers to fluid that builds up in the abdominal cavity. Often, the hearts of birds reared at high altitudes or under stressful conditions are unable to pump sufficient blood through the lungs, causing which causes an increase in blood pressure. Due to genetic selection, broiler chickens are now able to consume large quantities of feed and grow rapidly, resulting in high demand for oxygen. Under usual conditions, the bird’s cardiovascular system can accommodate this demand with the heart efficiently pushing blood through the lungs where oxygen exchange occurs. However, when oxygen is low due to altitude or poor ventilation the heart essentially pushes the blood through the lungs harder to increase the amount of oxygen available to the bird’s metabolism. Because the lung volume and cardiovascular volume within the lung tissue is fixed, eventually a point is reached where the lungs can no longer accommodate more blood being supplied by the heart. This is the starting point for heart failure and causes an accumulation of fluid in the abdominal cavity. The fluid and gel is removed from the carcass and it is then re-inspected and salvaged as necessary.
Photo courtesy Ewing and Biligili
Figure 1. The interior of a carcass with an airsacculitis infection and exudate
According to USDA-FSIS, a chicken that has died from a cause other than slaughter is called a cadaver and must be condemned. Cadaver birds are easily identified because they are bright red in color. This means that the birds were still breathing prior to entering the scalder.
Bruises and hemorrhages
Bruises are usually caused when the bird impacts something without breakage of skin. There is a hemorrhage of blood into the tissue from the ruptured blood vessels. Recent bruises are deep red or blue/black in color, whereas older bruises may be greenish-yellow in color. The USDA-FSIS requires that only bruises larger than the size of a dime be removed (Figure 5).
Breast hemorrhages (Figure 6) are often due to overstunning. In the U.S., stunning voltages are kept low to prevent this problem. Levels of 12-24 volts are used to allow the birds to be properly stunned, but these birds are able to recover. Overstunning birds using the European model (70-110 volts) can result in heart blowouts, blood splash and petechial hemorrhages, which downgrade the breast meat. Overstunning can also decrease speed of bleedout and increase organic loading of common waters. Thigh hemorrhages are generally due to rough catching or aflatoxin in the feed. If bloody thighs are excessive, both potential sources should be investigated. These hemorrhages must be removed by trimming.
As mentioned, if birds are mismanaged, they can pile up in the chicken house because of inequalities in temperature within the house or because something scares them, resulting in excessive scratching (Figure 7). The USDA-FSIS requires that scabs and the underlying sores greater than 1/8 inch be removed when the sore has not healed. Unhealed lesions will involve the skin and underlying subcutaneous or muscle tissue. Healed scratches and sores need not be removed.
According to the USDA-FSIS, any ingesta or fecal contamination must be removed from carcasses and carcasses must be decontaminated prior to passing inspection. The rule states that in slaughter establishments, fecal contamination of carcasses is the primary avenue for contamination by pathogens. Pathogens may reside in fecal material, both in the gastrointestinal tract and on the exterior surfaces of the bird going to slaughter. Without proper care in handling and dressing procedures during slaughter and processing, the edible portions of the carcass can become contaminated with bacteria capable of causing human illness. Once introduced into the establishment environment, the organisms may be spread from carcass to carcass or by other means, especially in common baths such as the immersion chiller.
Therefore, FSIS enforces a zero-tolerance standard for visible fecal material on poultry carcasses. Carcasses that are accidentally contaminated with the contents of the digestive tract during slaughter are not to be condemned if they can be reprocessed in a manner in which they can be found to be unadulterated. If contamination occurs on the external surfaces of cut meat, it must be trimmed from the carcass. Contamination of the inner surfaces of the carcass may be trimmed or vacuumed. All visible contamination must be removed, and if inner surfaces are reprocessed all surfaces of the carcass must be treated with chlorinated water (usually at 50 ppm).
Even ingesta must be removed from the carcass, and the carcass must be decontaminated prior to chilling. In general, ingesta is yellow because of the pigments in corn in the diet of chicken and fecal material is brown in color.
Unacceptable reasons for condemnation
In some countries, inspection agencies condemn birds based on a misunderstanding of the etiology of the condition. For example, carcasses with dark breast fillets, overscald marks on breasts, or undersized birds are, in many countries, regularly condemned. This costs companies an enormous amount of money.
Dark breast meat
Because breast meat is one of the most valuable portions of the chicken in the U.S., factors that affect its value have preeminent importance. In a survey of the color of retail breast fillets to determine the extent of breast fillet color variation, the author reported that up to 16.9 percent of the packages in the grocery store contained one or more fillets that were discolored. Breast fillets can appear significantly different with regard to color.
The reason for excessively light or dark breast meat is generally stress related. Stress on a live bird that does not possess the pale, soft, exudative gene causes a cascade effect ending in a high pH making the protein fold in a way that causes light to be reflected in the dark or red spectra.
This effect is not due to necrosis, ischemia, more blood in the muscle or more myoglobin in the muscle. If the bird has the pale, soft, exudative gene and is stressed, the glycogen in the breast muscle is converted very quickly to lactic acid and the pH of the meat drops drastically while the carcass is still warm, resulting in a very low terminal pH. This makes the breast meat reflect color in the white spectra. Also, the pale, soft, exudative meat is soft and spongy and does not hold water well. Overall, darker breast fillets will be tougher in texture than lighter breast fillets. Because the meat will not hold moisture when marinated, drip loss and cook loss will be much higher for pale, soft, exudative fillets. There is no reason to condemn carcasses because their breast meat varies in color. There is no food safety issue related to this condition.
Overscalding of the breast meat occurs when the carcasses are scalded using a hard-scald (140 F or 60 C). This causes the underlying breast meat to become slightly cooked in the apteria regions. Because the pterylae are thicker portions of skin, the underlying tissue does not become cooked and stripes are clearly seen (Figure 8). This causes inspectors in some countries to condemn the entire carcass. There is no food safety related issue associated with overscalded breast meat and these carcasses should not be condemned.
References:Allen, C. D., S. M. Russell, and D. L. Fletcher, 1997. The relationship of broiler breast meat color and pH to shelf-life and odor development. Poultry Science 76:1042–1046.
Ewing, M. L. and S. F. Bilgili, Training Manual For The HACCP-Based Inspection Models Program (HIMP), Sanderson Farms and Auburn University.
Fletcher, D. L., 1999. Color variation in commercially packaged broiler breast fillets. J. Applied Poultry Research 8:67-69.
Northcutt, J. K., Factors Influencing Optimal Feed Withdrawal Duration.http://www.caes.uga.edu/Publications/displayHTML.cfm?pk_id=6286
Oda, S. H. I., A. L. Nepomuceno, M. C. Ledur, M. C. N. de Oliveira, S. R. R. Marin, E. I. Ida, and M. Shimokomaki, 2009. Quantitative differential expression of alpha and beta ryanodine receptor genes in PSE (Pale, Soft, Exudative) meat from two chicken lines: broiler and layer. Brazilian Archives of Biology and Techology. 52(6):1519-1525.
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Figure 2. Cellulitis
Figure 3. An example of a diseased chicken liver
Photo courtesy of Ewing and Bilgili
Figure 4. Keratoacanthoma lesions on a chicken carcass
A cadaver or red bird that entered the scalder live and was killed during scalding.
Figure 5. A deep bruise on the skin of the breast of a chicken carcass
Figure 7. Scratches can be seen in the thigh of a chicken. Some of them have healed and formed scars (see red stripes at top of photo).
Figure 8. Chicken breast overscalding stripes are evident
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