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European perspective on poultry slaughter technology
European Perspective on Poultry Slaughter Technology THEO G. UIJTTENBOOGAART1 Department of Food Science, DLO-Institute for Animal Science and Health, NL 8200 AB Lelystad, The Netherlands ABSTRACT The slaughter process as it is presently conducted in Europe is described as well as the EU regulation with respect to handling, transport, stunning,
and killing of poultry. Furthermore, a description of new developments in poultry processing is described with special attention to bird handling and stunning.
(Key words: poultry processing, handling and transport, stunning, killing) 1999 Poultry Science 78:295–297
In the past decade, poultry meat consumption worldwide has increased rapidly. In the U.S., poultry meat consumption has outgrown that of both beef and pork. In many parts of the world, the per capita consumption of poultry meat will continue to grow far into the next century. Reasons for this growth are the health image of the product, which is considered lean and rich in protein, the increased availability of further processed products and, last, but not least, the relatively low price of this type of meat. To keep poultry meat attractive for a growing number of people, poultry operations have to be highly cost-effective. An important aspect here is the labor requirements in poultry processing plants. The high level of automation in poultry processing has contributed to the large increase in poultry meat output worldwide over the past two decades. Automation has also resulted in uniformity of end products and upgrading of working conditions. In most modern processing plants today, actual labor consists largely of monitoring and adjusting the process. As many skilled manual operations as possible are integrated in the processing equipment. Everywhere in the world the poultry processing industry is increasing its capacity to keep end products competitively priced for consumers. The cost of labor is increasing, whereas, on the other hand, people are less and less prepared to provide the required labor, especially when more attractive employment alternatives are available. For transport of live animals, container systems are used. Using these systems, manual handling is no longer
EU REGULATIONS Transport of animals for slaughter and killing of slaughter animals is regulated by EU regulations 91/628 (1991) and 93/119 (1993). Table 2 gives the minimum space requirements as these are regulated in the abovementioned EU regulation. The required surface depends on the size of the birds. Small birds need a greater surface per kilogram of body weight than the larger birds. For regular plastic transport crates, the load per crate (80 × 65 cm) is 28 kg for the lighter birds (< 1.6 kg) and 32 kg for the heavier birds (> 1.6 and < 3 kg). Also, requirements are set for the height of the container. There are two standard heights for light and heavy birds, respectively. Regulation 93/119/EEC (1993) for the protection of animals during slaughter or killing only allows a limited number of procedures. For stunning, any method that causes immediate unconsciousness after application to the animal until death should be used. During transport handling, stunning, and killing, any avoidable excitement, pain, or suffering should be
Received for publication August 5, 1997. Accepted for publication September 1, 1998. 1 To whom correspondence should be addressed: t.g. [email protected]
295
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
required, which means improved animal welfare during transport and handling at the plant. On arrival at the plant the birds are kept about 3 h. New plants build air-conditioned storage rooms in which birds are kept. Veerkamp (1997) describes the climate conditions during holding of the birds before slaughter. Optimal conditions for broilers with the lowest yield loss is an air enthalpy value of 11 to 13 kcal/kg. This is equal to the temperature/relative humidity conditions as given in Table 1. The use of low light conditions during the waiting time before slaughter reduces stress and further feed withdrawal for the bird. Together with the feed withdrawal time and the time required for transport, the intestinal tracts of the birds are empty, which is required for good hygiene during processing of the birds.
INTRODUCTION
296
UIJTTENBOOGAART
TABLE 1. Temperature and relative humidity values equivalent to yield losses of 11 to 13 kcal/kg (Veerkamp, 1997) Temperature
Relative humidity
(C) 25–29 22–25 18–22 16–18
(%) 40 60 80 100
QUALITY ASPECTS OF STUNNING/KILLING Although hemorrhages are caused mainly by electrical stunning operations, there are other factors involved that affect incidence of hemorrhages. Important in this respect are feed composition, handling, sex, genetic background, and period of feed and water withdrawal. The incidence and severity of hemorrhaging will be more or less pronounced depending on the sensitivity of a bird in a certain situation, as related to these factors. Hillebrand et al. (1996) showed that fixation (immobilization) of the birds for the prevention of wing flapping and free struggle before and during the stunning operation reduces the number and severity of hemorrhages. Also, the level of the current passing through the bird is related to the occurrence of hemorrhages. New gas stunning methods using CO2 and argon gas mixtures also reduce hemorrhages in breast meat (Raj
OTHER PROCESSING ASPECTS In the modern processing plant labor requirements are limited to hanging of the birds, control of the automated processes and veterinary inspection. Relatively more labor is required during cutting up, packaging and further processing. The number of broilers processed per laborer per hour (without giblet harvesting) increased in the period of 1970 to 1995 from 150 to 1,500. The increase in the U.S. during the same period was much smaller due to the greater number of people used for veterinary inspection, grading, and recovering of B-grade birds. In the Netherlands, certified processing plants are obliged to monitor flock quality. The official system of monitoring now is based upon visual inspection of the birds after feather removal. New systems are being developed using image analysis. Image analysis systems are also being implemented for carcass grading. Broiler processing in Europe these days relies on a low scalding temperature and air chilling. Most of the birds are dissected and meat is further processed in specialized plants. An aging period of at least several hours after chilling is essential for a good quality tender meat. Table 3 shows the effect of aging under different chilling conditions. From these data, during “normal air chilling” an aging period of at least 3 h after evisceration is
TABLE 2. Transport of poultry, dimensions of transport units depending on weight of birds as given in the EU regulation 91/628 (1991) Weight class
Available surface space
(kg) <1.6 >1.6 and <3 >3 and <5 >5
(lb) <3.5 >3.5 and <6.6 >6.6 and <11 >11
(in2/lb) 180 to 200 13 to 14 160 11 115 8 105 7.5 Height1
(kg) <4 >4
(lb) <8.8 >8.8
(cm) 24 to 27 34 to 36
1Inside
height of transport unit.
(cm2/kg)
(in) 9.8 to 10.6 13.4 to 14.2
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
prevented. Waiting conditions should be such that the animals are protected against severe weather conditions. During hot and humid weather, chilling should be provided. Fixation of poultry at their feet is allowed. Any avoidable pain, suffering, excitement, or injury should be prevented. Electrical stunning with a water bath also is subjected to a number of regulations. The most important are: The strength and duration of the current should be such that the animals are brought into an immediate state of unconsciousness. In the EU, the minimum current per bird for water bath stunning is 100 mA. The voltage in a water bath stunner in which more than one animal is stunned must be such that a current is obtained sufficient for stunning each individual animal. Furthermore, shackles are to be wetted to reduce electrical resistance between shackle and legs. Poultry must be executed as soon as possible after the stunning operation. At least one of the arteries in the neck should be cut. After the cutting operation, no further treatment, such as electrical stimulation, can be applied to the animals until the end of bleeding. Stunning is also a very important process affecting meat quality characteristics such as hemorrhages and tenderness development in poultry breast meat.
and Nute, 1995). Gas stunning using argon gas mixtures also appeared to accelerate aging rate (Raj and Nute, 1995), resulting in faster processing. Further research related to these stunning methods and the consequences for meat quality characteristics is required. At this time, gas stunning is not permitted for stunning poultry within the EU. Pigs can be stunned at a CO2 level of 70%. The authorities can permit gas stunning for poultry when it is carried out under the same conditions as pigs. Furthermore, studies are conducted on new developments in which other gas mixtures, as well as completely different and scientifically accepted methods, can be used.
SYMPOSIUM: RECENT ADVANCES IN POULTRY SLAUGHTER TECHNOLOGY
297
TABLE 3. Shear force values of chicken broiler breast meat at different chilling regimens and boning time (Uijttenboogaart and Reimert, 1993)
Treatment
Chilling procedure
Control
Ice
Aging period of time till boning after evisceration 0 min
30 min
60 min
120 min
180 min
60
58
43
38
26
22
17
19
34
33
22
23
36
31
27
23
(N) 56 Air Electrical stimulation
Ice 57 Air
REFERENCES EU, 1991. EU Regulation 91/628/EEC on Transport of Animals for Slaughter. Brussels, Belgium. EU, 1993. EU Regulation 93/119/EEC on Protection of Animals During Slaughter and Killing. Hillebrand, S.J.W., E. Lambooy, and C. H. Veerkamp, 1996. The effects of electrical and mechanical stunning methods
on hemorrhages and meat quality of broiler breast meat and thigh muscle. Poultry Sci. 75:664–671. Raj, A.B.M., and G. R. Nute, 1995. Effect of stunning method and filleting time on sensory profile of turkey breast meat. Br. Poult. Sci. 36::221–227. Uijttenboogaart, T. G., and H.G.M. Reimert, 1993. Effects of the method of chilling, electrical stimulation and boning time on quality characteristics of chicken broiler breast meat. Paper S-IVB.41. Pages 1–7 in: Proceedings International Congress of Meat Science and Technology. The Hague, The Netherlands. Veerkamp, C. H., 1997. Pre slaughter operations. Turkey World. Poultry Processing Worldwide: 28–33.
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
required. In the modern processing plant an in-line aging period is incorporated to prevent prerigor toughness in the hot boned meat.
and killing of poultry. Furthermore, a description of new developments in poultry processing is described with special attention to bird handling and stunning.
(Key words: poultry processing, handling and transport, stunning, killing) 1999 Poultry Science 78:295–297
In the past decade, poultry meat consumption worldwide has increased rapidly. In the U.S., poultry meat consumption has outgrown that of both beef and pork. In many parts of the world, the per capita consumption of poultry meat will continue to grow far into the next century. Reasons for this growth are the health image of the product, which is considered lean and rich in protein, the increased availability of further processed products and, last, but not least, the relatively low price of this type of meat. To keep poultry meat attractive for a growing number of people, poultry operations have to be highly cost-effective. An important aspect here is the labor requirements in poultry processing plants. The high level of automation in poultry processing has contributed to the large increase in poultry meat output worldwide over the past two decades. Automation has also resulted in uniformity of end products and upgrading of working conditions. In most modern processing plants today, actual labor consists largely of monitoring and adjusting the process. As many skilled manual operations as possible are integrated in the processing equipment. Everywhere in the world the poultry processing industry is increasing its capacity to keep end products competitively priced for consumers. The cost of labor is increasing, whereas, on the other hand, people are less and less prepared to provide the required labor, especially when more attractive employment alternatives are available. For transport of live animals, container systems are used. Using these systems, manual handling is no longer
EU REGULATIONS Transport of animals for slaughter and killing of slaughter animals is regulated by EU regulations 91/628 (1991) and 93/119 (1993). Table 2 gives the minimum space requirements as these are regulated in the abovementioned EU regulation. The required surface depends on the size of the birds. Small birds need a greater surface per kilogram of body weight than the larger birds. For regular plastic transport crates, the load per crate (80 × 65 cm) is 28 kg for the lighter birds (< 1.6 kg) and 32 kg for the heavier birds (> 1.6 and < 3 kg). Also, requirements are set for the height of the container. There are two standard heights for light and heavy birds, respectively. Regulation 93/119/EEC (1993) for the protection of animals during slaughter or killing only allows a limited number of procedures. For stunning, any method that causes immediate unconsciousness after application to the animal until death should be used. During transport handling, stunning, and killing, any avoidable excitement, pain, or suffering should be
Received for publication August 5, 1997. Accepted for publication September 1, 1998. 1 To whom correspondence should be addressed: t.g. [email protected]
295
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
required, which means improved animal welfare during transport and handling at the plant. On arrival at the plant the birds are kept about 3 h. New plants build air-conditioned storage rooms in which birds are kept. Veerkamp (1997) describes the climate conditions during holding of the birds before slaughter. Optimal conditions for broilers with the lowest yield loss is an air enthalpy value of 11 to 13 kcal/kg. This is equal to the temperature/relative humidity conditions as given in Table 1. The use of low light conditions during the waiting time before slaughter reduces stress and further feed withdrawal for the bird. Together with the feed withdrawal time and the time required for transport, the intestinal tracts of the birds are empty, which is required for good hygiene during processing of the birds.
INTRODUCTION
296
UIJTTENBOOGAART
TABLE 1. Temperature and relative humidity values equivalent to yield losses of 11 to 13 kcal/kg (Veerkamp, 1997) Temperature
Relative humidity
(C) 25–29 22–25 18–22 16–18
(%) 40 60 80 100
QUALITY ASPECTS OF STUNNING/KILLING Although hemorrhages are caused mainly by electrical stunning operations, there are other factors involved that affect incidence of hemorrhages. Important in this respect are feed composition, handling, sex, genetic background, and period of feed and water withdrawal. The incidence and severity of hemorrhaging will be more or less pronounced depending on the sensitivity of a bird in a certain situation, as related to these factors. Hillebrand et al. (1996) showed that fixation (immobilization) of the birds for the prevention of wing flapping and free struggle before and during the stunning operation reduces the number and severity of hemorrhages. Also, the level of the current passing through the bird is related to the occurrence of hemorrhages. New gas stunning methods using CO2 and argon gas mixtures also reduce hemorrhages in breast meat (Raj
OTHER PROCESSING ASPECTS In the modern processing plant labor requirements are limited to hanging of the birds, control of the automated processes and veterinary inspection. Relatively more labor is required during cutting up, packaging and further processing. The number of broilers processed per laborer per hour (without giblet harvesting) increased in the period of 1970 to 1995 from 150 to 1,500. The increase in the U.S. during the same period was much smaller due to the greater number of people used for veterinary inspection, grading, and recovering of B-grade birds. In the Netherlands, certified processing plants are obliged to monitor flock quality. The official system of monitoring now is based upon visual inspection of the birds after feather removal. New systems are being developed using image analysis. Image analysis systems are also being implemented for carcass grading. Broiler processing in Europe these days relies on a low scalding temperature and air chilling. Most of the birds are dissected and meat is further processed in specialized plants. An aging period of at least several hours after chilling is essential for a good quality tender meat. Table 3 shows the effect of aging under different chilling conditions. From these data, during “normal air chilling” an aging period of at least 3 h after evisceration is
TABLE 2. Transport of poultry, dimensions of transport units depending on weight of birds as given in the EU regulation 91/628 (1991) Weight class
Available surface space
(kg) <1.6 >1.6 and <3 >3 and <5 >5
(lb) <3.5 >3.5 and <6.6 >6.6 and <11 >11
(in2/lb) 180 to 200 13 to 14 160 11 115 8 105 7.5 Height1
(kg) <4 >4
(lb) <8.8 >8.8
(cm) 24 to 27 34 to 36
1Inside
height of transport unit.
(cm2/kg)
(in) 9.8 to 10.6 13.4 to 14.2
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
prevented. Waiting conditions should be such that the animals are protected against severe weather conditions. During hot and humid weather, chilling should be provided. Fixation of poultry at their feet is allowed. Any avoidable pain, suffering, excitement, or injury should be prevented. Electrical stunning with a water bath also is subjected to a number of regulations. The most important are: The strength and duration of the current should be such that the animals are brought into an immediate state of unconsciousness. In the EU, the minimum current per bird for water bath stunning is 100 mA. The voltage in a water bath stunner in which more than one animal is stunned must be such that a current is obtained sufficient for stunning each individual animal. Furthermore, shackles are to be wetted to reduce electrical resistance between shackle and legs. Poultry must be executed as soon as possible after the stunning operation. At least one of the arteries in the neck should be cut. After the cutting operation, no further treatment, such as electrical stimulation, can be applied to the animals until the end of bleeding. Stunning is also a very important process affecting meat quality characteristics such as hemorrhages and tenderness development in poultry breast meat.
and Nute, 1995). Gas stunning using argon gas mixtures also appeared to accelerate aging rate (Raj and Nute, 1995), resulting in faster processing. Further research related to these stunning methods and the consequences for meat quality characteristics is required. At this time, gas stunning is not permitted for stunning poultry within the EU. Pigs can be stunned at a CO2 level of 70%. The authorities can permit gas stunning for poultry when it is carried out under the same conditions as pigs. Furthermore, studies are conducted on new developments in which other gas mixtures, as well as completely different and scientifically accepted methods, can be used.
SYMPOSIUM: RECENT ADVANCES IN POULTRY SLAUGHTER TECHNOLOGY
297
TABLE 3. Shear force values of chicken broiler breast meat at different chilling regimens and boning time (Uijttenboogaart and Reimert, 1993)
Treatment
Chilling procedure
Control
Ice
Aging period of time till boning after evisceration 0 min
30 min
60 min
120 min
180 min
60
58
43
38
26
22
17
19
34
33
22
23
36
31
27
23
(N) 56 Air Electrical stimulation
Ice 57 Air
REFERENCES EU, 1991. EU Regulation 91/628/EEC on Transport of Animals for Slaughter. Brussels, Belgium. EU, 1993. EU Regulation 93/119/EEC on Protection of Animals During Slaughter and Killing. Hillebrand, S.J.W., E. Lambooy, and C. H. Veerkamp, 1996. The effects of electrical and mechanical stunning methods
on hemorrhages and meat quality of broiler breast meat and thigh muscle. Poultry Sci. 75:664–671. Raj, A.B.M., and G. R. Nute, 1995. Effect of stunning method and filleting time on sensory profile of turkey breast meat. Br. Poult. Sci. 36::221–227. Uijttenboogaart, T. G., and H.G.M. Reimert, 1993. Effects of the method of chilling, electrical stimulation and boning time on quality characteristics of chicken broiler breast meat. Paper S-IVB.41. Pages 1–7 in: Proceedings International Congress of Meat Science and Technology. The Hague, The Netherlands. Veerkamp, C. H., 1997. Pre slaughter operations. Turkey World. Poultry Processing Worldwide: 28–33.
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF PITTSBURGH on March 10, 2015
required. In the modern processing plant an in-line aging period is incorporated to prevent prerigor toughness in the hot boned meat.