At all times prior to slaughter pigs may experience stress from a range of handling practices, such as fasting, loading and transport, mixing and interaction with humans. Preslaughter stress is both an animal welfare and a meat quality issue. On one hand, behavioural and physiological studies revealed that poor handling practices at the farm, during transport and at the slaughter plant are aversive to pigs and may result in loss of profits due to animal losses during transport and in lairage. On the other hand, poor preslaughter handling can also lead to losses in carcass value due to contamination and meat quality defects.
Costs related to animal losses
The occurrence of a dead-on-arrival (DOA) at the slaughter plant is a major economic loss for producers and transporters. With approximately 100 million pigs being slaughtered annually in the United States (USDA, 2006), animal losses (downers and DOA) would cost pork producers more than 16 million dollars/year. Over the last years, up to 17,000 DOAs (CFIA, 2010) and 80,000 non-ambulatory pigs (BCSPCA, 2008) have been reported in Canada costing more than $3 millions to the Canadian pork industry. In US plants approximately 1 % of pigs has been characterized as downers (non-ambulatory, non-injured or NANI and non-ambulatory-injured or NAI, pigs; Carr et al., 2005). The presence of downer pigs on arrival at the plant can cost $20 per pig (total loss of $14 millions; Ritter et al., 2009) to producers and processors for the following reasons: 1) specific training of personnel for the handling of non-ambulatory animals. It has been recently reported that the use of untrained handlers at loading can result in 0.22% increase in the number of fatigued pigs on arrival at the plant (Fitzgerald et al., 2008); 2) loss of carcass value due to condemnation (up to 30 % price discount) and extra-trimming due to bruises (Ritter et al., 2009). The major cause of full or partial condemnation is due to unacceptable amount of residual blood in the carcass due to poor bleeding (Faucitano and Geverink, 2008); 3) extra-labour in the cooler for segregation of carcasses of non-ambulatory pigs from those of normal pigs according to the market targets; 4) higher incidence of dark or pale and of dry or exudative pork depending on when (long- or short-term stress) the pig becomes fatigued during the marketing process.
A recent epidemiological study (Sunstrum et al., 2006; Haley et al., 2008) identified the major source of mortality and downers rate variation (0.17 and 0.25%, respectively) as being the farm (55%), including the preparation of pigs at the farm, farm design and handling at loading, followed by the packer (25%), implying handling of suspect pigs on arrival at the plant, and the transporter (19%), including vehicle design and transport conditions.
Costs related to carcass bruises
The presence of blemishes or bruises on the surface of the pork carcass caused by fighting or rough handling is not only indicative of poor welfare, but it also detracts from the appearance of the carcass leading, in case of severe bruises, to a 6% carcass downgrading (MLC, 1985). The reduction of the speed of the dressing line to remove blemished tissues and the increased need for staff for carcass inspection represent additional costs. Further costs are also related to loss of market opportunities as severely bruised carcass and/or joints are rejected by the highly sophisticated international markets and can only be used for making lower value products with lower margin of profit. For example, in France, bruised backfat and hams can be depreciated by 1/3 and 1/5 of their price, respectively (Chevillon and Le Jossec, 1996), whereas in Italy bruised hams are discarded from the high quality Parma ham production line (Faucitano, 2001). According to US pork industry estimates (Vansickle, 2002; Schultz-Kaster and Hill, 2006), bruises alone contribute to $0.08 value loss per carcass or more than $48 million in annual trim losses.
Costs related to meat quality defects
Short- or long-term preslaughter stress-induced meat quality problems, such as PSE (pale, soft, exudative) and DFD (dark, firm, dry) pork, respectively, can produce great economic losses. The 5% increased incidence of PSE reported in a 2002 pork quality compared to a previous one run in 1993 in US generated an economic loss of $0.72 per carcass greater than the cost per carcass attributed to PSE in 1993 (Cannon et al., 1995; Scanga et al., 2003). More recently, the annual profit loss estimated by the US pork industry in relation to meat quality attributes was of approximately $200 millions (Schultz-Kaster and Hill, 2006).
Meat exudation ($0.50/pig), unacceptable colour ($0.43/pig) and high incidence of PSE pork ($0.90/pig) are major contributors to this economic loss (Schultz-Kaster and Hill, 2006). Approximately 20% exudative and 15% soft loins have been reported in Canada (Faucitano et al, 2010b; L. Riendeau, CDPQ, personal communication). It has been estimated that these meat quality defects decrease the value of the cut by $3 resulting in loss of $1.2 millions due to water exudation and missed opportunities for export (L. Riendeau, CDPQ, personal communication).
Costs related to food safety
Feed withdrawal prior to slaughter accounts for 71% of the variation in the carcass contamination rate at slaughter (Schoonderwoerd, 1997). At this stage carcass microbial contamination occurs due to nicking and spilling of visceral contents following gastro-intestinal (GI) tract laceration during the evisceration process. Despite this risk, sometimes this procedure is not used or misapplied by producers because of concerns related to carcass weight losses resulting in reduced revenue from the carcass sale. This attitude frequently results in complaints and penalties from the processor. In Eastern Canada the strict control of the GI tract weight has been undertaken on the evisceration line by the carcass grading agency since 2009 resulting in a 3% decrease of full GI tract at slaughter in less than one year (Gendron, 2010).
Research has shown that the application of 20-24 h feed withdrawal time allows producer to save 2 kg of feed per pig at no detriment of carcass yield and enables pork processors to get a two-fold lower stomach weight at slaughter, reduced waste to be disposed of at the plant and better meat quality (see review by Faucitano et al., 2010b).
BCSPCA 2008. Get on board. The British Columbia Society for the Prevention of Cruelty to Animals. Available at: http://www.spca.bc.ca/welfare/campaign-issues/facts-about-farm-animal.html.
Cannon, J.E., Morgan, J.B., McKeith, F.K., Smith, G.C. and Meeker, D.L. 1995. Pork quality audit: a review of the factors influencing pork quality. J. Muscle Foods. 6, 369-402.
Carr S.N., Gooding J.P., Rincker P.J., Hamilton D.N., Ellis M., Killefer J. and McKeith F.K. 2005. A survey of pork quality of downer pigs. J. Muscle Foods 16, 298-305.
CFIA 2010. Red Meat Condemnation Report by Species-Hogs. Canadian Food Inspection Agency. Available at:http://www3.agr.gc.ca/apps/aimis-simia/rp/index-eng.cfm?menupos=1.02.08&ACTION=pR&LANG=EN&R=134&PDCTC= Chevillon, P. and Le Jossec, P. 1996. Limiter le défauts sur couennes. TechniPorc 19.1.96.
Faucitano, L. 2001. Causes of skin damages to pig carcasses. Can. J. Anim. Sci. 81, 39-45.
Faucitano, L. and Geverink, N.A. 2008. Effects of preslaughter handling on stress response and meat quality in pigs. In: L. Faucitano and A.L. Schaefer (eds.), "The Welfare of Pigs - from Birth to Slaughter", Wageningen Academic Publ., pp. 197-224.
Faucitano, L., Ielo, M.C., Ster, C., Lo Fiego, D.P., Méthot, S. and Saucier, L. 2010a. Shelf life of pork from five different quality classes. Meat Sci. 84, 466-469.
Faucitano, L., Chevillon, P. and Ellis, M. 2010b. Effects of feed withdrawal prior to slaughter and nutrition on stomach weight, and carcass and meat quality in pigs. Livest. Sci. 127, 110-114.
Fitzgerald R., Stalder K., Matthews N., Schultz-Kaster C. and Johnson A. 2008. Effects of environment on non-ambulatory, injured and fatigued pigs and losses during transport and lairage at a commercial abattoir. J. Anim. Sci. 86 (E-Suppl. 2), 344.
Gendron, A. 2010. Des critères de qualité améliorés. Porc Québec 21, 42.
Haley C., Dewey C., Widowski T, Poljak Z. and Friendship R. 2008. Factors associated with in-transit losses of market hogs in Ontario in 2001. Can. Vet. Res. J. 72, 377.
MLC 1985. Concern at rindside damage in pigs. Meat and Marketing Technical Notes No. 4, Milton Keynes, Meat and Livestock Commission, Bletchley, UK, 14-16.
Ritter, M.J., Ellis, M., Berry, N.L., Curtis, S.E., Anil, L., Berg, E., Benjamin, M., Butler, D., Dewey, C., Driessen, B., DuBois, P., Hill, J.D., Marchant-Forde, J.N., Matzat, P., McGlone, J., Mormède, P., Moyer, T., Pfalzgraf, K., Salak-Johnson, J., Siemens, M., Sterle, J., Stull, C., Whiting, T., Wolter, B.,
Niekamp, S.R. and Johnson, A.K. 2009. Transport losses in market weight pigs: 1. A review of definitions, incidence, and economic impact. Prof. Anim. Sci. 25, 404-414.
Scanga, J.A., McKeith, F.K., Savell, J.W., Belk, K.E., Griffin, D.B., Wright, L.I., Stetzer, A.J., Person, R.C., Lonergan, S.M., Powell, T.H., Meisinger, D.J. and Smith, G.C. 2003. Benchmarking value in the pork supply chain: quantitative strategies and opportunities to improve quality. Final Report to the National Pork Board, De Moines, IA, USA.
Schoonderwoerd, M. 1997. Main factors responsible for visible pork carcass contamination. Proc. World Congr. on Food Hygiene, The Hague, The Netherlands, 67.
Schultz-Kaster, C. and Hill, J. 2006. Animal handling issues in the pork industry. Proc. 59th
RMC, Urbana-Champaign, IL, USA.
Sunstrum, J., Dewey, C. and Haley, C. 2006. Clinical signs of stress of finisher pigs transported to market in the summer. Proc. Am. Assoc. Swine Vet., Orlando, FL, USA, 45.
USDA. 2006. National Daily Livestock Summary. Available at: http://www.ams.usda.gov/mnreports/am_ls830.txt .
Vansickle, J. 2002. Quality Assurance Program Launched. Available at: http://nationalhogfarmer.com/mag/farming_quality_assurance_program/
This presentation was given at the Pork Expo 2010 e V Fórum Internacional de Suinocultura, Curitiba, Brazil and was provided to Engormix.com courtesy of the organizing committee.