Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2005
Publication Date: 6/30/2005
Citation: Ritter, M., Ellis, M., Johnson, A.K., Benjamin, M., Dubois, P., Marchant Forde, J.N., Green, A., Pfalzgraf, K., Matzat, P., Mormede, P., Moyer, T., Siemens, M., Sterle, J., Whiting, T., Wolter, B. 2005. A review of the fatigued pig syndrome. Journal of Animal Science. 83:(1):258. Interpretive Summary:
Technical Abstract: A workshop sponsored by the National Pork Board was held to review the literature relating to fatigued pigs. A fatigued pig (non-ambulatory, non-injured) was defined as a pig that - without obvious injury, trauma, or disease - refuses to walk at any one of the respective stages of the marketing channel from loading at the farm to stunning at the plant. Workshop objectives were to identify the causes and economic impact of this syndrome as well as production factors potentially associated with fatigued pigs. Also, intervention strategies to prevent the problem were reviewed and key gaps in the scientific literature were identified. Two potential mechanisms for the etiology of fatigued pig syndrome were identified: 1) acute stress resulting in acidosis; 2) chronic stress resulting in glycogen depletion and physical exhaustion. Substantial research supports the acute stress and acidosis mechanism. However, little is known about effects of glycogen depletion and physical exhaustion in market-weight pigs on incidence of fatigued pig syndrome. Also, several authors found elevated plasma ammonia concentrations in fatigued pigs, but the importance of this is not understood. The economic impact of fatigued pig syndrome is currently unknown because national statistics for its incidence are not available and losses associated with product-quality defects (i.e., fresh pork quality attributes, carcass trim loss, and pig/carcass disposal fees) are not known. Based on several field studies, it has been estimated that >50% of all pigs identified as non-ambulatory at the plant are fatigued and, thus, it is anticipated that ~0.3-0.4% of all pigs delivered to the plant will develop the syndrome. The fatigued pig condition is a multi-factorial phenomenon. Predisposing factors were characterized as pig, environment/facility, people, transport, and plant. Key gaps in the literature included but were not limited to the effects of genetics, health status, increased leanness/muscling, age/slaughter weight, production system, trailer design, transport time, and line speed at the plant.