Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1977 Porcine stress syndrome: inheritance, prediction and performance characteristics John William Mabry Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons Recommended Citation Mabry, John William, "Porcine stress syndrome: inheritance, prediction and performance characteristics " (1977). Retrospective Theses and Dissertations. 7621. https://lib.dr.iastate.edu/rtd/7621 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John's Road. Tyler's Green High Wycombe, Bucks, England HP10 8HR 77-29,850 MABRY, John William, 1950- PORCINE STRESS SYNDROME: INHERITANCE, PREDICTION AND PERFORMANCE CHARACTERISTICS Iowa State University, Ph.D., 1977 Agriculture, general Xerox University Microfilms, Ann Arbor, Michigan 48io6 Porcine stress syndrome» Inheritance, prediction and performance characteristics by John William Mabry A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Animal Science Major: Animal Breeding Approved: Signature was redacted for privacy. In Charge of Raj or Work Signature was redacted for privacy. For the Major Department Signature was redacted for privacy. For the Graduate College lovra State University Ames, Iowa 1977 ii TABLE OP CONTENTS Page INTRODUCTION 1 LITERATURE REVIEW 4 METHODS AND MATERIALS 22 RESULTS AND DISCUSSION 35 BIBLIOGRAPHY 75 ACKNOWLEDGEMENTS 85 APPENDIX 86 1 INTRODUCTION The Porcine Stress Syndrome (PSS) is a genetic abnormal­ ity in which an animal lacks the ability to adapt to stressors which are encountered during his lifetime. The condition is characterized by a sudden death after stress. Death is pre­ ceded by a rise in body temperature, metabolic acidosis» and muscle rigidity, with rigor mortis occurring promptly following death. Stressful situations which may trigger this syndrome include mixing of strange pigs, trajisport, handling, rapid change in environment, and certain management practices. The effect of PSS on subsequent meat quality is generally detri­ mental. In herds with high incidence of the syndrome there is an increased occurrence of both pale, soft, and exudative musculature (PSE) as well as an increase in dark, fim, and dry musculature (DFD) among the carcasses of slaughter ani­ mals. Pigs that are susceptible to this syndrome are usually very muscular with little external fat. The economic impact of PSS is manifest in more than one segment of the industry. Producers encounter death loss from routine management and handling of the pigs at the farm in addition to an increased death loss during transport to market. In addition, meat packers experience considerable loss due to decreased carcass quality of stress-susceptible animals. Hall (1972) estimated the adverse economic impact of PSS and its resulting poor quality lean to be between 230 2 and 320 million dollars per year in the United States; with, the loss at retail due to excess shrinkage and lower yields of PSE meat to account for approximately 95 million dollars of this. Briskey (1964) reported monetary losses amounting to millions of dollars to the meat packing industry due to PSE muscle. Adding to this the theorized reduced productivity of stress-susceptible animals makes the economic impor-tince of PSS quite sizeable. The incidence of PSS, as estimated by Livestock Conservation, Inc. (1971) in a survey, showed that 36% of those U.S. hog producers responding to their survey had experienced some problem with PSS. These affected herds constituted 44^ of the U.S. market hog production. Due to its large monetary importance and frequency of occurrence, this problem has received an enormous amount of research effort. The main areas of research concentration have been towards characterizing post-mortem muscle changes of PSS susceptible pigs and determining the etiology of the complex. Since the early work of Ludvigsen (1957) and Briskey et al»(1959a, i959b)» considerable research has bssn centered of this latter aspect of PSS. Beginning in the early 1970*s researchers at Iowa State University have concentrated on developing methodologies that would be useful in early detection of stress-susceptibility. Different techniques have been developed to aid in this determination of PSS susceptibility. Some of these include phenotypic scoring, halothane screening, blood enzyme assay, and more recently 3 blood typing. One goal of this dissertation will be to evaluate these different predictors of PSS susceptibility. Another primary goal of this dissertation will be to accurately determine the genetic mechanism of inheritance of the Porcine Stress Syndrome. Although the mode of inheritance of Malignaiit Hyperthermia has been the topic of limited in­ vestigation, the inheritance of these abnormalities merits much more complete investigation as the ideas concerning this topic which have been published are contradictory. 4 LITERATURE REVIEW Introduction to Literature Review The Porcine Stress Syndrome and its many aspects is an extremely broad and complex topic. Those interested in greater detail concerning the physical and chemical reactions involved in PSS, its etiology, and its effects on post-mortem glycolysis are referred to review articles concerning these topics by Briskey (1964), Cassens (1974), and Campion and Topel (1975)• An attempt will be made to review in broad terms the physical reactions, biochemical reactions, post­ mortem muscle characteristics, meat quality, and some pos­ sible etiologies concerning the Porcine Stress Syndrome. In addition the relationship of PSS to Malignant Hyperthermia, halothane screening, phenotypic scoring, blood enzymes, and blood types will be reviewed with special emphasis put on the genetic aspects of PSS. Physical Reactions and Changes The physical reactions that occur in an animal suscep­ tible to the Porcine Stress Syndrome has been cataloged quite extensively by many independent research efforts. Topel et al. (1968) described PSS as an acute shock-like condition that often oecurs during or following certain stressful situations. Eikelenboom (1972) reported that the intensity of the reaction of stress-susceptible pigs to the stressors can be so violent that the pigs expire before slaughter. Christian (1974) de- 5 fined PSS as sudden death in heavily muscled pigs after stress. PSS was characterized in the live animal by Topel et al»(1968), Muyle et al«(1968), Eikelenboom (1972), and Christian (1974) as showing an elevated body temperature, muscle ridgity, slight cyanosis, anxiety, and increased respiration rates. These researchers also noted that death was followed by a rapid onset of rigor mortis. It was also demonstrated by Briskey et al (19^2), Bendall et al. (1963)» Forrest ^ al. (1966), and Schmidt et al. (1970a) that muscle from stress-susceptible animals exhibited a shorter time course of rigor mortis than did muscle from stress-resistant animals. Biochemical Reactions One of the primary aberrant biochemical reactions found in animals susceptible to Porcine Stress Syndrome is an ac­ celerated rate of glycolysis. This accelerated glycolytic