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Title:Control and prevention of complicated Mycoplasma Hyopneumoniae among pigs reared in an age segregated production system
Author(s):Moreau, Isabelle Alexandra
Department / Program:Veterinary Clinical Medicine
Discipline:Veterinary Medical Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Mycoplasma Hyopneumoniae
Abstract:This thesis discusses two problems of increasing economical importance in modem pig production which are excess death loss and excess numbers of substandard pigs, that is, pigs which do not reach the minimal weight to assure optimal revenue. In one farm system studied, the proportion of weaned pigs sold at full value was 21.4 percentage points below a target value of 94.0%. A review of the literature proposes many potential causes for increased mortality, but relatively little published literature on substandard pigs is available. In a retrospective analysis of farm production data, the interaction quarter*year was associated with mortality rate and substandard rate (p < 0. 01), and sex was significantly related to mortality rate (p<0.01). In a prospective trial of 12 cohorts, the administration of an antibiotic with a bacteriostatic effect on M hyopneumoniae was associated with a 12.7% substandard rate, compared with at 26.4% substandard rate for cohorts offered feeds with antibiotics not labeled for respiratory diseases (p<0.01). It was concluded the respiratory diseases and M. hyopneumoniae infection in particular may have played a role in the increased mortality and substandard rates for this farm system. The scientific literature revealed little data linking M. hyopneumoniae to elevated mortality' and substandard pigs. To more precisely define this apparent relationship, a prospective analysis of 48 cohorts of growing pigs was conducted, each cohort containing approximately 1,200 pigs. Halt of the cohorts were vaccinated against M. hyopneumoniae and the study was blocked on farm site, sex, and time blocks. Cohorts vaccinated against M. hyopneumoniae grew 42 g/pig/day faster and had 15.2 fewer deaths per 1,000 pigs when compared with unvaccinated cohorts. The time to Porcine Reproductive and Respiratory Syndrome virus infection was directly associated with changes in mortality rate and the proportion of pigs culled for poor performance, but did not appear to modify the protective effects of M. hyopneumoniae vaccination.
Issue Date:2003
Rights Information:Copyright 2003 Isabelle A. Moreau
Date Available in IDEALS:2014-01-28

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