PAPERS & ARTICLES Epidemiology of enteric disease in grower-finisher pigs: a postai survey of pig producers in England G. P. PEARCE A questionnaire was sent to 238 members of local pig discussion groups in the West Midlands region of England to identify farm level fators associated with the occurrence of diarrhoea in grower-finisher pigs. The questions related to the occurrence, diagnosis and aetiology of scour problems on the farm, the prevalence of common porcine diseases on the farm, the classes of pigs, staff employment, source of replacement stock and biosecurity measures, the husbandry techniques such as piglet management, use of medication, movement and mixing of pigs, dung removal and pen preparation between batches of pigs, and the physical resources such as floor type, pen divisions, watering, feeding and dung disposal systems. Replies from 105 producers keeping grower-finisher pigs were included in the analysis, 50-5 per cent of which had had a scour problem at some time in the previous three years. The causes of scour had been identified as colitis (34-3 per cent), swine dysentery (10-5 per cent) or porcine enteropathy (3-8 per cent). There was a significant association between the following fadors and the occurrence of diarrhoea in grower-finisher pigs: the use of water medication for weaners (odds ratio=1 1-8; P=.002), the tail-docking of piglets (odds ratio=8-6; P=003), the use of a wet feeding system for finishers (odds ratio=5-9; P=0-009), finishers housed on partially slatted floors (odds ratio=3-6; P=0-044), and the use of an isolation procedure for incoming breeding stock involving exposure to dung (odds ratio=3-5; P=0-046). The use of disinfectant in the preparation of pens between batches of pigs appeared to be protective (odds ratio=0-3; P=0-046). ENTERIC diseases are acknowledged as important causes of suboptimal performance and mortality in grower-finisher pigs (Garden 1985, Mackinnon 1996). In addition, the treatment of these conditions has been reported to account for more than 50 per cent of the antibiotics administered to this class of pig (Tielen 1995). The concern over the wide- spread use of antibiotics in livestock production highlights the need for the development of preventive disease control programmes based on an epidemiological understanding of the diseases concerned. However, the epidemiology of even economically important diseases such as enteric conditions in pigs is often incompletely understood. Causes of enteric conditions associated with diarrhoea in grower-finisher pigs include infectious agents such as Serpulina hyodysenteriae (Taylor and Alexander 1971), Lawsonia intracellularis (McOrist and others 1993) and Serpulina pilosicoli (Trott and others 1996), parasitic infesta- tions such as Trichuris suis (Mansfield and Urban 1996), and nutritional disturbances such as anti-nutrient factors (Hazzledine 1987) and excessive dietary protein levels (Dewey 1993). Although most of the infectious conditions are known to be transmitted largely from pig to pig through the faecal-oral route, there is relatively little published information on the epidemiology of these conditions in the grower-finisher animal (Radostits and others 1994). The elucidation of the importance of management and environmental factors in the occurrence of these conditions would make it possible to develop soundly based preventive strategies. This study was designed to identify farm level risk factors associated with the occurrence of diarrhoea in grower-finisher pigs. MATERIALS AND METHODS Soure of data Questionnaires were sent to 238 members of local pig discussion groups in the counties of Shropshire, Staffordshire and Cheshire in August 1996. The variables recorded are shown in Tables 1 to 4. An accompanying letter was sent with the questionnaire explaining the purpose of the survey and offering entry to a £150 lottery for the first 50 replies received. A follow-up letter was sent to all non-respondents three to four weeks later in an attempt to encourage participation. Statistical analysis Data were recorded using the statistical and database package Epi-info, Version 6.02 (Dean and others 1994). The program was used to perform a univariate analysis to select variables having significant associations with the occurrence of scour in grower-finisher pigs on the farm (the dependent variable). Independent variables having significant associa- tions with the occurrence of scour were identified by using Yates' corrected chi-square test, using P<0.25 as the selection criterion, as suggested by Hosmer and Lemeshow (1989). These variables were then used to develop a logistic regression model utilising the program Logistic (Dallal 1988), with a backward elimination procedure being used to create the model based on likelihood ratios significant at P<0.05. Differences between the distribution of herd sizes in the sur- vey population, the general population (MAFF 1996) and Meat and Livestock Commission (MLC) recorded herds (MLc 1997) were assessed by using the chi-squared test. RESULTS From the 238 questionnaires distributed, 175 replies were received (73.5 per cent response rate). Of these respondents, 44 did not keep pigs and 26 were breeder-weaner producers leaving 105 producers of grower-finisher pigs which were induded in the analysis. A comparison of the units included in the survey with the units included in the latest general agri- cultural census (MAFF 1996) and with MLC recorded herds (MLc 1997) is shown in Fig 1. Although a greater proportion of medium to large units with more than 200 sows (P<0-001) and fewer small units with less than 50 sows (P<0-01) were included in the survey than are present in the general popu- lation, the distribution of the different sized units was simi- lar to that of herds in the MLC recording scheme (MLc 1997) The variables recorded from the questionnaire and the fre- quency of occurence among the 105 producers included in Veterinary Record (1999) 144,338-342 G. P. Pearce, BSc(Agric), PhD, BVSc, MRCVS, Animal Science Research Centre, Harper Adams University College, Newport, Shropshire, TF1o 8NB Dr Pearce's present address is University of Aberdeen, Department of Agriculture, 581 King Street, Aberdeen AB24 5UA 338 The Veterinary 1999~~~~~~~~~~~~~~~~~~~~~ The Vetednary Rewrd, March 27,1999 338 group.bmj.com on March 4, 2013 - Published by veterinaryrecord.bmj.com Downloaded from