Risk factors for intestinal pathogens in Danish finishing pig herds

The objective of this investigation was to identify risk factors for infect ion with the intestinal bacteria: Lawsonia intracellularis, Brachyspira hyo dysenteriae, Serpulina intermedia, Brachyspira innocens, Brachyspira pilosi coli and swine-pathogenic Escherichia coli (serogroups O138, O139, O141 and O149) in Danish finishing pig herds. A total of 79 herds was randomly selected and visited during 1998. From eac h herd, 20 faecal samples were collected from individual pigs weighing 30-5 0 kg. In total, 1580 faecal samples were collected and examined by polymera se chain reaction (L. intracellularis) or culture (all other agents). Infor mation on feed and management procedures was collected by filling in questi onnaires at the herd visits. The questionnaire, included information on 29 dichotomous variables and three continuous variables. Variables with P < 0. 25 in a preliminary screening (<chi>(2) or t-test) were selected for the st atistical modelling. Our conclusions, based on the results of multifactorial logistic regression (out-off: P = 0.05), were the following: 1. Consistent batch production was associated with reduced prevalences of L . intracellularis and weakly beta -haemolytic spirochetes (S. intermedia, B . innocens, B. pilosicoli) (OR's = 0.43 and 0.06, respectively). 2. Home-mixed (and/or non-pelleted) feed was associated with reduced preval ences of L. intracellularis and weakly beta -haemolytic spirochetes (OR's = 0.6 and 0.4, respectively). 3. Providing straw to finishers was associated with a reduced prevalence of weakly beta -haemolytic spirochetes (OR = 0.28-0.32). 4. Not using antimicrobial growth promoters for piglets was associated with an increased prevalence of S. intermedia (OR = 11.11). 5. Rare occurrence of post-weaning diarrhoea (as opposed to common) was ass ociated with an increased prevalence of weakly beta -haemolytic spirochetes (OR 8.3-13.7). (C) 2001 Elsevier Science B.V. All rights reserved.