Risk factors for M. hyopneumoniae piglet colonization during the lactation period
Published:September 30, 2014
By:Maria Pieters1, G Cline2, B Payne2, A Rendahl1 (1 Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, 2 Boehringer Ingelheim Vet Medica, St. Joseph, MO)
Introduction
Sow-to-piglet transmission is considered one of the most important aspects of the epidemiology of Mycoplasma hyopneumoniae. The degree of piglet colonization at weaning age has been suggested as a predictor of clinical disease at market age1. However, sow-to-piglet colonization widely varies among farms and weaning groups, and even within the same farm2-3. Therefore, the objective of this study was to identify risk factors associated with M. hyopneumoniae piglet colonization during the lactation period.
Materials and Methods
Three sow farms, belonging to three different productions systems (A, B, C) were visited and samples were collected in at least 5 weaning groups at each farm. The following samples were collected at every sampling event: 54 dam nasal swabs, paired piglet nasal swabs and sera. Sampled dams were randomly selected, while stratified by parity. One piglet per dam was randomly selected for sampling. A series of pig specific data were collected from each sampled group, along with climatic data collected on-site during the lactation period. Swabs were analyzed by real-time PCR (Life Technologies) at the UMN-VDL. Sera were tested by ELISA (IDEXX) for antibody detection. A generalized linear mixed model was fitted to test for the association of 9 factors on the risk of piglet PCR positivity at weaning age.
Results
All PCR results obtained from Farm A and C were negative. Positive PCR results were obtained in piglets and/or dams in 5/7 farm visits in Farm B. M. hyopneumoniaeprevalence at weaning ranged 0-56%, with negative groups detected in between sampling periods with positive results. Dam PCR positive status and piglet weaning age were significantly associated (p<0.001) with piglet M. hyopneumoniae colonization at weaning age. A relationship between dam PCR status and piglet age was observed, and is presented in Fig. 1.
Figure 1. Piglet probability of M. hyopneumoniae colonization as a result of dam PCR status and piglet age.
Conclusions and Discussion
Identifying risk factors for colonization at weaning age is of crucial importance to better design control strategies for M. hyopneumoniae infections. Under the conditions of this study, shedding of the dam during lactation significantly influenced the probability of piglet colonization at weaning, and this probability increased with piglet age in groups where at least one dam was positive. Our results highlight the influence of the sow in the sow to piglet colonization process, as previously reported2-3. Our results contribute to a more comprehensive understanding of the epidemiology of M. hyopneumoniae infections.
Acknowledgments
The authors would like to thank Cesar Prado, Jon Ertl, and Jason Daniels for their help in sample/data collection. Also, thanks to the owners, crew members and practitioners attending the participating farms. This study was funded by Boehringer Ingelheim Vetmedica, Inc.
References
1. Fano et al. 2007. Can J of Vet Res. 71:195-200 2. Villarreal et al. 2010. Veterinari Medicina. 55(7) 318-24 Nathues et al. 2013. Acta Vet Scandinavica. 55:30