Effect of nursery depopulation on the seroprevalence of Mycoplasma hyopneumoniae infection in nursery pigs
Dongkyun Suh, DVM, MS; Stephanie Rutten; Scott A. Dee, DVM, PhD, Dipl. ACVM; Han Soo Joo, DVM, PhD; Carlos Pijoan, DVM, PhD
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Objective: To examine seroprevalence of Mycoplasma hyopneumoniae in pigs of different age groups and retrospectively determine whether previous nursery depopulation (ND) was associated with the seroprevalence of M. hyopneumoniae in nurseries.
Methods: Sera of 4-, 8-, 12-, 16-, and 20-week-old pigs from seven herds were selected from a serum bank to serologically profile M. hyopneumoniae infections. Availability of representative sera in the serum bank was a major criterion for herd selection. Sera were tested for M. hyopneumoniae antibodies by ELISA using Tween-20 extracted antigen. Serum samples were also selected from 13 of 34 swine herds that previously participated in a ND study. To evaluate M. hyopneumoniae infection after ND, ELISA was performed for the 13 herds with 10 sera of 8- to 10-week-old nursery pigs collected prior to and three times after ND for up to 12 months.
Results: Serological profiles showed positive mean antibody titers (MAT) for two of seven herds at 8 weeks, four of seven herds at 12 weeks, six of seven herds at 16 weeks, and all of the herds at 20 weeks of age. Prior to ND, 10 of the 13 herds had positive MAT in sera of 8- to 10-week-old pigs. Sample seroprevalence by ELISA antibody titer ranged from 50%-100%. Following ND, six of the 10 herds were MAT positive in 8- to 10-week-old pigs; four of the 10 herds remained MAT negative for up to 12 months after ND.
Implications: Seroconversion to M. hyopneumoniae was detected between 10-16 weeks of age, indicating the occurrence of natural infection during the nursery age (4-12 weeks of age). Nursery depopulation appeared to be an effective method to control M. hyopneumoniae infection among nursery pigs in some herds.
Keywords: swine, Mycoplasma hyopneumoniae, nursery depopulation
Cite as: Suh D, Rutten S, Dee SA, et al. Effect of nursery depopulation on the seroprevalence of Mycoplasma hyopneumoniae infection in nursery pigs. J Swine Health Prod 1998;6(4):151-155.
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