A pilot study of the effects of Mycoplasma ovipneumoniae exposure on domestic lamb growth and performance.

Thomas E Besser,Melissa Ackerman,Jessica Levy,Jan Busboom,Danielle Nelson,Kathleen A Potter,Kezia Manlove,Margaret Benson,Jorge Ramón López-Olvera

doi:10.1371/journal.pone.0207420

Abstract

Mycoplasma ovipneumoniae is a globally distributed pathogen that has been associated with pneumonia in both domestic and wild Caprinae. It is closely related to M. hyopneumoniae, a respiratory pathogen of swine that is associated with decreased growth rates of pigs as well as clinical respiratory disease. In order to assess the effects of M. ovipneumoniae on lamb performance, we generated a cohort of lambs free of M. ovipneumoniae by segregation of test negative ewes after lambing, then compared the growth and carcass quality traits of M. ovipneumoniae-free and -colonized lambs from weaning to harvest. Some signs of respiratory disease were observed during the feeding trial in both lamb groups, but the M. ovipneumoniae-exposed group included more affected lambs and higher average disease scores. At harvest, lungs of lambs in both groups showed few grossly visible lesions, although the M. ovipneumoniae-exposed group did exhibit increased microscopic lung lesions (P<0.05). In addition, M. ovipneumoniae exposed lambs produced lower average daily gains (P<0.05), and lower yield grade carcasses (P<0.05) compared to those of non-exposed lambs. The results demonstrated the feasibility of test and segregation for elimination of M. ovipneumoniae from groups of sheep and suggested that this pathogen may impair lamb growth and productivity even in the absence of overt respiratory disease.

Highlights

The bacterium Mycoplasma ovipneumoniae was originally isolated and described from a Australian sheep flock experiencing a high incidence of pneumonia in lambs [1]
Prior to lambing in 2016, a group of commingled ewes was serially sampled to detect M. ovipneumoniae colonization using nasal swabs tested by a realtime polymerase chain reactions (PCR) assay that targets a species-specific region of the small ribosomal subunit encoding locus
Heterogeneity of M. ovipneumoniae detection was observed, including some ewes that tested positive on every sampling date while others consistently tested negative

Summary

Introduction

The bacterium Mycoplasma ovipneumoniae was originally isolated and described from a Australian sheep flock experiencing a high incidence of pneumonia in lambs [1]. Lesions associated with the disease included proliferative interstitial pneumonia with septal and bronchiolar epithelial cell hyperplasia and proliferation, with additional infiltration in some cases by lymphocytes or neutrophils.

Objectives

Methods

Results