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

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.

Experimental infection of specific-pathogen-free domestic lambs with Mycoplasma ovipneumoniae causes asymptomatic colonization of the upper airways that is resistant to antibiotic treatment

“…The twice-daily clinical screens and cellular and molecular analyses of the bronchoalveolar lavage fluid demonstrated that active M. ovipneumoniae colonization of the upper airways did not lead to clinical disease or lung pathology in our model. In contrast to recent studies, we also did not observe any differences in lamb body weights or daily gains associated with M. ovipneumoniae infection [6, 7]. Multiple different hypotheses have been proposed to explain why M. ovipneumoniae causes asymptomatic airway colonization in some instances, but severe pneumonia in other cases: (1) differences in M. ovipneumoniae strain virulence; (2) age-related differences in disease susceptibility; (3) differences in the immune response to M. ovipneumoniae; and (4) presence of additional facultative pathogens such as Mannheimia haemolytica .…”

“…In the United States, active M. ovipneumoniae infection was detected in 88.5% of commercial sheep flocks in a 2011 study [3]. While most cases of M. ovipneumoniae infection in adult sheep are thought to be asymptomatic or mild, significant production losses may occur due to reduced weight gains, lower carcass quality and increased mortality in lambs [1, 6, 7]. Moreover, M. ovipneumoniae -infected domestic sheep pose a significant threat to wild ruminant populations such as bighorn sheep ( Ovis canadensis ) [8, 9], Dall’s sheep ( Ovis dalli dalli ) [10], Argali sheep [11], and Norwegian Muskox ( Ovibos moschatus ) [12], where M. ovipneumoniae infection causes severe pneumonia outbreaks with up to 100% mortality.…”

“…In the United States, active M. ovipneumoniae infection was detected in 88.5% of commercial sheep flocks in a 2011 study [3]. While most cases of M. ovipneumoniae infection in adult sheep are thought to be asymptomatic or mild, significant production losses may occur due to reduced weight gains, lower carcass quality and increased mortality in lambs [1,6,7 ovipneumoniae greatly increases the susceptibility for infection with other opportunistic pathogens such as Mannheimia haemolytica and Bibersteinia trehalosi, which then leads to proliferative interstitial pneumonia with severe clinical symptoms and significant mortality [9, [13][14][15]. However, infection studies with M. ovipneumoniae alone have yielded conflicting results.…”

Sustainable lamb production: Evaluation of factors affecting lamb growth using hierarchical, cross classified and multiple memberships models

“…In terms of the effect of lamb health on lamb growth rates, a deleterious impact was identified from lameness, pneumonia and bacterial arthritis. For cases of pneumonia, a significant weight reduction was observed after the disease event and this is in agreement with a recent study investigating exposure to Mycoplasma ovipneumonie, which concluded that exposed lambs had significantly lower daily weight gains than non-exposed lambs (Besser et al, 2019). In terms of lamb lameness in the current study, a non-significant weight reduction was observed after the disease event.…”

Identification of Mycoplasma Species and Related Organisms From Ruminants in England and Wales During 2005 – 2019

“…The number of identi cations has increased since the last examination period of 1990-2000 (8). This organism is implicated in chronic non-progressive pneumonia of low mortality, but varying morbidity, affecting young and adult animals, sometimes referred to as 'coughing syndrome', with more severe pneumonia and ill-thrift presenting in younger animals (5,64,65). Subclinical infection of animals with M. ovipneumoniae is also reported, and this mycoplasma is thought capable of initiating pneumonia under certain conditions, predisposing the animals to further infection with secondary bacteria such as Mannheimia haemolytica, progressing to severe pneumonia (5).…”