DNA presence and viability of Mycobacterium avium subsp. paratuberculosis in semen of Pelibuey rams in subclinical state of paratuberculosis

Abstract

Objective: To determine DNA presence and viability of Mycobacterium avium subsp. paratuberculosis in semen of Pelibuey rams in subclinical state of paratuberculosis.

Design/methodology/approach: Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of paratuberculosis (PTB). It has been reported that MAP can spread to extraintestinal sites, confirming the presence of MAP-DNA in semen. However, contamination with MAP has not been reported in sheep-semen in the subclinical state of the disease. Such inadvertent contamination would represent a risk factor for reproductive and genetic management, even though the rams are asymptomatic. A descriptive, cross-sectional study was carried out with five rams naturally infected with MAP, and one PTB-free ram as a negative control. Nested Polymerase Chain Reaction (a-PCR) techniques and MAP culture were used to investigate the presence of DNA and viability of Mycobacterium avium subsp. paratuberculosis in semen of Pelibuey breed rams in a subclinical state of paratuberculosis, from an infected flock diagnosed with PTB.

Results: The presence of MAP-DNA was detected in the semen of 60% (3/5) of the rams in a subclinical state. However, there was no growth of MAP in the culture, suggesting that the MAP from the semen samples are not viable.

Limitations of the study/implications: For aspects of animal welfare and care, we worked with naturally infected animals in the subclinical stage, which is why the study was carried out with a small number of animals. However, it is recommended to increase the number of animals to obtain better measurements.

Findings/Conclusions: The presence of MAP DNA is confirmed in the semen of rams in a subclinical state; apparently, the MAP from the semen is not viable for culture.

Keywords: paratuberculosis, MAP culture, clinical signs, a-PCR, ELISA, semen.