DNA presence and viability of Mycobacterium avium subsp. paratuberculosis in semen of Pelibuey rams during the subclinical stage of paratuberculosis

Resumen

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

Design/Methodology/Approach: Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of paratuberculosis (PTB). Reports about the spread of MAP to extraintestinal sites have been confirmed by the presence of MAP-DNA in semen. However, contamination with MAP has not been reported in sheep semen in the subclinical stage of the disease. Such inadvertent contamination would represent a risk factor for reproductive and genetic management, even in the presence of asymptomatic rams. 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 (nested PCR) and MAP culture techniques were used to research the presence of DNA and the viability of Mycobacterium avium subsp. paratuberculosis in the semen of Pelibuey rams in the subclinical stage of paratuberculosis. The rams came from an infected flock diagnosed with PTB.

Results: The presence of MAP-DNA was detected in the semen of 60% (3 out 5) of the rams in the subclinical stage. However, MAP did not grow in the culture, suggesting that the MAP from semen samples is not viable.

Study Limitations/Implications: The study was carried out with a small number of naturally infected animals in the subclinical stage, taking into consideration animal welfare and care. However, more animals would result in better measurements.

Findings/Conclusions: The presence of MAP-DNA in the semen of rams in the subclinical stage was confirmed. Apparently, the MAP from the semen is not viable for culture.