MORTALITY OF EWES AND THEIR PROGENY IN A FLOCK INFECTED WITH MAEDI-VISNA VIRUS

The objective of the present research was the analysis of chosen factors contributing to mortality of ewes and their lambs from a flock naturally infected with maedi-visna virus (MVV). 1,406 mother sheep and their 2,234 progeny of two synthetic prolificmeat lines BCP and SCP and Suffolk breed were investigated. Summing up the research results concerning mortality of dams and lambs in a MVV-infected flock, a hypothesis on virus detrimental effect on production traits and consequently economic situation of sheep industry has been supported. The study findings highlighted some hazards related to the virus presence in a herd and losses produced, and they may aid in the development of appropriate virus eradication strategies. Such programmes should include, among others, shortening the exploitation period of infected animals up to 3-4 years, replacement of culled sheep with animals from MVVfree flocks and finally, including the infection factor to selection procedures of dams and their progeny.