Abstract
In bucks semen analyses are useful, although they may not predict actual fertilizing potential, but they predict low fertility and allow exclusion of those samples or even males from an artificial insemination (AI) program. It is therefore advised to test each buck in order to determine the preferred treatment of
... read more
its semen with respect to resistance to glycerol, extender and removal of seminal plasma. Based on these tests the most preferred storage treatment can be adapted for AI and higher pregnancy rates can be obtained.
Economical and physical damage caused by Small Ruminant Lenti Virus (SRLV) infections in sheep and goats can be limited by simple measures to minimize the risk of transmission and prompt recognition of infection. Housing is a critical event herein since the risk of infection is 10 times higher during stabling than at pasture. For the prevention and control of SRLV this means that management systems without housing run little risk of reaching the infection rates that cause economic damage, which implies that preventative measures should relate to the risk associated with the -mainly geographically determined- management system. Also the males have to be identified as risk factor. Shedding of proviral SRLV-DNA in semen has been proven for rams and bucks. Most males shed intermittently. Also a large proportion of the tissue samples from the male genital tract tested positive for SRLV-DNA. These findings support the possibility that SRLV's are sexually transmittable.
Polymerase Chain Reaction (PCR) tests proved to be useful in detecting proviral DNA in blood, tissue and in semen, whereas antibody detecting tests were also used to determine infection. Although the amount of SRLV susceptive cells can vary substantially, they were always detectable in any given sample. The hypothesis that shedding of virus is related to a high number of those susceptive cells in the blood and semen is not supported by our data. This also supports the hypothesis that shedding in semen can be accomplished by alternative routes than the postulated macrophage dependent delivery. Furthermore this thesis shows that there are individual differences with respect to the progressiveness of the lesions, that severe lesions can develop in a few months, that the progressiveness differs between the breeds examined, but that the lesions in the udder and probably the CNS are not inevitably progressive and may even regress.
In conclusion: Of optimal pregnancy results after AI, semen treatment and storage should be tuned to the individual male. For efficient SRLV control on farm level, first risk factors should be identified, than a goal should be set followed by a tailor made approach to lower incidence or even eradicate SRLV.
show less
