In a PRRS unstable farm, the amount of semen was decreased after the PRRS vaccination to boars. Is this situation related to the PRRS live vaccine? Can the semen quality and quantity be decreased due to PRRS field virus infection?
Modified live PRRS vaccination on boars should not affect semen quality or quantity based on what literature says.
But I have to say that boar vaccination is not a very common practice as often boar studs are PRRS negative, so vaccination is not routinely done.
But in this particular case the circulation of wild PRRS virus can have a negative impact on semen quality and maybe on semen quantity.
There are several publications which describe changes in sperm motility and also in the number of spermatozoa with normal acrosome after a PRRS infection either under experimental or field conditions. Those experiences did not find changes in volume.
Having said this, boars are very sensitive to any stress, disease or environmental changes which often can have an impact on semen production.
What could be the impact of these changes on semen quality?
During an PRRSv infection the animals will produce an innate immune reaction and an acquired immune reaction both of which include the production of different products: acute phase proteins, different inflammation products (interleukins …), antibodies, etc.
To produce those products, amino acids are needed which will be taken from feed and reserves competing with those amino acids required for semen production.
“Lack of certain amino acids has often been related to low ejaculate volume”
So, supplementation of the boar diet with amino acids can be something to bear in mind when we think semen production could be compromised due to an external effect.
If you want to know more about how PRRSv affects boars, read out chapter “Pathogenesis, Lesions and Clinical Disease”.
Marcovetgrup S.L. – Spain