Guidelines on the examination of rams for breeding – BTV update

• In order to achieve conception rates in excess of 85% of ewes in the first cycle ram health and fertility must be optimal.
• Bluetongue virus (BTV) replicates in the testicles in infected rams, causing significant impact on sperm production. This is in addition to the general effects on fertility of the high temperature and blood vessel damage making animals unwell. (Kirschvink et al., 2009, Puggioni et al., 2018)
• Rams do eventually recover sperm production but their fertility for the coming season is expected to be very poor.
• The time taken for sperm to develop is 50 days (Ridler et al., 2012) and recovery of breeding soundness after BTV infection is considered to be up to 100 days (Puggioni et al., 2018) therefore there are long lasting impacts on ram fertility for the current season.
• Ram MOTs and electro-ejaculation (EEJ) should only be carried out by those trained and competent in the techniques.
• Given the ongoing risk to fertility, unvaccinated ram assessment should happen as close to mating as possible to be useful at the time of mating but sufficiently in advance that alternative ram power can be sought if necessary.
• However, please be aware that BTV infection after a successful ram MOT test can still impact fertility, making vigilance and vaccination essential.
• Vigilance should include checking for clinical signs in all animals daily, using raddle on rams to detect returning ewes and scanning early.
• The standard advice remains that every ram should be physically examined every year (however note that this does not necessarily mean that EEJ should be included).
• It is not considered acceptable to perform EEJ on any ram that fails the first stage of a ram MOT and no ram should be condemned on the basis of an single unsuccessful EEJ.

*Risk period from start of July (with some variation depending on accumulated temperature-days and location).

Ridler, A.L., Smith, S.L. and West, D.M., 2012. Ram and buck management. Animal reproduction science, 130(3-4), pp.180-183.

Kirschvink, N., Raes, M. and Saegerman, C., 2009. Impact of a natural bluetongue serotype 8 infection on semen quality of Belgian rams in 2007. The Veterinary Journal, 182(2), pp.244-251.

Puggioni G, Pintus D, Melzi E, Meloni G, Rocchigiani AM, Maestrale C, Manunta D, Savini G, Dattena M, Oggiano A, Palmarini M, Ligios C. Testicular Degeneration and Infertility following Arbovirus Infection. J Virol. 2018 Sep 12;92(19):e01131-18. doi: 10.1128/JVI.01131-18.