To ensure rams are in peak condition, sheep farmers should be using a fertility test prior to tupping, says vet Hugh Thomas of Westpoint Vets.
“Ram fertility is paramount; they are responsible for 50% of flock fertility. The consequence of running sub-fertile or infertile rams are fewer lambs born and a greater number of barren ewes.”
Ram fertility testing should be an integral part of any modern day flock health plan, says Mr Thomas. “All rams should be tested every year, about 10 weeks prior to tupping.
“Over the last 12 months our practice has seen ram infertility rates as high as 20-25% in some flocks, with the average about 8-10%.
This may be related to systemic disease within the flock, such as a high incidence of lameness.
“At a cost of about £25/ram for pre-breeding checks, including semen evaluation, it is a worthwhile investment, particularly considering the potential losses that could occur from reduced pregnancy rates coupled with the value of cull rams.”
Also, a sub-fertile ram may prevent a fertile ram from serving ewes, so these are better removed from the flock.
You cannot afford this infertility rate, agrees David Evans, sheep consultant, Rural Options. “To give yourself confidence, it is essential to semen test at least one third of rams every year, 10-12 weeks before tupping,” he says.
“If you are not doing this, it may be necessary to put more rams out to account for this infertility rate.”
According to Liz Genever, EBLEX beef and sheep scientist, to ensure a successful breeding season, rams should be given an MOT, 10 weeks prior to tupping.
“Tupping is a pivotal moment of the year, get this wrong and flock fertility will suffer. A ram MOT should include a full health check considering the four ‘Ts’ – teeth, toes, testicles and tone.”
“Look for signs of lameness and infection and check the eyes, ears and mouth for any potential problems.”
In an ideal world, sperm from all rams should be checked at this stage. This is also the time to assess body condition. “At tupping, rams should have a condition score of 3.5-4. When they are on the thin side 10 weeks before breeding, this is the time to address rations accordingly.”
Rams of condition score below three need supplementary feeding, agrees Mr Evans. “These animals should receive 0.75kg/day of an 18% crude protein feed.”
About one third of problems can be identified from visual observations by the farmer, says John Vipond, sheep specialist at SAC.
“Palpate the testicles to feel for any lumps and bumps and check to see both testicles are of equal firmness,” says Dr Vipond.
There is a strong link between scrotal size and fertility. “Testicle diameter will vary according to breed, but a diameter of over 30cm is often quoted as good,” he says.
Anything that causes a rise in body temperature can also affect sperm production, so it is essential to treat any problems well in advance of tupping.
“When a ram is fighting or has a wound or foot problem, this can be detrimental to his fertility performance,” says Dr Vipond.