It’s been another difficult grass growing season and the prolonged hot weather this year has not only burnt many pastures off, it may also have caused heat stress in rams which could now have compromised sperm viability. What should you be doing now to maximise ewe and ram fertility before the all important autumn tupping period?
Ensure your ewes and rams are in optimum condition
The majority of sheep producers only get one chance each year to maximise lamb output, so it’s important to get it right. Ensuring ewes and rams are in the optimum condition for breeding sets the flock output for the following year, says Dr Liz Genever from AHDB.
“For many flocks, now’s the time for ewe and ram MOTs,” Liz points out. “Rigorous ewe culling that ensures only sheep fit for breeding are kept is vital to flock profitability. No ewe should be retained if it is unlikely to rear lambs next season and bringing in better stock will raise flock performance.”
Dr Genever says that efficient culling will boost lamb output, reduce lambing problems, ensure 2019 lambs get enough milk from healthy ewes, and cut veterinary and medicine costs.
“You must make sure ewes are fit and able to conceive, remain pregnant and are able to rear their lambs. Cull any with poor teeth, as these sheep may not be able to eat enough to sustain a pregnancy, and take out any with mastitis or low, slack udders and damaged teats, as this will seriously affect their ability to feed and raise their lambs. Also remove any that have had reproductive problems in the past, or any lame ewes.”
Boosting nutrition with forage and supplementary feed
Dr Genever points out that boosting nutrition with forage and supplementary feed before breeding can increase the ovulation rate in ewes and sperm production in rams.
“Improved nutrition is needed for at least one oestrus cycle (2-3 weeks) to encourage the ovaries to release more eggs. Over-fat or thin ewes will be less fertile than those with a body condition score of 3.0, which is the aim for the beginning of tupping with them gaining 0.5 BCS over tupping.”
However, she urges producers not to flush on pastures containing red clover as these contain oestrogens that can interfere with the ewe reproductive tract and depress fertility.
Putting a vasectomised (teaser) ram in with the ewes 16 days before breeding and then replacing with rams can lead to a more compact lambing period.
For rams, it is important to consider whether these are improving the genetic potential of the flock.
“Unfortunately, you can’t judge the ultimate performance of a ram by looks alone; important meat production traits such as growth rate and muscle depth are not visible to the naked eye,” Dr Genever says.
“Buying or hiring rams with known estimated breeding values (EBVs) for growth rate can increase the weight gain of lambs that are produced and reduce the time it takes to reach slaughter weight, which in turn reduces the cost of production. And using a ram with high muscle depth EBV can enhance the carcass conformation of his lambs, which means they are more likely to meet market specifications, which has a major influence on the price received.”
MOT your rams
Rams also benefit from a thorough MOT ten weeks before they start work. AHDB urges producers to concentrate on the five ‘Ts’ – teeth, toes, tone, testicles and treatments.
Teeth
• Check teeth to ensure the ram can eat well enough to gain weight pre and post tupping.
Toes
• Treat any lameness problems appropriately. Check older rams for arthritis.
Tone
• Aim for a ram body condition score between 3.5 and 4.0 (1 is very thin and 5 very fat) as tupping starts. Good body condition is vital as rams can lose 15% of bodyweight during a six week tupping period.
Testicles
• Should be large and as firm as a flexed bicep. Large, firm testicles produce 80% more semen each day than medium-sized soft ones. If more semen is produced, the more fertile the ram and fewer of them will be needed to service the flock.
Treatments
• Ensure all vaccinations and boosters are up to date.