Summer may be a distant memory, but the consequences of summer infertility in pig herds may only be coming to light now, according to pig vet David Chennells.
“Infertility problems occur in summer when fertility dips due to changes in light levels, depressed feed intakes from warmer weather and water flows increasing the number of urinary tract infections. These could have occurred anywhere in the pig’s cycle and often the problems are only found and realised in the autumn,” he says.
But good management in the summer and autumn can help minimise seasonal infertility, says pig technologist Mark Hawe.
“Often autumn infertility gets the blame when nothing else can be blamed, but it often comes down to management.
“Pigs naturally wouldn’t be fertile during the autumn period due to decreasing day length and also lighting intensity. This could then have a knock-on effect on fertility and this includes pigs coming into season, amount of time a sow stays in heat and conception. Therefore, cranking up management now is vital to detect any pigs returning,” he says.
Because sow reproductive behaviour is affected by shortening day length, Mr Hawe recommends making sure sows achieve at least 16 hours of daylight at an intensity good enough to read a newspaper.
Whitewashing walls can also help improve the light intensity in pigs building according to vet Alex Thomsett, The George Vet Group.
“Walls should also be whitewashed at sow eye level in buildings where pigs are housed after weaning and at and around service. And when using AI stalls, the compartment around the sow’s head should also be whitewashed to stimulate hormonal production.
“I have seen a marked improvement on reproduction in pig units that have whitewashed their walls, this is because light hitting the back of the eye stimulates hormone release which is linked to fertility,” Ms Thomsett explains.
And increasing heat detection to detect any individuals returning following embryonic deaths in autumn is vital, says Mr Hawe.
“You may see a few more early abortions in autumn, but these often won’t be seen and the animal will just return to heat. This is why it is particularly important to look out for returns and the best way to do this is to walk the boar down the dry sow house once a day.
“When you do this, make sure the boar is not distracted by food and don’t give him access to more than four sows at a time. Although this is time-consuming, it means any returns are not missed.”
He also recommends using ultrasonic scanners on sows at fours weeks following service.
However, if abortions are being seen, don’t assume it is a seasonal problem, says Ms Thomsett. “When seeing abortion and a high number of returns, talk to your vet to check it is not being caused by some other reason.
“Also, check records to see if you experience a similar problem every year or if it is a result of another underlying problem. Maintaining summer and winter feed intakes to prevent sows entering negative energy balance is also key to maintaining fertility.”
Reduced numbers of sows holding to service can be overcome with management changes, helping ensure as many sows as possible have good sized litters.