Heat detection is conducted early in the morning or late in the afternoon when it is cool. Once a gilt is observed to be in heat it has to be serviced there and then. A sow observed to be in heat is not serviced there and then. If a sow is observed to be in heat in the morning it is serviced late in the afternoon. A period of about 12 hours is allowed to lapse before a sow is serviced. The services should be conducted when it is cool because boars tire easily when it is hot. Sows that are weaned in good body condition normally come in heat within a week. Heat normally lasts for 2 to 3 days. It is recommended to service the sow or gilt 3 times at 12-hour intervals during the heat period.
Signs of heat
• Swelling and reddening of the vulva
• The sow mounts others and it will allow itself to be mounted by pen mates
• The sow will stand firm for the boar
• Pricking of ears in prick eared breeds
• The sow becomes restlessness and will give a characteristic grant to attract the boar
• Sow can lose appetite
• When pressure is applied on her back in the presence of the boar the sow will stand firm. In the absence of the boar some sows will not respond positively to the back pressure test.
Service Management
• Gilts are serviced when they are between 7 -8 months of age
• Its recommended to service them during the 2nd oestrus to increase litter size
• Gilts are serviced on the first signs of heat, sows are serviced 12hours later
• Service should take place when its cool i.e. early morning or late afternoon
• Make sure the vulva area is clean before service. If the area is dirty the stockman should first wash it, this will help the prevention of cystitis.
• Make sure the boar has gotten enough rest between services. A young boar (< 12 months) should complete one full service per week whilst an old boar (>12 months) should complete two full services per week.
• Do not mate related animals as this result in poor litter size and growth rate
• The service area should provide a good foot grip for both the boar and the sow. Slippery surfaces can seriously affect the confidence of the boar. They can also result in the premature termination of a service.
• Match the size of the boar to that of the gilt. Avoid giving a big boar to a gilt and a small boar to a big sow. A small gilt will find it very difficult to carry the big boar during the mating period. The small boar can be frustrated if it fails to mount the big sow. The frustration can result in reduced libido in the boar.
• Do not service the sow or gilt immediately after vaccination with farrowsure. Normally 14 days should lapse before services are done.
Getting higher pregnancy percentage
• Supervise the services
• A sow or gilt in heat should be serviced 3 times at 12 hour intervals
• Use crossbreds
• Service gilts from 2nd heat onwards
• Ensure good feeding management of sows before and after service
• Give the boar adequate rest between services
• Avoid stressing the newly serviced sows