Using boars for heat detection in sows

Boars can play an important part in stimulating and detecting heat in breeding sows. Follow these guidelines to optimise their use.

Pheromones (odours) produced by active and ‘chatty’ boars are the most potent and effective means of inducing the standing reflex in females.

The correct use of a vasectomised boar with breeding females can play an important part in stimulating and detecting heat. Make sure you discuss this with your vet.

Supervised entire boars can also be used for heat detection – but they must not be left in with a group of sows awaiting artificial inseminiation (AI).

• Only use a boar when the stockperson is there to observe
• To maintain the boar's libido, allow regular services with cull sows
• Females in heat will usually move forwards and assume standing reflex as a boar moves in front of them

• Use a designated pen rather than one where pigs are housed normally
• The pen design should allow observation and physical contact (fence line and direct)
• Take females to the boar

Check small groups

• Aim to check only two females at a time
• Apply the back-pressure test at the same time as exposure to the boar
• Remove females found to be in heat, to allow the boar to concentrate on checking/stimulating heat in others

Avoid habituation

• Avoid exposing females to the boar for extended periods
• Rotate boars used for heat detection

Contact with breeding sows

• Provide 10–15 mins/day of full boar contact for the first three days after weaning
• Fence-line contact with an entire or vasectomised boar should be enough
• It is essential to remove boar contact 24 hours before the start of oestrus detection, to heighten sow response from day four
• Mark and record sows in heat to aid timing of insemination

Checking for returns

Identifying females that come back into heat is important for highlighting problems and rescheduling inseminations.

Check for returns daily using a boar until confirmed in pig and pay attention to likely returns around the projected return date, which is normally 18 to 24 days after service.

• Watch for restless activity
• Note any females that mount or ride other females
• Provide and observe boar stimulation (10–15 mins/day)
• Mark and record any likely returns

Keep records and use markers

Being organised and efficient is essential for successful heat detection and insemination.

Clear records and coloured marks make it easy to know what is happening with each female and what needs to be done next.

Record responses, making sure you note the following:

• tag number
• date and time of proestrus
• date and time of oestrus and standing heat
• any other comments or observations

It is also useful to develop a coloured marker system. Use different coloured spray markers and/or the position, shape or number of marks to clearly show the status of each female.