There are some ways by which the estrus in pigs can be detected. Meanwhile, the two basic methods of detecting estrus in pigs include:
1. Back pressure test.
2. Boar test.
Meanwhile, Whichever method is used, there are early indications of which gilts/sows are coming on heat; Swelling and reddening of the vulva, decreased appetite, increased restlessness, attempts to court, mounting pen mates and attraction to the boar.
Now let us discuss them in detail below:
1. Back Pressure Test
Here , the sows are moved out of their own pen into the corridor and next to the boar’s pen. Don’t do the back pressure test in the sow’s own pen.
The boar used to stimulate the sow should be more than 10 months old.
When the sow is in head to head contact with a boar, approach quietly and gently massage her flanks and apply hand or sitting pressure on her back (shoulders to mid region), and look for signs of standing response indicating which the sows is in oestrus.
A slight response may indicate the gilt is at beginning of her estrus period, and will respond more positively in 8 to 12 hours.
Note: Farmers without boars for testing heat should check for standing response between 24 and 36 hours after the onset of oestrus and pigs inseminated within this period have higher conception rates.
2. Boar Test
This method relies on running a boar with the sows to see if they show the standing response to the boar. It involves taking the sows to the boar pen or to a pen familiar to the boar.
A desirous boar must be used to ensure effectiveness and the process will not work unless the boar has good sexual motivation. It is also advised to do the oestrus detection in the same pen the boar uses for mating to encourage their sexual interest.
Older boars should be used where possible because boars less than 10 months of age are less efficient at stimulating sows.
Note: Only mate/inseminate females that are definitely showing a standing response to the boar (in estrus stage). Mating/ inseminating gilts/sows in late oestrus after they have ovulated may cause infections and wastes time and money.
Equally don’t serve them too soon, they may be showing classical signs of proestrus in their behavior but will not stand rock solid for the back pressure test.