Fostering is a management system where piglets are moved from one sow to another, to increase the survival chances of disadvantaged or at risk piglets.
When to foster
Best practice measures for fostering piglets include:
- ensuring that during the first 12 hours of life all piglets have colostrum, which provides immunity and energy
- using artificial colostrum if the sows supply is limited
- fostering only after the piglets have received colostrum and between 12 to 24 hours after birth
- never moving good pigs back
- only moving piglets if they are missing out on a drink
- never use fostering to grade piglets according to size or sex
- selecting a nurse sow, if piglets have to fostered later in life.
If too many piglets are moved too often, this can:
- reduce piglet growth rate
- prevent effective disease control
- adversely affect survival rate.
First 12 hours after birth
To make the fostering process work effectively, it's essential that piglets to be fostered have colostrum during their first 12 hours of life. Colostrum provides energy, warmth and immunoglobulins (immunity).
Small piglets with full stomachs is usually an indication that they have suckled. If there is any doubt, artificial colostrum should be provided. Proprietary replacement milk powders are helpful for pigs that have had colostrum but need additional milk.
12 to 24 hours after birth
Fostering can be carried out between 12 and 24 hours after birth when:
- the number of piglets in the litter is greater than the number of functional teats available on the sow or gilt that produced the piglets
- the sow milk supply is not meeting the needs of the piglets
- a sow dies during birth of the her litter
- a sow becomes sick after given birth to her litter.
After 24 hours
Fostering can also be carried from day 2 of lactation to weaning when:
- a sow dies
- a sick sow is not responding to treatment
- piglets are not growing due to the mother not producing sufficient milk.
Avoid randomly allocating the piglets to milking sows at the same stage of lactation, otherwise they will struggle to make satisfactory growth.
Allocating the piglets randomly to sows in a later farrowing group is a health risk and should not be considered.
Selecting a nurse sow
- choose a young sow (parity 2–3) close to being weaning
- check that she has at least 12 functional teats
- confirm by performance of her litter that she is a good milker
- is in body condition score 3 plus
- check performance records confirm that she is not aggressive or restless.
Remove the mother of the at-risk litter and secure the litter in the creep or a box. Take the nurse sow to the litter's pen and supervise the bonding of the litter and nurse sow. The piglets remain in a room (environment) with piglets of a similar age. They are never moved into an environment with older piglets.
Fostering bigger piglets
Disadvantages of fostering bigger piglets include:
- big piglets do not easily fit in when they are moved to smaller or younger litters
- it takes about 6 hours for half of them to get a drink and they have a battle to establish teat order, even if they are a little bigger
- growth performance suffers and they never catch up to their unfostered siblings
- lifetime performance suffers and it is doubtful the survival of smaller pigs makes up for the loss
- moving the bigger piglets back just retards the growth of the fastest growing piglets and so, while the group looks more even, performance is not improved.
While producers may feel there is a sense of evenness about fostered pigs, the growth-check suffered means they do not achieve reasonable performance at weaning.
These observations have led to the recommendation to 'leave them alone and let them grow'.
Studies show that when litter weight variation is reduced, survival increases especially of the smallest piglets. The challenge is to make sure bigger pigs do not suffer.
The smallest piglets seem able to grow close to their potential, but the big piglets fall behind fairly quickly.
Advice for small farms
Fostering guidelines make it difficult to foster on small farms. The simplest approach is not to foster piglets if you can not foster within 24 hours of birth. It is better to leave the pigs where they are and top them up with artificial colostrum or milk replacer 2 or 3 times a day. It's also possible to split suckle in the first 24 hours after birth to enable small pigs to have increased access to a functional teat.
If you have to foster to equalise pigs and teats, do it as early as you can. If you have to move big piglets, make sure they get colostrum and top them up with milk replacer as you move them. Give them a bit more attention over the next few days to make sure they do not fall too far behind their new litter mates.
- Last reviewed: 22 Nov 2022
- Last updated: 22 Nov 2022