Within hours, newborn piglets are scrambling for the best nursing position. In a large litter, the strongest pigs tend to win out, leaving the weaker ones struggling to survive.

Your crossfostering management scheme determines whether all your pigs get
an equal chance to compete. While crossfostering isn’t a new concept, like most everyday tasks, people tend to get a little sloppy over time.

It all starts with shifting some pigs from a large litter to a sow with fewer mouths to feed. Sorting pigs of the same size into the same litter restacks the deck, especially for the small pigs. This way, the pigs get a fighting chance at survival, you help reduce your herd’s preweaning mortality rates and growing pigs are more likely to produce a more uniform group.

“Don’t view crossfostering as a crutch,” says Tom Fangman, University of Missouri extension swine veterinarian, “but rather as a tool to compensate for the natural variation that occurs during farrowing. This occurs for many reasons:

  • Farrowing concentration rates: most of you tend to over breed.
  • The number of pigs born alive per sow still may range from two to 20.
  • Teat considerations: How many functional teats are on each sow and in what position?
  • Differences in pig size and viability.
  • Differences in milk production, particularly in first-litter sows.

As you review your cross-fostering plan, Fangman has a few suggestions:

1. Examine all sows for teat number and via-bility. Check the animal’s mammary gland integrity. Look at the underline to determine if the teats are mature and producing milk. Check to make sure they are not inverted, red, swollen, hot or lacerated.

Also, review your production records to see which sows have weaned large litters consistently.

2. Transfer piglets within the first 24 hours after farrowing. If this isn’t possible, complete all transfers within the first two or three days after birth. Adding extra pigs to a litter after three days is difficult because they have established teat order and unused mammary glands begin to dry up. Attempt to foster pigs of similar age.

3. It’s best to transfer males to another litter rather than females if you retain seedstock replacement animals from your own herd. Otherwise you could loose track of the reproductive history, which can reduce the accuracy of female selection.

Gilts reared by foster dams tend to have poorer reproductive performance. For instance, if they don’t have the cholostral antibodies that the foster mother is shedding, then the gilts will be at a higher risk for disease and won’t grow as well.

4. When moving pigs, keep them dry, draft-free, clean and warm, preferably between 86F and 93F.

5. Foster pigs according to weight with an emphasis on equalizing size within the litter. You can pretty much size up the piglets by sight. A newborn piglet weighing about 3.5 pounds is average.

Litters composed of only small, weak pigs may not gain weight well due to a lack of inadequate mammary gland stimulation that reduces milk production. You may have to provide additional supplemental milk for some litters. The duration and amount differs with each litter.

6. Foster pigs to sows or gilts with strong mothering dispositions.

7. Allow pigs to maximize colostrum intake before fostering.

8. For best results, place the smaller pigs on second-parity sows that milk well. Place the larger pigs on older parity sows that tend to produce more milk.

Keeping your crossfostering program on track is the first card in keeping your pigs growing at an even pace.