• Don’t Cross-Foster After 24 Hours
  • Use a Milk Replacer, such as SoluStart™,to Create Nurse Sows

Several research studies agree that moving individual piglets from one litter to another when piglets are more than 24 to 48 hours of age will reduce pig weaning weights. Cross fostering disrupts nursing, increases bouts of fighting and impairs the growth rate of the entire litter.

MichiganStateUniversity reported the results of a study using 80 litters. In 40 of the litters, continuous cross-fostering was conducted from birth to weaning to minimize variation among littermates. In another 40 litters, fostering was limited to the first 48 hours of age.  Pigs were more uniform in the group with continuous cross-fostering. However, the average body weight of pigs in the continuous cross-fostering group was more than 2.0 pounds lighter at weaning. There was no difference in piglet mortality between the two groups (Table 1.).

Table 1. Effect of limited vs. continuous fostering on pig performance during lactation.a



Limited Fosteringb

Continuous Fostering

Average within–litter standard deviation of body weight at weaningc



Weaning weight, poundsc



Mortality, %



aStraw et al., 1998

bFirst 48 hours only


In a 32-litter Canadian study, 2 pigs from each of 16 litters were exchanged on day 6, while no fostering was done on the other 16 litters. This resulted in 3 groups of piglets. Adopted (piglets that were exchanged), resident (piglets that were not exchanged but were littermates to the adapted piglets), and control (no cross-fostering). Piglets were weighed at birth, fostering, weaning, and weekly during the month after weaning. The average body weight of pigs in the fostered litters was significantly less at every date. Piglets from the control litters were more than 1.0 pound heavier than resident pigs and 2.5 pounds heavier than adopted pigs at 45 days of age. A similar Canadian study following a similar protocol showed that adopted piglets weigh 13 percent less than control pigs at weaning.


Resist the urge to foster individual piglets after they are 24 hours of age. Piglets that fall behind should be transferred to nurse sows where entirely new litters of pigs are made.  Nurse sows can be created several ways. Some farrowing units use a plastic pen above a farrowing crate (1-2 pens/room).  The entire litter of the best milking sow is weaned into a plastic pen in the farrowing room at about 10 days of age and supplemented with milk replacer. Eight to 10 fall-outs are collected from various litters within the room and placed on the newly created nurse sow. Only transfer healthy pigs to reduce the risk of disease spread.

Milk replacer can also be used in farrowing crates to supplement fall-behind pigs.

Milk replacers have come a long way and are certainly a preference by some producers. Interest is growing and when looking at milk replacers it is important to keep in mind key distinguishing features such as those held by SoluStart milk replacer from Land O’Lakes Purina Feed,

  • Quality constructed milk replacer
  • Superior solubility/mixing
  • Health benefits “built in”
  • Provides superior nutrition
  • Excellent performance

For further information SoluStart pig milk replacer (Product # 1513000), please see your local feed sales representative at a Land O’Lakes Feed Co-op or Purina Mills Dealer. Visit us online at or

Information within this newsletter was adapted from an article published in the 2006 University of Nebraska Swine Report by Duane E. Reese and Barbara Straw.

Copyright © 2009 Land O’Lakes Purina Feed LLC.  All rights reserved. SoluStart is a trademark of Land O’Lakes Purina Feed LLC. Due to factors outside of Land O’Lakes Purina Feed’s control and because of market uncertainties, individual results to be obtained, including but not limited to financial performance, profits, losses or otherwise, cannot be predicted or guaranteed by Land O’Lakes Purina Feed.