The importance of piglets receiving enough good quality colostrum shortly after birth is well known. At birth, piglets have no circulating antibodies to protect them from potential disease causing pathogens in the environment. Therefore, the sow must provide these antibodies to her litter via her colostrum, which provides them with passive immunity.

Neonatal viability shows a positive correlation with the degree of passive immunisation and levels of circulating immunoglobulins (antibodies). Passive immunity provided to piglets by sows is required until their active immune system matures, usually about three weeks of age. Piglets are dependent upon the transfer of antibodies and other immune-modulating factors which are present in colostrum. Besides antibodies, colostrum also contains lymphocytes, cytokines, nucleotides, and various growth factors which may affect the post natal development of the immune system.

The amount of antibodies available in colostrum, as well as the ability of the piglet to absorb them, diminishes rapidly after farrowing. After six hours, the antibody content of colostrum is reduced by one-third and, by 12 hours, is reduced by two-thirds. Further, although the piglets have the ability to absorb antibodies and immune cells until ‘gut closure’ at about 24 hours following the first suckle, after about six hours following their first suckle, their ability to absorb these molecules and cells is reduced to about 50 per cent and progressively declines even further during the following six to 12 hours.

It is crucial to piglet survival to ensure consumption of sufficient colostrum as soon as possible after birth and before gut closure to maintain passive immunity. Failure to provide adequate passive immunity results in relatively poorly protected pigs that are more susceptible to earlier colonization by potential pathogens. Such colonised pigs can carry the pathogens and shed them in the nursery.

The issue of colostrum management has gained a new importance because of the realisation that serious diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine circovirus associated disease (PCVAD) are at least partly controlled on a herd basis by ensuring solid immunity among the suckling piglet population. Control programs for PRRS and PCVAD are examples of two major health challenges where ensuring adequate colostrum uptake to maximize passive immunity is emphasized. In the case of PCVAD, the earlier in life pigs are infected the more likely that severe disease will result. Maternal vaccination studies suggest high levels of passive immunity can prevent or reduces disease even into the grower phase. Taken together, it is clear that any practice that interferes with colostrum intake must be avoided. With respect to cross-fostering management, it has been suggested that fostered piglets may take several hours to start suckling their new sow. However, if these piglets have already suckled their own sow, the gut-closure clock is running and any delay in resuming suckling on the new sow may impair their passive immunity.

The importance of piglets receiving enough good quality colostrum shortly after birth is well known. At birth, piglets have no circulating antibodies to protect them from potential disease causing pathogens in the environment. Therefore, the sow must provide these antibodies to her litter via her colostrum, which provides them with passive immunity. Neonatal viability shows a positive correlation with the degree of passive immunisation and levels of circulating immunoglobulins (antibodies). Passive immunity provided to piglets by sows is required until their active immune system matures, usually about 3 weeks of age. Piglets are dependent upon the transfer of antibodies and other immune modulating factors which are present in colostrum. Besides antibodies, colostrum also contains lymphocytes, cytokines, nucleotides, and various growth factors which may affect the post natal development of the immune system. The amount of antibodies available in colostrum, as well as the ability of the piglet to absorb them, diminishes rapidly after farrowing. After 6 hours, the antibody content of colostrum is reduced by one third and, by 12 hours, is reduced by two thirds. Further, although the piglets have the ability to absorb antibodies and immune cells until "gut closure" at about 24 hours following the first suckle, after about 6 hours following their first suckle, their ability to absorb these molecules and cells is reduced to about 50 per cent and progressively declines even further during the following 6 to 12 hours. It is crucial to piglet survival to ensure consumption of sufficient colostrum as soon as possible after birth and before gut closure to maintain passive immunity. Failure to provide adequate passive immunity results in relatively poorly protected pigs that are more susceptible to earlier colonization by potential pathogens. Such colonized pigs can carry the pathogens and shed them in the nursery.

The issue of colostrum management has gained a new importance because of the realization that serious diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Circovirus-Associated Disease (PCVAD) are at least partly controlled on a herd basis by ensuring solid immunity among the suckling piglet population. Control programmes for PRRS and PCVAD are examples of two major health challenges where ensuring adequate colostrum uptake to maximise passive immunity is emphasised. In the case of PCVAD, the earlier in life pigs are infected the more likely that severe disease will result. Maternal vaccination studies suggest high levels of passive immunity can prevent or reduces disease even into the grower phase.

Taken together, it is clear that any practice that interferes with colostrum intake must be avoided. With respect to cross-fostering management, it has been suggested that fostered piglets may take several hours to start suckling their new sow. However, if these piglets have already suckled their own sow, the gut-closure clock is running and any delay in resuming suckling on the new sow may impair their passive immunity.

To see if this did occur, the authors employed 36 Yorkshire sows and their litters at the Michigan State University Swine Research Center. Sows ranged from parities 1 to 6 parities and were housed in farrowing crates. Warming mats and heat lamps were placed in the crates for newborn piglets.

Sows were observed during 16-hour intervals over three days to determine time of farrowing. To be used in the study, paired sows were selected for cross-fostering that had farrowed within an hour of each other.

At about fiv eto six hours after the start of farrowing, two piglets from each of the paired sows were cross-fostered onto the other sow of the pair. Instances of piglet aggression and time from fostering to first suckle were recorded and compared to non-fostered resident control piglets. Cross-fostered piglets were returned to their original sow after nursing the foster sow.

Recorded observations indicated that despite obvious efforts of newborns for locomotion and direction, the cross-fostered piglets almost immediately attached to a foster-sows’ teat and began nursing with resident piglets.

The range of times recorded for piglets to nurse following placement in the new farrowing crate was one to 12 minutes. There was no observed aggression by piglets or by the foster sow toward the cross-fostered piglets. There were a few cases where the fostered piglets seemed to need a little time to establish direction but from then on, they were intent on accessing a teat.

The authors say their results were surprising and suggest that cross-fostering, if done correctly, need not interfere with the ingestion of adequate colostrum and acquisition of passive immunity by cross-fostered piglets. Piglet survival continues to be an area that requires attention, especially as we continue to increase sow productivity.

Efforts to increase neonatal survival using appropriate cross-fostering techniques could ensure adequate colostrum intake and result in increased pigs out the door which may translate into greater producer profits.