Submitted to: The Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2012
Publication Date: 1/1/2013
Citation: Vallet, J.L., Miles, J.R., Rempel, L.A. 2013. A simple novel measure of passive transfer of maternal immunoglobulin is predictive of preweaning mortality in piglets. The Veterinary Journal. 195(1):91-97.
Interpretive Summary: The death of piglets soon after birth represents a major inefficiency in US Swine production. Most of these losses occur within 3 days of birth. During this period, sows initiate milk production in the form of colostrum, an early “milk” containing nutrients needed by the newborn piglet for survival that is also characterized by high concentrations of immunoglobulin G, proteins that are responsible for protection of newborn piglets against disease. Piglets are born immunoglobulin G free and receive immunoglobulin from colostrum. Thus, piglet serum immunoglobulin concentrations can be used to determine how much colostrum has been acquired. A very simple, rapid, inexpensive test was developed, the “immunocrit” that can be used to measure piglet serum immunoglobulin G. Results show that the test successfully measures immunoglobulin G in the serum, and low individual piglet immunocrit values predict subsequent piglet mortality. Litter averages provide an assessment of initiation of colostrum production by sows, and results indicated that failure to initiate colostrum production by sows is rare and for most sows, the overall ability to produce colostrum does not contribute substantially to newborn piglet mortality. The immunocrit procedure can be used to monitor the acquisition of colostrum by piglets from sows and is rapid, simple and inexpensive enough to be used routinely. The assay identifies colostrum deprived piglets while they are still alive so that remedial action can be taken if desired. Alternatively, it could be used to monitor management strategies (for example, split suckling protocols) designed to improve colostrum acquisition by piglets, or it could be used as a genetic selection tool to improve the success of colostrum acquisition by piglets.
Technical Abstract: Preweaning mortality of piglets represents a significant loss to swine producers. Two factors that contribute to this loss are the timely initiation of lactation by the sow, and the ability of individual piglets to nurse successfully within hours of birth. However, the contribution of these factors to overall preweaning mortality is not well documented. The objective of this study was to determine whether assessment of passive transfer of immunoglobulins from sow to piglet could simultaneously assess the effect of both factors on preweaning mortality. A simple, rapid method to measure passive transfer, the “immunocrit,” was developed for this purpose. The smallest piglets in litters from 204 gilts were sacrificed on d 1 after birth and blood samples and weights of stomach contents were collected. Immunoglobulin (Ig) G concentrations were measured in serum samples using protein A Sepharose precipitation, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and densitometry of the IgG heavy chain protein band. IgG in samples was also measured using a method based on absorbance and by the immunocrit procedure, which were similarly correlated (R = 0.86) with results from SDSPAGE. Immunocrit measures were correlated (r = 0.48; P < 0.01) with weight of stomach contents on d 1, indicating that the immunocrit reflects piglet nursing ability. To assess associations between immunocrit and preweaning mortality, blood samples and weights were collected on d 1 after birth from every piglet in litters from first (n = 90) and second (n = 145) parity sows from two farrowing seasons. Piglet serum immunocrit values and day 1 weights were independently predictive (P < 0.01) of preweaning mortality. Second parity sows had greater average immunocrit values compared to first parity gilts (P < 0.01). Results indicated that litter average immunocrit was not associated with preweaning mortality. In conclusion, the immunocrit is a simple, rapid test of passive transfer of immunoglobulin from sow to piglet, and can be used to assess neonatal piglet nursing ability, sow delivery of colostrum to piglets, and the likelihood of preweaning loss of piglets.