Getting young stock off to a good start is critical to the success of any livestock operation. For most livestock species, the successful transfer of maternal immunity from a dam to her offspring is the first step and also the cornerstone of neonatal health. Whether we are discussing foals, calves or goat kids, all rely heavily on the ‘passive transfer’ of immunity by means of the first milk or colostrum to provide protection from disease.
During the last 4-6 weeks of pregnancy the dam begins to concentrate proteins called immunoglobulins in the colostrum. Because there is little to no immunity passed to the fetus during pregnancy, it is critical that high levels of immunoglobulins (IgG) be present in the colostrum and available to the offspring immediately after birth. However, the neonatal intestinal tract is ‘open’ to absorb these proteins at birth. Closure of the gut happens quickly and little IgG is absorbed after 24 hours of age.
With this basic understanding of the process of passive transfer it is easy to understand the importance of this critical step as well as the opportunity that exists for failure of the transfer of immunity to a foal or calf leaving it immunologically naïve and therefore, susceptible to any number of diseases. Difficulty birthing is one of the most common and may lead to a weak neonate that is slow to stand and nurse. Poor nutrition level of the dam may lead to poor quality colostrum and/or an insufficient quantity to provide proper IgG levels in the neonate. Harsh weather conditions can also prevent adequate, prompt nursing to facilitate timely transfer prior to gut closure.
There are certain measures that producers can take to ensure adequate immunity in the neonate. First is proper care of the dam prior to the end of pregnancy. Proper nutrition is paramount. Strategic vaccination 1-2 months prior to birth can boost IgG levels in colostrum specifically related to those diseases represented by the vaccine. This strategy is commonly used to boost immunity to pathogens causing scours in calves. Close observation and assistance at birth will help to minimize the risks represented by dystocia. If a calf or foal is found weak at birth or slow to nurse, colostrum or a commercial colostrum replacer can be administered by stomach tube if necessary. This is best done in the first 6-12 hours of life to ensure successful absorption. If the window of proper absorption is passed, then your veterinarian can assist in the administration of an intravenous plasma transfusion to directly administer IgG into the bloodstream.
If there is a question in regards to the successful transfer if IgG in a neonate blood tests can determine the level of IgG or protein in the blood and whether or not there is a need for veterinary intervention.
No matter the type of operation, all livestock producers should make efforts to ensure proper passive transfer and discuss plans for assistance and intervention or even testing with their veterinarian.
Darren Loula, DVM, is owner of Christian County Veterinary Service, LLC, a mobile large animal vet clinic.
