By Suzanne Berry

MISSISSIPPI STATE -- Milk. It does a body good, especially a dairy calf's body.

Recently completed research at the Mississippi Agricultural and Forestry Experiment Station's Coastal Plain Branch in Newton has shown that immunity levels of newborn dairy calves that were tube-fed colostrum at birth were higher than those that nursed their mothers.

Colostrum, the first milk a cow provides after giving birth, contains immunoglobulins that are necessary for passive immunity to protect calves from infections. A calf is born without the necessary antibodies to resist viral and bacterial infections, which can cause high mortality rates within the first week of life. Acquired passive immunity from receiving colostrum is critical for the survival and subsequent growth of the newborn calf.

"We've studied colostrum in dairy cattle because in western states, 'chugging calves' has been going on for years. We wanted to see how it would affect calf immunity levels, given the hot and humid conditions during Mississippi summers," said Joey Murphey, Mississippi State University dairy science researcher and superintendent at the Coastal Plain Branch.

There is a tremendous increase in demand for milk in the early fall when school begins. For dairy farmers around the state to meet these demands, cows need to begin calving during the late summer and early fall.

"Cows suffer from heat stress just as some humans do. This complicates the birthing process and the immediate postpartum period," Murphey said. "The cow is exhausted after laboring and then giving birth, which makes it difficult for her to stand up and allow the calf to nurse. The calf is also stressed from the difficult labor process and is often too weak to stand and nurse. Without receiving high doses of colostrum from the mother's milk, the calf doesn't receive high levels of antibodies for immunity."

It has been estimated that 60 percent of calves that are allowed to nurse do not receive enough antibodies, as they are too weak at birth to vigorously nurse.

"Immunoglobulins found in colostrum are very large protein molecules. At birth, the wall of the small intestine is very permeable, allowing these large molecules to pass directly through the lining of the gut and into the bloodstream," Murphey said. "During the 24 hours following birth, the lining thickens, making it more difficult for the molecules to pass into the bloodstream. After this time, the digestive system recognizes the immunoglobulin molecules as large proteins, releasing enzymes that digest them, so they are of little benefit to the immune system."

Ensuring that a newborn calf has sufficient levels of colostrum for the immunity needed to survive is extremely important. Without enough high-quality colostrum immediately after birth, a calf can easily die from the viral or bacterial infections that might appear. However, acquiring proper levels of immunity within the first few hours of birth almost ensures the calf's survival.

The Mississippi dairy industry generated an estimated $381 million in 1999. This amount included cash receipts for the sale of 66.2 million gallons of milk, valued at $90.7 million, according to year-end statistics provided by the MSU Department of Agricultural Economics.

Researchers took initial blood samples to check for existing antibodies to ensure that test calves had not already nursed their mothers. If antibodies were found, the calf was excluded from the test group. If not, researchers tube fed the calf one gallon of colostrum. The control group was allowed to nurse their mothers without human intervention.

After the test cows gave birth, they were milked and the colostrum tested for quality before feeding to the calf. The specific gravity of the colostrum was measured. A reading of 70 micrograms per milliliter or greater provides the necessary volume of antibodies needed for immunity. The average score for dairy cows is between 50 and 60, whereas beef cows have much higher scores, between 300 and 400. First-calf heifers have lower scores, but as the animal matures, the level of antibodies in the colostrum increases.

Esophageal feeding tubes were used to feed calves colostrum. Additionally, the calves' temperature and a blood sample were taken immediately after birth and repeated at 48, 120 and 240 hours after birth. Calves that were allowed to nurse their mothers had consistently lower immunity levels than the calves that were fed a gallon of colostrum.

The dairy industry is a major contributor to Mississippi's annual income. The Tylertown area in southwest Mississippi is the center of the state's dairy industry and has been referred to as the "Cream Pitcher of the South." MAFES research can help Mississippi's producers across the state keep providing top- quality milk to the area.

Contact: Joey Murphey, (601) 683-2084