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Colostrum's Critical Role
When newborn calves get plenty of high-quality colostrum, they have a better chance of staying healthy through weaning and beyond. The passing of antibodies from dam to calf through colostrum provides passive immunity. It’s critical for newborns, because their disease-defense mechanisms are not fully developed.
“Colostrum provides the calf with a source of preformed immunoglobulin, some of which is actively absorbed across the small intestine, and it provides passive protection against systemic disease,” says Glenn Selk, Extension beef cow-calf specialist at Oklahoma State University.
A landmark study done at the USDA-ARS Roman L. Hruska U.S. Meat Animal Research Center in Clay Center, Nebraska, illustrates the far-reaching impact of colostrum on the health of cattle throughout their life cycle. The study compared the health of animals receiving sufficient and insufficient levels of antibodies within the first 24 hours of life.
“The study followed the calves through weaning and into the feedlot phase of production,” says Selk. “It did not track the health of heifers as replacements in the herd.”
The study found that calves receiving insufficient antibodies had a 5.4 times greater risk of death prior to weaning. They also had a 6.4 times greater risk of being sick during the first month of life and a 3.2 times greater risk of being sick at any point leading up to weaning.
“In the feedlot, cattle receiving insufficient antibodies at birth were three times more likely to show up in the sick pen,” he says.
Illness affects weight gain. Sick calves had weaning weights 35 pounds lower than healthy calves. In the feedlot, cattle developing respiratory disease had an average daily gain of .09 pounds less than healthy peers.
The sooner calves get colostrum, the better. Newborns rapidly begin experiencing a process of intestinal closure. As this happens, calves increasingly lose their ability to absorb antibodies from colostrum.
By the time calves are six hours old, they’ve lost 30% of their former ability to absorb antibodies. By 12 hours, their absorption capabilities drop by 50%. At 24 hours old, they have just 10% or less of their original ability as newborns to absorb the large immunoglobulin proteins.
A factor to consider in the management of calves requiring early supplemental feeding is that any type of fluid reaching the gut will speed up the process of intestinal closure. Thus, first meals should always be colostrum or a high-quality colostrum replacer.
Selecting cows with good mothering ability goes a long way toward ensuring that newborns get plenty of colostrum. “The initial licking of the calf dry appears to be very important to the cow-calf bond,” says Selk. “Mothered calves absorb 70% more immunoglobulin from a standard feed than nonmothered calves.”
Good udder conformation also encourages early nursing.
Selecting for calving-ease genetics indirectly ensures that newborns get sufficient colostrum early on in life. “Calves born after dystocia are at a high risk of failing to receive adequate colostrum by natural suckling,” he says.
A cow’s body condition at time of calving affects the quality and volume of the colostrum she produces.
“The higher immuno-globulin concentrations seen in calves born to better-condition cows may be due to increased immunoglobulin production by these cows or to increased calf vigor, allowing the calf to take advantage of the immunoglobulin present,” says Selk.
“Properly developed heifers mated to calving-ease sires will be a major first step toward reducing scours and pneumonia in newborn calves,” he says.