Fact: A healthy calf with strong immunity is less likely to become sick with scours or pneumonia. But achieving strong immunity can be a complex process.
In one way, it’s kind of like Murphy’s Law. If things can go wrong, they will – even when you think you’re doing everything right.
Getting it wrong can have dire consequences, so we’ve got some suggestions to help you avoid Murphy.
The complex part of immunity
Immunity begins with exposure to a pathogen, such as a certain virus or bacteria, which stimulates the body to create antibodies to fight that organism.
Antibodies are carried throughout the body in the blood and lymph systems where they can react with an invading agent and neutralize it. If an animal already has antibodies against a specific disease organism, whenever that particular organism invades again, an army of white blood cells and antibodies converge to kill the invader.
Buddy Westphal, from Valley View Charolais in Montana, says that anything you can do to help a cow develop a high level of antibodies will be helpful. That means making sure she is healthy and well nourished, with a strong immune system. She should be vaccinated for IBR and BVD, for example, to keep her healthy.
“At least two months before she calves, make sure she has adequate nutrition and enough protein to be able to create antibodies and have good colostrum,” he says. Antibodies are made up of protein; a cow that doesn’t have enough protein in her diet will have poor colostrum.
“She can build better colostrum if she has adequate nutrition through pregnancy. You can’t just wait until a couple weeks before calving; she needs good nutrition for several months,” he says. The cow doesn’t need to be fat, but her diet should contain the building blocks for creating antibodies.
“Availability of those antibodies is only meaningful and effective if the calf gets an adequate amount of colostrum within a few hours after he’s born, while he can still absorb them through the gut wall,” Westphal adds.
This timing can be affected by stress. If it is cold or the calf had a hard birth, his ability to absorb antibodies decreases quicker. This is why calves born in warm weather have a bigger window in which to get their first nursing accomplished.
Immediately after birth, the newborn calf has what is called an open gut – large pores in the intestinal lining that allow passage of antibodies (which are rather large protein molecules) directly through it.
These openings start closing quickly, however (to keep pathogens from slipping through), and by the time a calf is 24 hours old he can no longer absorb antibodies through the gut wall. Gut closure does not happen in linear fashion.
The optimal time for absorption is during the first 6 hours of life, but may be less than that in certain conditions – perhaps just the first 2 hours, in cold weather.
By the time a calf is 4 to 6 hours old he may have lost 75 percent of his ability to absorb antibodies into the blood and lymph systems. He can, however, still benefit from certain types of antibodies that stay within the gut to combat pathogens locally, such as some of the scour-causing organisms.
Getting immunity right
To be healthy, calves not only need adequate antibodies, but also a clean environment. Otherwise pathogens can quickly overwhelm a calf’s immune defenses. If a cow calves in wet, sloppy conditions and has a filthy udder, the calf will get a mouthful of pathogens when he nurses, and the antibodies he receives may be inadequate to protect him.
Westphal says he calves later than most producers in his area because, “I want warm weather so there won’t be frozen ears and tails on the bulls I sell. It’s a lot easier (for the cattle and the people taking care of them) to calve on green grass than in a snowbank. Calving on dry, clean ground is also a huge factor in keeping calves healthy.”
“We had not doctored any scours on our ranch for several decades, but then a couple years ago we had a tough winter with a lot of snow and then a lot of mud, and we had all kinds and colors of scours! We had coronavirus, rotavirus, E. coli and even some other ‘bugs’ we never did figure out. Weather makes a huge difference,” he explains.
Clean ground, healthy cows, and proper calf management (which includes making sure they all get adequate passive transfer of antibodies from mom) can help ensure healthy calves, especially if Mother Nature cooperates with decent weather.
Even so, you can only control what’s within your control.
Sometimes even with the best management, when you think you’re doing everything right, you can get scours outbreaks.
Maternal antibodies alone simply aren’t enough for you to relax and rest assured your calves will be protected. Vaccinating for scours works only about 80 percent of the time, and that’s in optimal conditions.
Consider this report in which researchers measured colostrum quality and specific antibody levels from cows in well-vaccinated herds. They wanted to know whether dam-level scour vaccines were providing adequate protection.
They found that in far less than 10 percent of cows sampled, colostrum was high in both general antibodies and antibodies against coronavirus, rotavirus and E. coli pathogens.
Your newborn calf’s immunity hinges on colostrum that consistently has a full artillery of protection. A high level of general antibodies serves as a shotgun, while concentrated levels of specific antibodies serve as snipers targeting the first scour-causing pathogens to which a newborn is exposed.
When you have both, Murphy’s Law will have a very hard time applying to you.