Win the race to protect newborn calves
A fast time is crucial to winning a race. Newborn calf care is a lot like a race: The faster you get quality colostrum in calves, the sooner they’ll start to build immunity through antibodies known as immunoglobulins.
“IgG” stands for immunoglobulin G, a protein produced mainly by plasma cells. The protein is used by the immune system to combat pathogenic bacteria and viruses. In cattle, they are transferred from the dam’s blood serum to colostrum in the mammary gland a few weeks before calving. This IgG “download” peaks one to three days before calving.
We hear a lot about IgG because it is the predominant immunoglobulin in colostrum, making up about 85 percent of the total of these type of antibodies in cows’ colostrum. Cows also produce immunoglobulin M and immunoglobulin A, which provide about 7 and 5 percent of total immunoglobulins, respectively.
Active early during infections, IgM helps direct many other components of the immune system to fight off the infections. On the other hand, IgA is typically found in mucus membranes such as the respiratory and intestinal tract to help fight off invading pathogens. In addition to other minor forms of antibodies, they coordinate, attack and try to eliminate invading pathogens.
As calves mature, their immune system eventually produces IgGs, which will circulate in their bloodstream to fight disease in their organs and body systems. But at birth, calves have none of these antibodies in their blood serum and require several weeks for their immune systems to mature and assume IgG production. Colostrum must fill this gap in immune protection.
Critical two-hour window
To give every calf the best chance of survival, the process of effective colostrum delivery is a race against time. The Dairy Calf and Heifer Association (DCHA) Gold Standards advise feeding colostrum at 10 percent of the newborn calf’s bodyweight (about 4 quarts for a 90-pound calf) within two hours of birth. This recommendation is based on research which shows multiple reasons why beating the clock is so important:
1. Maximizing IgG concentration at harvest
The concentration of IgG and other proteins and peptides in the cow’s milk diminishes quickly after calving. One study evaluated this decline measuring IgG levels in colostrum harvested at two, six, 10 and 14 hours post-calving. Samples yielded corresponding IgG levels of 113, 94, 82 and 76 grams per deciliter, respectively.
While these IgG levels were above the industry quality standard of 50 grams of IgG per deciliter, this study underscores the importance of milking fresh cows quickly – ideally within the first two hours after calving. With every passing hour, valuable IgGs are lost.
2. Enabling optimal absorption
The newborn calf’s small intestine can absorb large molecules like IgGs – but only for a limited time. After about 24 hours, intestinal closure occurs, at which time IgGs and other immune-supporting molecules are no longer well absorbed and passed to the calf’s bloodstream. This, too, is a gradual process, meaning the pathways to absorption are most open and functional in the first hours after birth.
As the hours pass, calves’ intestinal tissues begin to secrete digestive enzymes. By about 12 hours old, digestive enzymes may be sufficiently present to begin digesting IgGs rather than allowing these molecules to be absorbed whole.
3. Beating the bacteria
The calf’s intestinal tract is sterile at birth. But within a few hours, environmental bacteria naturally begin to colonize there. This colonization can accelerate if calves are born in a dirty environment, particularly if they ingest manure shortly after birth. Some researchers believe the rate of intestinal closure may increase with the presence of bacteria in the gut.
The impact bacteria has on absorption also emphasizes the importance of providing a clean calving environment and using correct harvest and storage methods – possibly pasteurization – to minimize bacterial growth in the colostrum itself. You don’t want the valuable IgGs in the first dose of colostrum to be canceled out by packing it with absorption-blocking bacteria.
What’s the risk of losing?
An estimated 35 percent of dairy calves in the U.S. have failure of passive transfer (FPT) of immunity. FPT means calves either did not receive colostrum or – for various reasons – did not absorb enough IgGs to achieve adequate immunity.
DCHA defines successful passive transfer as a minimum blood serum total protein in 2- to 7-day-old calves of 5.2 grams per deciliter for calves fed maternal-sourced colostrum and 5 grams per deciliter for calves fed colostrum replacer.
Failure to achieve passive transfer has far-reaching consequences. Many of these calves will die. Their lack of systemic immunity early in life leaves them unequipped to ward off pathogens. But what happens to calves that live?
Researchers suggest if calves do not have passive immunity, they will have to draw on their reserves to try to mount immune responses on their own earlier in life. They may succeed, but it will be at the expense of normal growth and development. There simply aren’t enough resources to go around.
We’ve all seen these poor-doing calves that manage to stay alive but don’t have the growth and vigor of their herdmates.
Other research has shown calves fed colostrum have more developed intestinal villi, which helps them absorb and process nutrients. A University of Arizona study on a large commercial dairy showed heifers with FPT had significantly lower average daily gains and higher mortality rates, particularly in the post-weaning period.
In another study by the same Arizona research team, heifers with FPT had significantly lower milk production in their first lactation and were more likely to be culled before their second calving. And a beef calf study at the U.S. Meat Animal Research Center in Nebraska showed FPT male calves also performed less efficiently in the feedlot, with three times greater risk of respiratory disease and death.
Don’t leave your newborn calves in the dust. If you don’t have colostrum protocols in place, it’s time to write and implement them. Consider consulting your vet or calf nutritionist for help developing these protocols. They may be able to provide valuable insight on developing a program that is effective but also feasible for you and your employees.
If collecting and processing colostrum will not work on your farm, you may want to consider a colostrum replacer – one that supplies at least 150 grams of IgG per dose according to DCHA Gold Standards. Colostrum replacers can help bypass some of the barriers to clean and timely IgG delivery and routinely win the race to set your calves up for a productive life.