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Build immunity to start calves right

Gene Boomer for Progressive Dairy Published on 30 April 2021

A newborn calf is the most vulnerable animal on a dairy. Born with an immature immune system, the calf can’t effectively handle pathogen challenges in the environment until 3 to 4 weeks old. In the meantime, young calves are bombarded with a host of stressors and disease-causing pathogens.

Dedicated animal husbandry and hygiene can help decrease the pathogen load, while feeding strategies can help build a gut barrier against disease and set calves on a path to healthy growth.



Clostridium perfringens, E. coli and salmonella are the biggest bacterial challenges to calf health during the first three weeks of life. Calf raisers should be aware that different pathogens attack calves at different stages of their young lives. Understanding pathogen prevalence can go a long way toward establishing a plan of attack for building calf immunity against disease.

Researchers at Arm & Hammer Animal and Food Production analyzed pathogens in more than 1,400 dairy calf fecal samples. Tests showed that C. perfringens and pathogenic E. coli are common in calves throughout the first 20 weeks of life. However, C. perfringens peaks at two to three weeks, when researchers found 84% of samples tested positive, and E. coli maxed out later, at eight to 20 weeks. On the other hand, salmonella was a concern primarily in very young calves under 1 week old.

Calfhood immunity starts with the dam

Building calf immunity against these and other pathogens starts with the dam prior to calving. Good nutrition is important throughout the dry period, but especially for close-up cows. During the last three to four weeks of gestation, cows have higher energy and metabolizable protein needs to support the growing calf and its immune system.

Scientists are learning more about metabolizable protein requirements during the dry period. National Research Council (NRC) recommendations may be too low in the last three weeks prior to calving, especially for heifers that are still growing themselves while supporting their calves’ growth. Newer nutritional models increase metabolizable protein requirements from 1,000 up to 1,300 to 1,400 grams per head per day. A more nutrient-dense diet ensures heifers produce adequate amounts of high-quality colostrum.

Prevalence of common pathogens in dairy calves by age


Feed intake is also a concern for springing heifers, as consumption may be limited due to their smaller size or as a result of pen crowding. If possible, keep heifers in a separate pen from other close-up cows to avoid competition with mature cows. Ensure heifers consume at least 11 kilograms of dry matter daily to get the full formulation of energy and nutrients.

Newborn calf strategies

After calving, the first three to five days are the most critical period for the newborn calf. Producers should focus on harvesting, storing and delivering high-quality and sanitary colostrum within one to two hours of birth. That step alone goes a long way toward eliminating problems with calf raising.

Besides timing, hygiene is the most important consideration for colostrum. Everything the colostrum touches needs to be clean and sanitary, including milking, storage and feeding equipment.

A second critical period for the calf is the transition from individual pens or hutches to group housing, when calves often experience a second spike in scours. Pneumonia is another high-risk disease during this time.

Keeping calves on feed and hydrated helps them navigate the stress of pen moves. Calves generally move from individual pens where feed and water may be just a step away to group housing where feeders and waterers may be at the other end of the pen. It’s not unusual for calves to literally be unable to find feed and water when they first move into group housing. Producers can overcome this issue by placing feeders and waterers at the centre of the group pen for easier access.

Building a gut barrier

Another key to calf immunity is the mucin barrier in the gut. Mucin is a protein that is the main component of the mucous in the intestinal lining and serves to protect the gut against pathogen challenges. The barrier is not a static wall but an immunological organ that is ever-changing and evolving. Managing this barrier is important for a strong immune system.


Naturally occurring beneficial bacteria help protect the gut wall from invasion by pathogens. However, stress situations can deplete these beneficial bacteria and allow harmful bacteria to penetrate the gut lining and cause digestive upsets and disease.

Probiotic ingredients added to milk replacer can bolster immunity in two ways: by building a strong defensive barrier in the gut and by targeting specific microbes. For example, refined functional carbohydrates (RFCs) improve the function of the barrier and improve gut integrity. RFCs strengthen the barrier so pathogens are not able to attach, colonize and invade the gut wall. Rather than attacking pathogens directly, RFCs prepare the immune system ahead of a pathogen challenge so the calf can successfully ward off the challenge.

Other ingredients contain beneficial bacillus bacteria, which directly target toxigenic and non-toxigenic clostridial bacteria, preventing them from causing disease in calves. For best results, it’s important to match the bacillus strain with the specific pathogens of concern in your calf-raising facility.

By keeping your calves’ immune systems functioning properly, you’ll avoid spending large amounts of time, effort and money on treatments – and avoid costly calf deaths. Supporting calves in their first days, weeks and months of life will pay dividends by producing healthy heifers and productive cows.  end mark

Gene Boomer is a ruminant technical services manager with Arm & Hammer. Email Gene Boomer