Ready for an Immune Response

By Jennifer Ryan
March, 2018

Dairy calf health – and future profitability – is linked to early illness

The first three weeks of life is a vulnerable period for a dairy calf. It’s also a critical time to prevent one of the most common illnesses: scours.

 More than 21 percent of all dairy calves have some sort of digestive challenge, including diarrhea, in the first two to three weeks of life, resulting in more than 56 percent of pre-weaned heifers contributing to more than 3.6 percent of all pre-weaning deaths in the United States, notes David Mathes, director of sales and marketing at DBC Ag Products.1  

“When a calf gets scours, producers move quickly to start a treatment program – antibiotics, nutraceuticals, electrolytes or a combination,” Mathes notes. “A lot of times that becomes where they focus their attention and base their success rate. If they get through the scours without losing the calf, they feel they’ve succeeded, but the real impact is becoming more evident, which is how that ‘hiccup’ effects producing milk down the road.”

University research indicates a heifer experiencing illness and/or nutritional deficiencies in the first six to eight weeks of life can experience reduced production over her lifetime, Mathes says.2

Improving calf health by focusing on digestive health and immune support at the start saves dairy producers money in time, treatment and labor costs – and lays the foundation for optimal milk production years down the road.

Causes of scours
Scours can be caused by pathogens, nutritional imbalances and even stress. Common pathogens include viruses, bacteria and protozoa, including rotavirus, coronavirus, 

E. coli, Salmonella, clostridia, cryptosporidia, coccidia and other protozoa.

The timing of scours in the calf’s life cycle helps indicate the cause, notes Andy Skidmore DVM, Ph.D., technical services – ruminant, Lallemand Animal Nutrition.

“Each of these causes has their own unique timelines and risk factors,” Skidmore says. “Scours caused by E. coli is most often going to occur in the first week of life. Part of that is the nature of the immune system, and part of it is the exposure period, which most likely occurs right at birth. Salmonella can occur any time, but it most commonly occurs later on in the animal’s life.”

Scours caused by rotavirus and coronavirus typically strike when the calf is between one to two weeks of age. Maternal antibodies initially help protect the calf from these viruses. Diarrhea caused by these viruses usually is not severe. However, the viruses can open the door for secondary infections.

Cryptosporidia and coccidia can cause scours about three weeks after the calf is born. While the animal may be exposed right after birth, the protozoa take weeks to replicate in the intestinal cells.

“I group pathogens into extracellular and intracellular. There are those pathogens that are going to attach to the cell wall and cause hyper-secretion where fluids leave the body of the calf, and, thus, you see diarrhea,” Skidmore says. “Then, there are intracellular pathogens like viruses and protozoa that damage the lining of the intestine and decrease the animal’s ability to absorb nutrients. In this case, everything is going to flush out. It also enables the pathogens to enter through or between intestinal cells, causing leaky gut and inflammation.”

No matter what the cause, Skidmore recommends producers fight scours by decreasing the pathogen load in the animal’s environment and giving the calf a strong immune system to fight disease.

Treatment options
The main concern when a calf gets scours is dehydration. Calves should receive adequate electrolytes and fluids. Antibiotics can be used to combat bacterial causes and septicemia that often occurs with the diarrhea.

“Antibiotics aren’t going to do anything to a virus,” Skidmore says. “The immune system still has to go through the whole process to fight the viral infection. Antibiotics can help if there is a secondary bacterial infection.”

Reducing infection
Dairy producers can minimize incidence of scours through good sanitation protocols.

“One of the biggest mistakes is in the sanitation of the colostrum collection equipment,” Skidmore says. “Look at the equipment you’re using to collect the colostrum. Maybe the bucket is fine, but the lid and gasket never get cleaned – or cleaned properly. Clean all the way from the milk hose to the bucket regularly with detergent and sanitizer.”

Diarrhea can also be caused by stress from changes in routine or weather that can impact digestive health, Mathes notes. However, it’s not always possible to reduce these stressors.

Don’t forget the cow
Dry cow vaccinations can help reduce the incidence of specific causes of scours in calves.

“Reducing scours goes all the way back to the dry cow program,” Mathes says. “Put the cow in the best position to be healthy and deliver passive transfer of immunity to the calf. A well-developed vaccination protocol is one way to boost a calf’s immunity through the cow’s colostrum.”

However, vaccines can only deliver protection against a specific disease challenge. Scours can be caused by a host of pathogens, which makes it a complex problem to vaccinate against.

Passive transfer of immunity from dam to calf also requires adequate colostrum intake. Most producers should aim for one to three feedings in the first six to 12 hours of the calf’s life, Mathes notes.

Healthy gut, healthy calf
Another way to ensure calves have a robust immune response is providing good nutrition to help fuel their immune system.

“In the last 10 or 15 years, producers have been increasing the amount of feed calves are getting, and it’s actually decreased the number of sick calves they see,” Skidmore says. “Their immune system is an expensive system, nutritionally, to support.”

Supporting optimal digestive health can also fuel the calf’s immune system, Skidmore advises.

“Maintaining the health of those intestinal cells – or using products that are going to help prevent adhesion of bacteria to the cell walls – helps minimize the impact of pathogens,” he says. “A healthy gut is more capable of fighting off pathogens.”

A healthy gut also prevents viruses and protozoa from entering into the intestinal cells. When the cells are stronger, they are better able to fight off pathogens.

Producers can help promote digestive health with specific products, but it’s important to ensure the products are backed by research and approved for use in for young calves.

“About 70 percent of the immune system resides in and around the digestive tract,” Mathes says. “Products that support digestive health are, at the same time, supporting a functioning immune system. It’s very difficult to eliminate exposure of pathogens to the calf. We have to rely on passive transfer of immunity and promoting the calf’s own immune system during this most vulnerable time. They can help to get the digestive system in tip-top shape – putting the calf in the best position to deal with digestive challenges that occur in the first few weeks of life.”

1 National Animal Health Monitoring Study, 2014 Dairy Study.

2 Van Amburgh M. Cornell University, Optimizing Nutrition and Management of Calves and Heifers for Lifetime Productivity. Western Dairy Management Conference 2017.

Topics: Dairy, Calf Health


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