A strong immune system is vital for healthy and productive dairy cows and calves. When an immune system doesn’t function properly, pathogens win and ultimately cause inflammation, rob energy and overwork organs. Unfortunately, there aren’t clear metrics to establish if the immune system is functioning properly, and for that reason it is important to take the right steps to strengthen your herd’s immunity.
Strengthen the barrier
Developing the immune system starts by building a strong defence barrier. The first immune component is the mucin barrier, which contains beneficial bacteria. A healthy mucin barrier protects gut lining cells against up to 90% of challenges facing dairy animals, but is easily impacted by decreases in feed and water intake. The mucin barrier has 4 components and the first 3 make up the ‘Kill Zone’, where pathogenic bacteria are identified and attacked.
- Mucous production. Goblet cells produce mucus that hold antibodies and other materials to protect against harmful pathogens. It also provides a matrix for organisms to grow.
- Anti-microbial peptides. These are produced by the normal bacteria in the gut and are the body’s natural antibiotics that kill bacteria considered pathogenic.
- IGA: Transports specific microorganisms across the barrier to attack foreign organisms.
- Tight junctions: Space between the cells that make up the barrier. The tight junctions keep cells together, preventing harmful cells from getting through. Inflammation causes the junctions to relax and cells to separate.
When the immune system is in balance, cows’ performance and ability to ward off disease improves. Photo: Arm and Hammer
Keeping the immune system in balance
Managing the barrier is important to keep the immune system in balance. Commensal bacteria—natural inhabitants of the gut—outside cell walls produce various compounds that cross the barrier to create anti-inflammatory hormones, keeping the immune system from overreacting.
Outside factors can impact how the immune system responds to attack, especially when cows and calves are stressed. When a stressor occurs, the kill zone is depleted and commensal bacteria are reduced. Harmful bacteria can then penetrate the barrier and cause inflammation, leading to potential issues such as leaky gut.
While a poorly functioning immune system allows pathogens to cause harm, an over-responsive immune system causes harm as well in the form of too much inflammation. Viruses like BRD and BRSV are adept at sending the immune system into hyperdrive and creating inflammation inside the lungs. Excess inflammation also reduces liver function. This activity causes decreased feed intake, a drop in milk production and increased prevalence of mastitis and metritis.
Feed for stronger immunity
Research on the impact of feed ingredients on immunity has identified ingredients that bolster immune function. This allows producers to improve function of the barrier and gut integrity, and target specific microbes.
Refined Functional Carbohydrates (RFCs) improve the function of the barrier and gut integrity. RFCs are effective at preventing pathogens from binding to the cell wall by agglutinating them, hampering pathogens from passing through the kill zone of the barrier.
Specific strains of Bacillus, such as those found in Targeted Microbial Solutions, are also effective at improving immunity. Traditionally, Bacillus are used to target toxigenic and non-toxigenic clostridia. Recent research, however, shows that some strains of Bacillus increase proteins responsible for maintaining tight junctions between cells.
The indirect effect of strengthening the killing zone and barrier renders pathogens unable attach to cell walls, colonise or replicate. While killing pathogens or rendering them inactive is important, strengthening the cow’s ability to prevent pathogens from doing harm is just as important.
When the immune system is in balance, cows’ performance and ability to ward off disease improves. Place emphasis on strengthening the kill zone, protective barrier and junction between cells to defend your herd against a broad spectrum of pathogens.
References available on request