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Jump-start calf rumen development with viable microbial products

Andy Skidmore for Progressive Dairy Published on 01 March 2020

From birth, calves’ naïve immune systems are assaulted by challenges: new environments, fast diet transitions, exposure to disease and sometimes transportation and commingling. That makes it no surprise the dairy industry continues to battle pre-weaning losses.

The Dairy Calf and Heifer Association (DCHA) Gold Standard for early survival rates is greater than 97% 24 hours to 60 days after birth. Yet the average mortality rate for pre-weaned calves is about 6.4% in Canadian dairies. That means nearly all operations can make improvements in this area. Some industry experts believe morbidity and mortality rates for pre-weaning dairy heifers are still alarmingly high.



Why are these mortality rates so high? Of course, any dairy producer will tell you a major calf disease threat is scours. At birth, the gut of a calf is just beginning to develop. During the past few decades, our knowledge of intestinal health has grown. There is conclusive evidence that microbes within the gastrointestinal (GI) system communicate and influence many aspects of an animal’s performance and well-being.

The next frontier in calf feeding

Now that we know what the gut is capable of, we can begin to positively influence it. One of the most effective ways to do this is through the use of a gut modifier or viable microbial product. A viable microbial is defined as a live micro-organism, which – when fed in adequate amounts – positively changes or modifies the gut microflora and environment. The Canadian Food Inspection Agency’s (CFIA) Animal Feed Division is leading the way in further defining the landscape of viable microbial products fed to livestock.

Preparing the rumen for forage

Proper rumen development sets the stage for future growth and lactation performance. During the first months of its life, the calf’s digestive tract undergoes significant changes as it evolves from its initial monogastric function to a fully functioning ruminant. Poor management during the pre- through post-weaning period will result in reduced rumen development, lowered feed intake and growth with increased diarrhea and morbidity. This can lead to long-term consequences. Performance as an adult lactating cow can be lost, and studies have shown a clear link between post-birth live-weight gains and future performance into the third lactation.

By weaning, calves need to have a suitably developed rumen to be able to digest forage-based diets. Peer-reviewed research has documented improvements in performance and rumen health in cattle fed viable yeast (ADY) microbials. The specific strain Saccharomyces cerevisiae CNCM I-1077 has shown increases in weaning weight and feed intake in calves. One study in New Zealand showed calves supplemented with S. cerevisiae CNCM I-1077 in the starter feed had steady feed intake and weight gain during the weaning phase, leading to improved bodyweight (Table 1).

Feed intake for weaned calves


The researchers attributed this to better rumen functionality at this important time of development.

Specific strains needed for success

Not all viable microbial products provide this response and not to the same level. Specific strains of these viable products are needed to influence the calf’s natural digestive function through an active process. This process works by favouring beneficial microbes in the GI tract.

Specific strains are much more efficient and perform to a greater level at delivering these effects, particularly in pre-weaned calves. Producers should look for specific strains that achieve the desired result and are proven to produce that result in dairy calves. It’s similar to choosing a breed of cattle. All cattle give milk and make steaks – it’s just that some breeds do one or the other more efficiently than others. All cows are not the same. The strain of a specific viable microbial is as important as the breed of cow is to the desired outcome. They are all very different. You wouldn’t use the same strain of yeast to make a donut as you would to improve calf performance.

In addition, the efficacy of a viable microbial is directly linked to manufacturing and quality-assured production processes. These are live, active microbes and must be carefully handled to ensure the desired results. The formulation of the product is also important. Well-formulated products can be added to starter feeds for easy delivery to calves.

Management remains a priority

Viable microbials can help support the digestive system, but they must be combined with other good nutrition and management practices that promote animal performance. To further improve calf growth, it is important producers continue to implement good management practices to reduce or eliminate the main causes of stress, such as:

  • Abrupt feed changes
  • Poor ventilation
  • Overcrowding
  • Exposure to sudden weather changes
  • Excessive heat or cold

In addition, carefully transport, vaccinate and handle pre-weaned calves to reduce the stress associated with these events. Viable microbials can be fed at any time, but many producers find it particularly helpful to supplement before stressful events to enhance an animal’s natural defenses.


Calves are less likely to experience scours when the natural balance of microbes in a calf’s digestive system are in balance. In addition, the digestive system is where feed provides the nutrients that power all other functions. An efficient, balanced digestive system can have positive systemic effects on the immune system, which can help the animal stay healthy, get the most out of their feed and attain its genetic potential.  end mark

Andy Skidmore received his DVM from Kansas State University and his Ph.D. in animal sciences from Cornell University and is employed by Lallemand Animal Nutrition, North America as a technical services – ruminant team member, since 2016.

References omitted but are available upon request. Click here to email an editor.

Andy Skidmore
  • Andy Skidmore

  • Technical Services – Ruminant
  • Lallemand Animal Nutrition, North America