Start calves off on the right foot to maximize lifetime production.

Written by Darian Livingstone | Ceres Industries
(306) 653-7258 | This email address is being protected from spambots. You need JavaScript enabled to view it.

As we head into spring and think about turning cows and calves onto pasture, we should also think about how to help those calves develop their digestive system. As most know, calves are born without a functioning rumen. In fact, they are technically born as a functional monogastric (single stomach). As the calf ages and begins eating solid foods, the rumen begins to develop and becomes a functioning organ.

Calves are unable to digest forages or other solid feeds at birth, so their digestion occurs in the abomasum portion of their four-compartment stomach. The lack of rumen activity means there is no ruminal fermentation, so nutrients are being used directly by the calf rather than rumen microbes. As the rumen develops over time, the calf must adapt to nutrients created during microbial fermentation.

Calves in a beef herd have an easier time going through this change since they are given months to adjust and accept their new diet of solid foods before weaning. However, for dairy calves, this shift is expedited, and producers may only give calves one month to make this transition.

Accurately understanding digestive physiology is the cornerstone to making sound calf nutrition decisions. A functioning rumen is a combination of several factors; microbial establishment and fermentation, rumen wall activity, and energy production.

It is crucial to provide calves with both hay and grain to maximize rumen development. The rumen begins to develop once liquid (milk) and solid feed - along with a microbial population - are introduced. Bacteria help to advance the development of the rumen. They are introduced from the calf's environment and the consumption of solid feed. The type of solid feed – forage or grain – that a calf consumes will determine the type of bacteria colonizing their rumen. Differing bacteria types will result in varying levels of volatile fatty acid (VFA) production.

Bacteria that are responsible for fermenting starch (grains) create butyrate and propionate. In contrast, bacteria that ferment fibre (forages) release mainly acetate. These three VFAs have distinctive and significant roles:

  • Acetic acid: used to generate ATP – the primary source of energy used at the cellular level. Also involved in creating essential enzymes.
  • Propionic acid: essential link in creating glucose in the liver. Arguably the most critical VFA.
  • Butyric acid: oxidized by the body for energy production. Plays a role in supplying the ruminal cells with energy for growth.

Starting calves on grain rations encourages the fermentation of starches, which can lower the rumen pH and foster more butyrate. Calves are not born with the appropriate enzymes to digest fibre (forages) so, feeding bulky feeds just takes up rumen space. Forages, if possible, should be limited until 2 months of age and then slowly introduced.

Ceres Industries - Fiber Level Affects How Calves Grow

However, not all grains are created equally. For example, corn is significantly higher in starch and lower in fibre than oats. So, oats will not release as much butyrate – remember, important for rumen growth – as corn. However, since the rumen's ability to digest starch is almost null in the beginning, much of the starch will skip the rumen and continue to the intestines, which may result in diarrhea. So, it is essential to carefully consider the type that you are putting in your creep feeders as specific stages of growth. It may be wiser to begin with an oat ration and slowly introduce corn over a two to three-week period.

In addition to grains and forages, producers can opt for yeast cultures to feed their growing calves. Yeast has shown numerous benefits that impact animal health and performance. Including yeast cultures in low or high-stress cattle, finishing diets, or in creep feeders is becoming more common in the cattle industry.

Yeast is a probiotic and is used to promote health and growth performance. The WHO defines a probiotic as a microorganism that, when consumed in adequate amounts, provides health benefits. Prebiotics, on the other hand, are a supplement that can modify the microbial population in the digestive tracts. Yeast exhibits properties of both pre- and probiotics.

Yeast stimulates rumen microbes by complementing and encouraging the growth of fibre digesting bacteria. This leads to increased feed efficiency by increasing the rate of fermentation. The increased rate of fermentation makes more nutrients available for calves, improving their growth and immune system. By increasing the rate of fermentation, and thus the feed intake rate, yeast can help speed up the development of the rumen. Here is a general outline of the benefits of including yeast:

  • Promotes digestion and utilization of nutrients.
  • Reduces fluctuation in pH and keeps rumen microbes steadily active, which speeds feed digestion and rumen turnover, allowing greater intake.
  • Promotes the growth of fibre-digesting bacteria in the rumen, increasing the rate and extent of forage breakdown.
  • Increases incidence of propionate production.
  • Optimizes animal performance.

Including yeast in livestock's diets is not a new idea. It has been reported in studies as early as 1924. Including a supplement containing yeast, such as the Saltec Fortified Pro (containing only 2% fibre), is a great option to complement starter rations. Developing a calf's rumen before weaning is crucial to reduce the nutritive stress and keep the health and growth status at an optimal level. To find out more how this product can help your operation, give Darian Livingstone a call at 306-270-6330 or email This email address is being protected from spambots. You need JavaScript enabled to view it..


Allen, J.. 2017. Understanding calf rumen development, IFA Cooperator Magazine. 83: 4.

de Ondarza, M.B.. N.D. The stomach of a dairy cow, Milkproduction.com [blog] http://www.milkproduction.com/Library/Scientific-articles/Animal-health/The-stomach- of-the-dairy-cow/

Dion, S., Seoane, J.R.. 1992. Nutritive value of corn, barley, wheat, and oats fed with medium quality hay to fattening steers, J. An. Sci. 72: 367-373

Hill, M., Jones, D., 2010. Calves are what they eat, Hoard’s Dairyman. [blog] https://hoards.com/article-1809-calves-are-what-they-eat.html

Jones, C., Heinrichs, J.. 2018. Rumen development, don’t wean calves without it! PennState Extension. [blog] https://extension.psu.edu/rumen-development-dont-wean-calves- without-it

Palmer, E. 2018. Effect of Yeast Supplementation During Various Stages of Beef Production. Pennsylvania State University. Theses and Dissertations.

Radke, A. 2015. 3 tips for rumen development in weaned calves, Beef Magazine. [blog] https://www.beefmagazine.com/blog/3-tips-rumen-development-weaned-calves

VIVO pathophysiology. N.D. Nutrient absorption and utilization in ruminants, Colostate. [blog] http://www.vivo.colostate.edu/hbooks/pathphys/digestion/herbivores/rum_absorb.ht ml