Bioguide #15

Rumen function under stress

Tips for healthy rumen function during animal stress.

A healthy functioning rumen is a home to billions of micro-organisms, including a wide range of bacteria, protozoa and fungi. All have a role to play. Ruminants rely on rumen microbes to efficiently convert pasture and other fibrous feeds into nutrients for milk and meat production. The populations of microbes in the rumen are greatly affected by the type and quality of feed, stress and the use of antibiotics or de-wormers. If the populations of microbes are out of balance, then the animal’s rumen function will be suboptimal and digestive efficiency will decline. A prebiotic rumen microbe enhancer, such as Biostart Ruminant, can help when the rumen function comes under stress 

Common stress experiences that can affect rumen function include:


This is a particularly stressful time in a lamb or calf’s life. Lambs, in particular, are often upset and forget to feed, instead, they call excessively for their mother. Removal of the regular milk supply and resulting feed change to pasture can negatively impact rumen function.  


In the 6 weeks prior to mating, raising a ewe’s nutrition can increase ovulation. Improving feed utilisation at this time can lead to better lambing ratios. Likewise, rams tend to be very active at this time and maintain a healthy rumen and efficient feed utilisation supports their overall condition.


Dairy cows, beef cows, ewes, calves and lambs can all experience stress at calving, with significant effects on their health, immune system and productivity. Stress also often leads to decreased appetite. Supporting animals with a dose of a prebiotic digestion enhancer after calving helps maintain optimal rumen function, animal well-being and digestive efficiency.


When an animal suffers from heat or cold stress, more energy is used to maintain body temperature, with an impact on milk and meat production. Under heat stress, a cow’s rate of rumen motility (the contraction of muscles that moves food through the digestive system), appetite and feed intake are reduced. At these times, ensure plenty of water and shade is available. Under cold stress, the cow increases dry matter intake and rumination – providing sufficient feed at this time is crucial. Under both heat and cold tress, consider dosing the animal with a prebiotic digestion enhancer to help stimulate rumen function and digestive efficiency.

Introducing a supplementary crop

When a supplementary crop is introduced, the makeup of an animals’ rumen microbe population needs to change rapidly to ensure they can digest the new feed and maintain feed utilisation and performance. This process of changing the microbe populations can take between 4 – 9 days under normal conditions. Introducing the supplementary crop slowly over a few days and administering a prebiotic digestion enhancer will help rumen microbial populations adapt.

Recovering rumen function after animal health problems

Conditions like acute or sub-acute acidosis, milk fever and grass staggers can depress appetite and production. High acid levels in the rumen, and the use of antibiotics, can also adversely affect rumen microbial populations and therefore rumen fermentation. Follow your vet’s treatment plan for the health problem and consider a prebiotic digestion enhancer to help restore rumen microbial populations and digestive efficiency.

Transport stress

Transportation is very stressful for stock. Prior to transport, moderately restrict feed intake, feed hay or silage as the low water content will help reduce the liquid content of effluent, and supplement with magnesium (with vet’s advice). Dosing animals with a prebiotic digestion enhancer prior to transport also help cows adjust to the feed change pre and post transport, minimising production losses.

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