Thinking with your gut? The role of microbes in ruminants
Most mammals have little ability to digest fibre.
Ruminants such as sheep and cattle are the exception to this rule due to their relationship with various micro-organisms in their digestive tract. The foregut of ruminants houses an ecosystem of micro-organisms that breakdown plant cell wall.
It allows the animal to obtain nutrients from both the plant material and the microbes themselves.
Rumen microbes (bacteria,fungi, protozoa) are a valuable protein source and can supply 60 to 70 per cent of the animal’s protein requirement.
This relationship allows ruminants to produce products such as milk, meat and wool that are useful to humans from human-inedible feed (forage).
Form determines function
The digestive tract is the largest body organ with the highest metabolic turnover (gut cells get replaced every three to five days). It is also the only organ that functions in non-sterile conditions.
Transport of nutrients from the gut into the body occurs across a single layer of cells called the epithelium. In the small intestine, the epithelium cells form finger-like projections called villi, increasing the surface area available for absorption. The epithelial cells responsible for absorption are called enterocytes, and they move as if on a conveyor belt up the villi. Once they reach the top, they get replaced.
Enterocytes are closely packed to form a barrier. If this barrier is compromised, the gut becomes permeable and susceptible to pathogens, described un-ironically as “leaky gut” syndrome. Symptoms include bloody or slimy diarrhea.
The development and protection of this single layer is critical for not only the growth of the animal but also its health as shown by the graphic below. This is where importance of microbial diversity comes into play.
The role of microbiota
In the small and large intestine the population of microbes is called the gut microbiota. Microbiota and its diversity, or lack thereof, can impact the ability of the gut to absorb valuable nutrients required for growth and production.
Animals are born without an effective gut microbiota but immediately pick up microbes, usually from their mothers after birth, to start inoculation and colonisation of the microbiota in the young animals’ gut. Colonisation prepares the immune system and its reaction to antigens. It also provides nutrients such as vitamins, amino acids, and short-chain fatty acids used for energy.
A diversity of microbes help keep the populations and conditions within the gut stable. Without any one group dominating or having exclusivity to nutrients or attachment sites on the gut wall through competitive exclusion.
Factors that reduce microbiota diversity, increase the risk of disease and gut damage.
Factors affecting gut health
Many challenges cause damage to the gut and/or the microbial population living within it.
- Feed – sudden changes in feed or feed quality (mycotoxins, mice contamination) will affect microbial populations. For example, feeding higher grain levels will increase the number of starch digesting microbes, reducing rumen pH, increasing the risk for acidosis and limiting fibre digestion.
- Stress – any physiological stress caused by extreme weather events (heat stress, floods), management or feeding practices (weaning, de-horning or feedlot induction) will affect the integrity of the gut epithelium and result in a poor immune system.
- Antibiotics – antibiotics reduce the diversity of the microbial population and creates the opportunity for pathogenic (Salmonella, E.coli, Clostridium bacteria) or resistant bacteria to become the dominant population causing disease and infection.
- Biosecurity – poor biosecurity increases the risk of animals being contaminated with disease-causing micro-organisms. Pay attention to stock handling equipment, transport, feed and water troughs, young stock and/or sick pens, irrigation.
Management practices can reduce feed challenges, stress, and/or biosecurity related factors on animal gut health. The main goals of any gut health strategy should be to:
- promote the development of a healthy and functional digestive tract
- enhance microbial diversity
- reduce Pathogen load or challenges.
Alltech Lienert’s Blueprint range is formulated with these goals in mind. With over 42 years of experience in promoting gut health, and optimising rumen efficiency with groundbreaking technologies.
Alltech Lienert understands that when it comes to ruminants you have to feed the bugs that feed the animal.
Article written by Michael Pretorius, ruminant sales manager, Alltech Lienert Australia for Seasons magazine.