The digestive system of cattle, and other ruminants, provides a complex mechanism for the digestion of feedstuffs indigestible by other animals.
The benefit is the conversion of those plant materials, indigestible by humans, into good sources of protein such as meat and dairy products.
Knowledge about how the ruminal microbes work and what they need to do their job is expanding. There are opportunities to improve overall animal performance by paying attention to these microscopic creatures cohabitating in the rumen.
How it works
Ruminants have a large fermentation vat containing a diverse population of microbes that digest cellulite compounds. The microbes break down feedstuffs for the animal.
Cattle still need nutrients that pass through the rumen and are absorbed in the intestines for the benefit of the animal. But you have to take care of the ruminal population first or the animal won’t perform well.
There are close to 200 species of ruminants worldwide and, contrary to what you may think, ruminants don’t have four stomachs; they have one stomach with four distinct components. Each component serves a different and complementary function.
The rumen, the first and largest component of the bovine’s stomach, is a large fermentation vat in which digestion of fiber occurs. The rumen can hold up to 50 gallons of digesta. Inside the rumen is a colony containing billions of anaerobic bacteria, protozoa, fungi that work to digest feedstuffs.
Microbes in the rumen turn fibers like cellulose and hemicellulose into protein and volatile fatty acids. The rumen-degradable protein fed to cattle feeds the microbial colony, and the volatile fatty acids are absorbed and used by the animal as energy. Bacteria also break down fats in the diet, which are absorbed in the small intestine.
The future of probiotics
Beef cattle nutrition has come a long way from the days of the Pearson Square. The microbial genome of the rumen has been mapped, but it is variable; it’s diet-specific and host-specific. The science of ruminant nutrition has moved to the microbial level. There’s a saying: “We’re not feeding cows; we’re feeding the microbes.”
Attention to this level of fermentation could be the last frontier in feed efficiency, immunity and overall sustainability of cattle production. On the horizon, we may be able to inoculate cattle with more efficient groups of microbes from another animal in the form of probiotics.
According to Matt Cravey, head of North American Ruminant Programs, Phileo, there is increasing industry pressure to reduce the use of antibiotics in animal production. “The beef cattle industry is looking for new technology to increase efficiency and profitability with great emphasis on non-antibiotic means to assist in digestion, animal performance, gains and improved health.
The Veterinary Feed Directive is prompting veterinary and nutrition consultants to look for non-antibiotic treatment options.”
The dairy industry is more advanced in the use of these products, perhaps because they collect performance data daily and can tell when management decisions are making a difference, but the beef industry is getting on board.
Cravey says, “Probiotics work especially well at the stress points of production, like receiving high-risk calves, incidences of heat stress, immune-compromised animals and baby calves with immature rumen.” There is strong research-based evidence that probiotics and paraprobiotics bind to pathogens and toxins like E. coli and mycotoxins – and by implication could have an impact on immunity.
Live yeast increases cow productivity with increased dry matter intake, reduces risk of acidosis, changes the bacterial profile and increases lactate-utilizing bacteria – improving digestion and overall performance.
Currently, research is being conducted to examine things like how the maternal environment affects establishment of the microbiome in calves; how the microbiome affects immunity, particularly respiratory health; and how supplementation with probiotics can improve feed efficiency, heat tolerance and milk production in cattle.
Probiotics and prebiotics defined
The term probiotics has been defined by the Food and Agricultural Organization (FAO) and World Health Organization (WHO) as “live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host.”
Probiotics can improve intestinal health by stimulating the development of a healthy microbiota, lowering the pH, preventing pathogens from overpopulating the intestine, increasing digestive efficiency and stimulating immunity.
Probiotics are live organisms, some derived from yeast, some are direct-fed microbial (bacteria like lactobacillus). Probiotics are used in dairy, poultry, swine and equine production as well as aquaculture, pets and human nutrition.
There is great scientific evidence that yeast, mannan oligosaccharides, bacteria can increase intake, increase milk production and reduce heat stress.
Paraprobiotics are a cell wall from yeast that contains proteins, chitins and saccharides, which feed the ruminal bacteria.
Prebiotics are non-digestible ingredients that serve essentially as fertilizer for beneficial bacteria in the digestive tract. They promote the growth of beneficial microbes. An example is yeast, which has been shown to improve lactation performance of heat-stressed dairy cows in a study from Brazil.
Carrie Mess is a Wisconsin dairy producer, advocate for animal agriculture and owner of dairycarr.com, a popular website. She says, “We feed our cows yeast; it helps the rumen bugs and our milk production.”
Mess also feeds probiotics like lactobacillus to calves to improve their immunity and reduce the incidence of scours. In young calves without a fully functional rumen, the widely used probiotic lactobacillus can decrease the risk of pathogens in the intestines, which cause scours.
John Richeson, an assistant professor at West Texas A&M University, is evaluating the vaccine response and animal performance for calves supplemented with probiotics. Richeson says, “We’ve lost the use of chlortetracycline and aureomycin, and we are hopeful the use of probiotics will at least replace a percentage of the animal performance gains we’ve lost from the regulation of these technologies.”
Richeson continues, “These technologies are accepted by the FDA and the scrutinizing consumer because they are natural; there is a positive connotation with probiotics because of this perception.”
Here’s a rundown of some of the probiotics and prebiotics being used:
1. Mannan oligosaccharides are produced from a yeast, are sold as prebiotics and may attach and bind pathogens and toxins such as gram-negative E. coli, Staphylococcus aureus and salmonella spp. as well as mycotoxins. Mannan oligosaccharides aren’t digested by intestinal enzymes and may enhance growth of beneficial bacteria.
2. Fructooligosaccharides are naturally occurring in plants like tomatoes, onion, garlic – and others, according to the NIH, improve mineral absorption and decrease serum cholesterol. They have been shown to stimulate the growth of beneficial intestinal microflora.
3. Yeast (Saccharomyces cerevisae) – A type of yeast changes rumen fermentation rates and patterns utilized in diets. Yeasts are utilized in segments of many industries.
Richeson is optimistic about research he is conducting using probiotic technologies. “We are also looking at how the use of probiotics may alleviate physiological load during beta-agonist feeding periods in hot summer months.”
Probiotics are available for producers at feed mills and are fed at between 5 to 15 grams per head per day. Necessity is the mother of invention; perhaps the changing regulatory environment is the catalyst for our industry to search for natural animal performance-enhancing alternatives. 
PHOTO: Cattle at the feed bunk. Staff photo.
Melissa Beck is a freelance writer based in Prescott, Arkansas. Email Melissa Beck.
