Rumination Is a Good Thing

by Darwin Kelsey, Executive Director

Back in April, my post (“Homo Sapiens Are Supposed to Eat What?”) was about what kind of animal homo sapiens are – eating-wise. Actually, that was a reprint of an article I wrote in 1999 for the Lake Farmpark Almanac – on homo sapiens as an omnivore. This current blog reprints a related article called “Rumination Is A Good Thing” which I wrote for the Lake Farmpark Almanac (Winter 1998), Vol. 4, No. 1 comparing humans and other animals according to their digestive tracts (gut types) – which helps determine what we want to (can) eat.

What’s a metaphor? A wag I know says it’s a place for cows to graze. Right. Speaking of cows grazing and metaphors brings to mind the important matter of rumination. According to Webster, the primary meaning of ruminate is to “chew again” or “chew the cud.” Cows and other ruminants swallow large amounts of poorly chewed vegetation while feeding. Later they regurgitate the vegetation (their cud) and masticate it some more.

A secondary, metaphorical meaning of ruminate is to “bring up” an idea of topic again, in order to “chew on it”, mull it over, reflect, ponder, meditate. Well, I’ve been ruminating of late (in the secondary sense, of course) on recent research explaining why animals eat what they eat – human animals and non-human (both wild and domesticated). It appears that American agricultural scientists and farmers can learn a lot about how livestock use feed by studying the management of wildlife on Africa’s vast game preserves. The reverse is true as well. And students of human nutrition will have their eyes and minds opened by comparing the human body’s digestive tract with the digestive tracts of other animals. Indeed, I think this new research will change the way many farmers farm. It will change the way we think about humans and other animals sharing our little planet’s finite resources. And so, ten years from now it will surely change what you see and hear at Farmpark. Read on – and ruminate.

You and I are not herbivores (eaters of plant matter only). My vegetarian friends would have me believe otherwise, but they can’t fool me. Their recently minted philosophical prescriptions  have not yet repealed physical anatomies, evolved over millions of years. I readily concede that that with great resolve and due diligence, vegetarians who eat little or no animal products can keep themselves more or less as healthy as the Eskimos of Greenland or the Masai of Kenya, who eat little food of plant origin. Vegetarians may even try to control their pet’s diets, too. But left to their own devices, their cats prefer squeaky mice and tweety birds – because cats are natural carnivores (flesh eaters almost exclusively)! Vegetarian dietary directives are better suited for cows. Animal nutritionist Peter Cheeke observes that cows do not find flesh palatable, do not have carnivore teeth, claws, speed, stealth, or other anatomical features, necessary to stalk and kill prey. But even if they did, they don’t have a digestive tract suited to the digestion of meat.

Cheeke is Distinguished Professor of Agriculture at Oregon State University. His book Impacts of Livestock Production on Society, Diet/Health and the Environment (1993) distills a fascinating array of research and practical experience derived from agricultural scientists, zoologists, botanists, nutritionists, farmers, zoo curators, and wildlife managers (among others). Cheeke explores fundamentally defining characteristics of animal life – among them, the manner in which animals interact with one another and their environment to obtain foodstuffs that meet their nutritional needs. Most of us, I think, would be surprised to learn that our nutritional needs (and those of other animals) depend very much on the structure of our digestive tracts.

Zoologists often refer to three broad categories of feeding strategies: carnivores (meat eaters), herbivores (plant eaters), and omnivores (eating both plant and animal matter). Humans, like pigs, chickens, and rats, are omnivores. We are attracted by and adapted to nutrient rich, low fiber foods such as seeds, nuts, meat, and fruit. We aren’t generally as fond of course hay, corn stalks, oat hulls, or bran, as are horses and cows. And we don’t much enjoy large quantities of high fiber material when it enters one end of our digestive tract or leaves at the other end. Our gut type isn’t well adapted to efficiently using such food.

Domesticated animals (including humans) – and a great many wild animals – can also be classified according to three kinds of digestive tracts (gut type): simple non-ruminants, ruminants, and non-ruminant herbivores. Simple non-ruminants include humans, pigs, chickens, dogs, and cats. We all have a simple, non-compartmentalized stomach and an intestinal tract. The stomach functions mainly to store ingested food, and then release it slowly to the small intestine where most of our digestion and nutrient absorption occurs. Our large intestine (hindgut) serves mainly to remove water and form feces.

Ruminants are animals with complex compartmentalized stomachs. While most ruminants have stomachs with four compartments, camels and other camelids have three compartments. Ruminant species range in size from the lesser mousedeer to the giraffe. A crucial characteristic of the ruminant stomach is that the largest compartment (the rumen) acts as a fermentation vat where bacteria, protozoa, and enzymes digest fibrous plant material that cannot be digested by simple non-ruminants. Wild ruminants – like domesticated cattle, sheep, and goats – vary greatly in their preferences for forage type and their abilities to digest it. Actually, such differences exist from breed to breed within domesticated species.

Non-ruminant herbivores have enlarged, large intestines (hindguts) which perform many of the same fermentation and digestion functions of the rumen in ruminants. But the chemistry of hindgut fermentation is significantly different and it enables these animal species to utilize much poorer quality roughage than ruminants can tolerate. Hindgut fermentors include equids (horses, donkeys, zebras), elephants, rhinoceroses, ostriches, and some monkeys and rodents. In the wild (or on a farm), these critters can carve out relatively non-competitive niches relative to food sources.

If this brief rumination on the nature of guts seems complicated, you have no idea how complicated this stuff really is. The biochemistry of what goes on inside us and other critters is staggeringly, mind-numbingly complex. But the good news is a few persistent, inquiring minds are now really focusing on the dazzling diversity of digestive processes, which critters use to fuel themselves. And that is crucial to understanding how we can conserve and even enhance natural ecosystems to feed humans. Intellectual rumination on how physical ruminants and non-ruminants can best share our planet’s resources is a good thing.


Fifteen years ago I said that the new research I was describing in the above article would “change the way we think about how humans and animals share our little planet’s resources.”  I haven’t seen much of that kind of thinking yet – mostly just increasing anguish and anger over how harmful, wasteful, and environmentally destructive industrial livestock production can be. But in the last couple of years some of the thinking I thought was going to happen, actually has begun. And, if implemented would probably mean that planet Earth, including homo sapiens, would be better off by raising certain kinds and numbers of animals in certain ways than by avoiding the raising of animals and eating meat. You know something good is starting to happen when high-profile environmental activists and vegans change their minds on animal agriculture. But changing the “system” is an excruciatingly slow process. Nevertheless, we’ll gaze into a newer, better crystal ball in a third blog a few months from now – I think there is a better version there for most of us, both omnivores and vegans.


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