Energy is always the shortage in nature. This is the thing we never quite grasp in the cattle industry.

I first began to realize this 15 years ago when I heard Harry Cope, a beef producer near St. Louis, say it and talk about how he used plots of standing grain sorghum -- because of the energy content -- for winter supplement in his fescue pastures.

Energy is nearly always limiting in nature. Winter is hard because there is no energy and little protein, either.

Certainly we miss this point in our own diets because our farming-based society has made carbohydrates so readily available that we can over-consume them every day of the year and they are actually much cheaper per unit of consumption than is meat/protein. This is a reversal of what actually happens in nature and it masks reality and naturally confuses us.

The same thing has happened in our cattle operations (and all livestock operations), so we think buying energy is no big deal. Truth is, for a long time it really was cheap, but only because the entire system has been subsidized for 100 years now through various government programs. Then it got high-priced when the ethanol subsidy came roaring in, and now overproduction of grains based on those contrived market signals has pushed the cost down again.

Anyway, the thing I'm getting at here is we've become very confused over nutritional needs and their cost because of our world view and what we've been told.

Here's an example, in my part of the world, where warm-season grass is the dominant form of grazing fodder for cattle, we commonly feed protein supplement in the winter. This is a sensible thing to do, but the small protein deficiency we're addressing is not the main point. It is energy the body needs to do ALL work. When the rumen microbes get the added protein, they do a better job digesting the high levels of cellulose and lignin in the dormant, warm-season forages and so they get more energy from the forage. That's been understood and explained by nutritionists at least all through my lifetime.

Instead, we've come to think of the animals' diets as protein-deficient, when in reality they are badly energy deficient. If small protein amounts didn't benefit both sides of that macronutrient duo, the animals would still suffer greatly.

Cool-season plants like fescue can be even more confounding, because they are usually high in protein content, but a significant portion of the crude protein rankings assigned them in forage testing is actually non-protein nitrogen (NPN). With adequate energy, the rumen microbes can turn some NPN into usable energy. But too much nitrogen from whatever source is simply too much nitrogen in the animals' bodies. Energy is very often a problem there, too.

If you think about past history, pre-farming hunter-gatherers and grazing animals alike really only had access to easy energy in the summer and early fall, when seed heads and fruits and nuts became abundant. The rest of the year was hard times, and the ability of the body to shear the amine groups off protein and use it as energy was vital, but it has a limited timeframe before those nitrogenous compounds build up. Also, I believe that fat stored in our bodies and the bodies of animals was probably even more vital to surviving the winters.

Forage content, animal needs

Here's a very simple example using TDN and CP content of forages and the needs of cows. TDN is not the best measure of energy, but it is simple and accurate enough to serve our purposes here.

Native grass in Oklahoma has long been measured at these approximate values:

In spring, TDN is 56% and crude protein is 10%.

In winter, TDN can be low as 36% and crude protein often is 3-4%.

National Research Council (NRC) data shows us basic discrepancies between what's available in that forage and what's needed by cattle.

For a 1,400-pound cow to maintain moderate body condition, producing 20 pounds peak milk in her second month of lactation, she needs 59.1% TDN and 10.3% CP as a percent of dry matter intake. Native grass can supply both in the spring, but comes up very short in the winter.

However, when that same 1,400-pound cow is dry nine months after calving, she only needs 48% TDN and 6.7% CP, as a percent of dry matter consumption. You can see the TDN is about half and the protein is about half of what's needed at that time. If you supplement the protein deficiency and get better digestion of forage as part of the bargain, you get that typical slow weight loss that cow-calf producers once counted on to get through the winter.

Incidentally, that 20 pounds of milk, at its peak, requires almost 50% more TDN (18 vs. 12.6 pounds) in that cow's diet, and almost 50% increase in CP (3.14 vs. 1.75 pounds).

For comparison, a 1,000-pound cow giving only 10 pounds peak milk would need 12.5 pounds TDN and 2.01 pounds CP. When she is dry nine months after calving, she needs 47.9% or 9.7 pounds TDN, and 6.7% or 1.35 pounds CP.

Breed that 1,00-pound cow to give 20 pounds of milk and her requirements change quite a bit in peak lactation. She actually needs a little higher TDN and CP than the 1,400-pound cow, as a percentage of dry matter, because her overall intake is smaller, but her total pounds of nutrients necessary still doesn't rise as high as the big cow. Her peak milk numbers are 60.9% TDN or 15.2 pounds, 11.2% CP or 2.79 pounds.

Running counter

Yet today, we have bred and managed our cattle more and more toward production that requires high inputs of energy. Examples are huge bodies, huge babies, and high milk production. Then we ask them to produce in times of the year when nature offers them the least energy. The best example of this is winter calving, commonly wrongly called spring calving.

We have been told over and over that our beef production system is the most efficient ever, but that is only true when you measure the number of cows in the national herd against the total pounds of beef produced. Frankly, that says absolutely nothing about profits, yet profits are the most important measure of efficiency for every level of production in every industry and every production system.

In the end, I believe we must retrain our ideas about cattle nutrition.

Retune your thoughts to see energy as nature's main deficiency, with protein deficient only part of the time, or in some environments perhaps not at all. Then attune those energy-v-protein thoughts to your specific production system and forage type. Then consider the ways you can address this issue with the timing of your production cycle and the genetic makeup and physiology of the type cattle you are raising.