The results are another recurring reminder of this lesson long-taught and repeatedly-reminded: there are very real physiological costs in terms of unintended consequences in reducing "normal" dietary intakes. It's been more than 20 years, for example, since Dr. Mark Cook of the University of Wisconsin published results that curtailing salt intake in chickens impaired their immune system function. That's before most of the world woke up to the AIDS catastrophe.

In order for us to survive, our circulatory system must have an adequate volume of blood that is under sufficient pressure to supply all our tissues with the nutrients they need and to remove all the toxic byproducts of metabolism. It is a finely tuned balance of water and salt that allows this to happen. Any amount of water or salt that is consumed in excess of our needs is quickly eliminated through our kidneys. However, an equally important issue is ensuring that we have ingested enough water and salt to make up for any losses we experience. This is where the incredible mechanism controlling the thirst for water and the appetite for salt comes in.

This latest publication shows that this multi-factorial system is so robust and includes so many failsafe mechanisms that it continues to fully function even after large sections of its system are shut down. Employing a complex cascade of physiological functions from powerful hormones, such as aldosterone, to pressure sensitive receptors in the brain, this water thirst and salt appetite mechanism moderates our behavior so that we are driven to quickly replenish the volume and ionic balance of our blood, so that it is pressurized sufficiently for our heart to circulate it through our bodies. When fluids and electrolytes are lost, such as with sweating, physical exertion, diarrhea or other circumstances, we immediately get a water thirst signal. So we drink water to make up the loss. After a delay, our salt appetite kicks in to ensure that the ion levels are replaced. If we don’t respond on time to the salt appetite, we die – a situation which was described in an earlier article where a young woman died in a water-holding contest.

It has been repeatedly suggested that policies must be developed to reduce the amount of salt in processed foods. In fact, some countries already have or are in the process of considering policies to effect this. Will these policies be effective? What indication is there that people who are provided with a lower-salt food supply will actually reduce their intake of salt? Based upon this latest publication on salt appetite, individuals faced with foods that are mandated to be low in salt may make up for this in other ways. They may eat considerably more food in order to get more salt or they may simply pick up the salt shaker and add more voluntarily.

The recent publication by Shapiro, Boaz, Matas, Fux, and Shargorodsky as described in a recent article legitimately brings up the question of minimum levels of salt intake. Based upon their data, we can justifiably ask whether the current recommended daily values are prudent. Should the 2,300mg daily upper limit for sodium be reconsidered? Should the Institute of Medicine recommended daily adequate intake of 1,500mg sodium be reconsidered?

Our thirst for water is a basic mechanism we have evolved in our fight for survival. So is our appetite for salt. It is time we realize that the two mechanisms are interdependent and basic to our survival. Any policies promulgated to regulate our consumption of salt must bear this in mind and be based on the most rigorous science. If not, harm will be done.

Rotational or management-intensive grazing, can increase beef production per acre by 30% when compared to traditional grazing. All it takes is good, hands-on management and a bit of common sense technique. Rotational grazing requires the division of large pastures to several smaller paddocks which are grazed in short (2-4 day) intervals before moving the cattle on to the next paddock. When 10 or more paddocks are involved, grazing cycle repeats itself at roughly 30-day intervals.

The benefits are self evident, but we’ll list them anyway. First of all there is increased beef production per acre, then more uniform grazing which prevents bare spots, then the animal waste is more evenly distributed across the paddock and finally, the improved nutrient recycling increases forage production, which brings us back to increased beef production per acre. Pretty nifty, isn’t it?

But it doesn’t stop there, because cattle that graze lush forages have an increased appetite for salt. In fact, they will usually consume twice as much salt as those fed high cost, high-concentrate diets and salt is an excellent carrier of essential micronutrients as well as ionophores such as monensin. Feeding studies report that self-feeding a salt-monensin-supplement gave the same daily gain as hand-feeding the monensin supplement without salt. Salt, the most reliable intake regulator can be made even better when combined with monensin leading to increased beef production. But, it doesn’t stop there either.

A deeper knowledge of cattle and their grazing habits prompted the use of salt feeders as management tools to accomplish other objectives aside from meeting the cattle’s nutritional requirements. For instance, fly populations are a major challenge to grazing animals. The Noble Foundation found that combining the salt feeder and cattle rub in the same tool, was one of the most effective ways to control flies. Recent research show that weight gains were increased 27 lb. per head for weaned calves and by an average of 17% in yearling grazing cattle when flies were controlled.

To sum up, rational hands-on grazing management, using salt and rotational grazing leads to increased beef production per acre – or did we say that before?

You can read Larry Berger’s latest Salt and Trace Minerals Newsletter, “Factors Affecting the Trace Mineral Status of Feeder Calves,” along with a full library of practical nutrition and feeding papers at the Salt Institute salt and trace minerals in animal nutrition

The latest research reports coming out from down under indicates that such a costly and complex system may not be necessary to increase wool production.

The May 14, 2007 issue of the AllAboutFeed Newsletter indicates that increased dietary salt can increase wool growth across a range of sheep diets. These results suggest that increasing salt in the feed ration may be a viable strategy to increase wool production efficiency.

In trials carried out over 2 months, 18 month old Merino wethers were individually penned and offered one of l6 different diets. The feeds were formulated with four levels of added sodium chloride (nil, 7%, 14%, and 21%) and four levels of organic matter digestibility (55%, 62%, 69%, and 76%). Treatment feeds were offered ad libidum for seven weeks and at maintenance during the final week. Researchers found that clean wool growth, corrected for digestible organic matter intake, increased by 16%, 18% and 27% as added sodium chloride was increased by 7%, 14% and 2l% respectively. On the other hand, liveweight gain was reduced from increasing dietary sodium chloride, mostly as a result of reduced feed intake at the higher salt levels.

While higher levels of dietary salt may be favourable for wool production efficiency, the decrease in the feed intake of sheep needs careful management for commercial livestock production.

Now, if the same mechanism worked for hair, we might have a highly palatable cure for baldness.

For ease in reference and classroom assignment, chapters can be downloaded individually or the entire book can be downloaded as a single document.

And the cost makes it the best bargain of the 21st century: it's free!

If your mare lives outside and has access to lots of good-quality grazing, that might satisfy all of her nutritional requirements for the first eight months of her pregnancy. Indeed, a great many broodmares receive no grain, protein, or mineral supplements through most of their "in foal" time and do very well. If, however, your pasture is of less-than-wonderful quality, if her turnout is limited, or if she's carrying one foal while nursing another, you will have to supplement her diet. She first needs lots of high-quality legume or early-cut grass hay, and second needs the possible addition of a concentrate (grains). Don't forget her salt/calcium/phosphorus mineral lick.