<p>All animals need minerals. Thanks to almost 100 years of nutrition research, we know a lot about the mineral needs for each horse - whether, it is sodium (from salt), potassium or iodine. We know that a horse rarely lacks potassium, since plant foods are rich in this mineral. For sodium, however, there is a much smaller margin between what is in the plants and what the may horse needs. This explains why we must give salt supplements, but not potassium supplements. Sodium and potassium are present as positive ions (cations) in the feed, i.e. they have a positive electric charge. Since the feed as a whole is electrically neutral, cations are always accompanied by a corresponding number of negative ions (anions).</p>
<p>Although the overall amounts of sodium, potassium, chlorine and sulphur in the ration are important, the horse's metabolism is also affected by the balance between these ions. With sports horses in particular, rations need controlling to avoid an imbalance that can lead to acidification. This may happen with horses on high concentrate rations with extra supplements of minerals. All of this explains the growing interest of horse people in the cation-anion balance of rations. It is also  why the next version of PC-Horse will enable its users to calculate cation-anion balances.</p>
<p>The cation-anion balance is referred to as DCAB (dietary cation-anion balance) or CAB, and is calculated as the sum of the positively charged minerals sodium and potassium (Na + K) minus the sum of the negatively charged minerals sulphur and chloride (Cl + S). The unit used is milliequivalents (mEq). It is important to remember that the cation-anion balance is not a nutrient such as potassium or chlorine, but a calculated number that characterizes a feed or ration. With a predominance of sodium and potassium (cations) in relation to chloride and sulphur (anions) in the ration, the DCAB will be positive, and have an alkalizing effect on the body, as shown by a slight increase in blood pH. A dominance of chloride and sulphur in relation to sodium and potassium will have an acidifying effect on the body, and blood pH will decrease slightly.</p>
<p><img src="images-joomla/stories/seasons/DCAB-scale.png" alt="DCAB-scale" width="145" height="174" /> <img src="images-joomla/stories/seasons/DCAB-BALANS.jpg" alt="DCAB-BALANS" width="139" height="174" /></p>
<p>The DCAB value for common roughages used for horses is in the range +250 to +450 mEq per kg dry matter. In oats, the value is around +30 and in barley +40 to +50 mEq per kg dry matter. Thus we see that forages</p>
<p>have significantly more positive DCAB values than corn. The concentrate mixtures vary widely depending on the DCAB of the ingredients, and the mineral additives used. In ordinary table salt DCAB is 0 because we have just as many milliequivalents of sodium as we have chloride!</p>
<p>As we have seen above, diets with plenty of forage will generally have a positive DCAB. As the proportion of concentrate increases, the DCAB value of a ration will decline. DCAB can be expressed in three ways: as per kg dry matter in a feed, as a value for the ration, or else per kg of body weight of the horse.</p>
<p>A feed ration with only hay (8 kg/day) given to a 500 kg horse will typically have a DCAB of about +2500 mEq. This corresponds to +5 mEq per kg of body weight. In the case of a trained horse on a ration of 6 kg hay plus 3.5 kg oats, the DCAB-value for the ration changes to +2000 mEq, or +4 mEq per kg of body weight. Mineral supplements, commonly given to race horses, may change these values ​significantly. In fact, mineral additions are used by the feed manufacturing industry to obtain specific DCAB-values for a feed or a ration. The physiological processes underlying how metabolism is affected by the cation-anion balance are complicated. Using the new PC-Horse version, which comes in August, you can calculate DCAB values for your own feeds, and read and learn more about cation-anion balances.</p>
<p><em>This article was originally written by Dr. Day Austbø.</em><br /><em> Copyright: PC-Horse International - Norway 2012.</em><br /> <em>Feel free to use and publish the material. Please indicate the source and author.</em></p>