Across many parts of the country the spring green-up has begun earlier than in years prior. As exciting as dormant pastures coming to life may be, the risk that they present should not be overlooked. Rapidly growing grass, as well as wheat pasture and other cool season annuals are extremely high in potassium (K) and incredibly low in magnesium (Mg). When combined, these two factors substantially increase the risk for cattle to develop grass tetany. Luckily, providing cattle with access to a high quality free-choice mineral supplement that contains a relatively high Mg content (often referred to as "high-mag" mineral supplements) is an economical and effective means of preventing grass tetany. In addition to protection from grass tetany, a year-round mineral supplementation program will yield a return on its investment through improvements in growth, reproduction, and health.
After taking a stroll down the aisle at your local feed retailer, or having a conversation with your nutritionist or feed sales representative, the number of available options becomes evident. At times, it may even seem overwhelming. Fortunately, this reflects the number of opportunities that exist to find the product that complements your forages, in the form that matches your management style. Due to this wide diversity in product offerings, there are a number of options that will work for nearly every unique management system. Find the product that not only contains your desired level of minerals, but also that your cattle will consistently consume. Avoid trace mineralized salt, as the high salt content and extremely low level of target minerals make those products ineffective at meeting mineral requirements of cattle.
Many – but not all – high-mag mineral supplements are notorious for low or inconsistent consumption. And while this is generally more of an issue with "economy-line" mineral supplements, it is often due to the fact that magnesium oxide – the most common source of supplemental Mg – is unpalatable to cattle. They generally don't like its taste. Because of this, it may take some trial and error to identify the best option for your operation. In addition to mineral content, focus on the expected daily consumption that is listed on the label or tag. Most free-choice mineral supplements are labelled for an expected average daily consumption of 2 to 4 ounces. This is an important factor to consider, as 4 ounces of a 6 % Mg mineral supplement will provide the same amount of Mg to an animal consuming 2 ounces of a 12 % Mg mineral supplement. Due to other issues that exist in terms of TN forage mineral content, it's also important not to overlook the level of other important minerals such as calcium (Ca), phosphorus (P), manganese (Mn), selenium (Se), copper (Cu) and zinc (Zn). If necessary, consult with your county Extension agent or nutritionist to determine the specific level of each that will be most appropriate for your operation.