Spring Grass Management

Calving season is wrapping up across most of the SFG territory, and for many producers that means one thing: it is almost time to turn cows out on grass. But before opening the gates, it is important to remember that not all spring grass is created equal. Early spring forage grows fast, contains a high amount of water, and can create health and nutrition challenges if cattle are not managed correctly. Loose stools, reduced condition, and even metabolic disorders can all show up when cows are turned onto immature forage too quickly. Fortunately, most of these problems can be avoided with good planning and management.

One of the biggest concerns during spring turnout is grass tetany, an often fatal disorder caused by low magnesium levels in cattle grazing lush, rapidly growing forage. Risk factors matter. Cows in a body condition score of 5 or higher, dry cows, or cows that are full from a TMR ration before turnout are generally at lower risk. Still, prevention is far easier than treatment. Feeding a high-magnesium mineral or a high-mag breed-up tub before turnout is one of the best management tools available. Since magnesium can make mineral bitter and reduce intake, adding garlic or salt can help improve palatability. High-mag tubs are often more consistent because cattle tend to consume them more readily. Ideally, high-mag products should be fed for at least two weeks before turnout and continued for roughly three weeks afterward before switching back to a standard breeding mineral.

Another issue producers may notice is what many western cattlemen call “warshy grass.” While the term is more common on irrigated pastures out west, the same situation occurs in Iowa and northern Missouri every spring. From green-up through early June, grass is growing extremely fast and is made up largely of water. Cattle may appear full, but because the forage lacks enough dry matter, they can become extremely loose and may even lose body condition. It may not be popular advice, but continuing to feed some hay during this period can provide the dry matter needed to keep the rumen and lower digestive tract functioning properly.

Mineral nutrition also becomes critical during spring grazing. Salt alone is not enough. Proper mineral products contain balanced levels of salt, trace minerals, and vitamins designed to complement rapidly growing forage. Cattle naturally crave salt, but they cannot recognize deficiencies in nutrients like calcium, zinc, or magnesium. If cattle are consuming large amounts of mineral, it is often because they need not only the salt, but the additional vitamins and trace minerals included in the mix as well. Keeping a quality mineral available at all times is essential for maintaining herd health and performance.

Perhaps the most important management decision is simply waiting until the grass is truly ready before turnout. Turning cattle out too early because chores are piling up can reduce pasture productivity for the rest of the grazing season. Waiting until forage reaches at least eight inches tall allows the plant to establish stronger root reserves and improves summer regrowth. A few extra days of feeding hay in May can prevent weeks or even months of hauling hay later in the summer when pastures burn up during July and August.