It’s May here in the West, and that brings warmer temperatures and green grass with summer right on its heels. As you turn out onto the new green grass, keep in mind the potential health implications that come with the decision, and with some mitigation hopefully they are avoided. Two main considerations come to my mind when talking early season grazing: bloat and grass tetany. These health risks can have varying impacts depending on your range and grazing conditions and your local climate.
Bloat is one of the most-talked-about problems with cattle, and for good reason due to how fast an animal can go from appearing normal to dead within hours. Bloat is characterized by a distended rumen on the left side of the animal. There are two types of bloat; a frothy bloat and a gaseous bloat. Cattle on pasture are mostly associated with frothy bloat caused by excess foam and froth buildup in the rumen. This is attributed to grazing high-legume pastures, generally when the stand is made up of over 50% of legumes such as alfalfa or white clover.
The best way to deal with frothy bloat is following the old adage of “An ounce of prevention is worth a pound of cure.” To mitigate risk, dilute high-legume-content pastures with grass seed and use low-risk legumes such as birdsfoot trefoil or cicer milkvetch. Other strategies for dealing with bloat include managing your cattle’s appetite by feeding hay before turning into the pasture or using feed supplements such as polaxalene, which reduces froth buildup in the rumen. Using these practices along with keeping an eye on cattle turned out to green pastures can help reduce the impact bloat has on your herd.
Grass tetany is caused by low blood magnesium; however, it is not a deficiency but rather a metabolic reaction gone haywire. Interactions between other minerals in the animal do not allow proper magnesium absorption, leading to a tetany or misfiring of muscle signals in the cells. Grass tetany is characterized by animals lying on their side and “windmilling” their legs uncontrollably. Again, this metabolic disease relies on prevention rather than treatment. Before grasses reach 4 to 6 inches, they are very low in magnesium, leading to animals not getting enough for their physiological needs. Older animals with young calves (less than 2 months) are more susceptible to grass tetany because of the demand on their bodies to lactate. Legumes have a higher magnesium content, and cattle grazed on pastures mixed with growing legumes generally do very well. Some other ways to curb the impact of grass tetany are feeding a magnesium supplement, managing what class of animals are on the pasture (nonlactating), feeding a legume-grass mix hay or grazing later in the season when the plants are more mature.
Having a pasture management plan is crucial to mitigate these diseases, which hopefully will not show up in your herds this year. If you have any questions, reach out to your local beef extension personnel or your veterinarian.
