Grazing alfalfa in the late fall can be a great economical feed source. However, with these warmer fall temperatures (or lack of hard frosts) and high cattle and lamb prices can create a situation where bloat could be very costly. There are no “for sure” rules to determine when alfalfa is “safe” to graze, however below are some things produces should consider when turning out on alfalfa fields:
1. Use caution when alfalfa plants are just beginning to show frost damage, this is when alfalfa grazing can be the most dangerous for bloats. Hard frost/freeze ruptures alfalfa cell wells, resulting in more soluble protein being immediately available for consumption by the animal. The increase in the soluble protein increases the rate of rumen fermentation, thus increasing the risk of bloat. Alfalfa generally becomes “safer” to graze after several consecutive frost in the 20’s that cause visible plant damage and drydown.
2. Fill calves or lambs up with good quality hay prior to moving onto alfalfa fields. Not only will this help reduce animals from gorging themselves, but is also important to allow the ruminal microbial population to adapt to higher quality feeds. This is especially important if animals are coming off low quality forage (corn stalks, dry grass/range pastures). Animals should be turned out in the late morning or early afternoon, rather than early morning.
3. Provide bloat blocks or bloat preventing additives in the water for several days before and after the start of grazing alfalfa fields. Monitor cattle several times per day when animals are turned into a new pasture.
Submitted by Sarah M. Smith