Fall Grazing For Livestock

By PR Extension Office

With the mild fall temperatures and the recent moisture, the green up of grass and regrowth of crops has extended the Fall grazing season. One question we have received is “when is it safe to graze alfalfa in the Fall?” said MSU Powder River Extension Agent Mary Rumph. In checking with our Extension Beef Specialist, Megan Van Emon, located at Ft. Keogh, she recommended waiting to graze the alfalfa until at least 5-7 days after a killing frost.

Alfalfa generally becomes “safer” to graze in the fall after several consecutive frosts in the 20’s that cause visible plant damage and drydown. In one study, well-irrigated alfalfa regrowth was grazed during the week in mid-September when first frost was predicted. The weather was similar to right now, warm afternoons and cool nights. A few minor bloat cases occurred until the morning following the first frost – which was about 28 degrees for a couple mornings in a row. That result was many incidences of bloat for several days.

The best recommendation is to avoid grazing until there is significant alfalfa frost damage.

Van Emon said that if alfalfa grazing is required prior to killing frost, she recommends setting out bloat blocks at least 10 days before turning livestock into the alfalfa to limit the potential for bloat. Putting bloat blocks out after they begin grazing won’t help, according to Van Emon, because the rumen won’t be conditioned. The cows are probably going to get loose with their feces again, so making sure they have some of the more mature forage available helps ease those issues.

Pre-conditioning for all livestock seems to be a key ingredient. Slow adaptation to the new feed is needed. Due to the improved quality of some of the fall pastures, cattle should graze the mature forage they have been on in the morning and moved to the new pastures in the afternoon to limit their intake that first day. Monitor livestock daily and if any suspected bloats occur, treat them and remove the rest of the herd immediately.

Another potential problem is the nitrate levels in regrowth on annual crops, including but not limited to millet, barley and oats. Again, these are best left to graze after a killing frost and resulting plant die down and using the same grazing management in slowly introducing the lusher feed source to the livestock is recommended. In this situation, bloat is not the primary concern, nitrate poisoning is. Plant material can be tested at the Extension Office for nitrate levels prior to grazing.