Fall Grazing Opportunities and Cautions
After a summer of drought, pastures have been heavily utilized. Cattlemen are looking for options to move to additional grazing during the fall months. In areas with some late summer rains, there has been some green up of hay lands, regrowth from cereal and annual forages cut for hay, or crop volunteer growth.
Barley and oats cut for hay over a month ago may have regrown to the stage of heading and sorghum and millet may have greened up. With continued moisture stress and anticipated cold temperatures and possible frosts, there are concerns with potential toxicities and transitioning cattle from a dry fibrous mature plant diet to highly digestible immature regrowth.
The issue of nitrate accumulation in annuals may have lessened but risks remain. Clipping a representative sample and testing can provide an indication of nitrate levels and potential toxicity at a point in time. Additionally prussic acid can accumulate In several crops such as sorghum and sorghum-sudan grass crosses. Waiting several days after a killing frost, allowing plants to dry and will lessen risks and generally make them safe.
Anytime cattle have an opportunity to consume large quantities of immature readily digested forage there is a potential for bloat. The risks of bloat tend to be greater early in the day, following a rain, or after a frost. Best management practices would include turning cattle into regrowth in mid-day after grazing and when full. This may entail feeding some hay and placing some bales in the field for grazing. Avoid turning in shortly after a rain or frost.
If possible, provide access to other grazing as a permeant pasture simultaneity. In particular, regrowth alfalfa and volunteer canola have resulted in bloat after frost. When feasible limiting the time grazing will adapt the rumen to the new feed.
If volunteer grains matured to seed formation or there are abandoned areas of the field with mature grain, there is concern with grain overload from selective grazing. High grain intake by cattle not adapted to grain, can also lead to bloat, founder, or death.
Finally provide salt and mineral. Even consider feeding a mineral high in magnesium if grazing is predominately new lush growth with little mature forage to avoid risks of tetany.
Areas fortunate to have gotten some rain and have seen fall green up, now may have potential for much needed additional grazing into the fall. This can be particularly beneficial in getting calves to traditional weaning at good weights and putting some weight back on cows. With testing, avoiding turning hungry cows into changing feed, and watching for problems, these opportunities may me managed for good benefit.