Grazing with the Weather
Precipitation and temperature play major roles in pasture productivity, and knowing how to adjust grazing to match current conditions is key. Are you shifting your management to meet pasture conditions?
Stocking and grazing management aren’t static. When forage production is limited — especially during a drought period — stretching forage resources is a high priority. In contrast, during wet years, grass growth can get ahead of our grazing rotation and lose quality.
By mid-summer, most pastures have already produced the majority of the forage they'll provide this season. Using temporary electric fence to crossfence can increase utilization, slowing down a grazing rotation and stretching forage considerably during dry weather.
This strategy becomes even more effective once plants go dormant because of heat or lack of precipitation. Normally, grazing management balances forage utilization with plant health, but dormant plants can tolerate heavier use without damaging the crown.
On the flip side, grass that is getting tall and lanky ahead of a grazing rotation could benefit from flash grazing. Moving animals through quick can help prevent plants from becoming overly mature. Keep up this fast pace while growth is rapid. Once growth slows, then the rotation can slow down as well.
Speeding up grazing when things are wet and slowing down during dry times is a good rule of thumb to use as we adjust to the weather Mother Nature throws our way. Doing so can help you find the perfect balance for your pasture and animal health.
Control of Flies in Pastures and Rangeland
In Nebraska, there are two species of fly that cause the most economic injury to pasture and rangeland cattle — the horn fly and face fly. Selection of an appropriate control method for each will depend on the time of year, the efficacy, cost and convenience of treatment, and your herd management practices.
Horn flies are a major pasture pest, causing an estimated $1 billion in economic losses annually in the U.S. These blood-feeding insects are typically found on the back, sides and poll area of cattle. The economic injury threshold is 200 flies per animal. Above that level, horn fly infestations can reduce both milk production and weight gain by altering grazing behavior.
In Nebraska, horn fly populations typically peak twice each year — once in early summer and again from late August through mid-September.
Although face flies don't feed on blood, they can cause significant irritation by feeding on animal secretions from the eyes, mouth and muzzle. It is also a vector of the pathogen that causes pinkeye in cattle, and feeding by the female fly causes eye tissue damage. Face fly populations usually peak in late July and August and are most common near waterways, in areas of significant rainfall, and in irrigated pastures.
Horn fly and face fly management options vary widely and include forced use methods such as dust bags, back rubbers and traps, as well as product application methods such as pour-ons, animal sprays and insecticide ear tags. For more information on control methods, contact your local extension office.
Sorghum Hay Risks
Sorghum, sorghum-sudangrass and sudangrass can be valuable emergency forages in dry years, but they carry one major livestock risk: prussic acid, or hydrogen cyanide (HCN).
The risk comes from dhurrin, which is found naturally in all sorghum species and breaks down to release HCN when plants are stressed or damaged by drought, frost, wilting or chewing. This toxin acts quickly and can cause difficult breathing, staggering, collapse and death in livestock.
Risk is highest in young plants, drought-stressed forage, regrowth and frost-damaged plants. Young upper leaves typically contain the highest concentrations of dhurrin, making them riskier than stems or mature leaves.
For grazing, wait until sorghum-family forages are at least 18 inches tall. After frost, wait seven days before grazing, and restart the clock if another frost occurs. Those recommendations have long been the standard guidance.
Recent research from Dr. Shelby Gruss at Iowa State found that dhurrin can remain in dried sorghum and sorghum-sudangrass hay, where it may still release HCN during digestion. So hay made from drought-stressed, immature or frost-damaged sorghum should not automatically be considered safe.
If conditions were risky when hay was put up, test before feeding.
Nitrates remain a separate concern, so testing for both nitrate levels and prussic acid potential may be appropriate.
