Extreme heat and varying degrees of soil moisture currently impact an expanding area of our country, says Jim Krantz, South Dakota State University Extension Cow/Calf Field Specialist.

“For many South Dakota crop and livestock producers, these conditions that prevailed last year in the southern plains have migrated northward, now threatening livelihoods earned from both sectors,” Krantz said.

He adds that adapting to these conditions has challenged generations of farmers and ranchers and forced them to place renewed emphasis on their management skills in times of drought.

“As they do so, a systematic approach may provide the means to overcome or minimize the impact of Mother Nature,” he said.

On the crop side, Krantz says that adequate moisture for most of the state provided almost ideal conditions for field preparation, planting and weed control. However, many areas are witnessing extremely dry conditions in the midst of a monster heat wave.

“Agronomic practices were part of a well-planned crop strategy that, until now, provided row crops and grains with the framework for rewarding yields. In drought-stricken areas, those yields now may be measured by tons of forage, not bushels of grain,” Krantz said.

Avoid nitrate poisoning with these tips

If this scenario becomes a reality, there are some considerations Krantz says producers need to think about as they plan their forage options:

• Well fertilized crops, under stress condition caused by drought, have higher nitrate levels than non-fertilized crops.

• Plant parts closest to the ground contain the highest concentrations of nitrates. Most are in the lower third of the plant.

With this in mind, Krantz says strip grazing is not recommended.

“This practice forces the animals to eat all of the plants. Overgrazing is not recommended for the same reason, as cattle will be forced to consume plant parts with the greater levels of nitrates,” he said.

If grazing is the preferred choice for utilization of these high nitrate crops, Krantz says livestock should never be allowed access if they are especially hungry.

“Hay or other forage should be provided to them prior to turn-out. Producers should only allow the livestock access for a portion of the day to begin with,” he said. “This is recommended until the livestock become acclimated to the higher nitrate levels.”

He adds that if the forages are harvested for silage, cutting heights should be adjusted higher, leaving the lower stalk unharvested.

Although the costs involved with mechanically harvesting high nitrate forages are significant, Krantz says there are livestock safety benefits to this approach.

“The ensiling process reduces nitrate levels making them much safer for consumption,” he said. “However, it is not recommended to green chop these forages and let them heat overnight as this process favors the formation of nitrite which is even more toxic that nitrate.”

Oats, corn and barley consistently have been documented as crops with the most potential to account for nitrate poisoning in livestock; however, Krantz says that annual forages such as sudangrass, sorghum-sudan hybrids and millets can be dangerous as well.

“Weather conditions may intensify the accumulation of nitrates in forages. Plants that survive an extended period of drought will experience increased levels of nitrates immediately following a rain as the parts of the plants begin to resume their growth. The nitrate levels will continue to increase for several days afterward,” he said.

Quick nitrate testing is available at all SDSU Extension Regional Centers

Suspected crops may be brought to SDSU Extension Regional Centers for a preliminary test that only takes a few minutes. Although exact nitrate levels cannot be determined through this procedure, their presence can be determined. If and when nitrates are verified in the plant tissue, samples are then sent to a lab for further testing.

“If nitrates are not found, producers can be confident that the forage is safe for their livestock,” Krantz said.

Water may be an additional source of nitrates for livestock whether consumption is from a dugout, dam or well. Krantz recommends producers obtain a livestock suitability analysis for water sources.

“This is especially important in areas where nitrate poisoning potential from crops is a concern,” Krantz said.

Initial water tests for total dissolved solids can be accomplished at SDSU Extension Regional Centers. Depending on the levels recorded, further sampling at a lab may be required.

Managing a cattle herd for drought conditions

Drought conditions continue to challenge the management skills of livestock producers. Utilizing a well-planned, systematic approach to dealing with drought conditions can provide long-term benefits.

“Drought conditions may require cattlemen to adjust their systems to meet the limitations demanded by the lack of grazing resources or harvested forages,” said Krantz.

He says that culling the herd is one option that can be emotional, although inevitable. However, any herd reduction should be part of a systematic approach to dealing with meeting livestock needs:

• Early weaning: According to the University of Nebraska, for each 2.5 days that a calf is weaned, there is one more day of forage available for grazing. Calf removal is an accepted management procedure when calves reach 45 days of age. Weaning at this age when grass is restricted not only provides more grazing for the dry cow, it encourages her to cycle and rebreed under conditions that may prohibit that when nursing a calf. Weaning at an age of three to five months will not provide the reproductive benefits noted above but it will result in the same effect as reducing your cowherd by one third. In any case, early weaning should be given serious consideration prior to making a decision to begin the culling process.

• Culling considerations: When possible, culling decisions should be made after the cow has had an opportunity to become pregnant. After cows are confirmed pregnant, the process should begin with cows that may have been cull-candidates regardless of the drought conditions: non-pregnant, physically impaired, poor producing and those with marginal dispositions should head this list.

Krantz says the decision to cull producing cows or replacement heifers has no universal answer. From a feed perspective, the replacement heifer will consume less; however, what they do consume needs to be of higher quality.

“Since heifer calves will not provide the operation with income for some time, justification for retaining them needs to be weighed against the merits of maintaining the producing core herd,” Krantz said. F

– SDSU Extension