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Five considerations for spring grazing in a drought

Rebecca Kern-Lunbery for Progressive Forage Published on 31 January 2022
Pastures near farms need to watch water source

Under the drought conditions of the 2021 growing season, I heard many concerns from livestock producers about forage supply shortages, low quality of the forages available and, of course, nitrate accumulation in those forages.

Going into 2022, the outlook is not improving. The three-month U.S. drought forecast shows drought persisting in the western U.S. and developing in Southern states. Going into another year of drought, of course, water shortages are an obvious concern. Furthermore, we can’t just kick our herds out to pasture for spring grazing confident in our usual ponds providing a plentiful supply of fresh, clean water. Since we ended the summer 2021 grazing season in a drought and conditions have not improved, we are likely to have low water levels in our ponds this spring. Therefore, more concentrated water sources.

Typically, we advise livestock producers to monitor pond water as temperatures rise and pond water levels drop. However, this spring, we will be starting the grazing season with low water levels and concentrated water sources. Here are five considerations for pond water quality this spring.

1. Total dissolved solids (TDs)

Low water levels and concentrated water sources to watch for during the grazing season

This is a measure of all the minerals dissolved in the water. As drought conditions persist, minerals become more concentrated, and this measurement is more important to determining if a pond is a suitable source of water for livestock. An early sign of high TDS is diarrhea in young calves and excessive water intake by all animals. TDS contributes to mineral imbalances, which result in decreased production performance including average daily gain (ADG) in calves. This can impact weaning weight. Extreme mineral imbalances can manifest as clinical conditions as well. Always consult with your vet when these situations occur.

2. Total hardness

Similar to TDS, total hardness is a measure of the calcium and magnesium ions in water. These ions also contribute to mineral imbalances. Specifically, calcium-to-phosphorus ratios, which can affect bone formation and growth and therefore negatively impact calf production performance. Small ruminants are more susceptible to the formation of urinary calculi and “water belly” in males due to consumption of hard water. The excess minerals accumulate in the urinary tract and form small stones which block excretion.

3. Sodium

Another mineral dissolved in the water, sodium concentration tends to increase under drought conditions and pond water receding. High sodium levels have a diuretic effect and form a cycle of leaving animals thirsty, so they drink more of the toxic water and become more dehydrated. In cattle, salt intake should be reduced at water concentrations of 800 parts per million (ppm) sodium. Occasionally, adjusting sodium intake through salt can result in a chloride deficiency. So it is important that nutritionists examine all minerals when adjusting rations to accommodate low-quality water.

4. Nitrates

Most producers are already aware that under drought conditions, nitrate accumulation can occur in forages and be costly to animal health. Similarly, nitrates become more concentrated in pond water under drought conditions. Therefore, it is that much more important to have a low-nitrate diet. Producers with pastures near farmland should be extra-cognizant of the potential for nitrates to have leached into their water from sandy soils or heavy fertilization rates.

5. Sulfates

High sulfates in water can have a laxative effect on livestock. High-sulfate waters result in diarrhea and poor ADG. Monitoring stools and body condition scores can help catch some subtle signs that water should be tested before a bigger health condition occurs. High levels of sulfate in the water can also result in the development of polioencechalomalacia (PEM). PEM is a neurological disease in ruminants. Producers often refer to affected animals as “brainers” due to the nature of their symptoms. Signs of PEM include wandering, blindness, head pressing and uncoordinated movements. Producers with moderate sulfates in their water should avoid high-sulfur diets. This may mean reconsidering a mineral supplement, not feeding distillers byproduct-based protein supplements or supplementing cattle grazing brassicas with hay.

In conclusion, water is undisputedly one of the most important nutrients required for livestock health and production performance. We usually turn our herds out to pasture in the spring and don’t give too much thought to water quality until the hot summer months. This year, we should be monitoring pond water quality and adjusting diets or finding alternative water sources starting in the spring and throughout the grazing season to ensure animal health and success through this drought.  end mark

PHOTO 1: Producers with pastures near farmland should be extra-cognizant of the potential for nitrates to have leached into their water. 

PHOTO 2: The grazing season will start with low water levels and concentrated water sources. Photos by Hannah Dorn.

Rebecca Kern-Lunbery

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