What are they drinking?

by Sally Colby

Anyone who raises livestock knows the importance of water. Water intake and water quality affect feed intake, the absorption of nutrients and productivity aspects such as overall health, the ability to gain weight, milk production and fertility.

Leah Clark, livestock specialist at the Saskatchewan Ministry of Agriculture, said water aids in elimination of waste products of digestion, regulates blood osmotic pressure, transports nutrients, hormones and other chemical messengers throughout the body and aids in temperature regulation. Depending on age and production stage, cattle require nine to 21 gallons of good quality water every day.

Beef cattle are less likely to drink poor quality water, which can result in depressed production that may not be immediately obvious. Aspects of water quality such as hardness, alkalinity, conductivity, pH and total dissolved solids (TDS) can all affect production. Testing can reveal the presence and levels of nitrates, sulfates, iron, sodium, manganese, uranium, arsenic and other components. However, no matter what’s in the water, availability has the most impact on production.

Herd managers can use handheld meters to test water for TDS, but should understand that such meters test electrical conductivity (EC), the ability of water to carry an electric charge. A conversion factor of 64% determines TDS. However, Clark said conductivity is not the same as TDS, and urged cattlemen to have handheld meters calibrated and submit water samples to a lab for more accurate results.

Sulfur is one component in water that can have serious negative effects on cattle. Excess intake of sulfur may cause direct toxicity, but in many cases, detrimental effects are associated with metabolic interference. Sulfur interacts with trace minerals in the animals’ systems, which can lead to trace mineral deficiencies, either by outcompeting other trace minerals for absorption or by binding minerals for absorption. One example of binding is the combination of copper, sulfur and molybdenum to form thiomolybdate, which is unavailable to ruminants.

Excess sulfur can impair thiamine (vitamin B1) synthesis and can lead to polioencephalomalacia (also known as polio or PEM). Animals with thiamine deficiency exhibit signs such as lack of appetite, recumbency, blindness, stumbling and other gait abnormalities.

However, sulfate is a required nutrient. The recommended rate for sulfate in cattle ration is 0.15% of the ration, with a maximum level of 0.3% – 0.5% of the ration. Clark noted that these figures are based on dated research conducted on dairy cattle, which are slightly more sensitive than beef cattle.

A guide for sulfates based on the maximum tolerance establishes a level of less than 500 ppm as satisfactory. At 500 – 1,000 ppm, there’s potential for subclinical trace mineral deficiencies, especially in high-performing cattle with higher metabolisms. At that rate, trace mineral supplementation and monitoring is important. At 1,000 – 2,000 ppm, trace mineral supplement is required, and the animals’ health status may be compromised.

Sulfate levels greater than 2,000 ppm are risky, with severe clinical deficiencies likely. Animals should be monitored and receive a chelated trace mineral supplement. “These animals may not respond to supplementation,” said Clark. “Performance and health status effects are pronounced, and there’s risk of death by polio, especially in high performing cattle under stress.”

Nitrates can also be an issue, and Clark said this problem is usually an indicator of wellhead contamination. The cautionary limit for nitrates in livestock is 100 ppm. “We say ‘cautionary’ because in reality we should be looking at total diet nitrate,” she said. “This is extremely important in winter because we tend to feed higher nitrate feeds in winter. Green feed is the biggest culprit.” Clark added that annual crops, when frozen, accumulate nitrate.

Another component of water that can cause trouble is sodium. The upper limit is 800 ppm; above that, animals will consume less feed, water and minerals. “When sulfates are up, sodium is up,” said Clark. “A lot of mineral products have salt in them to encourage intake. So when sulfates are an issue in the water and may be causing trace mineral deficiencies, they can be compounded with salt in minerals and animals don’t go after those minerals. Sodium can also cause diarrhea, so limit high salt forages.”

Iron can be a problem, but it’s usually a nuisance issue that affects palatability and reduces water intake. Animals that don’t drink sufficient water will have reduced feed intake and lower gains. Iron can interact with other elements and impact metabolism.

Several factors influence water quality during the growing season. Water demand increases, which can result in higher intake of concentrated minerals. Water quantity decreases due to consumption, evaporation and lack of rainfall that recharges water sources. In hot, dry weather, water evaporates and undesirable components become concentrated. Bacterial growth increases in summer, leading to higher potential for contamination.

Algae can be a good indicator of water quality. Algae grow rapidly in warm, stagnant water that is high in nutrients, which is often due to fecal contamination. “Smelly bacteria” can persist in winter when anaerobic bacteria and nutrients are present.

The oft-discussed blue-green algae is actually cyanobacteria and not algae. Clark described this bacteria as planktonic, or free-floating in water. The water surface may appear green, dark brown or red. It’s important to identify cyanobacteria accurately because beneficial algae such as duckweed can look similar. When cyanobacteria are present, duckweed can be beneficial because it floats on the water surface and blocks the light required by cyanobacteria.

Cyanobacteria don’t present a problem when alive and growing. However, when they become stressed and die, toxins are released. Clark said weather conditions such as wind can stress cyanobacteria, leading to kill-off, toxin release and potential livestock poisoning. When animals are kept out of streams, adequate pasture cover is maintained and setbacks for pastures near water are in place, runoff is less likely to enter bodies of water and lead to favorable conditions for cyanobacteria.

Depending on type, cyanobacteria can produce neurotoxins or hepatotoxins. Neurotoxins are fast-acting and cause skeletal and respiratory paralysis; hepatotoxins affect the liver and result in prolonged illness and death. Animals can also experience scours, neurological signs, muscle tremors and stiffness.

Treatment efforts to decrease bacteria and algae in water sources depend on the problem, and often require a water quality expert for accurate diagnosis and subsequent treatment. Many producers rely on aeration and dye to inhibit algal growth. After treating water for cyanobacteria, livestock should be kept off for 10 to 14 days to avoid ingesting released toxins.

Testing water and making adjustments in minerals and feed rations can have a significant impact on the overall health and well-being of a beef herd. It’s up to the producer to test water and provide the best quality water for optimum performance.

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