Soil and Plant Testing Laboratory
573-882-0623
Interpretation guide for livestock water analysis
Unsuitable water for livestock can reduce performance, cause illness or
in severe cases cause death. When chronic poor animal performance continues
despite changes in management, nutrition, environment and the health program,
water quality problems may become suspect. Some natural water sources in Missouri
are unsuitable for livestock, while contamination can spoil other sources.
The following list describes different water analyses and their relevance to livestock use.
- pH
A general water quality indicator, pH indicates whether water is acid or alkaline. The type of substances dissolved in water affects its pH. Acid water with a pH less than 6.0 will be corrosive to plumbing of water delivery systems. Low pH also tends to make metals and hardness minerals more soluble, which can dissolve metals from pipes and result in an unusual taste Water with a pH greater than 8.5 will have a bitter soda like taste.
- Total dissolved solids
Total dissolved solids is a measure of salinity. Water salinity may
be derived from any inorganic substance dissolved in water, but the ions of magnesium,
calcium, sodium and chloride are the primary contributors to salinity. Animal
tolerance to salinity varies with age, species, water requirement, season of
the year, and physiological condition. As the salinity of water increases, animals
will increase their intake of water until the salinity increases to the point
that animals will refuse to drink it. Use the table below for guidance. The slight
salinity in good water may cause mild diarrhea to animals accustomed to better
quality water. Animals may temporarily refuse water of fair quality or have diarrhea.
Poor water is unsatisfactory for lactating or pregnant animals. Water that approaches
the unacceptable level should be especially avoided during hot weather, although
older animals may tolerate it during times of low stress.
- Electrical conductivity
Electrical conductivity is another measure of salinity.
- Sodium
Sodium exists in water as a positively charged ion. When associated with sulfate in water, it can cause diarrhea. Salt may need to be reduced in diets when sodium levels in water are high.
- Chloride
Chloride exists in water as a negatively charged ion. It contributes to a salty or brackish taste to water.
- Nitrate
Nitrate in water interferes with blood's capacity to absorb oxygen.
Nitrate poisoning of animals can occur from excess consumption of nitrate
from both water and feedstuffs. Water nitrate concentrations between 100
and 280 ppm should be avoided when high nitrate feedstuffs could contribute
significant amounts of nitrate to animals' diet. Swine are very resistant
to nitrate. Levels greater than 750 ppm are necessary before daily gain will
decrease.
- Sulfate
High sulfate in water is usually a natural problem, i.e. not caused by man's activities. The primary problem with excessive sulfate in water is its laxative effect. Animals given a new water source of marginal sulfate levels may experience a temporary laxative effect until becoming acclimated to the water. The larger the animal the greater the laxative effect. Therefore, young animals are most susceptible to the laxative effect. High sulfate may also impart a bitter taste to water.
- Iron
Iron supplied by water constitutes only a small portion of iron available to animals. But because iron is inefficiently absorbed, it poses no health hazard to animals. High levels can cause a bad odor or taste.
- Manganese
High manganese concentrations can impart a bitter taste to water.
- Copper
In combination with phosphorus, copper plays a role in bone development. Ruminants are susceptible to copper toxicity. Problems with copper can also occur when dietary molybdenum is either low or high. Copper concentrations exceeding 1 ppm impart a bitter, metallic taste to water. Copper levels as low as 0.1 ppm may affect the flavor of cow's milk.
- Calcium and magnesium
These minerals are responsible for water hardness. High levels of
magnesium in combination with sulfate can cause a laxative effect.
Updated
5/21/08
