Water Quality for Sheep

Stock Journal Feature, November 2022

Too often when we talk about improving performance, a major component gets overlooked – water. In particular, the quality of water can influence wool production, growth rates and consumption of feed and water. Put simply, you wouldn’t fill a race car with dirty oil and still expect it to run well!

The tolerance of sheep to various quality parameters can vary depending on factors such as age, stage of reproductive cycle, level of performance, weather and feed sources. For example, the increase in water requirements of sheep over summer means they are much less tolerant to factors such as salinity and temperature than they would be in cooler weather on green feed.

Salinity is often the main limiting factor for performance. Sheep are more tolerant to saline water sources than cattle, pigs and poultry but are not without limits. Dry, mature sheep can handle levels up to 10,000 µS/cm. Lambs and lactating ewes however, due to their higher energy and water requirements require salinity levels below 6000 µS/cm to maintain performance. Feedlot lambs would be better with lower levels again.

The type of feed that sheep are grazing also plays a part. For example, sheep grazing saltbush tolerate lower levels of water salinity than their counterparts grazing green grass/legume pastures as they are also getting high levels of salt from their diet.

Water pH can also play a part. Ideal ranges for sheep are between pH 6.5 and 8.5. Water that is too alkaline can cause diarrhoea and lower feed conversions, while acidic water can cause acidosis and reduce feed intake.

Physical properties can affect water intake too. Much of this comes back to the palatability of the water, with factors such as temperature and odour affecting intake. In hot weather, sheep will drink 40% more than they would in winter, using water intake to help regulate body temperature. Burying pipes can make a big difference to water temperature and will change how much a sheep drinks, and therefore grazes, on a hot day.

Water cleanliness can often be another hurdle. Water should be free of contaminants such as debris, excess minerals from fertilisers and heavy metals. Fertiliser run-off can also promote the growth of algae, which can block pipes, deter stock and in the case of blue-green algae, cause poisoning in stock. Regular cleaning of water troughs is a must, especially in feedlots and grazing stubbles where higher intakes are needed.

Sheep may not always avoid the water source altogether, but may reduce their intake, often leading to a decrease in feed intake and consequently overall performance.

Sometimes it is simply a change in water quality that can affect intake, such as moving from dam to mains water, even if both meet the desired quality specifications.

Much like when we are assessing the quality of feed, testing is available for a range of water quality parameters. It is always worth a call to the lab first before submitting your sample, as many tests have different sampling and storage requirements.

Matching stock to the water quality of different areas of a farm is another great way to manage variances. Run dry mature ewes or adult wethers where water quality is poorer and save the paddocks with higher quality water for weaners and lactating ewes. Areas with poorer water may be better utilised in winter when reliance on water sources is lower. In some instances, it may be possible to shandy different water sources to dilute salinity.

Knowing the quality of water sources on your farm is a critical part of maximising production. Whether it is salinity, pH, temperature or something else, make sure your sheep are getting what they need to perform.