By Grace Thomas, M.Agr.Sc., P.A.S.
Calves are born with 75-80% of their body consisting of water; as they mature water content drops to 50-60%. Animals with higher body fat have lower body water content. Water is not only essential to sustain life; it plays numerous vital roles in the body. Many of which influence not only health but the animal’s performance. Cattle get water from three different sources, ingested water, water from food and metabolic water. The roles water plays in the body are listed below:
• Maintains proper body fluid and ion balance.
• Transports nutrients to and from body tissues/cells.
• Digestion and metabolism of nutrients.
• Elimination of excess heat and waste materials.
• Provides a fluid environment for the fetus.
Dehydrated cattle have been shown to have an impaired immune response. Even moderate levels of dehydration in cattle, despite showing no clinical symptoms (sunken eyes in sockets and skin tenting) have reduced performance. As the rumen acts as a fluid reservoir and in the short term maintains body fluid balance, it can be difficult to recognise moderate dehydration in cattle.
Water is lost from the body through milk production, excretion of urine and faeces, sweat and vapour loss from the lungs. Any factor that influences these losses will influence the water requirements of the animal. Table 1 outlines the factors that influence the daily requirements for both beef and dairy animals.
Intake and Quality
Achieving required intakes relies on animals having free access to good quality water. The water delivery system should permit at least 10% of the herd to drink at any one time, allow for 10cm (4 inches) of space per cow in the herd. Cows are social animals and like to drink together; as one cow can drink 4 – 5 US gallons (15-20 litres) per minute, the water flow on farm needs to be able to cope with the pressure put on it at peak drinking times after milking.
Water quality can impact on both performance and intake, troughs should be clean and free from any contamination. Cows have a very sensitive sense of smell and will chose not to drink dirty water. Not all quality issues can be seen, water must be analysed to get an accurate picture of quality. Most water analysis reports are comprehensive and show a wide range of parameters. Some of the key elements that play a large role on performance and intake are listed below:
• Total dissolved solids (TDS)
Total dissolved solids is a measurement of minerals that are soluble in water. The level of salt or salinity in the water is closely associate with TDS. The higher the TDS, the greater the impact it will have on performance and intake, this can be seen in Table 2.
Nitrates are used in the rumen to help synthesize bacterial protein; however, nitrates can get reduced to nitrite, which at high levels can reduce the oxygen carrying capacity of the blood. Even low amounts of nitrates have been shown to cause poor fertility, lower growth rate and general unhealthiness. There is an additive effect of nitrates in feed and water, therefore it is advantageous to analyse nitrates in feed as well as water to help indicate any potential nitrate problems. The guidelines for nitrates and nitrate nitrogen and the response by the animal are outlined in Table 3.
Both Sulphur and Manganese tie up other minerals. The presence of these elements, even at low levels (Manganese 0.05ppm), decreases the palatability of water leading to lower intakes. Sulphur levels of below 250ppm is ideal, any higher can lead to lower milk production, reduced feed intake and diarrhoea. Water containing sulphur in the form on Hydrogen Sulphide, will have the odour or rotten eggs; levels of Hydrogen Sulphide above 0.1ppm decreases intakes.
Water containing iron tends to have a metallic taste which is unpalatable. Iron bacteria also can cause slime build up in the troughs leading to lower intakes of not only water but feed. The iron in water is more toxic to animals than iron contained in feed; this is due to iron in water being more freely available to the animal. Iron ties up phosphorus and trace minerals, animals fed high iron water have higher copper requirements as high iron reduced copper absorption. Levels above 1ppm can lead to oxidative stress, reproductive problems and reduced immunity.
A pH level of 6.5-7.5 is standard. Any level outside this range can affect the pH of the rumen leading to digestive upset causing metabolic acidosis for low pH water, or metabolic alkalosis for high pH water.
Ideally, water should have no bacteria present. If bacteria are present at high levels it is a good idea to determine the type of bacteria. This can help determine the source of contamination and if it is disease causing. Bacteria in water can compete with rumen bacteria, which can lead to low butter fats.
Agri-King provides as part of its feed programme regular water analysis. This service can help identify any issues with water and water quality on farm. Agri-King’s Micro XX® includes technology that helps counteract the effects of feeding water containing nitrates or that has a high pH. It helps improve the nutrient digestion and availability in the rumen. Levels of other minerals, not listed above, may be elevated in your water. Please contact your local Agri-King representative for advice if you have any concerns. AK
Reference: Beede, D. K. 1992. Water for Dairy Cattle. In: Large Dairy Herd Management. Ed. H. H. Van Horn and C. J. Wilcox. Amer. Dairy Sci. Assoc. Champaign, IL.