Livestock's water requirements in intensive and extensive production systems

The Earth's total water supply is estimated at around 1 386 million km³. However, only 2,5% of this comprises freshwater. Of that small fraction, approximately 68,7% is locked away in ice and snow formations in Antarctica, the Arctic, and mountainous regions.

- By Christal-Lize Muller

Another 29,9% exists as groundwater, while only 0,26% is found as surface water in lakes, rivers, and dams. The remaining portion is distributed across soil moisture, swamps, and permanent ice (permafrost). Despite its fundamental role in sustaining life, freshwater remains a scarce resource. Dr Ockert Einkamerer, senior lecturer in the Department of Animal Science at the University of the Free State, says among the five essential nutrients - energy, protein, minerals, vitamins, and water - water is arguably the most critical for livestock.

Water in mother's milk

On average, an animal's milk contains 85 to 87% water, while the body itself consists of at least 65% water. No physiological function can occur without water, as it is the medium through which nutrients are transported via the blood. This is because water is chemically neutral, allowing for the easy ionisation of various substances.

Water also provides the environment for most chemical reactions in the body. It plays a vital role in maintaining osmotic balance and supports healthy rumen function, which is central to ruminant digestion. Microorganisms in the rumen need to move freely between nutrients, and sufficient water availability makes this possible, says Dr Einkamerer.

Water is essential for the excretion of waste products such as urine, manure, sweat, and even milk. It also plays a critical role in thermoregulation, helping animals control their body temperature. Cooling occurs through evaporation via the lungs, mouth, and sweat glands on the skin. Because water has a high latent heat of vaporisation, it is highly effective in cooling animals under hot, humid conditions. Access to clean, cool water in such environments is therefore vital in both extensive and intensive production systems.