Importance of ensuring cows have sufficient access to water

Ensuring that cows have access to water at all times is vital particularly in warmer weather.

During wetter weather, water intakes are reduced as the dry matter (DM) content of the grass is lower. During dry weather conditions as we have been experiencing, the dry matter content of the grass starts to decrease from the more typical 16-18% to over 20%. The dry matter content of grass over that last few weeks has been ranging between 20-23 %. In addition to increased DM of grass, concentrate feeding has increased on a lot of farms to reduce grass demand where grass growth has slowed which will further increase the DM intake. This can result in a rise in water intake. When combined with higher than average temperatures we can see water intakes increase to as much as 70 litres per day.

Dry matter intake is directly related to water intake, and the less an animal drinks, intake will reduce accordingly. This leads to reduced milk production and animal performance. So ensuring that cows have access to adequate, clean water is important.

Milk is approximately 87% water thus cows drink 4-4.5L of water/kg of milk produced. For the average lactating cow needs 100-120 L of water per day.  Furthermore, cows drink 30- 50% of their water requirement within 3 hours of milking.

Such a jump in intake and demand within those 3 hours post-milking will put pressure on water systems where trough reserve or size or flow rates are sub-optimal.

Teagasc recommendations:

• A flow rate of 0.15 litres per minute per cow in the herd – so for a 100 cow herd, a flow rate of 15 litres per minute; if a trough is empty after cows use it, it is likely that the flow of water is lower than the demand.
• A trough reserve of approximately 7 litres per cow –for a herd of 100 cows, that’s a 700 litre trough size. This is needed to provide a reserve of water when cows first come to the trough to drink.
• Adequate trough space for 10% of the herd to drink at one time – so for 10 cows that’s enough space for 10 cows (6 linear metres) to drink at the same time.

Before cows enter into a new paddock the trough should be checked to ensure that it is working and cows aren’t potentially left without water.

Published 13 June 2023