Water and shade can prevent heat stress in organic cows on grass

Grazing at night can be an advantage on very hot summer days, as it can help the cows to have a higher grass intake. At the same time, it is crucial that the cows have easy access to drinking water and shade.

By Linda Rosager Duve

The cows must have access to shade in the middle of the day

Hot summer days with high temperature make the cows lazy and the grass in-take decreases. During these periods, it may be a good idea to switch to night grazing and keep the cows in the shade during the day.

Organic cows should be on grass as much as possible. From January 1, 2022, the requirement for at least 6 light hours on grass was abolished. The cows should preferably have permanent access to grass by keeping the gates open and in all cases, there must be a grazing strategy that ensures as much time as possible on grass and a large grass intake when grazing.

Free access to the grass field, as for example at AMS, requires that the daily practice of grazing is organized so that every cow is out as much as possible.

Water demand increases on hot days

When the ambient temperature rises from 20 ⁰C to 30 ⁰C, the cow's requirement for drinking water increases by 30 litres. The cow uses the extra liters of water to dispose of heat through exhalation and evaporation.

Figure: The daily water balance of a cow with a yield of 40 kg of milk at 20 ⁰C and 30 ⁰C, respectively.

High water intake is best ensured when the distance to water is no more than 200 m, when the cows are outside. At the same time, there should be direct access to drinking water after milking.