Some details so that the cows are not gasping…
The summer comes and the impact of the combination of high temperatures and high relative humidity levels have an impact on the drums with a significant reduction in the consumption of dry matter and the resulting decline in the production of milk and a decline in pregnancy rates.
There are several alternatives to cushion this impact as it is to provide shadows properly sized, the same for the offer near water the cows while grazing his plot, also modify times of milking avoiding the movement of cows in peak of heat. The combination of the shadows near the room of milk which has a system of sprinklers of water that wets the cows accompanied by the evaporation forced fans probably the most effective method (see photo), with a duration of 2 hours of the effect of the cooled (the cow returns to want to eat!).
An issue that we must consider in dealing with the problem, is that of the temperature of the drinking water.
The resources that account for the cow to dissipate heat limited to: (1) Increase in circulation of blood perisférica; (2) Breathability (which is inefficient because the cost of energy to vaporize 1 gram of water is 540 cal); (3) Increased respiratory rate, making the increase in the loss of steam. The respiratory rate goes from 35 to 155 breaths/minute for cows Jersey, and from 50 to 125 to Holstein.
Increases in ambient temperature of 25°C to 40 °C for 6 hours a day, increase to a 30% maintenance requirements. By increasing the frequency of wheezing, it increases the energy consumption between 7% and 25% on requirements NRC. To compensate for the respiratory alkalosis (due to the increase in wheezing occurs a greater evaporation without the subsequent elimination of CO2), the cow increases the segregation of bicarbonate in the urine. In the midst of the increase of the requirements and the elimination of extra minerals, we have to deal with a decline in the voluntary consumption that can reach 50% of what they would eat in a thermoneutral environment (in the range between 4°C to 24°C).
The water has a physiological function given by the volume of intake and physical function given by the temperature of the same. When you combine extreme situations (for example more than 30 °C and relative humidity above 50%), many times the shade is not enough and is growing in importance as the last resort of the cow : the intake of cold water. Ten liters of water at 18 °C reduce the temperature in the rumen of 40 °C to 30 °C for 2 hours. Considering this, it is interesting to take note of the temperature that you can present to the water in various locations within the field:
A strategic place to provide cold water, minimally the overflow of the refreshed at 20-22°C, it would be close to the exit of the drum as it is when the cow has the greatest desire to consume water. The dimensioning must be greater than the required for a mangada of cows to prevent overcrowding. The ideal is to combine a shade available for you after you drink the treasury can eat and rest until the hours of greatest heat to pass.
All of this should go well accompanied with a strategy for the control of insects because they are attracted to the cool shade!
Here we leave you a link with a work from INTA with details for the construction of shadows: Shadows for cows of dairy farm INTA 2011 ficha_17
M. Snyder
