INIA Termoestrés

ITH forecast of up to 7 days and heat waves, for cattle

This application consists of providing the user with information based on the recognized Temperature and Humidity Index (ITH), for two production systems - meat and milk, under extensive or intensive production conditions.

This Index, which allows characterizing the environment and relating it to the biological response of livestock, is the most widely used worldwide.

Having the ITH, seven days in advance, will allow producers and technicians to take the necessary measures to minimize the effects of heat stress and avoid losses in animal welfare and production.

Uruguay is not in an area where heat stress for cattle is sustained and dangerous, but INIA research results have shown significant losses, due to physiological and metabolic changes in animals, due to the lack of mitigation mechanisms. . For example, high-producing dairy cows, with access to shade, during the summer, produced on average 5 liters more of solids-corrected milk than cows that did not have access; in beef cattle, animals in the finishing phase to corral with access to shade vs. permanence in the sun had an improvement in the average daily gain of 15% and in the conversion efficiency of 7%, while in grazing there was an increase of 14% in the average daily gain of weight.

Biometeorological Index

ITH dairy cattle (Thom, 1959)

Formula Valtorta and Gallardo, 1996

ITH = (1.8 x Ta + 32) - (0.55 - 0.55 x HR / 100) x (1.8 x Ta - 26)

ITH beef cattle (Mader et al., 2006)

ITHadjusted = 6.8 + ITH - (3.075 × VV) + (0.0114 × RAD)

Being:

Ta = mean daily air temperature (ºC)

RH = daily average relative humidity of the air (%)

VV = mean daily wind speed at 2 meters. height (m / s)

RAD = daily solar radiation (W / m²)

Forecast weather information

For this calculation, the GFS (Global Forecast System) Model of the NOAA Agency (National Oceanic and Atmospheric Administration) of the USA is used, with meteorological information in grid points over Uruguay. These numerical exits are available in a resolution of 27 x 27 km. In them, the meteorological variables (surface temperature, relative humidity, wind speed and solar radiation) necessary to build the mentioned index are selected. Subsequently, the average or accumulated daily values ​​are obtained for the next seven days.

Finally, the ITH is estimated from this information, with the required transformations or conversions, and outputs are generated in the form of maps at the national level, with a visual representation of the index in a color scale with four ranges. This procedure is performed daily, generating maps for the estimation day and the next six days (seven-day forecast).

Additionally, outputs are presented in the form of bar graphs by showing the hours in the day (on a three-hour basis) that the ITH is at each risk level for the 7-day forecast. These graphs are made for the grid corresponding to the selected point, thus obtaining a graph where each bar is a forecast day.

The thresholds established for each system are:

MILK

- up to 67.9 would be indicating conditions without risk (green)

- 68 to 71.9, alert (yellow)

- 72 to 78.9, danger (orange)

- 79 and higher, emergency (red)

MEAT:

- up to 68.9 would be indicating risk-free conditions (green)

- 69 to 74.9, alert (yellow)

- 75 to 78.9, danger (orange)

- 79 and higher, emergency (red)

For more details on the methodologies used and bibliographic references: http://www.inia.uy/gras/Alertas-y-herramdamientos/Prevision-ITH-Vacunos

In short, the user will be able to access a forecast, of up to seven days, of the daily index and the presence of heat waves, which will allow preventive measures to be taken against thermal stress, minimizing well-being and productive problems.

it is