News / Blog

Breaking Through Heat Stress Bottlenecks
March 14, 2016

Cooling cows may not be top-of-mind at the moment, but the need for heat abatement programs to kick into gear is just around the corner. Soon sprinklers, fans and other cooling technologies will be working overtime to reduce the negative effects of warmer temperatures.

While decreased milk production is a readily seen heat stress casualty, reproductive performance is an even greater victim of rising temperatures and humidity.

Estrus expression, follicle quality, pregnancy and conception rates, as well as embryo quality all drop dramatically in summer months while embryo losses increase. For example:

  • Dairy cows are 3.7 times more likely to lose their embryo during hot versus cool seasons.1
  • Another study found undetected estrus events estimated at 76% to 82% on a Florida dairy for the months of June through September.
    • That percentage dipped down to 44% to 65% for the months of October through May.2


In addition, data3 from Israel showed a 7% milk production decrease in the summer and a 51% drop in conception rate in herds producing milk at an average level. Estrus detection efficiency may also be reduced as a result of heat stress.

These disturbing data more than make the case for cooling cows. Yet even dairies that have invested in heat abatement technologies often find there are areas that benefit from increased cooling analysis.

Hunt for Hot Spots

The first step in any evaluation is to scrutinize current equipment to make sure it’s working properly. Once that’s done, it’s time to determine whether enough cooling is in place.

To do so, assess where any ‘hot’ spots may exist for the cows. This can be as simple as placing thermometers in key areas around the dairy and tracking peak temperatures, as well as how long cows spend in these areas. Record how warm these places get and when the spikes occur.

Dairies that have invested in animal monitoring systems can also use rumination time and ambient temperature to determine animals’ reaction to their environment. Users can evaluate where cows are on the dairy at a given time and then analyze a location’s impact on rumination. This information can then be used to gauge the effectiveness of cooling strategies.

Several smart phone apps4 are also available to help producers to make timely decisions on managing the livestock environment and reducing animal stress. These tools enable users to monitor environmental temperatures and humidity to modify heat abatement measures as needed.

Targeted Solutions

Once you’ve found where problem areas exist, work with your dairy’s advisors to determine the best way to remedy the situation.

It may be as straightforward as adding more waterers to parlor exit lanes, adding shade to walking lanes and dry lot pens, or improving fan placement and volume in holding areas. In other cases, it may call for a more intense revamp of your entire heat abatement program, so be sure to work with your team to be sure that you do so in the most efficient way possible.

Also, be sure to include dry cow cooling needs in your cooling analysis. Results5 published in the October 2015 issue of the Journal of Dairy Science show that compared to cooled cows, heat-stressed dry cows exhibited:

  • Higher rectal temperatures
  • Greater respiration rates
  • Decreased dry matter intake

In addition, research6 shows that calves born to heat-stressed dams weighed 13 pounds less at birth and 28 pounds less at weaning than calves born to dams with access to cooling. Calves born to heat-stressed dams also had reduced passive transfer of immunity and compromised cell-mediated immunity compared to calves born to cooled cows.

The link between successful passive transfer and improved calf performance is well-established, so the potential influence of impaired immune status on calf performance in hot weather (regardless of feeding level) should not be forgotten.6

Cooling Considerations

When fine-tuning heat abatement strategies on your dairy, keep these six factors7 from experts at Kansas State University in mind:

  • Consider the temperature of the location.
  • Consider the relative humidity of location.
  • Consider the cooling mechanisms of the cow that you will target.
  • Increase soaking frequency at THE feed lane as temperature increases.
  • Provide minimal supplemental airspeed over feed lanes and freestalls.
  • If utilizing evaporative cooling systems, consider adding feedline soakers to increase cow cooling during peak feeding periods.

Source – Dairy Business


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