It’s not difficult to justify heat abatement for your lactating cows. The math is usually pretty easy when you look at potential returns on investment. Additional income from a 10 percent or higher increase in milk production adds up quickly.
But it isn’t quite so clear-cut in the case of pre-fresh cows. Previous research centered on shade versus no shade for these cows, and there didn’t seem to be much difference in performance, says Todd Bilby, University of
However, recent research shows that providing evaporative cooling for cows before calving pays off in improved reproductive performance during their next lactation, as well as increased milk production.
Here’s why you should consider evaporative cooling for these cows.
If you think that dry cows handle heat stress better than lactating cows, think again. Cooling during the dry period, especially the late dry period, is particularly critical. That’s when a number of important physiological processes occur, including mammary gland regeneration, rapid fetal growth and colostrum production. It is also when follicles for the next reproductive cycle develop and mature.
“When dry cows are heat-stressed, it damages all follicles and the eggs inside,” explains Bilby. But, more importantly, it damages the small follicles and eggs inside which will not ovulate for 40 to 50 days later, coinciding with the start of the breeding period during lactation. Because of the damage, fertilization chances are reduced, making it unlikely the eggs will develop into viable embryos.
Heat stress during this time can also affect endocrine responses that may increase abortions and shorten gestation length. In addition, it may also decrease thyroid hormones and placental estrogen levels, while increasing blood non-esterified fatty acid concentrations.
According to researchers at
Furthermore, heat stress depresses dry matter intake, which impacts post-partum milk production and a host of metabolic disorders as cows move through the transition phase.
More than shade
Cooling offers you the greatest opportunity to reduce these negative effects.
And shade does help because it reduces the solar load on the animals. Back in 1984,
Therefore, it’s going to take more than shade to accomplish your goals. “The key is evaporative cooling,” says Bilby.
Research published in the December 2006 journal Livestock Science shows that feed-line sprinklers, fans and shades reduced services per conception and days open, while increasing milk production during the ensuing lactation.
The study found that days open for
More milk in the tank
Need more evidence that this is a worthwhile endeavor? Research published in the June 2006 Journal of Dairy Science shows that adding shades and fans to a feedbunk-mounted sprinkler system have financial rewards. The results were compared to a pen of cows that only had sprinklers. The cows in each pen were at least two weeks from calving.
The cows in pens with maximum cooling had a 60-day milk production total nearly 186 pounds above that of cows that were under sprinklers only. According to the study’s partial budget, that nets you a projected economic return of $8.92 per cow. For every 100 cows, that’s an additional $892 per year in your pocket.
The study did not show a dramatic increase in cow health, but researcher Dale Moore, Washington State University director of veterinary extension, notes that the 3,000-cow
“In addition to a significant milk response, there is a health response in that all of those ancillary metabolic diseases are probably reduced,”
When you look at everything — the extra milk production and health benefits compared to the cost of fans, shade structures and water — it certainly makes a good deal of sense to use evaporative cooling for your dry cows, she says.
Bilby agrees. “We can show a financial return on investment, as well as improved animal and reproductive performance. Why not do it?”
Set cooling priorities
When investing in cow cooling, be sure to set priorities and follow them.
Your very first priority should be to ensure that all cows, including pre-fresh and lactating cows, have adequate water, says Dale Moore, Washington State University director of veterinary extension. “That means all cows can drink as much as they want, whenever they want.”
Second, provide shade for all cows, lactating and dry.
Next, add fans and sprinklers to all groups for evaporative cooling. “It is especially important to cool close-up, fresh and early-lactation cows,” she says. Then, you can move down the list to mid- and later-lactation cows and the early dry-off period.
“At a minimum, cows should have water to drink and shade. Then, get water on their backs.”