It's 2 a.m., you're sound asleep, but some of your cows are wide awake and exhibiting estrus activity. This brings to mind the phrase, "If you snooze, you lose." But, you don't have to hire someone to catch heats that occur at night. Instead, you can improve heat detection during the night, or anytime you're not around, thanks to heat detection aids.

Heat detection aids "watch" the cows exhibit estrus activity and report back to you through a variety of means. Sure, heat detection aids aren't fool-proof – they can fall off, give false readings, be misinterpreted, or get lost, not to mention the extra expense involved. But, if you think you do a good enough job of heat detection by visual observation alone, you might be surprised to find that heat detection aids can work for you when you're not around – boosting your detection efficiency and saving you money by reducing days open.

Here's why you should consider using heat detection aids as a supplement to visual observation.

Improved heat detection efficiency
Observing cows yourself can allow you to identify heats more accurately than a device that can fall off or be difficult to interpret. But, with the average heat detection efficiency falling at or below 50 percent, there's still plenty of room for improvement. That's where heat detection aids come into play. Studies show that combining visual observation with detection aids boosts heat detection efficiency with a high degree of accuracy.

For example, a study published in 1981 in the Journal of Dairy Science found that combining a detection aid with visual observation improved detection efficiency by 15 percent.

In the study, researchers found that visual observation resulted in 68 percent detection efficiency and 95 percent accuracy, while observation combined with the use of pedometers increased efficiency to 83 percent with 80 percent accuracy.

Although heat detection aids cannot replace your accuracy, a combination of observation and detection aids can improve your detection efficiency.

Continuous heat detection
"The human eye is the best way to be a herdsman," says Dick Viney, North Bloomfield, Ohio, producer. While it's true that top-notch managers such a Viney can identify a cow in heat more accurately than a heat detection aid, it's time to face the facts. As much as you'd like, you can't be with the cows 24 hours each day. In fact, if you watch for heats 20 to 30 minutes two or three times per day, you leave the cows unobserved for a large portion of the day. And, the larger your herd, the less time you spend observing each cow individually.

But, with the use of detection aids, it's possible to "catch a lot of cows that we would have probably missed," says Robyn Hostetler with L & R Farms in Marshallville, Ohio. And, using heat detection aids, such as rump-mounted devices, allows the 265-cow operation to catch heats that occur late at night. "We've done better with them than without," she adds.

Likewise, Pierpont, Ohio, producer Gaylord Millard admits, "We don't spend as much time observing the cows as we should." And that, Millard says, is why he invested in rump-mounted devices for his 230-cow herd.

Economics of reducing days open
Although the cost of heat detection aids varies, they can improve your heat detection efficiency. In addition, they can help you get cows bred back faster, reduce days open, and ultimately save you money.

According to Ray Nebel, extension dairy scientist at Virginia Tech, a producer loses about $2 each day that a cow remains open. But, remember that the combination of visual observation and heat detection aids can increase your heat detection efficiency. And, increasing heat detection efficiency reduces days open.

For example, a study published in 1981 in the Journal of Dairy Science found that increasing heat detection efficiency from 55 percent to 75 percent decreased the number of days open from 119 to 105 days. If you eliminate those extra two weeks, you save $28 per cow. Or, if you have 10 open cows in a 100-cow herd, you save $280. And that $280 can be put toward 28 straws of $10 semen.

Therefore, boost your detection efficiency by combining observation with detection aids. It can help you cut days open and save money which you can apply to other areas of your reproductive management program.

Choose your heat detection aid

Heat detection aid Management considerations Cost/device
TAIL CHALKING Effective for dairies which use headlocks. Chalk all animals for best results Cost device: 1 chalk will cost between $0.65 and $1.00
RUMP MOUNTED DEVICES Use on dairies where cows can move about freely. Include cow number on device, if possible, in case it falls off. $0.75 - $2 per device
ANDROGENIZED ANIMALS Use on small dairies with less than 100 cows. Animal maintenance cost about $500 per animal per year.
PEDOMETERS Requires free-stall or open lot where cows can be active. Consider using when updating or building a new parlor. Typically use one device per cow. $45 to $100 per device.
ELECTRONIC HEAT DETECTION SYSTEM (i.e. HeatWatch) Requires 40 transmitters for a 100-cow herd. One device will typically last for two cows. Initial cost of $6,500, breaks down to $30 per cow over a three-year period.(1)

(1) This initial cost is for a 100-cow operation.