Pedometry
to Improve Reproduction
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Pedometry offers the opportunity for medium- to large-sized
dairy herds to improve heat detection and, at the same time, reduce dependence
upon labour. A pedometer is a motion-detecting and -recording device, one of several
precision dairy management tools that are providing opportunities to save labour,
and improve individual cow care and management through the use of technology.
Heat
Detection
Heat detection rate is a key factor in determining pregnancy
rate and reproductive success in a dairy herd. This area has the most opportunity
for improvement in dairy herds. Heat detection efficiency in dairy herds is less
than 50%, and failure to accurately detect estrus costs the dairy industry millions
of dollars each year.
The decision to breed a dairy cow is dependent
upon using one of three management systems:
- systematic observational
heat detection
- synchronization and timed artificial insemination (AI)
- use
of pedometry or activity monitors
In high-producing cows, the period
of mounting activity lasts an average of 5.8 hr, and some cows only stand to be
mounted one to two times per heat cycle. Accurate heat detection requires observation
of the herd by a trained individual three to four times per day, seven days per
week. The biggest challenge to systematic heat detection is to be able to carry
out observations consistently when required every day.
Synchronization protocols
and timed AI, on the other extreme, offer excellent control and timing of breeding,
as well as the opportunity to schedule workload, and addresses some of the 20%
of cows that are anestrus in early lactation. The downside is cost, the need to
maintain strict protocols and the reliance on drug treatments.
Figure
1. Activity monitors may be neck- or leg - mounted.
How Activity Monitors
Work
A pedometer is mounted by a strap around a cow's lower leg to detect
and record motion such as walking. An activity monitor is attached with a strap
to the cow's neck (Figure 1). The pedometry data in the monitors on each cow are
accessed by a reader device, and the data are recorded in a dedicated computer.
Software is used to create reports on the activity of each cow over previous
time periods. Cows show increased activity prior to the onset of standing heat
by a factor of two to four times normal. Cows should be considered for breeding
within 12-24 hr of being identified with increased activity by the pedometer system.
Pedometers
and activity monitors provide the opportunity to identify cows coming into estrus
while reducing the dependency upon labour. Studies have shown 80%-85% heat detection
rates with pedometers when one animal is in heat and up to 90% when two or more
are in heat.
Figure
2. Spikes in activity associated with heat cycles compared to days in milk.
Text
Equivalent of Figure 2
System Costs
Initial investment in a
pedometer or activity monitor system can be significant, at about $14,000 for
a standalone system or an additional $30,000 if added to an existing parlor ID
system. Prices will vary, depending upon features of the system, number of readers
and number of monitors. The initial capital cost can be justified in improved
heat detection and labour savings.
With arm's length farm labour costs of
$13-$16/hr, an observational heat detection program costs about $6,000 per year.
At 6.5% interest over 7 years, a $30,000 investment in an activity monitor system
would break even in labour replacement costs alone. Investing in a $14,000 standalone
monitoring system would pay if labour on the farm is valued at $8/hr or higher.
Typically, activity monitors attain better heat detection rates than strictly
observational methods, which would be further justification over savings in labour
costs. Figure 2 shows how the cows activity levels spike associated with heat
cycles compared to her days in milk.
When compared to a synchronization
program, strictly on a cost-per-cow basis, the activity monitor program tends
to be much cheaper and also has some economies of scale, which is not the case
with synchronization protocols.
Other benefits of an activity monitor system
include the tracking of activity over a number of days and its integration with
other production information on each cow to assist in management decisions. Sudden
decreases in activity may indicate the onset of lameness or other illness. Other
patterns of activity, such as increases followed by decreases, may be related
to metabolic disorders.
Summary
Pedometers or activity monitors
provide an alternative for heat detection in freestall-housed dairy herds, especially
as a replacement to labour in a traditional visual heat detection system with
as good and frequently better heat detection rates.
Pedometry systems tend
to be integrated with milking parlour data systems, although some may be standalone
as well. Pedometer systems have a higher capital cost, but they are a reasonable
economic alternative to visual heat detection with its costly labour component,
or a synchronization-based program with less reliance on injections and high associated
costs per cow.
Pedometer/Activity monitor systems and related software
provide valuable management information, along with other production data, for
managing the dairy herd.
