When Dairy Cows Leave Too Soon
Dairy cows leave a herd for numerous reasons. Some are sold as heifers
for replacements to other dairies, others leave as dairy replacements,
some leave as a result of health concerns, and some pass away. Initial
review of culling in Pennsylvania between 2003 and 2005 showed herd’s
cull rate within a given year reached high levels over 50 percent. The
top two reasons why cows left were injury/other and reproduction. The
third highest reason was mortality, which may seem surprising at first.
Recent studies suggest that mortality rates have been steadily
increasing in dairy cows over the past few years. These mortality
losses could affect three segments of a dairy operation: voluntary
culling decisions, replacement inventory, and potential production
levels.
One of the immediate impacts cow lost to death
has on the farm is the culling decisions. The result of an involuntary
culling by losing a cow means there is one less chance to cull another
cow voluntarily. Ideally, the cow that died could have been one that
was going to be culled in the near future, but rarely this is the case.
Most mortality cases are unexpected, leaving little time to plan a
course of action. By losing a cow, the producer also loses a culling
choice and is faced with the decision: which cow should I keep around,
if any? This usually means a cow that needs more specialized attention
remains in the herd just to maintain herd size.
There is
also the financial impact of these involuntary culls. The average dairy
in PA receives 5 percent of their yearly income from livestock sales,
either for dairy or beef purposes. Any mortality case on the farm means
there is one less animal going to auction for dairy or beef. Combine
that lost revenue costs associated with animal disposal or rendering of
mortality cases and the immediate economic impact of a lost cow begins
to eat away at a producer's wallet. The death of a cow also impacts the
replacement inventory. Once a cow leaves the herd, voluntarily or
involuntarily, she will need to be replaced to maintain herd size. Here
the producer has two options. First, replace her with a first calf
heifer that is about to freshen. Hopefully the herd has an adequate
supply of heifers, both pregnant and those nearing breeding age. On
average, a 100 cow herd maintaining herd size with a cull rate of 30
percent should have roughly 70 heifers to select from on any given
year. Half of these will be under one year, and the other half should
be bred and hopefully pregnant. If heifer inventories for the herd are
low, or there are no heifers freshening in the immediate future, the
producer may be forced to purchase a springing heifer or a cow already
in lactation. This can be risky, as stress of moving the animal between
locations may affect the health and thus the milk production of the
animal.
The final area affected by a mortality case is the impact on milk production. If a
cow that dies is at or near peak production, let us say 110 pounds, and
she’s replaced by a first lactation cow that starts at say 30 pounds,
it will be awhile until that cow will peak, resulting in lower herd
production for a few weeks. A riskier scenario would be if the cow that
has died is in her first lactation. This cow may not have been in
production long enough to cover the $1200-$1500 investment the dairy
producer has in her as a replacement. Let’s assume the producer makes a
profit of $0.06 per pound of milk for this cow. She would need to
produce 20,000 pounds of milk (which is roughly the amount of milk for
1 lactation of the average cow in Pennsylvania) to cover her
investment. When this cow dies before she finishes her lactation, she
is taking part of the producer’s investment along with her.
No producer likes to see a cow leave the herd as a mortality case.
It reduces their chance to cull a different cow, reduces their
replacement inventory, and can decrease production. Depending on the
age of the lost cow, it may also impact the farmer’s ability to break
even on their investment into that cow. Controlling which cows leave
the herd may not always be an option, but the best way to manage
mortality in a herd is keeping accurate records of mortality and cull
cases, as well as adequate levels of replacement animals.
The information presented in this article was provided by Penn State
dairy cow mortality research sponsored by PA Department of Agriculture.
Special thanks to the Pennsylvania Department of Agriculture Animal
Health and Diagnostic Commission Research for funding of this ongoing
project.
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Robert C. Goodling, Jr., Extension Educator - Dairy, Penn State Extension, Lebanon/Berks County
& Dr. Chad Dechow, Assistant Professor Dairy Cattle Genetics, the Pennsylvania State University
