by Daryl Meyer, DVM
Heifer spaying is a management tool with several advantages that outweigh
the few disadvantages. For cattlemen unfamiliar with the advantages,
here’s a quick review. First, spaying heifers maintains stocker
and feeder heifers in an “open” or neutered status. This
also enables early detection of pregnant stocker heifers accidentally
bred at a young age.
Prevention of pregnant heifers in a feedlot situation is a plus for
all involved, especially considering all the associated complications
such as Cesarean surgeries, vaginal/uterine prolapses, down and dying
heifers and frustrated feedlot personnel.
By spaying heifers, you eliminate feeding estrous suppression feed
additives, saving $2-4/head during the feedlot phase of production.
You also eliminate the need to pregnancy check (palpate) heifers upon
arrival at feedlots saving $1.50 – 2.00/head plus labor costs.
The need to test stocker heifers for brucellosis and/or tuberculosis
when marketed to out-of-state feedlots is removed, saving $1.50-3.00/head
plus labor costs.
Additionally, spayed heifers show improved average daily gain and
feed conversions when spayed heifers are implanted versus intact implanted
heifers. By spaying heifers, cattlemen gain the ability to graze/feed
heifers and steers together, as well as the ability to graze spayed
heifers near cow/calf herds with bulls present.
There are a few disadvantages to keep in mind, however. The surgery
is irreversible; therefore spayed heifers are no longer candidates
as breeding replacement heifers. The typical cost is $5-6/head depending
on the number being spayed at a particular location.
There is a minimal risk of death loss related to the surgery, depending
on expertise of surgeon.
Heifer Performance
It has previously been reported that spayed heifers had a performance
disadvantage compared to intact heifers. However, these studies involved
heifers spayed with the flank method and without the use of growth
promotant implants.
This is not the case when comparing implanted spayed and implanted
intact heifers. For spayed heifers the source of progesterone and
most of the estrogen source has been removed. Therefore, it is important
to implant spayed heifers. Studies have shown that spayed heifers
respond more positively to implants than do intact heifers. Spayed
heifers can be grazed, fed, and implanted in a manner similar to steers.
Heifers that were spayed and implanted tended to deposit more lean
tissue and less fat during this experiment.
Other grazing/growing studies have shown an overall 5.5% gain advantage
(0.12 lb/day) for spayed implanted heifers versus implanted intact
heifers. Finishing studies have shown a 2.5 – 3% gain advantage
for spayed implanted heifers. Feedlot surveys have indicated a 0.10
– 0.30 lb/day advantage for spayed implanted heifers.
The pregnant heifer that calves in the feedlot costs the feeder approximately
$150-200 due to calving problems, infection, decreased gain, decreased
carcass quality and yield.
Dr. Bill Bennett and his co-workers, in a 1984 survey of feedlots
and packers, found almost 15.5% of the feeder heifers coming in to
feedlots were pregnant. The total cost to pregnancy test and abort
or to inject all heifers to abort those pregnant averaged 5.29 percent
of the purchase price of the heifer. The open heifer was worth from
$30-50 more than the pregnant heifer entering the feedlot (Based on
1986 cattle prices and data).
Dr. Bennet’s data on over 10,000 heifers showed an average carcass
yield decrease of 5.6% on pregnant heifers. Based on carcass weight
gain, pregnant heifers gained 12.6% less and had a 13.3% higher feed
conversion rate than non-pregnant heifers.
Research trials indicate that spayed heifers in the feedlot, implanted
and marketed at the correct time, have about a 2% gain advantage compared
to the implanted intact heifer.
The 2% advantage is based on a combined average of studies conducted
over a 6 to 7 year period on spayed yearling heifers shipped to feedlots.2
Good quality spayed heifers finish and grade at 90-110 days on feed
and yield a quality carcass. The spayed heifer will reach optimum
grade sooner than her intact counterpart. In conclusion, the spayed
heifer implanted and marketed at the proper time will outperform her
intact counterpart.
Feedlot operators realize that these figures, coupled with the potential
problems of abortion, calving/dystocia problems, and increased labor
costs of pregnant heifers make pregnant heifers a definite liability
in the feedlot. Spaying also eliminates the visual exposure of the
public and customers to heifers calving in a feedlot setting which
can lead to poor public perception of the individual feedlot and the
industry regarding animal welfare and care. ©
