CATTLE
A
merican cattlemen have been dealing
with Bovine Trichomoniasis or “Trich”
since 1932. Interestingly, only in the past
10 to 15 years has this disease been getting the attention it deserves. I say deserves because there is not another disease that carries
the financial impact that Trich does for the cow-calf
producer in the southern U.S. There are certainly
lots of opinions on this disease surrounding testing,
management and prevention. Of significant concern
to a lot of folks in the cattle industry is the variation
SUPPLY
ultrasound and confirmed with a testing procedure
similar to that of the bulls. Of great concern to me is
the often misunderstood notion that sexual rest of the
exposed females results in spontaneous clearance of
the infection. It should be pointed out that in a low
percentage of the cow population persistent infection
(cow carries the infection through pregnancy into
the next breeding and re-infects the bulls) has been
documented. Though the estimated frequency is low (
less than one percent), it requires consideration of the
female carrier state for management decisions when
Trich is diagnosed in the herd.
Bovine trichomoniasis affects most, if not all,
components of the equation for cow-calf operation
net income.
in understanding and awareness of this disease. In my
practice experience, I’ve seen several instances where
this misunderstanding has actually worsened the
problem of Trich on the ranch. In this article, I will
attempt to help clarify some of these areas.
Understanding the Disease:
The bull is the long-term carrier of the organism
without ill effects or visible lesions. As reported in
1941, we used to think that older bulls “carried” more
trich in structures known as epithelial crypts located
on the penis and prepuce. Recent research from
Auburn University has proven the crypt theory to be
a myth. There are no structures that resemble crypts
and no structural differences between young or older
bulls.
In female cattle, the organism is introduced following breeding and initiates the infection. An early
symptom of the presence of T. foetus is a vaginitis.
Shortly after, the organism reaches the uterus, causing
a metritis to develop. Though the organism is introduced at the time of breeding, conception or pregnancy is generally not impaired. Fetal death generally
occurs two months after pregnancy. This gives rise
to the extended time period between observed heats.
In a small percentage of the infected cattle, a uterine
infection or pyometra develops. This infection can be
detected by your veterinarian via rectal palpation or
Economics
A key factor in the profitability of the cow-calf
operation is weaning a high percentage of uniform
healthy, heavy calves while keeping inputs reduced
to an acceptable level. According to University of
Florida’s Dr. Owen Rae, net income from the cow-calf
operation can be defined as:
[(# of calves weaned X weight of calves weaned) X
price per pound] – maintenance cost per cow/calf
Bovine trichomoniasis affects most if not all components of the equation. Reduced pregnancy rates
and the variable distribution of the live born calves
over the calving period are the most obvious. The increased testing, culling, and prevention costs decrease
the overall net per exposed female. The impact to the
cow-calf producer’s profitability based on simulated
models was significant. Rae’s disease model predicted
a reduction of 14 to 50 percent in annual calf crop,
a prolonged breeding season, a reduction of 5 to 12
percent in the suckling/growing period, a reduction
of 4 to 10 percent in pounds of marketable calf crop at
weaning, a reduction of 4 to 10 percent in monetary
return per calf born, and a substantial reduction of 5
to 35 percent in the return per cow confined with a
fertile bull. Prevalence in this model varied from 20 to
40 percent (one to two infected bulls out of five total
breeding bulls). Income from calves sold was reduced
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