The Rural Voice, 2003-01, Page 38Advice
Many calves get mycoplasma before they're born
�lanv
ot the problems cattle
producers have with animals infected
with mycoplasma come from animals
infected before. they are born.
Rob Tremblay. a veterinarian with
the drug company Boehringer -
Ingelheim (Canada) Ltd. told the
Beef Symposium 2002 in Brussels.
November 28 that there's nothing a
feedlot operator can do with these
animals except to protect other
animals from the mycoplasma they
shed. The sick animals are infected
by their mothers in the womb before
their immune systems develop, he
said. creating what is termed
persistently infected (P1) calves
which no medication can cure. The
animals will keep sliding no matter
what. and though one cow managed
to live 12 years. providing infected
offspring to infect other herds. the
majority of cattle die by 18 months.
But vaccinating all cattle arriving
at a feedlot for BVD may actually
help because it may cause some of
the PI calves to die earlier. meaning
at least they didn't add to their feed
costs. Tremblay said.
Mycoplasma is also often a tactor
in deaths of cattle in feedlots that are
diagnosed with other diseases,
Tremblay said. It seems like
mycoplasma plays a role in the
deaths of cattle from chronic
pneumonia. polyarthritis syndrome
(CPPS) with 44 per cent of deaths
from CPPS in one test group being
found.to have been infected by
mycoplasma. It seems mycoplasma
plays a role but nobody knows for
sure, Tremblay said.
There is unlikely to be a
vaccination developed for
mycoplasma. he said. For one thing,
mycoplasma knows how to avoid the
calf's immune system. It has
probably been around a long time
and has discovered how to adapt.
Researchers feel they'd need a
vaccine that dealt with at least three
strains of mycoplasma to be effective
and one of those strains would need
to be changed every two or three
years or the vaccine would be
worthless.
"I don't think vaccination is going
to solve the mycoplasma problem."
Tremblay said. "We don't even know
what bug we're dealing with. The
Ontario virus is different than the
European strain but it's unknown if it
is different than the western
Canadian or U.S. strain.
"We don't know enough about
mycoplasma bovis to, know how
many bugs we have. There may be
subtle differences we don't know."
A way for feedlot owners to protect
themselves from PI calves might be
to get more information about their
mothers. Tremblay said.
"I'd be asking how the cows from
which the calves came were
vaccinated (for BVD)," he said. The
last time someone did a count only
about 30 per cent of the cow herd
was vaccinated, he said. "If people
don't start asking for vaccination
we're not going to get it."
Dennis Martin, OMAF feedlot
specialist later emphasized that the
way to get the best "bang for the
buck" is to vaccinate all cows with a
live -virus BVD shot before they get
pregnant, thereby protecting the
calf.0
Calf vaccination programs predict feedlot health
By Ann Godkin importance ot the timing ot
Vet. Science, OMAF vaccination to convince producers
Over the last 10 years. that the extra effort of vaccinating at
experiences with Bovine Viral the right time is really worthwhile.
Diarrhea (BVD) have left cattle American researchers assessed the
producers and veterinarians in this impact of differences in vaccination
pro\ ince wiser about critical programs in 24 cow -calf herds on the
elements of successful vaccination health of the calves after entry to a
urograms. Vaccination works. but feedlot. All calves were processed
ou have to do it right. identically after arrival. All received
Vaccinating beef calves against one shot of modified live virus
important diseases they will face in (MLV) vaccine for IBR, BVD, PI3
the feedlot is a battle between and BRSV on arrival. Just prior to
effecu\eness and convenience. Often vaccination, blood was collected for
�e most convenient time for the antibody detection.
-roducer to \acctnate does not result There were a great variety of
1 the degree of protection needed to vaccination programs used in the 24
tep the call healthy under stress. herds. Ten herds used killed
As 1)r Carl Ribble of the Ontario vaccines, nine used MIN and five
-'eterrnary College has said, "when used a combination of MLV and
.acetnt works. nothing happens killed. Of the 417 calves, 114 (27 per
because nobody gets sick.' Producers cent) were treated and four (.96 per
therefore are ternpted to slip back to a cent) died. Two were salvaged.
more "convenient' vaccination Antibody levels on arrival
program. it behooves us as vets and predicted susceptibility to illness
educators to continually evaluate afterwards. f'or (RVI), the three herds
research or cases that prove the whose calves had the least illness had
34 THE RURAL VOICE
high BVD titres on entry (means
were 192, 406 and 50) while the
three herds with the most illness had
low titres on entry (means were 0, 5
and 2). Among individual calves,
BVD titres not only predicted
whether they got sick but also the
number of treatments they
underwent. Calves not treated at all
had a mean titre of 78.5; those treated
once had a titre of 74.2; while those
treated twice or more had a mean
titre of 22.4. Those needing multiple
treatments had significantly lower
titres at entry from those not treated
or treated,a single time.
Treatment predicted. calf value.
Compared to calves never treated,
those treated once were worth $40.64
less; those treated twice, $58.35 Tess;
and the multiply treated calves
itlui ti((l $291.9)3 less.
I h !hive herds whose calves had
the Hue,' illness used killed virus
vac, Ines but did not give the second
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