VEAL CALVES
bought as preconditioned calves from western provinces. These bull calves are raised
to produce high quality meat, however due to the nature of sourcing these animals,
biosecurity and early management practices in place at the birth farm and the stress and
exposure to pathogens from commingling during transport and at sale barns, they are at
an inherently greater risk of illness and need for antimicrobial use.
As in replacement heifers, the stress of shipping calves, combined with the exposure
to animals from many different sources, creates a population that is highly susceptible
to infectious diseases. The strongest predictor of calf health is proper management of
colostrum. This includes testing colostrum immunoglobulin (Ig) levels, ensuring the calf
is given a sufficient quantity within 12 hours of birth and then testing the serum Ig level
of the calf. Failure of passive transfer is associated with respiratory and gastrointestinal
disease, the two most common ailments in calves.
Approximately 45 per cent
of Canadian veal is raised in
Ontario, although production is
predominantly of grain-fed veal
cattle.
College of Veterinarians of Ontario
To combat the stresses faced early in life, antimicrobials are often added to calf milk
replacer. This practice can delay morbidity and decrease mortality, as well as promote
increased growth and improved feed efficiency. European facilities often give blanket
“start treatments” to newly arriving calves. This practice is contentious due to the link
between antimicrobial usage and diarrhea. Almost 25% of dairy calves are affected by
diarrhea before weaning, making it the number one cause of morbidity and mortality.
Antimicrobial therapies may cause diarrhea through disruptions of the normal intestinal
biome. The normal biome is likely compromised to begin with, since calves are unable
to pick up beneficial microbes from their dam due to early separation. Even if the cause
of the diarrhea is not bacterial, it is possible that antimicrobial therapy will be effective,
as secondary E. coli overgrowth may develop in the small intestine. However, most
drug therapy for mild diarrhea is not beneficial and, in fact, antibiotic treatment may
be associated with higher mortality. Respiratory disease is the other major reason for
antimicrobial treatment in veal production.
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