The prophylatic effect against respiratory disease in feedlot calves of an immunomodulator, based on an inactivated avipox virus preparation, was evaluated in a double blind, placebo controlled field trial. The effect of the immunomodulator on phagocytosis and on the reactivity of the lymphocytes was also tested.
On the day of arrival at the feedlots and 3 days later 257 calves were injected with either the immunomodulator or with placebo. All calves were then observed for respiratory disease and treatments were recorded. The immunomodulator did not reduce the frequency of disease, compared to the placebo. Thirty percent of the calves treated with the immunomodulator and 27 % of the controls were treated with antibiotics for respiratory disease.
The cell mediated immune reactivity of 7 calves treated with the immunomodulator and of 7 untreated calves was tested. Monocytes isolated from the animals were examined for their ability to ingest latex beads and lymphocytes from the animals were examined for their response to different mitogens. Sera from each of the two groups were also investigated for the effect on phagocytosis. No difference in these parameters was observed between the two groups.
En immunomodulatory baserad på ett inaktiverat avipoxvirus, användes i ett placebokontroller at fältförsök, där den profylaktiska effekten mot luftvägsinfektioner hos förmedlingskalvar utvärderades. Immunomodulatorns effekt på fagocytos och på lymfocyternas stimulerbarhet undersöktes också.
På ankomstdagen tili köttdjursbesättningarna och tre dagar senare behandlades 257 kalvar med antigen immunomodulatorn eller med placebo. Under en månads tid observerades kalvarna med avseende på sjukdomssymtom och behandlingar med antibiotika mot luftvägsinfektioner noterades. Immunomodulatorn minskade ej sjukdomsfrekvensen. Trettio procent av de kalvar som behandlats med immunomodulatorn och 27 % av kalvarna i placebogruppen behandlades med antibiotika mot luftvägsinfektioner.
Det cellmedierade immunsvaret mättes hos 7 kalvar behandlade med immunomodulatorn och hos 7 obehandlade kontroller. Monocyter, som isolerats från djuren, undersöktes på sin förmåga att fagocytera latexpartiklar, och lymfocyter från djuren testades på sin förmåga att svara på olika mitogen. Sera från kalvar i båda grupperna undersöktes i en fagocytostest. Ingen skillnad i dessa parametrar observerades mellan de två grupperna.