Bactericidal activity of blood sera as a quantitative trait of nonspecific resistance in population immunological investigations in cattle
1995
Viltrop, A. (Estonian Agricultural Univ., Tartu (Estonia). Inst. of Infectious Diseases)
The goal of the present study was to learn the extent of the variation of the blood serum bactericidal activity among Estonian cattle and to clarify the possibilities of using it as a quantitative trait in population immunological surveys. 715 cows from six herds were tested for bactericidal activity of blood sera to E. coli 0127 and Micrococcus lysodeikticus. In three herds the influence of the age of animals on phenoclass structure of the herd was examined and the influence of the phenoclass on the average milk fat production in first two lactations was investigated. A turbidimetric micromethod for detection of bactericidal activity of blood sera was developed. The method enables to examine multiple samples in one experiment and is suitable for population studies. The results of the present study demonstrate that in four of six investigated herds the distribution of animals between immunological phenoclasses was close to expected distribution which confirm the statement that the natural selection is not sufficient for elimination of the weak individuals from the populations. The methods applied in the present study enable to define the immunological structure of the herd and also to determine the risk groups more susceptible to infections. The latter in its turn enables to make correlations in herd immunity either by eliminating susceptible animals from the herd or by prophylactic treatment with immunostimulators
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