Whole blood optimization and genetic association of ex vivo TNF-alpha responsiveness to killed E-coli in Danish Holstein cows

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Whole blood stimulation assay (WBA) has been widely used to study production of the pro-inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha) and is considered a relatively good predictor for the in vivo release of TNF-a during endotoximia in dairy cattle. However, it requires a standardized and optimized dose of lipopolysaccharides (LPS) to simulate the in vivo cytokine response during WBA when using killed bacteria. Moreover, if an association between genome (e. g., Quantitative trait loci) and ex vivo TNF-alpha responsiveness can be established; it helps to reduce mastitis in dairy cattle using selective breeding. Three experiment scenarios for pathogen dose, stimulation time and estimation of genetic variables effect in ex vivo TNF-alpha production were carried out to investigate differences of TNF-alpha responsiveness in early lactation in 4, 38 and 40 Danish Holstein Friesian dairy cows respectively. Statistical analysis done using ANOVA, t.test and lm functions in R software. Results showed that, ex vivo TNF-alpha response to E. coli is dose and time dependent and a dose of 2.5 x 10(6) CFU/mL for 3.5 h is optimal for observing TNF-alpha response after ex vivo stimulation.

Relatively consistent inter-individual cow differences in the TNF-alpha response ex vivo were observed from week 3 to week 8. No statistically significant association were found between the ex vivo TNF-alpha responsiveness and the two E. call associated mastitis QTLs which may be due to the low number of animals (n =) in the study.

OriginalsprogEngelsk
TidsskriftLivestock Science
Vol/bind201
Sider (fra-til)92-98
Antal sider7
ISSN1871-1413
DOI
StatusUdgivet - jul. 2017

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