POSSIBLE ASSOCIATION BETWEEN A SEROLOGICALLY DETECTED HAPLOTYPE OF THE BOVINE MAJOR HISTOCOMPATIBILITY COMPLEX AND SUBCLINICAL MASTITIS

The incidence of subclinical mastitis in Simmental and Simmental-Red H olstein cattle in relation to the bovine major histocompatibility comp lex (BoLA) was investigated. Quarter milk samples of 166 cows consisti ng of fifteen halfsib groups of different ages and lactation stages we re analysed for somatic cell counts (SCC) and bacteriological infectio n. From these data the udder health status (UHS) of the animal was det ermined. Each cow was typed serologically for BoLA class I and class I I specificities. The statistical evaluation for UHS was performed usin g a logistic regression model. The effect of BoLA on SCC was estimated by least square analysis. Animals carrying the BoLA class II haplotyp e ''b'' were significantly more affected by subclinical mastitis than those without this haplotype. Breed group showed a significant influen ce on both UHS and corrected mean logSCC (P < 0.0061 resp. P < 0.05). Lactation stage had a significant effect on SCC but only a weak influe nce on UHS (P < 0.0001 resp. P < 0.13).