INFLUENCES ON THE DISSEMINATION OF BILATERAL CONVERGENT STRABISMUS WITH EXOPHTHALMUS IN DAIRY-CATTLE

Between October 1993 and May 1995 a total of 310 animals affected by b ilateral convergent strabismus with exophthalmus (BCSE) of different a ge and sex was ascertained. The breed German Black and White showed in ascertained herds the highest incidence of BCSE with 12.3% affected c ows and 2.7% affected young stock, respectively. In German Fleckvieh t he lowest incidence was found amounting to 1.7% in cows and to 0.5% in young stock, respectively. The corresponding incidences in German Bro wn cattle were 5.5% and 0.9%, respectively. The conclusions of the gen etic analyses were that the defect allele is predominantly segregating within cow families and herds. The rather equal distribution of the a ffection rate in progeny groups of Al-shes and the expected allele fre quencies assuming transmission of the defect allele on the sire path c onfirm that AI-sires have transmitted the defect allele only in single cases. The dissemination of the defect allele via the path bull dam t o AI-sire or natural service sire seems to be of minor importance. The association analysis among milk production traits and BCSE could be b ased on 12,376 cows. The analysis revealed no significant differences between affected and nonaffected cows as well as between cow families with and without affected members. There was no indication of an assoc iation between milk production traits and occurrence of BCSE within co w families. Neither selection effects nor linkage nor pleiotropic effe cts may have influenced the occurrence of BCSE.