It's not exactly my research area (bovine studies); however, other researchers appear to have been able to impute the Bovine 50k microarray with other datasets, and Beagle seems to be used frequently across these and other studies:

• The feasibility of using low-density marker panels for genotype imputation and genomic prediction of crossbred dairy cattle of East Africa (take a look at the section entitled 'Genotypes')
• Short communication: Imputation performances of 3 low-density marker panels in beef and dairy cattle

The first study that I listed used, in addition to other studies, data from The Bovine Genome Database for the purposes of a reference panel for imputation.

Kevin