More than one in every four litres of milk sold in Ireland last year used imported milk, a new report has found.The annual National Milk Agency (NMA) report found that 156m litres of milk was imported from Northern Ireland into the Republic in 2015, which was up from 145m litres in 2014. There was a 1m litre increase, to 94m litres, in the volume of imported milk sold in consumer packs in retailers last year.