Complex sentence: Unlike the outbreak in the 60s the main reason that MAFF failed to respond quickly enough was the high level of cattle movement in the modern day market: today cattle are moved quickly up and down the country without tests for disease.
Split into simpler sentences: Unlike the outbreak in the 60's the main reason that MAFF failed to respond quickly enough was due to the level of high cattle movement in this modern day market. Cattle in this day and age are moved quickly up and down the country with lack of any tests for disease.