The authors analyzed bacterial counts in frozen spare colostrum supplies from 42 commercial dairy farms in the Netherlands. They found that 58% of samples had bacterial counts higher than 100,000 cfu/ml, which is too high to safely feed to newborn calves. 17% of samples had coliform counts higher than 10,000 cfu/ml, indicating potential contamination. Based on these results and management practices observed on the farms, the main sources of contamination were determined to be milking and milk collection materials as well as delays in cooling colostrum quickly after collection.