At the 1973 American Association of Bovine Practitioners (AABP) meeting, Dr. Paul Blackmer of Ontario, California reported on an interesting survey which he had run in his dairy practice. On dairy or calf ranches experiencing a mortality problem, he collected serum samples from calves 24-48 hours old. Then he ran the sodium sulfite turbidity test on these samples. by this test calves were grouped into three groups based on visual turbidity. Then after three to four weeks he correlated the morbidity and the mortality data with the sodium sulfite test results.