BULK MILK COLLECTION—BACTERIOLOGICAL INVESTIGATIONS

Summary (1) During the six months preceding the start of the Angus scheme 118 milk samples from the thirteen farms concerned were examined when approximately thirty hours old. Twenty‐six per cent of these samples were coliform positive in 1/100 ml. and 7 per cent had 37°C. colony counts exceeding 200,000/ ml. (2) Of 230 milk samples from the farm tanks examined within ten hours of sampling 9.6 per cent were coliform‐positive in 1/100 ml. and 1.3 per cent had 37°C. colony counts exceeding 200,000/ml. Eighty‐seven per cent of the samples had counts below 10,000/ml. (3) Surface plate counts at 27°C. showed much higher counts and greater variation than the 37°C. counts. Bacterial counts at both 27°C. and 4°C. frequently showed big increases after storage of the samples for eighteen hours at 4°C. (4) Forty‐nine milk samples were taken from the road tanker. Twenty per cent of these were coliformpositive in 1/100 ml. but the greatest count obtained was only 54,000/ml. (5) Of 163 swabs arid rinses from fourteen farm tanks 10 per cent were coliform‐positive in 1 ml. and over 46 per cent had 37°C. counts greater than 100/swab. Surface plate counts at 27°C. frequently exceeded 100,000/swab. Rubber‐seated thermometers generally gave unsatisfactory swabs. A detergent‐hypochlorite cleansing routine gave fewer coliform‐positive swabs and lower counts than did a Q. A.C. routine.