Factors affecting the hygienic quality of bulk tank milk

This study aimed at determining the effect of factors associated with conditions of husbandry for cows and replacement heifers as well as conditions of milking on somatic cell counts (SCC) and total microorganism counts (TMC) in bulk tank milk. The investigations were carried out on 35 farms. SCC were measured once a month, and TMC were measured every two weeks. The arithmetic means for SCC and TMC were 294 000 and 32 000 in 1 cm(3) of milk, respectively, whereas the correlation coefficient between these variables was 0.45 (p less than or equal to 0.01). A multi-factorial analysis of variance demonstrated that outdoor access for cows in the summer season, approximately 12-hour time-intervals between morning and afternoon milking, pre-milking udder and teat cleaning by wiping (vs. washing with water), appropriate level of concentrate (4-10 kg/day), use of MgO additive in the feeding ration for cows, and avoiding the milk from mastic cows in calf feeding are factors that decrease SCC in milk. The following factors decreased TMC in milk; short-length (<200 cm) cubicles for cows, use of antibiotics at drying-off, practicing fore-stripping after udder and teat cleaning, premilking udder and teat cleaning by wiping, manual post-milking udder massage, use of the "Duovac" device in milking, and use of a vitamin A supplement in cow feeding in the transition period.