Effect of omitting teat preparation on bacterial levels in bulk tank milk

Abstract

The objective of this study was to investigate the effect of omitting teat preparation prior to milking on the bacterial levels in milk directly after milking and after a period of milk storage. Eighty Holstein–Friesian dairy cows were assigned to two pre-milking teat preparation treatments: (i) washing of teats and drawing of foremilk, followed by drying with paper towels and (ii) no teat preparation. Individual cow measurements included individual quarter somatic cell count (SCC) and teat swabs for the presence of Bacillus cereus sensu lato. On seven monthly occasions, all milk produced over a 24 h period from each treatment group was segregated into a separate tank and sampled. Sub-samples of this milk were stored at 4 °C for 0, 24, 48 and 72 h, and the milk was analysed for total bacterial count (TBC), thermoduric bacterial count and the presence of B. cereus s. I. Individual quarter SCCs were numerically higher for unprepared teats (159,000 cells/mL) compared with those for prepared teats (133,000 cells/mL; P < 0.09). A similar trend was observed for bulk tank SCC, with the unprepared teat treatment tending to have a higher SCC (155,857 cells/mL) compared to the prepared teat treatment (102,286 cells/mL; P< 0.09). The TBC was not significantly higher from unprepared teats (3,152 cfu/ mL) compared with milk from prepared teats (1,678 cfu/mL) (P< 0.10). Milk TBC was significantly higher after storage for 72 h compared with that after 0, 24 and 48 h (P< 0.01). The results of this study indicate that under good hygienic conditions in an outdoor grazing situation, the omission of pre-milking teat preparation has a minimal effect on TBC and SCC.

Keywords

• bacterial counts
• dairy cows
• somatic cell count
• teats
• teat preparation