The smooth muscles surrounding the teat duct should becontracted and the teat canal tightly closed between milkings to avoid bacterial passage from the teat orifice into the interior of the gland. A teat-end in good condition is an important resistance factor to bacterial colonization of the mammary gland.
Teat skin condition is also a main point of a mastitis control strategy. Chapped and cracked teats are a perfect environment for bacteria to develop: warmth, humidity and food are available and Staphylococcus aureus or Streptococcus agalactiae like to colonize these places. Thus, the quarter easily gets contaminated: directly (propagation of the germs) or indirectly (via milking machine contamination).
What's the score for your cows? Find it out with the teat condition test!