Relationship between penetrability of the papillary duct (teat) and phagocytic capability in lactating dairy cows

To determine whether there is a reciprocal relationship between penetrability of the papillary duct of the teat (streak canal) and phagocytic capability, 3 cows with highly penetrable papillary ducts and 3 with ducts highly resistant against penetration were identified, using a penetrability assay. Leukocytes harvested from milk from these cows were tested for their capability to phagocytose Staphylococcus aureus. Phagocytic capability was found to be independent of the ability of microorganisms to gain access to the interior of the mammary gland.