Dissecting the mammary gland: Understanding udder health and milk quality

During their presentation and udder dissection lab at the Vita Plus Midwest Dairy Conference, Dr. Meghan Connelly, Vita Plus, Dr. Kolby McIntyre, Marsh View Veterinary Clinic, and Dr. Matt Schaefer, Waupun Veterinary Service, discussed udder health and its relationship to milk quality.

Milk quality can be multifaceted and interpreted differently from the perspective of the producer, the processor, or the cow. Regardless, we can most all agree that milk quality is often a good metric for udder health. Thus, finding ways to improve upon udder health can help to improve milk quality.

The dairy cow herself has a variety of innate mammary defenses to prevent pathogens from entering the gland and migrating into the body of the udder where the vast majority (more than 90%) of milk is made and stored. These defenses come in the form of both physical barriers and humoral and cellular defenses. When these lines of defense are compromised and pathogens gain entry, mastitis can occur.

Mastitis is an inflammatory reaction that can be caused by bacteria and result in damage to the milk-secreting tissue. Mastitis is a costly disease for the dairy industry, and recent work has focused on understanding the tissue-level changes that occur within the cow in response to infection. Not only can mastitis cause tissue damage within the gland, but it can also change the constituents that make up milk. Thus, to prevent infection and ensuing changes in milk quality, we need to take advantage of the external and internal natural defenses of the cow as well as environmental factors.

Human impact itself can play a large role in udder health. Milk quality due to environmental conditions such as housing type, prep routine, and vacuum equipment all play roles in mastitis risk.

Lack of or improper prep routine can lead to bacteria entering the teat cistern and provide a potential opportunity for pathogens to gain entrance into the gland. Lack of or improper prep routine may also result in an improper stimulation and letdown, which can impact unit on-time and result in an incomplete milk out.

Additionally, vacuum equipment can play a large role in udder health based on attachment. For example, if a liner collapses, it can create a pulse of pressure and force milk down and up into an adjacent quarter liner where the resident teat end is open. Foreign milk particles and bacteria from one teat may now be transferred to another during this incidence. Short-term effects of this equipment failure can result in udder edema due to blood flow changes, delayed closure of the teat canal and potentially mastitis. Long-term effects of these malfunctions can result in hyperkeratosis, decreased production and possible mastitis.

Collectively – while udder health and milk quality may elicit different definitions when discussing across sectors in the industry – ensuring properly functioning milking equipment as well as proper prep routine to ensure a full cleaning of the teat, adequate stimulation, and utilization of the cow’s natural mammary defenses can aid in creating a gland that is healthier.

Click here to download the PowerPoint presentation from this session at the Vita Plus Midwest Dairy Conference.