Mastitis is defined as an inflammation of the mammary gland, most often caused by bacteria entering through the teat canal. To prevent bacteria from entering, heifers have an additional defense mechanism composed of a wax-type substance called the keratin plug. However, this plug in the teat canal can become overwhelmed with bacteria if heifer hygiene is pushed to the wayside and can have negative effects on mammary gland development. “Additionally, infected heifers can serve as a reservoir for mastitis-causing bacteria, particularly Staphylococcus aureus, which can create chronic problems in your milking herd,” Plunkett warned.
Dirty bedding and flies are major carriers of bacteria and make it easy for pathogens to spread. While lactating cows generally receive fresh bedding daily, heifer bedding should be cleaned thoroughly at least once a week and spot checked. Clean, dry bedding is an easy way to cut down on bacteria levels. Flies multiply quickly in manure, wet feed, or spoiled bedding, and are prime suspects of transmitting mastitis-causing bacteria such as E. coli, Klebsiella, and Staphylococcus spp. “Constructing a pest management plan that includes proper sanitation protocols along with the use of a larvicide, if needed, can be a helpful strategy to mitigate bacterial reservoirs and fly breeding grounds,” she said.
Cross-suckling in calves can also introduce bacteria to the teat and can also cause physical teat trauma as well. Although direct links to first-lactation mastitis are inconclusive, it remains a concern. Stressor events such as weaning, pen moves, and transportation, can weaken immune defenses, allowing more exposure to bacteria. Reducing unnecessary moves and ensuring smooth transitions helps keep additional bacteria at bay.
Mammary growth occurs mostly between 3 and 12 months of age, while the most important period of mammary development happens during the first gestation. Introducing bacteria during either stage can be detrimental. Mastitis damages the number and function of milk-secreting cells, destroying secretory tissue. As a result, this tissue is replaced with scar tissue, reducing milk yields for the rest of her milking career.
Preventing heifer mastitis begins the moment a calf hits the ground. Clean housing, effective fly control, reduced stress, and management of factors like cross-suckling all play vital roles in maintaining a healthy heifer. “By making sure we are doing the little things right, we can have a big impact on reducing the risk of heifer mastitis and raise high-quality replacements that have the most milk-secreting potential, which is a plus for your future pocketbook,” Plunkett encouraged.
