Mastitis in heifers is a real problem in some herds

Heifer mastitis can be a significant problem for some herds. Heifer mastitis can threaten production and udder health in the first lactation and in subsequent lactations. It has been demonstrated that heifers that develop mastitis in the first 30 days after calving produce less milk and are likely to be less profitable over their lifetime.

Given the substantial costs associated with rearing heifers until first calving, and given that the break-even point is not achieved until second lactation, it is imperative that mastitis is prevented in the first lactation. In addition to the direct costs associated with a case of mastitis, the effect on longevity in the herd and detrimental effects on production must also be considered.

Mastitis is caused by a variety of bacterial pathogens and results in inflammation in the udder, most often caused by bacterial infection. Mastitis can be defined as clinical or subclinical.

Clinical mastitis occurs when there are visible changes in the milk, these changes can be further classified as mild, moderate and severe cases. It is most common that the only sign is abnormal milk. Clinical mastitis can also be recognised in colostrum.

Subclinical mastitis exists without obvious changes in the milk but with an increase in somatic cell count (SCC) and relies on indirect tests such as SCC counts on milk records to detect it.

There are many definitions for what constitutes a case of subclinical mastitis but a widely accepted definition is that SCC >200 000 cells/ml for

first lactation animals at any milk recording is indicative of subclinical mastitis. Even in the absence of visible changes in the milk, bacteria can still be present in cases of subclinical mastitis.

Heifer mastitis also includes cases where one or more quarters are non-functional in animals in their first lactation.

Although it is unusual to see clinical mastitis in heifers before calving, it is possible that heifers develop subclinical infections with mastitis pathogens before calving. It is most common that heifer mastitis is diagnosed after calving when the animal begins milking and either abnormal milk is detected or an increased SCC.

In order for mastitis to develop, bacteria must gain entry into the teat canal via the teat orifice to establish infection and provoke an inflammatory response which results in either clinical or subclinical mastitis.

Although many pathogens that cause mastitis in adult cows may also result in heifer mastitis, Streptococcus uberis and Coagulase negative staphylococcus are commonly involved in heifer mastitis. Exposure of the teats to pathogens in the pre-calving environment can result in infection before calving. Some infections may arise from bacteria living on the teat skin, while others are bacteria from the environment that enter the teat and initiate infection.

A number of risk factors for heifer mastitis have been identified but are often farm and region specific: these include but not limited to udder oedema and hygiene of the environment as well as issues such as cross suckling in calves and young stock, fly control during the summer period, housing and calving environment and interaction with older cows in the herd, nutritional deficiencies particularly with regard to vitamins and minerals such as Vitamin E & Selenium, Energy Imbalance, teat spraying heifers pre calving.

Before considering control strategies you must first decide if you have a specific heifer mastitis problem. Then in conjunction with your veterinary practitioner investigate the problem and decide on a specific management strategy that is most relevant to your farm. For any strategy to be effective very good records of clinical mastitis cases is essential and a first milk recording carried out early in the year.

In summary, if you think that there may be too many incidences of mastitis in heifers in your herd then you should consult with your vet to discuss the possible causes and solutions that are most relevant to your farm.