Is "Heifer Mastitis" a Problem on Your Farm??
Dairy Pipeline: March 2000
Virginia-Maryland Regional College of Vet Medicine
A number of researchers presented information regarding the udder health status of first-calf heifers at the recent annual meeting of the National Mastitis Council. Investigators in a study involving 60 dairy herds in Ontario, Canada, cultured milk samples taken within 3 days of calving from 1062 first lactation animals. They found that, overall, approximately 12% of the heifers had an infection with a mastitis-causing organism within 3 days of calving. Presumably, quite a number of these infections were already present in the udder before calving.
Researchers in Tennessee reported the level of infection in 2 herds in which they were carrying out a "precalving mastitis treatment" study. They found that about 73% and 96% of the heifers in these herds were infected when sampled 2 weeks before their expected due date! They also found a number of significant positive results from treatment of first calf heifers before calving. This is in agreement with some of their earlier studies.
These research reports do NOT mean that all heifers in all herds should be treated with an intramammary antibiotic prior to calving. They do however suggest that we should evaluate the udder health status of our heifers at calving so that appropriate measures can be taken if problems are found. It is quite likely that some Virginia herds will have no significant level of infection whereas others may have numbers that rival those found in the Tennessee studies.
DHI data can be useful for monitoring the udder health status of heifers as well as older cows, but an equally beneficial approach might be to culture a composite milk sample from (all) fresh heifers immediately after calving. If, over a period of time, a significant percentage of the heifers are found to be infected, an appropriate "precalving treatment plan" could be considered in consultation with your herd veterinarian.
However, we must not overlook other methods that might prevent these infections from occurring in the first place (a clean and dry environment, appropriate fly control, etc.). These management practices would also need to be evaluated as part of a complete approach to "heifer mastitis". Finally, when taking milk samples remember to take the time and effort to collect the sample in the proper way. It's frustrating, as well as a loss of time and money, to end up with a culture report that states that the sample was "contaminated"!