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Extension > Agriculture > Dairy Extension > Milk quality and mastitis > Mastitis Control in First Lactation Heifers

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Mastitis Control in First Lactation Heifers

Neil Broadwater

Published in Dairy Star July 02, 2010

The Minnesota DHIA Herd Summary report has three important tables to check to monitor the somatic cell count (SCC) status of the dairy herd. The Current SCC Evaluation table shows the number of cows and percent infected by lactation number and by linear score within each lactation. The Changes in SCC Status table shows the fresh vs. last dry off and current vs. last test percentages for cures, chronics, negatives, and new infections. The third table is the Yearly SCC Summary, showing the percent infected by days in milk and by lactation number.

When analyzing these tables in herds with mastitis problems, two questions especially come to my mind: why are the first lactation heifers infected; and, why are so many infected within less than 30 days in milk? For example, the DHI report may show 35 to 45% of first calf heifers infected within 30 days in milk or perhaps 30 to 40% complete their first lactation infected, some reaching linear scores of 6 or 7, indicating they are shedding high numbers of somatic cells.

Although it would be great if all first lactation heifers entered the milking string infection free, it cannot be assumed that this will ever be the case. Heifers can become susceptible to mastitis pathogens as soon as they begin to produce mammary secretions, as early as 6 to 8 months of age. Intra-mammary infections at any time thereafter can persist throughout pregnancy and into lactation.

What are some reasonable SCC goals to aim at with first lactation heifers?

Sources of mastitis infection - Although it is not known for sure how heifers contract mastitis, sources may include:

Solutions - University of Minnesota Diagnostic Lab culture records indicate that most of the mastitis in Minnesota dairies is coming from environmental pathogens. So in most cases, it comes down to hygiene and finding ways to reduce the number of mastitis-causing bacteria at the teat end, even for first lactation heifers. Here are some solution ideas:

First lactation heifers represent the future milking herd. Find out what is causing mastitis infections to show up within days of freshening. Then develop an action plan to reduce the level of SCC in future first lactation heifers. Lower SCCs in first lactation heifers could be a partial answer to a lower SCC for the whole herd.

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