Predicting intramammary infection in late-lactation cows
Over-use of antibiotics is linked with the development of antimicrobial resistance. To reduce this risk, the EU introduced a regulation that means dry cow antibiotics can only being used on cows that demonstrably have an intramammary infection, Clare Clabby tells us more.
Cows that are not infected should only be treated with an internal teat sealant. Typically, cows with a SCC less than 200,000 cells/ml are considered not infected. Teagasc, in conjunction with Kerry Agribusiness, conducted a study in 21 spring-calving dairy herds (2,074 cows) with a monthly bulk tank SCC of less than 200,000 cells/ml to predict infection in late lactation.
Quarter-level milk samples were collected from all cows in late lactation (more than 240 days in milk) for bacteriological culturing. If samples had bacterial growth, a cow was defined as infected. Test-day SCC data was used to determine the ability of the average, maximum and last test-day SCC to predict infection.
The last test-day SCC (37 to 64 days before dry-off) was the best predictor of infection. The cut-off-point for last test-day SCC which maximised sensitivity and specificity to identify cows without infection was 64,975 cells/ml. The inclusions of lactation, milk yield at last test-day and the number test-days greater than 200,000 cells/ ml did not improve the ability of last test-day SCC to predict infection. This study indicates that in Irish low SCC, seasonal pasture-based dairy herds, the last test-day SCC (37 to 64 days before dry-off) is the best predictor of intramammary infection in late lactation.
Moorepark Dairy Open Day
More information on this work will be outlined at the Moorepark Dairy Open Day, which takes place on Tuesday, July 4th. This year’s event will feature the One Health, One Welfare Village, where cow and calf nutrition, health and welfare will be discussed. Herd health, milk recording and mastitis control will also feature. For more information on the activities of the Moorepark Dairy Open Day, click here.
This article was adapted from the May/June issue of Today’s Farm.