Dramatic drop in high cell count herds, NMR study reveals

The latest key performance indicator (KPI) report of a cross-section of 500 NMR recorded herds shows a significant reduction in the proportion of herds keeping high numbers of cows with chronic high somatic cell counts (SCC).

A chronic cow is defined as one with two or more consecutive SCC recordings more than 200,000 cells/ml, while a chronic herd has more than 15% of milk samples originating from these chronic cows, says report co-author James Hanks.

See also: Selective antibiotics use cut cell counts

The latest report, now in its seventh year, shows 18% of the 500-herd sample were chronic herds. This is a significant improvement since the first report was published in 2010 where 40% were chronic herds.

“Even more encouraging is 51% of herds are now keeping fewer than 10% chronic cows.

“This is more than twice the number of herds with low chronic cow levels than we recorded in 2010.

“And it is good news, because low levels of chronic cows are strongly linked to low herd somatic cell counts,” he says.  

The annual report also analyses health, fertility and production parameters from the cross section of black-and-white NMR recording herds.

The 2016 report shows that the median, or mid-point, SCC for the surveyed herds is now 185,000 cells/ml, down from 210,000 cells/ml in 2010.

“Perhaps most important is the reduction in the level of high SCC herds. In 2016, 75% of herds have a herd SCC below 227,000 cells, compared with 61% in 2010.”

New mastitis benchmarks

The increase in herds keeping accurate mastitis records has enabled four new mastitis parameters to be included in the 2016 report.

“We now have detailed information on mastitis cases from more than 50% of the study herds so we have included data on mastitis rates and the percentage of cows dried off with no mastitis cases. These trends will now be monitored,” adds Dr Hanks.

“The 2016 report shows the median number of cases of mastitis was 36 per 100 cows per year, while the top 25% recorded 21 cases/100 cows or less.

“At drying off, 79% of cows in the median herd had recorded no mastitis cases in the lactation compared with 87% of cows in the top 25% of herds.

“The increase in mastitis recording is very encouraging,” says Dr Hanks.

“Good information puts producers and their advisers in a far better position for managing mastitis and udder health, and in reduced use of antibiotics.”

Fertility interest

An increase in calving to first service of two days and a 2% increase in the percentage of cows eligible for service that conceived suggests that heat detection is improving on farms.

“Improvements in these parameters are being seen year on year,” adds Dr Hanks.

“The percentage of cows re-served 18 to 24 days after a previous service has improved again.

“These parameters contribute to improvements in calving interval.

“The median has dropped by three days to 407 days in the past 12 months to August 2015 with the top 25% of herds now achieving calving intervals of 393 days or less.

“Particularly important, in view of its impact on herd efficiency, is the improvement in lifetime daily yield.

“This has increased from 10.5kg/day in 2010 to 12.2 kg/day in 2016, and by 0.3kg/cow/day in the past 12 months.

“The current target, set by the top 25% of herds, is 14.1kg/day.

“Producers can use this information to see where the strengths and weaknesses are and where they can make improvements that will help to improve their efficiency in a cost-effective way,” adds Dr Hanks.