Heat detection and SCC are key to improvements

Heat detection rates and somatic cell counts are two areas where UK dairy herds can make big improvements to overall performance, according to University of Reading researcher, James Hanks.

Commenting on analysis of 500 NMR recorded herds, representing a cross-section of UK black and white herds, he says the variation between the top and bottom performing farms, particularly for these two parameters, is both frightening and encouraging.

The study looked at the variation in herd performance for 25 parameters, covering production, fertility and health. Data from the randomly selected farms – which provide good representation of the national herd – is used in NMR’s InterHerd+ dairy management program as a benchmark for other producers.

A target for each parameter is set at a realistic level and reflects what one in four of the herds sampled are already achieving, says Dr Hanks.

“A lot of farmers, who are in the middle in terms of performance, think this is OK, but they need to challenge themselves. By doing so they have the opportunity to maximise efficiencies.”


Heat detection was a key area of weakness flagged up by the recorded herds. This was demonstrated by a lower-than-desired percentage service interval at 18-24 days.

“When a cow is served, but fails to conceive, you would assume she will come back cycling after 21 days. This figure shows the percentage of these cows that are served at the next available opportunity,” explains Dr Hanks.

“One in four farmers is achieving more than 38% in this period, which is excellent. However, 25% of herds achieve less than 22%.”

Heat detection is an easy way to improve pregnancy rates, says vet Den Leonard, Lambert Leonard and May.

“However, many farmers focus on conception rates, miss oestrus detection and let the voluntary waiting period get too long.”

As yields increase, cows are less likely to express obvious signs of oestrus. This, coupled with an increasing number of cows for every person, means it is getting harder to spot bulling animals.

However, vet John Cook, of Genus ABS, stresses that when a cow is not healthy enough, she will be incapable of expressing heat.

“When a cow is not capable of expressing oestrus, you won’t see it. Heat is as much a psychological event as a physiological one. When cows are over stocked or housed on slippery flooring, she won’t express oestrus.”


The percentage of persistently high somatic cell count (SCC) cows was also worryingly high, with 25% of farms having more than 19% of cows repeat offending, says Dr Hanks.

“These chronic cows are very important. When a farm has less than 10% chronics, they are unlikely to have overall SCC problems.” And according to Dr Hanks, 57% of high SCC samples sent to NMR are from persistent offenders.

Persistent, high somatic cell count cows is an issue we see time and time again through our practice, says Mr Leonard.

“Farmers want to look at cows with the longest run of high somatic cell counts. However, these cows are already broken. The aim should be to stop them from emerging in the first place.”

Milking routine, surveillance and control are essential in preventing these cases, says Mr Cook.

The data also shows a significant portion of herds are being penalised for having SCC of more than 200,000 cells a ml, says Dr Hanks. “Twenty-five per cent of farms had SCC of more than 268 cells a ml. When you relate this to the national herd, it’s a huge number.”