Sussex dairy farmer halves his calving block

Friday, 13 November 2020

Halving the calving block to just six weeks is no mean feat for an autumn-calving herd, but even more tricky for an organic one averaging 6,000 litres/cow.

With no hormonal intervention allowed – so heifers can’t be synchronised to front-end load the block – Sussex dairy farmer Dan Burdett had to come up with a comprehensive plan based on stockmanship and an eye for detail.

Within three years, he and the team at Cockhaise Farm had pushed one of his Key Performance Indicators (KPIs) off the scale and, since 2015, he has continued to follow his plan and maintain 95% of cows and heifers calved within the first six weeks. Dan, who runs 320 crossbreds on 304ha near Haywards Heath, believes the rewards are worth the effort and even without a full cost-benefit analysis, says benefits are tangible.

The benefits of a tighter calving block

He gets a full parlour shutdown for four weeks and an eight-week dry period for the cows. Calving outside from August 10th avoids terrible weather and there is ample recovery time between calving and serving, with plenty of opportunity for holidays for himself and the workforce. All of which keeps staff keen and motivated. Farm and parlour maintenance can be planned and done during shutdown, which helps avoid breakdowns and major repairs during busy periods. And breeding more fertile cows has resulted in more heifer replacements being born during the block each year.

“We had a 12-week calving block and hated it. Everyone was fed up by the end and beginning to lose focus and we had ‘forgotten’ cows, struggling to get back in calf. If we calve for a full 12 weeks, then we finish on 10th November and start breeding on the 17th and it’s not long enough recovery time to rest and get ready for mating,” Dan explains.

“Now, everyone gets some time off between the end of calving in mid-October and mid-November. Then it’s all about how we manage cows, from calving to mating and during the first six weeks of mating. It relies on attention to detail. It was – and still is – lots of small things: looking at every single aspect and throwing extra resource in. As the farm owner, for instance, it means finishing washing down the parlour or scraping out, so that staff can finish serving and you don’t have cows hanging around till 10am. Go the extra mile.”

Fertility is key to ensuring a tight calving block

With such a concentrated calving block, fertility really must be the number one driver. Having always calved in 12 weeks, Dan looked at what other successful farmers were doing to achieve six weeks, then used their experiences to formulate a strategy for change. “We started by serving a few days later each year, so that more cows in the block were eligible. It gave them an extra few days to recover from calving and start cycling again. They are now always calved 10-12 weeks before serving, so are fit, healthy and fertile, cycling well on day one of mating,” he says.  

Dan also put everyone trained in AI on a refresher course and bought a straw warmer – effectively a warm water bath that maintains a constant temperature to thaw semen straws correctly and maximise sperm motility. He asked his vet to give stock bulls a full health check (including assessing their semen viability) and test batches of semen straws. “Over seven years, we’ve tested four batches of straws a year and found one dud batch that had to be sent back. It would have been worse to find this out after three weeks of using it,” he says, adding that bulls are still tested annually, even if they’ve been on the farm for several years.

Trying to save money by splitting straws was given up in favour of making sure that every cow was given the correct dose of sperm: “It’s not worth trying to cut corners. One extra cow in-calf is worth £500 more alive and, in the block, than as an empty cull,” he stresses. Dan also introduced a policy to return to serving on standing heat only, ensuring that straws were going in at the right time: “Not when a cow winked at the herdsman or had a glint in her eye! We used to get a lot of that and had an uneven repeat rate which showed we were serving at the wrong time. It’s just wasting semen and time if a cow isn’t properly in heat.”

For heat detection, the herd is tail painted, with heat mount stickers used on Not Seen Bulling (NSB) cows. Observations are done four times a day for 30 minutes between 7am and 9.30pm and whenever anyone is working with stock. Three staff are trained in AI with two doing most of the work. “We serve AM and PM. Anything bulling from midday to midnight is served the following morning; anything from midnight to midday is served that afternoon. This eases the pressure on each serving session.”

To make sure cows are ready, pre-service vet checks start 28 days before planned start of mating. Even with detection aids, Dan finds that heats can be missed when cows are at grass but looking earlier does find NSB cows sooner. “We pick up cows that have had twins or retained cleansing to be seen early and vet visits are booked, so everyone knows the days and is organised.”  

Guide to improving fertility in block calving herds

Changes in diet supported good fertility

Diet always plays a big role in getting cows back in calf, but like many autumn calvers Dan has realised that changes at key times can affect fertility performance. He stopped feeding dry cows on silage about seven years ago. Instead, the ration comprises standing hay plus dry cow rolls. Although initially the rolls were thought too expensive, Dan found that cows were sorting the home-mix leaving the important dry-cow minerals aside. Incorporating them into a compound, however, means that they are eaten, and this has helped reduce the incidence of milk fever from 10% to 1%.

The herd is housed at the end of October, on good quality self-feed silage, plus cake in the parlour thus creating a rising plane of nutrition. This allows them to settle onto the winter routine at least three weeks before service. “If there is a late flush of grass, the temptation is to keep them out longer, but the difficulty is heat detecting and diet changes too close to serving” he adds.

Understanding dairy cow nutrition

Benchmarking is critical to success

A final, but important part of getting and keeping a tight block is regular benchmarking. Creating a bit of competition for those doing the AI, helps motivation. But it is equally important that the team knows all the figures and is congratulated when they are successful, he feels. “Yes, it’s a challenge to maintain a six-week block (we had a blip two years ago when the herdsman was ill) you can quickly get it wrong and lose the block if the first three weeks aren’t right. You can make a major blunder by taking your eye off the ball such as not testing semen or getting someone else to do the AI. You need to maintain that focus.”

Explore Cockhaise Farm's story and compare your performance

Key Performance Indicator (KPI) definition - Cows and heifers calved within the first 6 weeks %

This indicator is calculated by the number of cows and heifers calved in the first 6 weeks from the planned start of calving divided by the total number of cows and heifers due to calve timed by 100. This calculation provides the 6-week calving rate %

AHDB KPI benchmarks


Excellent performance (top 5%)

Good performance (top 25%)

Average performance

Cockhaise Farm 

Cows and heifers calved within the first 6 weeks (%)





Dan’s strategy for improving cows and heifers calved in the first six weeks

  • Delay planned start of mating by a few days to ensure cows get 10-12 weeks to recover and start cycling
  • Arrange early vet checks particularly for NSB cows essential
  • Use heat detection aids on NSB cows
  • Have four observation periods, 30 minutes each
  • Ask your vet to do full bull health and semen check and test batches of your semen straws
  • Ensure there are no changes to housing or diet 3 weeks before serving
  • Train your staff properly and do regular refreshers
  • Only serve on standing heat
  • Add resource to get routine jobs done so staff can AI cows
  • Ensure you benchmark and share data with your team

The key measures and targets for blocking calving herds

Compare your performance figures

Learn more about fertility in dairy cows