4 ways to further improve herd fertility

Many farmers could make big improvements to the fertility of their herds by paying greater attention to dry cow management, stable nutrition and routine vet visits.

According to vet Graeme McPherson of Synergy Farm Health, the industry has made huge gains in fertility performance over the past 20 years.

He puts this down to wider uptake of automated heat detection systems, breeding for fertility – thanks to the introduction of the Fertility Index in 2005 – improvements in farm infrastructure and better nutrition.

See also: 4 tips to optimise dairy cow fertility

However, data from 500 National Milk Records (NMR)-recorded herds suggests there is still room for improvement on many farms (see Fertility performance panel below).

Mr McPherson suggests four key areas farmers should focus on to boost fertility.

1. Dry cow management

Dry cows are the most important group on the farm. Maximise dry matter intakes pre-calving by providing a bespoke, palatable diet and enough feed and water space.

Achieving good intakes prior to calving will set cows up to eat well post-calving. This will limit metabolic disease and loss of body condition score which could otherwise adversely affect fertility.

Provide 90cm of feed space a cow in the 30 days before calving and at least 10cm of water trough space.

2. Good stable nutrition in the milking cows

Consistency of feeding is essential for good fertility. Wherever possible, avoid making changes to the diet, as it takes about 10 days for the rumen to adjust to any dietary alterations.

Stress should also be limited, so handle animals quietly.

3. Excellent record keeping

Recording service is a “no-brainer”, but all heats should be recorded, even if a cow isn’t eligible for service.

For example, if a cow bulls at 35 days and the voluntary waiting period (VWP) is 50 days, recording this information allows for predictions to be made as to when she will come bulling again.

Monitoring body condition score (BCS) at calving, the end of the VWP, mid-lactation and drying-off allows for changes to be tracked.

A cow that loses more than half a BCS after calving is less likely to get pregnant.

This is not just about condition loss, but the speed of that loss, as this will compromise egg quality and delay resumption of cycling.

Fat cows are more likely to lose condition; ensuring all cows are at BCS 2.75-3.25 will reduce the risk of weight loss.

4. Routine vet visits

One of the pillars of good fertility is pregnancy diagnosis (PD). Early PD will allow quick identification of any cows that are not in-calf so they can be flagged up as needing to be served again.

Any cow that has not been seen bulling within a certain number of days, depending on the farm, may need to be presented to the vet for checking.

This could be, for example, any cow not seen bulling 21 days after the VWP.

Fertility performance

vet pregnancy testing cow

© Tim Scrivener

Results from a University of Reading herd performance study of 500 Holstein/Friesian NMR-recorded herds for the year to August 2020, showed:

400 days
Median (middle herd) calving intervals in 2020. This has remained at a similar level since 2018, following a steady reduction from 424 days in 2010

Median conception rate in 2020, unchanged since 2018

29% or less
Conception rate of one herd in four

+ Heat detection rate has steadily improved since 2010

Median submission rate – a 13% increase compared to 27% in 2010, but only a 2% improvement on the 2016 rate

Median pregnancy rate in 2020, an increase from 9% in 2010, but relatively unchanged since 2017


Although performance targets should be farm specific, vet Graeme McPherson suggests the following:

All-year-round calving herds:

  • >25% pregnancy rate
  • >40% conception rate
  • >65% submission rate
  • <400-day calving interval (ideally 385 days in a Holstein herd)

Block-calving herds:

  • 30-40% pregnancy rate
  • 365-day calving interval

Case study: Mark Larwood, Oak House Farm, Larling, Norfolk

Mark Larwood with cows

© Tim Scrivener

Farm Facts

  • 250ha (617 acres)
  • 250 Holsteins calving all year round with strong autumn bias
  • 10,450 litres a cow a year at 4.3% fat and 3.32% protein
  • Milked twice a day
  • 70% calve August to Christmas with all replacements (75) taken in this period
  • Heifers and first and second calvers served twice to sexed semen; the rest served to Limousin
  • Heifers served twice to sexed semen and then Aberdeen Angus

Fertility performance at Oak House Farm for 12 months ending October 2021


  • 31.5% pregnancy rate
  • 69% submission rate
  • 45% conception rate
  • 57% 100 day in-calf rate
  • 1.81 services/conception
  • 374 days calving interval


  • 47% pregnancy rate
  • 1.56 services/conception

Good teamwork is one reason for average pregnancy rates of 31.5% and a 100 day in-calf rate of 57% at Mark Larwood’s dairy farm.

The Farmers Weekly Dairy Farmer of the Year 2021 cites four further factors helping the fertility performance of his herd.

Automated heat detection

Mr Larwood believes the use of automated heat detection on cows and heifers has been “crucial” in achieving high levels of performance.

Cows have automated heat detection collars with rumination sensors, while heifers have heat detection ear tags. This has taken pressure off staff who previously had to observe cows for two hours a day.

“There’s no doubt performance has improved. Our pregnancy rate has lifted, and particularly on the heifers,” he says.

Prior to installation, heifers were achieving conception rates of 57%. This increased to 68% in 2020 after the system was up and running. Mr Larwood says this is because each animal they serve is definitely bulling.

Transition cow management

“I believe it’s possible to get good fertility in high-yielding cows, it’s just about consistency day to day, and, if you’ve got a bottleneck in your system, sorting that out. For us that was our transition cow shed,” he says.

Consequently, in the autumn of 2020 he invested in a new, more spacious transition cow building.

Lying space has increased from 6sq m a cow in the old shed to 11sq m a cow in the new one. Feed space has risen by about 10%, helping dry matter intakes.

As a result, the level of retained foetal membranes has dropped from 11% to 5% and just 1% of animals get milk fever.

“If those cows are clean and cycling well, they’ll get in-calf,” says Mr Larwood, who feeds transition cows a consistent partial dietary cation anion balance (DCAB) diet.

This helps transition cows mobilise calcium and reduces the risk of milk fever.

Any cows that show a drop in rumination rates, and therefore a drop in DM intake, post-calving will also have their temperature checked daily.

Vet checks

The farm has a voluntary waiting period (VWP) of 45 days. Any cow not seen bulling or served by 60-67 days after calving will be presented to the vet for checking or enrolment onto hormonal synchronisation.

About 10-15% of cows go onto hormonal protocol OvSynch. The farm also runs a weekly pregnancy diagnosis session.

Health status

The closed herd has accredited bovine viral diarrhoea-free status. It is also free of infectious bovine rhinotracheitis and leptospirosis and has no cows with Johne’s disease.

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