Milk test streamlines fertility management

With kind consent from NMR – Article published from @CowManagement in Oct 2021, written by Karen Wright.

Using a milk-sample test to confirm pregnancy is proving highly accurate, and it’s also helping to improve fertility management on one large-scale Somerset-based dairy unit.

Running an all-year-round calving herd of 750 high-yielding Holstein Friesians means there’s not much slack in the system. So when herd manager Matt Hilton sees a reliable way of out-sourcing vital services, which is cow friendly, cost-effective and saves time, then he’s keen to try it.

One service that’s ticking all these boxes at the Bridgwater-based unit is a pregnancy test that identifies pregnancy-associated glycoproteins (PAGs) in a milk sample. PAGs are produced by the placenta, so are specific to pregnancy.

Matt and his team have been using this test on cows at around 30 days and then around 70 days after insemination since May 2021, as part of a trial run by NMR and veterinary diagnostics company IDEXX Laboratories, which developed the test.

Milk samples

Milk samples are taken from selected cows every two weeks, as part of routine four-weekly recording or by milking staff. In both cases, samples are collected and delivered to NMR’s lab with results sent back, via the UNIFORM system, within three days.

The herd, which averages 12,000kg of milk at 3.88% fat and 3.25% protein, is milked three times a day through a 60-point rotary parlour. High-yielding and mid-lactation cows are housed in groups, and low yielders and dry cows graze during summer.

Housed cows are fed a TMR, based on grass and maize silage, with compound fed to yield through the parlour. Heat-detection eartags are used – another aid to fertility, which Matt finds accurate and efficient, and helps spread the workload. Cows are served after a 60-day voluntary waiting period.

The herd has grown organically, using home-bred replacements. Heifers and the top 20% of cows are served twice with sexed semen before a beef bull is used, and the rest of the cows are bred to beef. Dairy sires with high health and longevity scores are selected to improve herd efficiency.

Matt says pregnancy testing used to be the vet’s job. “We’d have about 40 cows to test each week. But, with help from Sally Wilson from Evolution Farm Vets, we brought this inhouse in 2018.” Sally runs DEFRA-approved scanning courses for producers. She trained assistant Steve Pike and Matt, and sourced a scanning machine for them.

Pregnancy checks

“Steve, who carries out most of the fertility work, has been scanning cows for three years, and we’re now proficient and getting good results,” adds Matt. “Any cows not in calf are synchronised, re-inseminated and then re-checked.”

Having run the two pregnancy checks – scanning and the PAG tests – side-by-side for the past six months, Matt says the milk test is at least as reliable and as accurate as the ultrasound check. And the big advantage with the milk test is that cows don’t have to be separated and held back after milking.

The herd has routinely used PAG tests for checking pregnancy from 150 days to ensure non-pregnant cows are not dried off. “We’ll continue to do this,” adds Matt. “We find it 100% accurate and picking up just a few cows that are not in calf pays for this test. “As part of the trial we’re also adding a PAG test at 70 days post insemination, so we can identify cows where foetuses have been reabsorbed. This happens in about 6% of cows and picking them up straight away also makes commercial sense.”

Results, so far, are in line with expectations, with a 90% accuracy at 30 days after insemination. “If this continues, I will consider replacing some scanning with the PAG test, which is much less time-consuming and far less hassle.

The herd’s calving interval is 384 days, with a 37% conception rate, 52% of cows are in calf by 100 days, and the pregnancy rate is 27%.

“There will always be a place for scanning – for identifying cows with twins for example – but I think we will be relying more on PAG tests for checking pregnancies, and definitely for a re-check 70 days after insemination, and at drying off.”

Matt also believes the milk test is relatively cheap, costing around £3.50 a test. “And we’re able to use the vet for more consultancy advice, to review data and identify problems so we keep on track, which is beneficial to the herd’s progress.

Sally Wilson is fully supportive of this move and admits herds of this size, which have invested heavily in new technology and where staffing is paramount, need to implement time-efficient and cost-effective protocols, which don’t compromise quality.

“PAG testing is an additional tool to keep things running smoothly and save time for the farm team while keeping the data complete and accurate,” she says. “There’s always a place for scanning though, and cows testing negative should still be checked by the vet. I will check a group of ‘problem’ cows as and when required – typically once every six weeks – to ensure they are fit to go on a synchronisation programme.

“And since the team took on their own scanning and are now using PAG tests, and out-sourcing other services as required, there’s more time for improved recording, such as the AHDB QuarterPRO plan for mastitis management, which will promote herd health and performance further.”

Matt and his team now meet quarterly with Sally to analyse herd health and fertility data. “Sally’s input in helping us improve cow health and meet the evolving standards required by our buyer, Muller, is invaluable. We’re making best use of our time, and of her time, while improving herd performance.”