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Fresh approach improves fertility performance (Oct 23)

Using fresh sexed semen requires concentrated and timely management, but one dairy business’ block-calved herds are reaping the rewards, and they’re set to use more in the future.


TEXT JULIETTE MCDANIEL



Switching from conventional to fresh sexed semen has helped a Leicestershire-based dairy business to tighten the calving pattern and improve conception rates in its two dairy herds.


George Wade milks 380 cows on an autumn-block calving grazing system, near Lutterworth, and his brother Ben milks 360 cows on a nearby unit. Both brothers work alongside their father, Martin, as well as eight staff, across both units. The main 200-hectare unit is a 40-year farm business tenancy (FBT), with a further 285 hectares acres in surrounding villages on another FBT.


George’s Honeypot Farm-based herd supplies milk, on a liquid milk contract, to Tesco Müller, and the herd managed by Ben, at Oak Tree Farm, sells to Long Clawson Dairy for cheese and focuses on components. The two units also have different feeding strategies. George’s milking herd is grazed between March and October, while Ben’s herd is fed ad-lib silage.


There are 200 followers on each unit, split into two separate groups of younger R1 heifers and older R2s. With a target age at first calving of between 23 and 24 months old, AI begins in November and the aim is for the autumn-calving period to start in early September. Previously using conventional dairy semen on the heifers across both herds, George and Ben were looking to tighten the calving pattern by achieving greater conception rates at first service. In Autumn 2021, with help from Cogent’s Ryan Archer, they used Cogent’s 4M fresh sexed dairy semen on maiden heifers for the first time.


For logistical and productive benefits, Ryan recommended using a controlled internal drug release (CIDR) synchronisation programme when using fresh sexed semen. Heifers should be the highest genetic merit cattle in the herd – and the most fertile.


One insemination


“So, paired with a CIDR synchronisation programme, only one insemination is required, compared to double insemination with other methods. And this reduces costs and handling,” says Ryan.


“This protocol allows for fixed-time insemination, and ensures that on the day of insemination all heifers are caught at the optimum point in their cycle. This pulls heifers to the front of the calving block to achieve additional days in milk and keep them as a collective and manageable herd,” he adds.


Cogent’s 4M fresh sexed semen straws contain four million female sperm cells. The semen is collected in the morning and then sent to the in-house laboratory for processing. Straws are then packed in tubes in sets of 15, with each tube in its own insulated pouch, and placed in an insulated box with internal and external thermometer and monitor alarm.


Fresh straws: semen needs to be used within 48 hours of delivery


Delivered direct


“Fresh semen needs to be used within 48 hours after leaving the laboratory, so is delivered direct to clients by the Cogent team, to ensure it’s delivered on time and in the best condition. It also allows technicians to assist with insemination, if required,” adds Ryan.


Once on farm, fresh semen is actually less fragile than its frozen counterpart. With no need for thawing, and a wider temperature range, it has better ease of use with more viable sperm cells. It is estimated that fresh sexed is, on average 10% more fertile than frozen.


After a successful calving period in September 2022, George and Ben served 200 14-month old heifers in November 2022 following a five-day CIDR synchronisation programme. The heifers were served with Cogent Ultraplus fresh semen, which was launched in 2022 and offers a further 3% lift in conception rates compared to the previous 4M used the year before. They achieved a conception rate of 68% to first service. Any heifers seen returning to heat for the first three weeks following the synchronisation were served again, which resulted in a three-week in-calf rate of 80% after two services.


Across the heifers and cows on both units, the brothers aim to produce around 200 heifer replacements each year. Following the three-to-four-week period of service to dairy sires, any remaining open heifers are put to an Aberdeen-Angus bull.


"We have easily achieved this target, which is a nice problem to have,” says George. “We’re four weeks into a 12-week calving period, and already have 250 heifer calves. And 80% of heifers put to fresh sexed semen have Fresh straws: semen needs to be used within 48 hours of delivery calved and they’re all heifer calves on both units. “When using fresh sexed semen, there are certainly many things to consider, and it doesn’t come without its challenges,” he adds.


“Using this semen requires additional planning and the logistics of getting it on farm can be difficult to execute within the 48-hour period. Everything happens at once, so the workload is extremely heavy in a concentrated period. Time and cost of syncing, which certainly makes the process more effective, should also be considered,” he says. “But when it comes to the fertility of the fresh sexed semen, I’m really impressed. Our conception rates are good and we’ve achieved tight calving patterns, which is what we were looking for when we made the switch from conventional.”


The herds comprise Holstein British Friesian crosses and Irish Holsteins, predominantly derived from Irish genetics. George aims to breed a 600-kilogramme cow that produces an average yield of 8,000 litres per lactation.


Sire selection


When selecting sires, he uses the Irish Economic Breeding Index (EBI) and focuses on moderate stature, high milk production, a positive fertility index, good feet and legs, and robust conformation.


Ben’s herd, supplying milk to Long Clawson Dairy, is starting to differ on genetic selection compared to the cows on George’s unit, choosing higher protein sires for cheese production. That said, George also selects for components because he believes they will become more important in future.


And when it comes to conventional semen, the brothers have decided to make the switch across both herds, opting to also use sexed dairy semen for the cows this year. “More recently, we’ve been using some of the leftover fresh sexed semen on the cows. Now that we’ve built up our trust in it, and calved plenty of heifer calves, we’re planning to move in this direction,” says George.


“We’ll try frozen sexed semen though because syncing that many animals all at one time may be one challenge too far. And, if that proves to be a success, we’ll look to use sexed beef semen too. But we’re taking one thing at a time.”

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