High-fertility semen is as key to achieving top pregnancy rates, and improving profit, for one Devon-based 12,000-litre-average herd.

When Tom Dibble returned to help manage his family’s dairy unit, he was determined to build on the success of the business. And, supported by his parents, Steve and Ali, in four years he increased cow numbers from 240 to 930, managed on only 105 hectares. Based near Tiverton in Devon, efficiency became the family’s watchword, with every management practice assessed for its effect on the business’ bottom line.

An intensive management course in the US in 2014 was a pivotal moment for Tom, reinforcing his determination to give every pregnancy a high value and instilling in him a strong desire to achieve a pregnancy rate of 30%.

Working with Alta UK’s adviser George Murphy, the family set about achieving this goal. Their plan was to improve heat detection and increase conception rates by using the latest technology and designated high-fertility semen.

And, for the past 12 months, the dairying team has consistently hit Tom’s 30% target, dwarfing the UK’s national average that’s below 20%. This is all the more remarkable in the context of production, which has levelled out at 12,000 litres, at 4.10% fat and 3.36% protein, from a herd that’s milked three times a day and comprises 860 Holstein and 70 Jersey cows.

More impressive still is the fact that, in October 2020, sexed semen was introduced and reproductive performance has continued to excel.


Maiden heifers

“We first trialled it on maiden heifers, in November 2019, and were happy with the results. They were similar to those seen with conventional semen,” says Tom. Sexed semen is now used for all maiden heifers and mature cows of any age, providing they’ve had no health interventions.

Key to the herd’s pregnancy-rate success has been selecting bulls that are branded CONCEPT PLUS. This means the semen has been rigorously tested for its fertility. “This is done in the laboratory and on-farm, and is constantly updated because bulls’ semen can change over time,” explains George. “The semen is ranked from one to five star, and we will only use four or five star on the Dibbles’ herd.

“We can’t afford to take risks with overall conception rates and heifer inventory,” says Tom. “I used to chase the most recent high-genetic-merit sires, but we learnt from experience this could come at a cost. These bulls were too young to have their own fertility record and, on one occasion, we had some heavy losses.”

He now uses CONCEPT PLUS for every insemination, confident of a high value pregnancy in every cow. Those not bred to sexed will be put to beef, once the team knows that 42 dairy heifers have been conceived every month.

All bulls are now supplied by Alta to fulfil the herd’s breeding objectives, which include a high US Net Merit (NM$) and good health, as well as robust conformation without too much stature. “I’m interested in pedigrees, but now we want cows that look after themselves and put milk in the tank. Our priority is to keep the farm financially sound,” he says.

Using DIY AI, Tom says training is imperative and he joins herdsman Ghita Stanciu, who carries out most inseminations, on a refresher course every six months.

Outstanding heat detection is also key to hitting targets and this is achieved with Alta’s COW WATCH monitors. Recording rumination feeding and activity, it provides a reliable early warning of health events and heat detection. “To help produce the most feed-efficient milk, we need to keep the herd full of the freshest cows possible,” adds Tom. “Our aim is to hold the cost of purchased concentrates below 8ppl and we find a 30% pregnancy rate helps keep us on track.”


Boycott Farm Facts

  • 930-cow herd, managed on 105 hectares
  • 12,000 litres, at 4.10% fat and 3.36% protein
  • Alta CONCEPT PLUS semen used for sire fertility
  • 30% pregnancy rate achieved during past 12 months
  • COW WATCH monitors activity, rumination, feeding


Written by: Ann Hardy