Each spring the farm was provided with 100 straws of semen from about 10 new, young unproven bulls.
"We could use the straws to inseminate any cow," said Willis, who is also a trained artificial insemination technician.
"I enjoyed being part of the programme because it helps highlight the best bulls for the industry."
The 2019-20 season was Jessica's first year milking the first progeny testing daughters born on the farm.
The herd was milked twice a day from the start of calving until dry off. Photo / Supplied
"There were some really good heifers in the group," she said.
She preferred the heifers born as the result of nominated matings. The business started using overseas genetics from World Wide Sires two years ago.
It also sourced semen from other bulls through CRV Ambreed.
Jessica and Alan had a goal of breeding capacious cows with strong udders and high milk production.
The sires they used included Waihou Thadius Murphy S3F, Lornlace Rupert Dunstan, Maire Mint Geronimo, HSS Mint Rivington, Oakura Oman Overdrive and HSS Format Pascal-ET.
"They produced beautiful daughters, with good, well-attached udders," she said.
Being a sire proving herd meant all two-year-olds were scored for traits other than production (TOP) each spring.
Jessica Willis managed the 48-hectare farm for four seasons. Photo / Supplied
About 50 replacement heifer calves were reared each year. Any surplus heifers would end up at Alan and Sandie's Rotorua dairy farm.
It has been six months of change for Willis.
In mid-December last year, she married Andrew Willis, who is an agri-business banker with ANZ.
A month earlier they bought a house in Rotorua where Andrew lives.
Willis moved to the geyser city in late May, leaving behind the farm she had called home for the past four years.
"We're keen to start a family, and that's hard to do if we both lived in different parts of the Bay of Plenty," she said.
Willis is still undecided about her next career move, but as a proud member of Holstein Friesian NZ she aspires to one day own her own herd of Holstein Friesians.