Mr Gent had been a voice for Northland dairy farmers on the Fonterra board.
"If we lose this [election] opportunity, Northland will lose its voice," Mr Guest said.
"With its 10 per cent stake in the industry, Northland needs a voice on a board which could otherwise be a Waikato-Southland club inclined to forget about the milk supply north of the Auckland Harbour Bridge."
Voting closes at 10.30am on Tuesday and results will be announced later that day via media release and on Fencepost.
Ken Hames, 47, runs 800 bulls and dairy heifers on 364ha at Paparoa. He and his veterinarian wife Janine also have equity partnerships in dairy farms at Wellsford and Tomarata, one 207ha, the other 156, with staff milking 900 cows.
Mr Hames is a director of Northpower and of Australia's West Coast Energy. He has toured dairy markets in the US, Europe, China and Japan on an Agmardt scholarship, and taken part in a Fonterra governance development programme, which included a study tour of Brazil and Chile with Fonterra directors.
Greg Gent, 54, began his career working for the Bank of New Zealand in 1972. Five years later he moved into dairying with 700 cows on the Ruawai property previously farmed by his parents, and he now has four farms with 1000 cows.
Mr Gent became chairman of the Northland Co-operative Dairy Company in 1993, led its amalgamation with Kiwi Dairies in 1999, and was deputy chairman of Fonterra from the formation of the co-operative until that position was disestablished nine years ago.
Mr Gent is chairman of FMG Insurance and a director of Equestrian Sports NZ, Agri Private Capital Fund and Rugby World Cup (Northland).
He also has a ministerial appointment as a member of the Northland District Health Board and was recently appointed chairman of the Northland section of the Bank of New Zealand's new regional structure.