While farmers would have expected milk output to fall by 8-10pc from peak by this time of the year, he said some farmers had seen yields drop by as much as 30pc.
"The ground is perished from all the rain. The air temperature is actually high but the ground is very cold," Mr Quain said.
"Good weather is the only thing that will offer redemption at this stage."
Mayo farmer John O'Donnell said that he had never experienced a June as bad as this year's.
Mr O'Donnell, who farms near Ballina, reckoned that 50pc of the silage locally had been cut, but the quality had been very poor.
He maintained that it would take a good period of drying before land was dry enough for farmers to be able to cut the remainder of the crop.
"A lot of damage has been done to fields where farmers have tried to get in to cut silage," Mr O'Donnell explained.
"The butt of crops is completely drenched at this stage."
John Robinson from Callen, Co Kilkenny, has his cows housed for the past two weeks and expects them to be kept in for at least another week.
He has no silage cut so far this year and has been working off stocks left over from last year's harvest and zero-grazed grass provided by a friend.
He said some farmers in the area were feeding up to 6kg of meal a day to cows to maintain milk output.
"The cost of re-housing and feeding cows wouldn't stop at €2/cow/day, which is around €1,400 a week for a man with a 100-cow herd," Mr Robinson estimated.
The situation has prompted the ICSA to call for an advance Single Farm Payment (SFP).
"The advance payment on October 16 has become a regular feature but it is important to remember that it is not guaranteed," said ICSA president, Gabriel Gilmartin.
"The Government has to present a strong case as to why funding should be released early to farmers. The hardship being caused by the poor weather at the moment cannot be ignored," he said.
Meanwhile, rainfall figures for June were almost double the 30-year average for the month before last Thursday's cloud burst struck the country.
The average June rainfall is around 65mm but more than 130mm had been recorded by most weather stations prior to last Thursday's downpour.
That dumped a further 40-50mm of rain on already saturated ground.
Met Eireann said that it was the wettest June on record for most of the country, with weather stations at Cork Airport, Casement Aerodrome in Dublin and Ballyhaise in Cavan all recording nearly three times the monthly average.
Soil temperatures and sunshine hours have suffered as a result, with less than 75pc of normal sunshine recorded everywhere except Belmullet in Mayo. Soil temperatures were up to 1°C below normal nationwide.