In a statement yesterday, the co-operative's board said it had requested Hewett step back into the co-op chairman's role to bridge that transition period.
He would continue as co-chairman of Silver Fern Farms Ltd.
Hewett thanked Young for his "significant contribution" over the past two years.
Listen to Jamie Mackay interview Rob Hewett on The Country below:
"Over that time, he has led the development and establishment of a clear vision and purpose for the co-operative, which ensures we continually work cohesively with our investment in Silver Fern Farms Ltd, but also ensuring the voice of our farmer shareholders is heard," he said.
Over the next three years, there would be "significant managed transformation" in the board composition as several farmer-elected directors, including Hewett, came to the end of their maximum terms as allowed in the constitution.
"While the constitution does allow for term extensions on a case-by-case basis for directors who have reached their maximum term, it is the clear intention of the co-operative board to manage succession proactively," Hewett said.
The board was very focused on the importance of developing the next generation of governors.
That had led to the establishment of the To the Core governance programme, along with scholarships to support shareholders to develop their personal governance development plans.
Hewett said he was particularly pleased with the high calibre and good number of candidates who put themselves forward for a place in the recent farmer director election.
"I have real confidence that our governance future is strong when we see committed people like this put themselves through the election process for the opportunity to serve their fellow shareholders," he said.
Gabrielle Thompson, a board-appointed farmer director on the co-operative, was elected to the board last week as a farmer director.
The appointment of Thompson freed up a board-appointed director role which the co-operative board would seek to fill later this year, Hewett said.
