Farmers are being urged to consider delaying pre-lamb shearing this winter as feed resources in many parts of the country are already stretched.
He will also have the role of CEO of the New Zealand Meat Board.
Beef + Lamb New Zealand chairman James Parsons says McIvor is an experienced CEO who brings a range of strategic thinking and management experience to support both organisations' work for sheep and beef farmers, and the broader sector.
McIvor is currently the group general manager farm operations at Ospri and he has held the roles of CEO Preston Corp Ltd and CEO of New Zealand Pork.
His primary industry career has spanned on-farm activity through to processing and retail. This included Beef + Lamb New Zealand's predecessor organisation Meat & Wool New Zealand as the research and development manager and product and information transfer manager.
McIvor will replace current CEO Dr Scott Champion on April 1. Champion leaves the organisation following seven and a half years as CEO of Beef + Lamb New Zealand and the New Zealand Meat Board.