Moy Park has confirmed selling part of its McLarnon Feeds business to John Thompson and Sons Ltd for an undisclosed sum.
Belfast-based Thompsons - part of the W&A Barnett Group of companies and already Ireland's biggest animal feed manufacturer - now owns the ruminant feed part of McLarnons.
McLarnons produces meal for beef, sheep and cattle from its base in Randalstown, Co Antrim.
Poultry giant Moy Park said the deal - first revealed in Business Telegraph last week -would allow it to focus on making chicken feed at its mill in Randalstown.
Thompsons now owns the McLarnon name - a familiar brand in the agricultural sector.
The value of the deal has not been disclosed, but it is thought to be worth around £500,000.
Moy Park director of agriculture, Alan Gibson, said: "Moy Park has undergone significant growth over the past two years and we are now processing over five million fresh chickens per week throughout the UK.
"Now is the right time to optimise our own mill capacity in support of our business and this will also enable a £1.2m investment to be made in 2016."
Declan Billington, chief executive of Thompsons, added: "Given Moy Park's focus on poultry expansion, and our long-term relationship with them, it seemed only natural that we would come together to support the growth prospects of the McLarnon ruminant business.
"The business will continue to trade its own unique brand and range of products and services with which the McLarnon customer base is comfortable.
"We view this as a complementary business to our own, and we also believe that this acquisition will enable us to support the future growth ambitions of the McLarnon sales team."
Thompsons was founded in the 1880s and has grown through investment and acquisition to become one of the largest single-site feed mills in Europe. It also sells and distributes fertilisers.
Its roots go back to a family company based in a townland outside Ahoghill in 1870, though it was taken over by W&R Barnett in 1963, and is now run by Barnetts in a joint venture with Origin Enterprises.
Economist John Simpson described the purchase of McLarnon's by Thompsons as evidence of "further consolidation in the farm feeds sector".
In Thompsons latest results for the year ending July 31, 2015, company turnover was £213.2m - down 8.9%.
Pre-tax profits were steady at £4.65m, compared to £4.72m a year earlier.
A strategic report by the company's directors filed with the results insisted that the sales fall was "a result of both lower commodity prices and lower sales volumes". The report added: "In a challenging agricultural environment, the company is constantly striving to maintain its position through an ongoing focus on customer service and product innovation (including participation in a number of local research and development initiatives) and a continuous appraisal of production and other processes."
The McLarnon deal is the latest in a series of acquisitions for W&R Barnett.
Back in November the company acquired a majority share in the packaging firm Logson Group.